Do you have to worry about steam holes in the heads and the like with a Dart 400 block?

I am also trying to figure out whether 350 or 400 mains would be better for me. I prefer an internally balanced engine.

I am now planning my next blower engine for same car to build while I drive the current set up. I would go with a 3.8 or 3.875 crank for 406-414 displacement. I assume I need 6" rods and maybe a raised cam location for this? Scat or Eagle H-beams should do the trick.

I do worry about the closer bores with the bigger small block and the 12 pounds of boost I expect to have. Of course I will be using Cometic MLS gaskets as I do now.

I also wonder if I will need custom pistons to achieve about 7.8:1 static compression with 74cc chambers on the heads.

I am also planning a Lunati sledgehammer or Pro-series crank (no more Eagle cranks for me - I have already been bitten), the new AFR 195 heads with close to 300cfm intake flow! (or perhaps the 210's if I use the bigger 3.875 stroke), and a 236/248 @ 0.050" and .520/.540+lift billet hydraulic roller nitrous cam to keep peak rpm at 6000 rpm or just below. Do you think the odd-fire cams are worth it? - they claim a few extra horsepower. I want the stock exhaust and valve locations on the heads.

Informed opinions appreciated.

Do you have to worry about steam holes in the heads and the like with a Dart 400 block?

I am also trying to figure out whether 350 or 400 mains would be better for me. I prefer an internally balanced engine.

I am now planning my next blower engine for same car to build while I drive the current set up. I would go with a 3.8 or 3.875 crank for 406-414 displacement. I assume I need 6" rods and maybe a raised cam location for this? Scat or Eagle H-beams should do the trick.

I do worry about the closer bores with the bigger small block and the 12 pounds of boost I expect to have. Of course I will be using Cometic MLS gaskets as I do now.

I also wonder if I will need custom pistons to achieve about 7.8:1 static compression with 74cc chambers on the heads.

I am also planning a Lunati sledgehammer or Pro-series crank (no more Eagle cranks for me - I have already been bitten), the new AFR 195 heads with close to 300cfm intake flow! (or perhaps the 210's if I use the bigger 3.875 stroke), and a 236/248 @ 0.050" and .520/.540+lift billet hydraulic roller nitrous cam to keep peak rpm at 6000 rpm or just below. Do you think the odd-fire cams are worth it? - they claim a few extra horsepower. I want the stock exhaust and valve locations on the heads.

Informed opinions appreciated.The main size is personal preference.You,don't need a raised cam location.The jury is still out on the 4-7 swap.How did the Eagle crank bite you?

Well, here's my .02.

Since its a blower deal, don't worry about extra stroke. Stick with a 3.75 or maybe even a 3.625" crank. This will make it easier to find a piston. With a 3.75" crank you're gonna need ~35cc dish to hit your target compression. Shelf pistons are availabe around this size, but for a 5.7" rod. Finding a piston with that much dish to fit a 6" rod/3.75" stroke may be a custom piston, IF it's doable. Also, if you go the 5.7" rod/shelf piston route, plan on either external balancing or big $$$ for an internal balance job.

As far as rods, if you stay with a stroke 3.75" or below, the "typical" h-beam rod will clear. If you decide to stroke it, seriously look at the Lunati Pro-Mod or Pro-Billet rod. It has a more compact big end and gives more clearance all around.

I'm curious about the Eagle crank also.

Thanks - On the crank, engine was all built/ balanced/ and installed. Went to bolt up my new TKO trans and the stock pilot bearing just fell inside the hole for the bearing..the end of the crank was machined all wrong and I could not find a roller pilot bearing to fit it. An auto car may have missed this problem. I called Eagle and they denied the problem (which angered me more), but just happened to have some machined bronze pilot bearings to fit the mis-machined bore. I had to get the crank vendor involved and everything and it took me 3 months to resolve and ended with Eagle custom machining some roller bearings for me after Tremec advised me not to use a bronze bearing. At the same time, the machine shop had 2 eagle cranks in the corner they had to send back because the journals were so far off. I am satisfied with their rods, but not the cranks.

Yes-it is the 4-7 swap cam I was referring to.

No raised cam needed? so perhaps I also do not need the spread oil pan rails of the Iron Eagle block so I can re-use my Stef's oil pan?

By the way, I currently have 5.7: eagle H-beam rods. It would be nice to reuse them, but I understand I need a 6" rod with any stroke of 3.8" or larger.

Mike,
I will be watching this post closely. I have been planning my next engine as well (based on a dart block). The problem I see is getting the compression down. Small block heads just don't have big enough chambers for larger cubic inch engines (as far as blower engines go). I have been looking to see what kind of pistons are out there and I just don't see anything that will work. I would think going with a shorter rod would help that would leave more room for a dish. Let me know what you find out. I was leaning towards going with the largest cubic inch small block I could build and keep the compression in the 8.5:1 range.

As far as the swap cams, they typically show gains in large cubic inch engines 500+ cubic inches. I can't find the info on them right now but, I did research it and that was the "conclusion" from the people "in the know". Not worht the hassle on smaller engines.

Do you have to worry about steam holes in the heads and the like with a Dart 400 block?

I am also trying to figure out whether 350 or 400 mains would be better for me. I prefer an internally balanced engine.

I am now planning my next blower engine for same car to build while I drive the current set up. I would go with a 3.8 or 3.875 crank for 406-414 displacement. I assume I need 6" rods and maybe a raised cam location for this? Scat or Eagle H-beams should do the trick.

I do worry about the closer bores with the bigger small block and the 12 pounds of boost I expect to have. Of course I will be using Cometic MLS gaskets as I do now.

I also wonder if I will need custom pistons to achieve about 7.8:1 static compression with 74cc chambers on the heads.

I am also planning a Lunati sledgehammer or Pro-series crank (no more Eagle cranks for me - I have already been bitten), the new AFR 195 heads with close to 300cfm intake flow! (or perhaps the 210's if I use the bigger 3.875 stroke), and a 236/248 @ 0.050" and .520/.540+lift billet hydraulic roller nitrous cam to keep peak rpm at 6000 rpm or just below. Do you think the odd-fire cams are worth it? - they claim a few extra horsepower. I want the stock exhaust and valve locations on the heads.

Informed opinions appreciated.
=
You do not need steam holes with the Dart block, it does not have the "pockets" the stock block has but I always run the rear water returns from the intake.

While I prefer the 6" rod I would use a 5.585 rod for this so you can keep the rings down & get some dish with the std deck block.
At 3.75 you will be able to internal balance with a little work & a crank designed for a 6" rod.
You may need a pc of Tungsten, depends on what the weight ends up at.
You will need to machine the crank some for piston clearance.
I balanced one recently with 5.85 rods at 1800gm bobweight with no Tungsten.
This was a 3.750 stroke.
If I were doing a longer stroke I would go with the tall deck block.
It has the raised cam, spread pan rails & tons of room for a rod, pistons & rings.
You will need to spring for a new pan though.

Wolfplace,
What kind of pistons are out there for lower compression (blown) applications in a large bore small block? Even with 76cc heads you are going to need a pretty good dish to get the compression down to the 7.5:1 range.

i built a 415 with the dart block for a procharger, used the 3.85 stroke, had a custom ground hyd. roller-- used the lunati rods and crank(wasnt a great experience with them) i think your 195 heads are on the small side
i had a target of 9-1 comp, used ross pistons, had them coated, used a receiver groove in the heads-i ran over 20 lbs boost thru it
i had it int. bal., i think they had to do some work on the throws for that, thats what lunati said anyway, i guess thats why it took 3 months!!!!!
some of the turbo guys think 406 is the best bore/stroke combo, but lots of opinions out there(if i wasnt deep into my 489/f1r project, i would prob. go to a twin turbo, s/b-lol)

was the balancing the only problem with the Lunati crank?

there are different ways to achieve a 406, which one was it?. a 4.155 bore with a 3.75 stroke or a 4.125 bore with a 3.80 stroke?.. probably the former as it is easier/ cheaper.

Wolfplace,
What kind of pistons are out there for lower compression (blown) applications in a large bore small block? Even with 76cc heads you are going to need a pretty good dish to get the compression down to the 7.5:1 range. Why do you think you need a 7.5 to one compression? Are you going to run pump gas? This motor won't make a lot of power if your compression is too low. One Ford racer here started his race blower motor with 11-1 compression and it's pretty fast. It would seem to me if you want a big small block you'd want a raised block to make clearing all the internals easier.The block is only a few pounds heavier and everything clears much better with a 9.325" deck. All small blocks have build problems when you cram a long stroke crank in a block designed for a 3.5" one. A chevy racer here with a SB-2 has more power than he can put on the ground with a 368" motor and everything fits well.

My mate has just had an Eagle crank break. It was in a 474 Pontiac Engine with all of the best gear & only lasted a few months. The engine was constantly breaking crank pulleys & we could not work out why then one night there was a couple of clunks & it was turned off & pulled out of the car. When the sump was removed the crank was broken everywhere , the engine has not been completely pulled apart as of yet so not sure what else is stuffed but the engine was brand new , would have been lucky to clock up a couple of thousand miles & a couple of runs down the quarter. We have heard that Eagle used to make the cranks in the US but then they started getting them made in China & apparently there is quite a few guys having problems with them.

Not sure how to post photo's but have a look at the attached link

http://camaro-firebird.dyndns.org/viewtopic.php?t=96&start=15

My mate has just had an Eagle crank break. It was in a 474 Pontiac Engine with all of the best gear & only lasted a few months. The engine was constantly breaking crank pulleys & we could not work out why then one night there was a couple of clunks & it was turned off & pulled out of the car. When the sump was removed the crank was broken everywhere , the engine has not been completely pulled apart as of yet so not sure what else is stuffed but the engine was brand new , would have been lucky to clock up a couple of thousand miles & a couple of runs down the quarter. We have heard that Eagle used to make the cranks in the US but then they started getting them made in China & apparently there is quite a few guys having problems with them.
http://camaro-firebird.dyndns.org/viewtopic.php?t=96&start=15


Over the years we've done hundreds of "Blown" units in all configurations. Both SB's AND BB's. If they are destined for any "street" use whatsoever you want to stay in the 8.25 range, if it's a "race" unit you go the 7.5 number. This has been determined through much testing on these units that end up in either area.

One tip I can pass along here is make certain you choose the proper size blower for a specific size unit. Many customers decide they want some additional power after they've grown accustomed to the "new" one and figure they'll simply "turn up the blower", this doesn't fly, only creates more heat!
Thanks, Gary in N.Y.

P.S. As to "broken" parts, almost 100% of the time these parts on the market that are classified as "defective", usually by the "breakee", actually comes down to "customer oriented" issues. Don't care too much about the brands, I've personally had "Scat" rods break on the beam, I've had many issues with "Eagle" with respect to dimensions, and I've recently had both a
"Crower" AND a "Lunati" shaft that had to be "corrected". Both "Scat" and
"Eagle" are off-shore items, Chinese! Below is a shot from the another forum of a "Scat" crank. They've yet to figure out the cause. It's easier to blame the vendor. Doing this as long as we have, there's a second photo of the main bearing area I didn't include, this photo at least to me, leads me to believe why the crank "snapped". (Add) The main IS shown, I left the piston/rod out!

http://i16.photobucket.com/albums/b28/GOSFAST/PES%20Engines/th_ScatCrank-01.jpg (http://i16.photobucket.com/albums/b28/GOSFAST/PES%20Engines/ScatCrank-01.jpg)

Harold,

I know this site has many full racers, especially BBC race engines, but this is a street engine that sees the track a few times a year.. the choice of cam duration and carbs should be a give away. The motor is built to run on pump gas and I would go no further than 8.2:1 on compression for a big roots blown pump gas engine. Please note I currently have 7.6:1 and have run as high as 15 lbs of boost with 38 degrees total timing on pump gas w/o a hint of detonation. Right off idle, I do not miss any lost torque or throttle response from the lower compression, in fact I already have too much and desire to loose some low end torque. The lower compression allows me to run more boost when I do get on it, and it is said that boost is better than static compression within a reasonable limit.

Last time I went to the tracks, I spun the new MT ET Drags all the way to the 1,000' mark, so why the desire for a bigger engine? We all know that we share the same disease in this hobby, even if it defies logic. We are all trying to build what we think is the "perfect" engine. My blower will make 25+ pounds of boost, about double what I am running, and this is just like having a bigger engine with more torque and HP all thru the power band, but I can't do it on pump gas.

Many of my questions relate to CI size vs. cost and hassle. It would be nice if I could reuse many of the parts I already have on the 355. I am not going to miss much power between a blown 400 and a 414, but if I could do the 414 just as simply as the 400 w/o too much hassle, I would.

Wolfplace,
What kind of pistons are out there for lower compression (blown) applications in a large bore small block? Even with 76cc heads you are going to need a pretty good dish to get the compression down to the 7.5:1 range.
=
Pistons are not an issue, I can get anything you want made from a number of vendors & for this type of engine an extra $400 or so should not be an issue.
If it is you probably should not be building blower engines but you already knew that,,, :D

I did one recently that is a true street engine with shelf SRP 26cc dish piston & the 5.850 rod.
My preference would have been to use a custom reverse dome as I feel they are more efficient but this worked out quite well.
It was 8.1 with 72cc heads, .040 down & .040 gasket.
It runs just fine on pump gas at 10% under.
Just to add, this is a street rod engine not a race deal, about 600HP
If you wanted to "lean" on it I would suggest a blower specific piston.

Harold as Tokyo already cleared up he was shooting for 7.5:1 not myself. I run 8.47:1 currently with no issues on pump gas and 12lbs of boost. I was asking about pistons to see if there was anything out there to get him in that range with a large bore.

Wolfplace,
When time comes for a new short block $400 extra will not be an issue. Custom pistons are no big deal and not hard to get. I was just under the impression with the little research I did, that of course with a long rod you only have so much room for the reverse dome/dish. Even with a shorter rod you are still sweeping a lot of volume into a limited space. I personally prefer a "D" dish (maybe this is what you are calling a reverse dome?). Even with my stroker 3.75", and a 22cc "D" dish I had to open up my 72cc chambers to 75cc, to get down to 8.47:1. So with a larger bore and longer stroke, the dish is going to have to get pretty larger/deep to keep the compression blower friendly, correct?

OH, I just re-read your post, you used a .040 gasket and .040 in the hole. I know there are different schools of thoughts when it comes to quench and blowers. After lots of research I still think a good quench is needed when pushing the envelope with a blower on pump gas.

Harold as Tokyo already cleared up he was shooting for 7.5:1 not myself. I run 8.47:1 currently with no issues on pump gas and 12lbs of boost. I was asking about pistons to see if there was anything out there to get him in that range with a large bore.

Wolfplace,
When time comes for a new short block $400 extra will not be an issue. Custom pistons are no big deal and not hard to get. I was just under the impression with the little research I did, that of course with a long rod you only have so much room for the reverse dome/dish. Even with a shorter rod you are still sweeping a lot of volume into a limited space. I personally prefer a "D" dish (maybe this is what you are calling a reverse dome?). Even with my stroker 3.75", and a 22cc "D" dish I had to open up my 72cc chambers to 75cc, to get down to 8.47:1. So with a larger bore and longer stroke, the dish is going to have to get pretty larger/deep to keep the compression blower friendly, correct?

OH, I just re-read your post, you used a .040 gasket and .040 in the hole. I know there are different schools of thoughts when it comes to quench and blowers. After lots of research I still think a good quench is needed when pushing the envelope with a blower on pump gas.
-
Yep reverse dome, "D". "turbo piston",,,, all pretty much the same thing.
And I agree completely with a tight quench but this guy wanted to try this with his existing heads & it seems pretty happy so far.
But this thing definitely ain't "pushin the envelope" :D

Why do you think you need a 7.5 to one compression? Are you going to run pump gas? This motor won't make a lot of power if your compression is too low. One Ford racer here started his race blower motor with 11-1 compression and it's pretty fast. It would seem to me if you want a big small block you'd want a raised block to make clearing all the internals easier.The block is only a few pounds heavier and everything clears much better with a 9.325" deck. All small blocks have build problems when you cram a long stroke crank in a block designed for a 3.5" one. A chevy racer here with a SB-2 has more power than he can put on the ground with a 368" motor and everything fits well.

Hello!

Very interesting thread, especially for me since I'm leaning towards a turbocharged smallblock for my -72 Chevelle.

Anyway when I did some reasearch some time ago I found myself reading the tech pages on www.inductionmotorsports.com and there it's stated that 1 psi of increased boost equals 1 whole point of compression.

I reckon a blown or turbocharged v8 will have enough low end torque even if the compression is as low as 7,5 or even 7.0. If you're supposed to run an application with an 11:1 compression ratio you can forget about pump gas and start looking towards methanol or perhaps high octane race fuel if I have things pinned down somewhat correctly.

Regards Martin Öling.

Hello!

Very interesting thread, especially for me since I'm leaning towards a turbocharged smallblock for my -72 Chevelle.

Anyway when I did some reasearch some time ago I found myself reading the tech pages on www.inductionmotorsports.com and there it's stated that 1 psi of increased boost equals 1 whole point of compression.

I reckon a blown or turbocharged v8 will have enough low end torque even if the compression is as low as 7,5 or even 7.0. If you're supposed to run an application with an 11:1 compression ratio you can forget about pump gas and start looking towards methanol or perhaps high octane race fuel if I have things pinned down somewhat correctly.

Regards Martin Öling. The Ford i mentioned is running alchohol i believe and it ran 8.00 @ 178 MPH the firsrt time out. I bet the head gaskets don't hold up for long. I heard he has already hurt the F2 Procharger though. These things have many other problems too when you lean on them.

Just out of curiosity when do you start O ringing a block due to the cylinder pressure?

Fords have what 4 bolts around the cyl to clamp it. Isn't that some of the issue with them. I had read the same about LS motors but I dpn't know a thing about them.

That was a good article Martin and was always what I had beleived and the reason why I went for the low compression I have.

===========================================
when talking purely about on-boost power potential, compression just doesn't make any sense.

People have tested the power effects of raising compression for decades, and the most optimistic results are about 3% more power with an additional point of compression (going from 9:1 to 10:1, for example). All combinations will be limited by detonation at some boost and timing threshold, regardless of the fuel used. The decrease in compression allows you to run more boost, which introduces more oxygen into the cylinder. Raising the boost from 14psi to 15psi (just a 1psi increase) adds an additional 3.4% of oxygen. So right there, you are already past the break even mark of losing a point of compression. And obviously, lowering the compression a full point allows you to run much more than 1 additional psi of boost. In other words, you always pick up more power by adding boost and lowering compression, because power potential is based primarily on your ability to burn fuel, and that is directly proportional to the amount of oxygen that you have in the cylinder. Raising compression doesn't change the amount of oxygen/fuel in the cylinder, it just squeezes it a bit more
========================================

It's a fact making your power with boost is better than trying to run higher compression. This is only true to a point, you don't want 5:1 compression thinking you will make up the power with boost. The "optimum" range for roots blowers is 7.5 - 8.5:1 anything lower or higher doesn't do you any good.

As with all performance modifications, it depends on the combination. If you have a mild cam then you are probably better off with lower compression because the mild cam and boost will build cylinder pressure down low. Too many variables to say one certain compression ratio is best, there is a range that will work if you plan the combo properly.

Now when talking centrif blowers or turbos they can benefit from a little more compression.

If it's a street motor you should have the steam holes. Or just contact someone at Dart like Tony Mcafee. 350 mains would be less friction, but I don't know how much hp it would be worth.

If it's a street motor you should have the steam holes. Or just contact someone at Dart like Tony Mcafee. 350 mains would be less friction, but I don't know how much hp it would be worth.
=
Regarding the steam holes, this is not correct.
You do not need steam holes in a Dart block.
Plus where exactly are you going to put them considering the block is solid to the mains where the steam holes would normally go in a stock block.
All you need to do is take a look at the casting & you will see there is no place for the water to get trapped & turn to steam.
This is the purpose of the holes in a stock block.

In the Dart you have a thick deck, blind head bolt holes, very "rounded" smooth castings under the head bolt bosses.

So what is the point of trying to stick a hole into the deck that does nothing??

Regarding main size, you will have a much stronger crank with the 400 mains & bearing speed is a non issue in this type of engine.
Give me a crank with as much overlap as I can get in an engine that tends to make a LOT of low end torque. ;)
GM really did have a reason to go to the 2.100 journal in the 350 as well as to increase the main size as the stroke went up.
The main reason to lower the sizes is for bearing speed with the side benefit of slightly reduced friction.

Wolfplace,

I have always been concerned about using a 400 SBC for a blower motor for the reason that there is less gasket between the bores. I was into hotrodding back in the early 80's and in those days, a 400 SBC was not recommended for blowers as they had a reputation of losing the head gasket between the bores.

Today we have much better gasket technology and perhaps the Dart block is not so prone to losing head gaskets as the stock GM block.

What is your personal opinion on this?

thanks.

Wolfplace,

I have always been concerned about using a 400 SBC for a blower motor for the reason that there is less gasket between the bores. I was into hotrodding back in the early 80's and in those days, a 400 SBC was not recommended for blowers as they had a reputation of losing the head gasket between the bores.

Today we have much better gasket technology and perhaps the Dart block is not so prone to losing head gaskets as the stock GM block.

What is your personal opinion on this?

thanks.
=
"Back in the 80"s" :D ,,, damn kid,, make me feel older than dirt :D :D

I quit driving professionally in the mid 80's,,,,
First let me qualify this by saying blown engines are not what I normally do so I am hardly an expert here,,,
Now to your question, let me answer you this way..
The dragster I last drove in competition was a small block & one of the most competitive ones in the country.
It belonged to S&S Automotive.
George Santos was the brains behind it,,,, I just broke the parts for
them,,, :rolleyes:
His son is Rick Santos & when I quit driving Rick started driving about a year later.

It ran a fair amount of boost & had very few issues with head gaskets
This little mouse was originally built using stock factory blocks & then used some GM BowTie blocks & was tried with differing bores including 4.125 based stuff
I believe the last iteration before it was retired was 388 inches with an aluminum block that ran 5.60's at about 235.

So with today's blocks & gaskets I don't really think you would have an issue with reliability but I certainily would not try to use something like a 4.185" type bore, I don't even care for these with "normal' stuff,,,
This is all assuming of course you don't detonate it :p

On another note, the MLS gaskets like Cometic have virtually made my "O" ringing tooling obsolete.
I have "O" ringed maybe four or five blocks in the last few years & my understanding is that a number of folks are using Nitrous & blowers without "O" rings with these gaskets in some pretty serious stuff
But the majority of what I do is circle track now so,,,,

Hey guys,wondering about blower motors huh.Well let me give you a little advise,nothing is unbreakable in a blower motor.We have had cranks break in as few as 2 1/8 mile passes.But we've also had them last 2 full seasons.Now the motor gets a new crank every year and sometimes 2 or 3 of them.Boost is not the whole problem,it also involves flex.And the more stroke you have the harder it flexes,cause blower motors don't have forgiveness...

Hey guys,wondering about blower motors huh.Well let me give you a little advise,nothing is unbreakable in a blower motor.We have had cranks break in as few as 2 1/8 mile passes.But we've also had them last 2 full seasons.Now the motor gets a new crank every year and sometimes 2 or 3 of them.Boost is not the whole problem,it also involves flex.And the more stroke you have the harder it flexes,cause blower motors don't have forgiveness...
=
How true,,,, :D
I had pictures of the blown engine at the March meet in Bakersfield where the only thing holding the front of the crank up was the blower belt,,
The first burnout on the first blown engine when we switched from BFD (B fuel, not blown,,) busted the block from the mains to the cam,,
Next engine had a "bit" less compression & blower ;)
The absolute number one enemy of a blown engine is detonation & they like to detonate when you lean on them...

BTW, as I recall all the engines were in the 3.5-3.625" stroke area.
3.75 was tried a few times & they never made the power of the shorter stroke engines but this is from memory & it was a "few" years ago,,,

If I were doing blown small block I would limit the stroke to 3.75 max for a few reasons.
Stronger crank
Much easier to fit crap in the block if it is a standard deck
Getting enough head to feed the thing.
Cam core size
More power is a pulley away,,, :D

=
"Back in the 80"s" :D ,,, damn kid,, make me feel older than dirt :D :D

I quit driving professionally in the mid 80's,,,,
First let me qualify this by saying blown engines are not what I normally do so I am hardly an expert here,,,
Now to your question, let me answer you this way..
The dragster I last drove in competition was a small block & one of the most competitive ones in the country.
It belonged to S&S Automotive.
George Santos was the brains behind it,,,, I just broke the parts for
them,,, :rolleyes:
His son is Rick Santos & when I quit driving Rick started driving about a year later.

It ran a fair amount of boost & had very few issues with head gaskets
This little mouse was originally built using stock factory blocks & then used some GM BowTie blocks & was tried with differing bores including 4.125 based stuff
I believe the last iteration before it was retired was 388 inches with an aluminum block that ran 5.60's at about 235.

So with today's blocks & gaskets I don't really think you would have an issue with reliability but I certainily would not try to use something like a 4.185" type bore, I don't even care for these with "normal' stuff,,,
This is all assuming of course you don't detonate it :p

On another note, the MLS gaskets like Cometic have virtually made my "O" ringing tooling obsolete.
I have "O" ringed maybe four or five blocks in the last few years & my understanding is that a number of folks are using Nitrous & blowers without "O" rings with these gaskets in some pretty serious stuff
But the majority of what I do is circle track now so,,,,

Mike, you drove for Santos!! You ain't kidding about "the most competitive car in the country" Holy crap, the Santos car was one of the most feared cars in Top Alcohol. If memory serves me right, Rick was a NHRA world champion in T/A, (maybe several times over)? You were a little before my time :( (sorry not trying to make you feel old, I'm not exactly a spring chicken myself, LOL), but I do remember Rick driving the car and beating the crap out of those big bad hemis with that wittle old mouse motor. That was one bad MO-FO small block. He was the man in Alcohol, I loved that car....too bad they let injected nitro in, it kinda muffed up the class in my opinion. I've been out of touch with NHRA, are the Santos' still racing?

Sorry about the hijack, please continue.

Rob

LET ME MAKE one thing clear,if any one thing is not correct in a blower motor ,power and your wallet will suffer.Every one talks like big boost numbers are a good thing.On the contrary just the opposite is true.If for instance you have a motor that makes 15 lbs. of boost,and you PORT the exhaust runners and boost drops to 12 lbs.you have made more power.The reason being is you have made the motor more effecient!Blower motors love to breath.I know this because I myself crewchief on a TAD IHRA that we use in quick 16 races. It is a 235in. rail that lays down high 4.20 passes at 169 mph. in the 1/8. Changing nothing more than a larger exhaust valve and CNC porting of the exhaust runner made the car 1 1/2 tenths quicker and dropped boost from31 to 27 lbs.Thats power people.That is the same reason why the Brodix 2X heads are comming off and the Pontiac big chief heads are going on.The motor is a 555ci.blown and injected Merlin with O-ring block and reciever grooves in the heads.Compression is 11.25 static and 31 to1 at full boost.Thats with the blower set at 27over.Can turn it 57 over.

Mike, you drove for Santos!! You ain't kidding about "the most competitive car in the country" Holy crap, the Santos car was one of the most feared cars in Top Alcohol. If memory serves me right, Rick was a NHRA world champion in T/A, (maybe several times over)? You were a little before my time :( (sorry not trying to make you feel old, I'm not exactly a spring chicken myself, LOL), but I do remember Rick driving the car and beating the crap out of those big bad hemis with that wittle old mouse motor. That was one bad MO-FO small block. He was the man in Alcohol, I loved that car....too bad they let injected nitro in, it kinda muffed up the class in my opinion. I've been out of touch with NHRA, are the Santos' still racing?

Sorry about the hijack, please continue.

Rob
=
Hi Rob,
Another "sidetrack" of the post,, sorry about that "Tokyo Torquer",, sorry, don't know your name??

Yep, drove for them for almost 10 years & the car was always pretty fast
I quit driving in 84 the year we won Division 6&7. They were combined for one year.
I haven't driven anything for about a year now but am still licensed in FMD & Pro Stock so I can drive about anything except TF & Floppers but will probalby become "inactive" this year.
Yes, Rick won the world championship for 4 years but it was with a Hemi after they retired the small block
Hooked up with Jack Obannon & Oakwood Homes with Norm Grimes of LA doing the engines with Georges help.
Huge dollar deal for a "sportsman" class :D
They don't race anymore, quit when the Oakwood homes deal went belly up but I don't know all the "details",,,
Chassis was sold to a team in the Bay Area & then to the Wills Trucking family & is the one Hillary Wills drove before she got the TF deal.
Super people & Rick is as sharp as his dad, he virtually grew up in the shop.
Here is the older car I drove I have posted before at Fremont circa 1980
http://wsm.ezsitedesigner.com/share/scrapbook/19/190264/Rear_Engine_Color1.JPG

LET ME MAKE one thing clear,if any one thing is not correct in a blower motor ,power and your wallet will suffer.Every one talks like big boost numbers are a good thing.On the contrary just the opposite is true.If for instance you have a motor that makes 15 lbs. of boost,and you PORT the exhaust runners and boost drops to 12 lbs.you have made more power.The reason being is you have made the motor more effecient!Blower motors love to breath.I know this because I myself crewchief on a TAD IHRA that we use in quick 16 races. It is a 235in. rail that lays down high 4.20 passes at 169 mph. in the 1/8. Changing nothing more than a larger exhaust valve and CNC porting of the exhaust runner made the car 1 1/2 tenths quicker and dropped boost from31 to 27 lbs.Thats power people.That is the same reason why the Brodix 2X heads are comming off and the Pontiac big chief heads are going on.The motor is a 555ci.blown and injected Merlin with O-ring block and reciever grooves in the heads.Compression is 11.25 static and 31 to1 at full boost.Thats with the blower set at 27over.Can turn it 57 over.
=
Well,, I don't think "everyone talks about big boost numbers being a good thing"
At least not everyone I know,,,
If you do a search on this site you will find that this has been discussed before a few times :)
I believe a gentleman named Thomas on here for one has explained it among others.

But you are correct, boost is simply a measure of what is NOT GETTING INTO THE CYLINDER
It is manifold pressure & is an important number but just being a higher number doesn't necessarily mean more power.
Basic reason to keep track of it is it will tell you if the blower is going south..
More overdrive with a lesser number usually means a more efficient system & more power.
Not always, but usually,, you can lower the number with a ton of overlap too but putting the fuel out the exhaust is probably not going to make you faster,,
Unless of course you point the exhaust straight back & use it for "forward thrust",,, :D :D

And on a serious note, all "O" rings we do are with a receiver groove, have been for about 8 or 10 years now. Much more efficient system as you have a "double seal".

=
"Back in the 80"s" :D ,,, damn kid,, make me feel older than dirt :D :D

I quit driving professionally in the mid 80's,,,,
First let me qualify this by saying blown engines are not what I normally do so I am hardly an expert here,,,
Now to your question, let me answer you this way..
The dragster I last drove in competition was a small block & one of the most competitive ones in the country.
It belonged to S&S Automotive.
George Santos was the brains behind it,,,, I just broke the parts for
them,,, :rolleyes:
His son is Rick Santos & when I quit driving Rick started driving about a year later.

It ran a fair amount of boost & had very few issues with head gaskets
This little mouse was originally built using stock factory blocks & then used some GM BowTie blocks & was tried with differing bores including 4.125 based stuff
I believe the last iteration before it was retired was 388 inches with an aluminum block that ran 5.60's at about 235.

So with today's blocks & gaskets I don't really think you would have an issue with reliability but I certainily would not try to use something like a 4.185" type bore, I don't even care for these with "normal' stuff,,,
This is all assuming of course you don't detonate it :p

On another note, the MLS gaskets like Cometic have virtually made my "O" ringing tooling obsolete.
I have "O" ringed maybe four or five blocks in the last few years & my understanding is that a number of folks are using Nitrous & blowers without "O" rings with these gaskets in some pretty serious stuff
But the majority of what I do is circle track now so,,,,

Wolfplace,

I was thinking back to about 1982-4 when I built 2 blower motors. 1982 is 24 years ago, almost a quarter of a century. I was young and had little money, but it was easier (cheaper) to hot rod then. The technology was not as high as today, but it was enough, fewer things to go wrong, and the quality of most of the parts was far higher. I cannot tell you how many silly problems I have had with my current motor due to poor quality control in name brand parts. Few people have pride in their work or care anymore in the US...they just try to push it out the door and grab your dollars.

There is a lot more info about performance engine building today due to the internet, but at the same time there is so much more bad info/ wrong advice. I have learned quite a bit from you though, and you are my first choice to work with on my next motor.

What I have learned is thatr I may be best off by not going too crazy with the size of the SBC stroker blower motor. I am thinking;
-a new Dart Little M block with a 4.125 bore and "400" mains, stock deck height, stock pan rails (so I can use my current still new Stefs pan)
-3.75" Lunati 4340 crank with a 2-piece seal (a 1 piece seal sounds inviting, but I understand it requires me to change oil pan, flywheel and other parts?)
-AFR 210 competition ported heads (I think my 195's would work, but I do not want to make torque over horsepower as I have too much already
-Hydraulic roller 236/248 @ 0.050", .520/.540 lift @ 113 LSA

I am wondering if I will be able to use my current 5.7" H-beam rods and be able to use off the shelf pistons that will get me between 7.5:1 to 8:1 compression with 74cc chambers with the wrist pin not too far up into the ring lands, or I need to get custom pistons? or if the 5.7" rods will be a problem?

many thanks,

mike

Wolfplace,

I was thinking back to about 1982-4 when I built 2 blower motors. 1982 is 24 years ago, almost a quarter of a century. I was young and had little money, but it was easier (cheaper) to hot rod then. The technology was not as high as today, but it was enough, fewer things to go wrong, and the quality of most of the parts was far higher. I cannot tell you how many silly problems I have had with my current motor due to poor quality control in name brand parts. Few people have pride in their work or care anymore in the US...they just try to push it out the door and grab your dollars.

There is a lot more info about performance engine building today due to the internet, but at the same time there is so much more bad info/ wrong advice. I have learned quite a bit from you though, and you are my first choice to work with on my next motor.

What I have learned is thatr I may be best off by not going too crazy with the size of the SBC stroker blower motor. I am thinking;
-a new Dart Little M block with a 4.125 bore and "400" mains, stock deck height, stock pan rails (so I can use my current still new Stefs pan)
-3.75" Lunati 4340 crank with a 2-piece seal (a 1 piece seal sounds inviting, but I understand it requires me to change oil pan, flywheel and other parts?)
-AFR 210 competition ported heads (I think my 195's would work, but I do not want to make torque over horsepower as I have too much already
-Hydraulic roller 236/248 @ 0.050", .520/.540 lift @ 113 LSA

I am wondering if I will be able to use my current 5.7" H-beam rods and be able to use off the shelf pistons that will get me between 7.5:1 to 8:1 compression with 74cc chambers with the wrist pin not too far up into the ring lands, or I need to get custom pistons? or if the 5.7" rods will be a problem?
=
Thanks, I try but after 40 some years of this I still be learnin,,, :D
Still don't know your name ought to put it in your sig,,

I cannot disagree with you at all regarding the quality of some of the stuff we get these days,, seems any time someone uses the words "bolt right on" it is time to run like hell,,,

I would not be afraid to put more head on it.
The new AFR 210 if Tony ever gets done with the damn things will be a killer head but I think it is a little small.
Remember, your engine is going to think it is a big block when you stick a blower on it.
Think more air with less restriction.

For a out of the box head I would not go with anything smaller than the Brodix Track One CNC 227 or the AFR 220, something in that vein in conventional 23 degree heads.

Your 5.7 rod will work but the balance will probably be an issue. Who's rod is it?
I prefer to internal balance & it may get a bit pricy with the shorter rod.
I can do it but the pricing depends on the piston & rod weight.
Don't know about a shelf piston, have to do some checking but I highly doubt you will find one especially in a 4.125 bore.

As has been mentioned, by Royce (camaroman7d) a custom reverse dome with good quench is a much better deal & this will be a custom if it can be done.
Pin height will be no issue with either rod.
Not a big deal here though, customs are a phone call away from a bunch of folks,, I can usually get Wiseco in about 4 weeks, not always but usually,,
I would prefer a 5.850 rod for your deal & my preference is a Callies crank.
You might also consider doing this with a 5.625 stroke just for giggles,,

No issue on using the standard block with the 3.75" stoke, possibly a little clearancing, no big deal.

Cam seems a bit small for a 383 & I would spread the centers another degree but I would discuss this with the people that know way more about cams than I. :)
Probably start with something like Comp's 3115/3116 lobes & work from there.
304/314, 244/252, 164/169, .600/.600

But as I said earlier, I am far from a "blower expert" & am open to any reasonable suggestions,, I like learnin too,, :D

Thanks Mike, but I did include my name at the end of the last message, it is "mike", same as you.

I am thinking about a 400CI with a new Dart block, rather than making the current 355 a 383.

I would not go any bigger on the duration for a hydraulic roller as I have already been through the valve float issue with my current cam. If we decided we needed more cam, I would go solid flat tappet.

I also would be hesitant to go with the AFR220 heads as I don't want any new headaches trying to make special parts fit. I thought I recall people having troubling finding headers to work with the 220 heads, and the AFR site also states that the 220 head is "Not recommended for street use, unless shaft mount rockers are used". I would like to stick with the "KISS" philosophy.

This engine will be 95%+ street. My current blower engine cruises at 1800rpm on the highway at 70mph with the overdrive trans and gets 18mpg to boot. I would want to maintain intake port velocity to maintain the great response I have cruising around when I am not making any boost. That was the thinking of going no bigger than 210 on the heads and the modest cam duration. I am thinking of a slightly bigger vrsion of what I currently have. I definitely want the new heads Tony@AFR was telling us about. I am thinking peak power at 6000rpm max with the hydraulic roller. I do agree on the extra degree on the LSA, as I care more about making a very broad power band rather than maximizing peak power. The reality is that this motor will make more power than I can actually use, heck I can't even use the power I have now (yes, I have that uncurable disease :) , so reliability is more of a factor and why I was thinking of a lift at the rocker closer to .550". I get a kick out of trying to build a better motor every winter.

I use a reverse dome piston with Cometic MLS gaskets now, and hope to use the same. I was looking at the SRP pistons and they seem to have some reverse domes that might work.

I currently have Eagle H-beam rods. If the 5.7" rods are a stumbling block, I won't compromise here and will go with new rods, that way I can sell the current engine complete rather than part it out.

I have always been leary of callies cranks as I have heard many stories of people snapping the snouts off them on blower motors.

As for timing, I live in NJ and I pull the motor every December and that gives me about 4-5 months to rebuild and reinstall. My final choice of heads/cam will be greatly influenced by how well I do at the track this year. The car usually sees only car shows most of the summer while it is still freshly detailed, and will hit the track from September. My past ventures to the track have all been disasters.. I have a big roots blower, a 4.33 launch ratio, and a stick, and the car has been severely traction challenged..actually a handful at the track. I hope to work this out by the next time I hit the drag strip.

Thanks Mike, but I did include my name at the end of the last message, it is "mike", same as you.

I am thinking about a 400CI with a new Dart block, rather than making the current 355 a 383.

I would not go any bigger on the duration for a hydraulic roller as I have already been through the valve float issue with my current cam. If we decided we needed more cam, I would go solid flat tappet.

I also would be hesitant to go with the AFR220 heads as I don't want any new headaches trying to make special parts fit. I thought I recall people having troubling finding headers to work with the 220 heads, and the AFR site also states that the 220 head is "Not recommended for street use, unless shaft mount rockers are used". I would like to stick with the "KISS" philosophy.

This engine will be 95%+ street. My current blower engine cruises at 1800rpm on the highway at 70mph with the overdrive trans and gets 18mpg to boot. I would want to maintain intake port velocity to maintain the great response I have cruising around when I am not making any boost. That was the thinking of going no bigger than 210 on the heads and the modest cam duration. I am thinking of a slightly bigger vrsion of what I currently have. I definitely want the new heads Tony@AFR was telling us about. I am thinking peak power at 6000rpm max with the hydraulic roller. I do agree on the extra degree on the LSA, as I care more about making a very broad power band rather than maximizing peak power. The reality is that this motor will make more power than I can actually use, heck I can't even use the power I have now (yes, I have that uncurable disease :) , so reliability is more of a factor and why I was thinking of a lift at the rocker closer to .550". I get a kick out of trying to build a better motor every winter.

I use a reverse dome piston with Cometic MLS gaskets now, and hope to use the same. I was looking at the SRP pistons and they seem to have some reverse domes that might work.

I currently have Eagle H-beam rods. If the 5.7" rods are a stumbling block, I won't compromise here and will go with new rods, that way I can sell the current engine complete rather than part it out.

I have always been leary of callies cranks as I have heard many stories of people snapping the snouts off them on blower motors.

As for timing, I live in NJ and I pull the motor every December and that gives me about 4-5 months to rebuild and reinstall. My final choice of heads/cam will be greatly influenced by how well I do at the track this year. The car usually sees only car shows most of the summer while it is still freshly detailed, and will hit the track from September. My past ventures to the track have all been disasters.. I have a big roots blower, a 4.33 launch ratio, and a stick, and the car has been severely traction challenged..actually a handful at the track. I hope to work this out by the next time I hit the drag strip.
=
Mike,
Sorry about that, missed it in your last post.
You are correct, the 220 head should not be used with conventional rockers. To get them correct shaft rockers are necessary.
The 210's will work without question but they are on the small side.

Cam is not an issue, they all cost the same so it can be ground any way necessary but the way all these head flow not getting the valve open is almost a sin,,,
With the correct spring & decent lifters like Morel's 6000-6200 should not be an issue even with boost.

Far as I know the best you are going to do in SRP is about 20cc's which fall way short of what you need for 8.0
As you have cheap rods now I would leave them in the engine & go with new but no, 5.7 is not a stumbling block, just harder to balance most of the time.

I don't know where this crap about Callies cranks breaking snouts off comes from, it happens with any crank & more times than not it is because of something that was done wrong like a gear without enough chamfer for the radius, fluid type dampers, no dampers,,,,
In blown applications except underdriven street stuff a too small snout or a belt too tight & yes in some cases crank failure.
Hell, in the 10% under stuff there are a bunch of street rods & such running around with stock single key GM cranks in stock "crate engines"
The blower engine on my site is an out of the box Scat crank with a single key & an ATI damper & so far so good but as I mentioned before, this is not any where near a "max effort" deal,,,

I hear the same thing about Scat & it seems one crank breaks & now they are all junk & a friend of a friend of someone's uncle knew a guy that had a friend that used to race somewhere & broke a crank,,, :sad:

This stuff is performance stuff & it does fail but not near as often as the internet pros would have you believe.
I know of an awful lot of top shops that use Callies as an upgrade from the less expensive stuff that don't seem to get a ton of them back.
Fact is I had an LA billet in two pieces I had for a number of years that broke in a circle track engine the second season.
This was a $2500+ crank,,,
Stuff happens but I do not consider all LA cranks suspect because of it.

My preference would be to use Oliver rods & Bryant or LA Billet or Crower cranks in everything but it just isn't in most people's budget.
I left Oliver cranks out because as of a couple of months ago they are discontinued,, bummer as they were a work of art.
Another crank most do not know about that is outstanding is the Scat Billet ones but they are also not cheap.

Being as you are in NJ, while I will be glad to help with your engine, but in your case I would suggest that for the machining you contact Carl at CNC Blocks NE, very good at what he does & a hell of a lot closer to you. ;)
And who knows,, by December there is even a chance the new AFR heads will be available :rolleyes:

I almost always go to dinner with the AFR gang at the PRI show in Dec so at least I can harass Tony in person if he doesn't come by here next month. :D
He was talkin about coming up on a short vacation to say hi but we shall see,,,,

=
Hi Rob,
Another "sidetrack" of the post,, sorry about that "Tokyo Torquer",, sorry, don't know your name??

Yep, drove for them for almost 10 years & the car was always pretty fast
I quit driving in 84 the year we won Division 6&7. They were combined for one year.
I haven't driven anything for about a year now but am still licensed in FMD & Pro Stock so I can drive about anything except TF & Floppers but will probalby become "inactive" this year.
Yes, Rick won the world championship for 4 years but it was with a Hemi after they retired the small block
Hooked up with Jack Obannon & Oakwood Homes with Norm Grimes of LA doing the engines with Georges help.
Huge dollar deal for a "sportsman" class :D
They don't race anymore, quit when the Oakwood homes deal went belly up but I don't know all the "details",,,
Chassis was sold to a team in the Bay Area & then to the Wills Trucking family & is the one Hillary Wills drove before she got the TF deal.
Super people & Rick is as sharp as his dad, he virtually grew up in the shop.
Here is the older car I drove I have posted before at Fremont circa 1980
http://wsm.ezsitedesigner.com/share/scrapbook/19/190264/Rear_Engine_Color1.JPG

Mike, thanks for bringing back some fond memories, that is just too damn cool in my book. :)

And to the other Mike (yeah the good looking one :D) I apologize for popping in here and adding absolutely nothing of value to your thread. The truth is, I don't know squat about a small block, but I sure do like your Camaro, good luck with your project.

Rob

Lewis racing engines sent me this link (Thanks Mike) We also CNC machine blocks and we are on a deep deal with Dart and if we can do anything to help you out feel free to give us a call as we offer free shipping as well.

Hey guys,wondering about blower motors huh.Well let me give you a little advise,nothing is unbreakable in a blower motor.We have had cranks break in as few as 2 1/8 mile passes.But we've also had them last 2 full seasons.Now the motor gets a new crank every year and sometimes 2 or 3 of them.Boost is not the whole problem,it also involves flex.And the more stroke you have the harder it flexes,cause blower motors don't have forgiveness...

In most cases using steel rods in a blower engine will cause a crank to break as on the ones we build for competition we use Fowler aluminum rods and we have the small end of the rods machined for the BBC pin size .990 and the pistons are custom as well.

Both of these engines we build and maintain runn 871 blowers one is a SSI which every 2 years is sent back to be dynoed and up graded.

We have been using Cranks from Kings Crankshaft CO. in NC we have been using the small block snouts as we use a crank support on the front of the engine and this has worke for us fro the last 11 years with no problems and we also designed and built the drive on the front of the engine for the fuel pump and the 44 amp mag as these engines spin up to 9500 and Fowler has thse rated around 1500 horse.

Here is a pick of the short block
http://i7.photobucket.com/albums/y276/CNCBLOCKS/blowerengine003.jpg
Pic of the engine almost complete
http://i7.photobucket.com/albums/y276/CNCBLOCKS/blowerengine010.jpg

Carl,
On a race only engine aluminum rods are fine and I trust you are correct about being easier on the crank. On a streetdriven engine aluminum rods are a no no. I just wouldn't want guys to see what you posted and run out to buy a set of aluminum rods for their blown street car.

Carl,
On a race only engine aluminum rods are fine and I trust you are correct about being easier on the crank. On a streetdriven engine aluminum rods are a no no. I just wouldn't want guys to see what you posted and run out to buy a set of aluminum rods for their blown street car.

Yes I highly doubt they are going to be making 1500 horse either or be running an 8-71 blower on alky and turning 9500 RPM and 12:01 compression either.

But I would spend a good chunk of change on a good crankshaft.

Carl, is it common place to run that high of compression in a blown alcohol app?? A buddy of mine asked me about it one time and I thought it sounded high, but I don't know dicky-doo about blown anything, much less blown alc.

First of all ,Mike (Wolfplace),I didn't mean to sound hasty.As I said ,I crewchief on a T.A. (top alchahol) car, and all I ever hear from people who dont understand blower motors is, WOW, you made how much.And 27 lbs. isn't high when you know what turbo cars make.Got a friend in Tenn.,who's single turbo Mustang makes 1300 hp.with a 347ci.small block.WOW,WOW.
.As for Carl Hinkson,thank you, maybe now I can breath again;been a member for a week and already got someone upset at me.We run 11.25 to 1 compression in a 4.560 bore and a 4.25 stroke.Ohio Crankshaft 4340.BME 426 rods with 1.094 taper wrist pins.J&E Blower pistons with a small dome.Cam is from Comp. Cams. 292 and 302 duration at .050,with 798 lift int. and ext.113.5 LSA.and 112 int.cl.Makes power from 4500-7800, says the card.Bull ****,it makes power from idle to the finish line!!!! As I said before,it's a 235in.rocket on wheels.the top end gets Pontiac heads at the end of the season.Blower is a Littlefield 14-71 with down nozzles.Enderle injection,Vertex mag,powerglide,and 9in.Ford. ".972" 60's 4.20's@169.in the 1/8 mile. Nice to hear from a racer.

First of all ,Mike (Wolfplace),I didn't mean to sound hasty.As I said ,I crewchief on a T.A. (top alchahol) car, and all I ever hear from people who dont understand blower motors is, WOW, you made how much.And 27 lbs. isn't high when you know what turbo cars make.Got a friend in Tenn.,who's single turbo Mustang makes 1300 hp.with a 347ci.small block.WOW,WOW.
.As for Carl Hinkson,thank you, maybe now I can breath again;been a member for a week and already got someone upset at me.We run 11.25 to 1 compression in a 4.560 bore and a 4.25 stroke.Ohio Crankshaft 4340.BME 426 rods with 1.094 taper wrist pins.J&E Blower pistons with a small dome.Cam is from Comp. Cams. 292 and 302 duration at .050,with 798 lift int. and ext.113.5 LSA.and 112 int.cl.Makes power from 4500-7800, says the card.Bull ****,it makes power from idle to the finish line!!!! As I said before,it's a 235in.rocket on wheels.the top end gets Pontiac heads at the end of the season.Blower is a Littlefield 14-71 with down nozzles.Enderle injection,Vertex mag,powerglide,and 9in.Ford. ".972" 60's 4.20's@169.in the 1/8 mile. Nice to hear from a racer.
=
Hi Eric,
If your referring to me being upset, no way :)
I rarely get upset & was agreeing with what you said.
About the only thing that bothers me is misinformation & BS Dyno numbers,, :D

John,
About 11.0-12.0 is pretty much the norm for these things or was when I was involved & apparently still is.
I think it kind of depends on who is doing the tuning & there ideas of what works.
I do know about 12.5 with a lot of overdrive didn't work on the first burnout we did with a stock block though as I posted earlier...
It split the block from the cam to the mains,,,
Had a "slight" vibration so I shut it off,,,

And yes, aluminum rods are pretty much mandatory if you want to keep bearings in these things past the starting line,, they make excellent "shock absorbers" :D

Thanks Mike L. & Carl H. Will be in touch when I am ready to start the new motor.

I think this thread is getting a little confused between a street blower motor and a full competition only motor. I am building a street engine and will be using steel rods and shooting for a static compression ratio between 7.5 and 8.0:1. It is interesting to hear the specs on a full race blower motor, though.

I have seen the 3.562" crank spec in a few all-out blown SBC's.. a bit of an uncommon stroke and I wonder what if this is supposed to be some sort of magic stroke for a 4.0-4.03" bore blown SBC?

mike

Carl,

what is the bore X stroke on the motors you pictured above and what are you running for heads.

I believe you are located in upsate New York, is that correct? I am in northeastern New Jersey.

i think your right, its gotten away from a blown street setup-lol
as your aware, you will prob. have to watch your cam specs. because of the stick setup, you will be driving around in 1st gear or bucking like crazy
i tried the tko 5sp, used the .8 o/d with 3:73's on my procharged 383
i prob should have gotten the .6 o/d and used 4:11's
i yanked it out and went with a turbo 400, 2:75 1st gear setup, droped back to 3:50 gears, could'nt be happier-stop anywhere on the street and let it rip, slap the shifter and keep burning-i have a 4l80e im gonna build 1 day
when considering bore/stroke, think about what shelf pistons you can get-some b/s's you need custom pistons, break one and your down 6 weeks(been there) i always hone fit the balancer/crank snout, tighten belt after warm up(they tend to tighten when warm)always worried about the snout, more so when i ran the roots, but never had a problem(yet) of course you can run a s/b crank w/bb snout-my new motor is a 489 b/b, should, just so i can have a bigger snout-lol

I have no problem putting around with the TKO in high gear with the current cam.. maybe that is the difference between a roots and a centrifugal at low speed.

Dear Tokyo,sorry if I got a little sidetracked.Back to your thinking now.As we know blower motors make tons of torque.When I think of a motor such as this in a street car,the first thing that comes to mind,is traction.Can you hook all the power you are trying to put on the ground?Adding stroke adds torque as you aready know.Adding TORQUE to a torque pig on a small tire is a no no.THE 3.55 gears help some, but what is your first gear ratio? And what size tire are you running?If you do go to a 406 remember you'll be adding 1/4 stroke.Thats a lot of torque.
If you want to be the torque of the town,build a 406.
If you would like to run a little faster, and not have to worry about breaking as many parts,build a 377 destroke.
We have this little saying that goes like this,"If you think it's bulletproof,stick a blower in it."
Have a nice day.

Carl, is it common place to run that high of compression in a blown alcohol app?? A buddy of mine asked me about it one time and I thought it sounded high, but I don't know dicky-doo about blown anything, much less blown alc.

John

In this class these two engines run they are only allowed to run a 10% over drive and we run about 36 to 38 pounds of boost thats why these engines run so much RPM and they pull up to 45 seconds at a time and this compression works for us so far and I think that would be the max for our application.

Carl,

what is the bore X stroke on the motors you pictured above and what are you running for heads.

I believe you are located in upsate New York, is that correct? I am in northeastern New Jersey.

The stroke on both engines are 3-5/8 X 4.063 and we are running the old Buick high ports and both blocks are raised cam tunnel blocks one is a Dart 9.325 and the Brodix is a 9.500 and that engine has 6.300 rods as we have found that the longer the rods in these engines the better power we have seen.

I am from Maine an hour from the NH border and my CNC shop is 10 minutes from Portland Inter. Airport and my engine shop is 20 minutes from my CNC shop.

Carl; Many thanks. ***There is that magic 3.625 stroke on the roots blown SBC again. I often see that on all out blown SBC's. It is an uncommon stroke, so could someone please tell me about this.. what is so magic about the 3.625 stroke SBC?***

Does the 3.625 stroke add that much more benefit as it would require custom pistons and such when there are plently of off the shelf blower pistons for 3.48 and 3.75 stroke engines, which would be much easier/ cheaper??

Eric; I admit I have a traction problem now, already. With the low 3.27 1st gear on the TKO trans, I have an effective launch ratio of 4.33. Yes, it is a stick to make matters worse. I have new 10" X 26 MT ET Drag slicks. Last November on an extremely cold, unprepped track (only time so far on slicks), even backpeddling I was spinning them to the 1000' mark in the 1/4. If you increase the stroke with same heads and cam, yes, you build lots more torque than before. However, I am also adding bigger heads and a bigger cam, along with a bigger bore. This is just a slightly bigger SBC engine, is all. The goal would be to mimic the current engine's power band with a bit more power all around, so I am looking for more horsepower as well. I am not wanting to build only more torque. I am only thinking about 50 more horse at most. I don't see much excitement in going from a 355 to 377 blower motor, as the benefit will be marginal. I know it is impractical in reality, but you know the disease.. and I just have a little SBC with a tiny cam... I wonder about all the BBC guys building 700-800hp+ for the street!!! My weak links will be my clutch, and maybe the trans 2nd, and the eaton posi 3rd, but I have pretty stout parts everywhere else, especially the driveshaft, U-joints, axles, etc which would be good for ~1000+ hp.

Carl; Many thanks. ***There is that magic 3.625 stroke on the roots blown SBC again. I often see that on all out blown SBC's. It is an uncommon stroke, so could someone please tell me about this.. what is so magic about the 3.625 stroke SBC?***

Does the 3.625 stroke add that much more benefit as it would require custom pistons and such when there are plently of off the shelf blower pistons for 3.48 and 3.75 stroke engines, which would be much easier/ cheaper?

With the cubic inch rule that we have to maintain this is what we have used for a combo for the last 10 years and where these engines run they seem to win most of the event theys pull in.

And where we use the .990 wrist pins and the 6.300 rods everything is custom made.