[M.Apesland]

Hey guys, new here but i have been reading some posts and and learning a bit, but i have a question. I am building my first car a 1967 el camino(original 283 powerglide) into one hell(i think) of a fun street machine that will see very limited racing(nearest 1/4mile is 2 hours away).

Right now i have a good local machine shop building a supercharged 383 for it, the motor has a callies compstar bottom end, AFR 195cc heads, the block hase been machined and is being all put together(taking a while funds dont come as fast as i would like) but i have finally reached the point of deciding what blower to put on it. I really want a roots style blower for a couple of reasons. first they look cool as sh!t sound awsome and have serious street cred, i know you can make more power with a turbo application and maybe a vortech style but i'm willing to do the trade off for the looks and what not of the roots style blower, anyways im stuck in deciding what company to purchase the unit from. I really like the looks of BDS they seem rather specalised in that particular industry, as upposed to Weiand who seems more of an all around performance company. I plan on running it on pump gas(91 octane around here) with a 10% overdrive and then when i want to turn up the wick put a 10%underdrive pully on it and some race gas and go hard. with the 10% overdrive on it my engine builder figures i should hit about the 600-620hp mark then about an extra 100hp or so with the addition of more boost with the 10% underdrive and race fuel. If there are any other companies i should look at please let me know and any help would be greatly appreciated.

Also i guess i should pute some plans down for the rest of the car, right now due to $$ i think i will end up installing a built TH400 behind the motor with probably around 3200converter, a 12 bolt(gotta keep it GM) with some aftermarket suspension to help the thing launch with no weight over the rear tires(which are going to be as big and sticky as i can fit, might end up doing a mini tub) the interior will be fairly stock just with upgraded guages and floor shifter, the whole thing is going to be lowerd about 2 inched in the front a about and inch in the rear to fit slicks, the car has been a work in progress since me and my dad picked it up when i was 15( mostly used as a shelf in the winter) but had fun with it in high school(open headers whoo-hoo i was so smart)but now its time to get serious and again any whelp would be greatly appreciated.

 

[Mike]

Welcome to TC.
Underdriving a roots type blower gives you less 'boost' than overdriving the blower.
Sure hope your builder understands the difference.
Weiand was one of the dominant supercharger companies and was bought out by Holley.

 

[M.Apesland]

whoops thought i might have screwed that part up about the under drive over drive. would you say weiand is the better company to buy from then ie. customer assistance part quality etc?

 

[tt 383]

Whipple has some nice superchargers for bigger displacements, thats what I would look at. The blower shop has 6,8,10-71 in high helix that will supposedly be more efficient than a regular roots.

 

[Mike]

Post your current build specs.

 

[M.Apesland]

It's a 350 4 bolt block bored .030" over, callies compstar bottom end(all forged,5.7" H-beams, all the good stuff) 9:1 static compression ratio, AFR 195cc fully CNC'd heads w/ 2.02intake 1.60 exauhst valves, lunati hydraulic roller 219/227 @ 050 with 112lsa, 515/530 lift with 1.5 rockers.

 

[Mike]

Crank cut for dual keyway's or your builder not recommend that?

 

[M.Apesland]

i dont know for sure, is that a big deal->something i should inquire about? i know there can be alot of tension on the crank snout, but i didnt think i had to worry about the pully ripping the single key in half.

 

[671jimmy]

I have just had a 671 blown 383 put together wih a new Eagle crank cut for dual key ways. The engine was on an engine dyno last week and made 642 hp at 6000 rpm and 580 lbs of torque at 5000 rpm. The point of this story is that the flexing of the crank snout is quite visible and pretty alarming. I'm now at the point of looking at crank supports or replacing the crank for one with a big block snout. Live and learn. Dual key ways and big block snout highly recommended!
With a 671 pumping 10lbs plus accessories we are taking about as much power off the front of the crank as the original designers of the 265ci small block got off the back.

 

[Mike]

Well ,might not help on a stock SBC type snout ,sometimes causes more issues.
As above ,a crank support might work better than re-machining a small diameter crank snout.
http://www.goodvibesracing.com/bearing_supports.htm
But you may not have room for one if this is mostly street.

 

[M.Apesland]

Hmm thats definately something i will talk to my engine builder about. i talked to him earlier today about the cam specs and what not and we talked a little about my options supercharger wise, he seemed to like whipple when i brought it up, being that they are very efficient and i could run a single carb insted of a duel set up(making tuning and everything easier which is a wise choise i think as this is my very first engine build and the first time i will be working on and tinkering with an engine that makes this much power). i think the whipple also uses a thinner belt so i wonder if it would cause less strain on the crank snout than a standard GMC style supercharger with the really wide belt. the only problem with the whipple that i can tell is its not as loud as the standard roots which i know is because of increased efficency, but still the roots style sounds soo goood.

 

[Mike]

While your talking about carb's ,also note that the Holley will need to be boost referenced to work with a blower ,unless you plug the power valves and jet up.
Not an issue with a AFB type carb such as the Edelbrocks.

 

[M.Apesland]

ya i fully intended in getting a special build carb for draw through supercharged applications like the ones from holley or BDS.

 

[camaroman7d]

As far as which blowers to look at, Weiand would be the bottom of the list. Take a look and www.hamptonblowers.com www.theblowershop.com or www.superchargersusa.com Littlefield also builds nice blowers.

As far as the double keyway, it is not needed and not recommended for many applications, you are just taking more material off the already small snout. Running one long 1/4" key the whole length of the snout is another option and it was I chose to do with both of my blown SBC's I can link you to information about this if needed.

Stick with the Holley carbs if you are trying to make power, they are a much better carb for blown applications. Boost referencing is no big deal. You can also have the carbs "calibrated" and get away with no boost referencing.

 

[camaroman7d]

I have just had a 671 blown 383 put together wih a new Eagle crank cut for dual key ways. The engine was on an engine dyno last week and made 642 hp at 6000 rpm and 580 lbs of torque at 5000 rpm. The point of this story is that the flexing of the crank snout is quite visible and pretty alarming. I'm now at the point of looking at crank supports or replacing the crank for one with a big block snout. Live and learn. Dual key ways and big block snout highly recommended!
With a 671 pumping 10lbs plus accessories we are taking about as much power off the front of the crank as the original designers of the 265ci small block got off the back.

Do you run a damper or a hub?

 

[Mike]

RE: dual key ways:

Well ,might not help on a stock SBC type snout ,sometimes causes more issues.

At this point ,the single ¼" key way would be a good option.

 

[671jimmy]

Do you run a damper or a hub?

I am running a damper which adds to the leverage affect. Crank support kits seem to do away with the damper and have hubs, however this may get me into a shorter blower snout, then shorten up the tensioner brackets and problems driving my accessories. I have run an unstroked 350 with this blower, tufftrided crank and a Fluiddamper. I would not have known that the crank was flexing if the engine had just gone into the car (ignorance in this case is bliss) I'm guessing that that they all flex but people generally don't see it. Now that l know, l'd always be concerned running it the way it is.
I'd love a simple solution to this problem!!

 

[tt 383]

I'd love a simple solution to this problem!!

the solution is called turbocharger :thumbsup:

 

[Tokyo Torquer]

Here is my assessment;

The new big whipple 305 screw blower will make the best power of all, but much more expensive.

Many of the serious guys running an 71-series roots run a Littlefield (per Yellow bullet). Nice looking blower, too.

The Hampton and Dyers blowers are nice too, but not seen too often.

TBS makes the best looking blower from solid billet and price is still reasonable.

I think you would do very well with any of the above blowers.

Next comes BDS. They look nice, but the quality I hear may by slightly less and their prices are some of the highest around.

At the bottom of the list, is Weiand.. a favorite with the fair ground ground crowd that go more for looks than performance and often dont know too much about their engines. They do the job, but they run a little looser, a little less quality, and I see that now they are pricing at the same level as the best blowers out there, so I think one would only buy one because they didn't know that there are better blowers out there for the same price. Still, they work fine (roots blowers are simple technology) and get the job done, but there are better blowers out there for the same price.

For the 383 the 195cc runner heads are OK, but I would recommend 210-220cc runners for more power and almost no considerable downside.

Your cam is a little small and compression a little high.. but he is still building a nice, low boost (8-10lbs) street motor that will be funner to drive on the street, but not really optimal if the motor will ever see the track in the future. I guess it will be a 580hp/ 580 ft lbs motor, all done by 5800rpm, but crazy off idle torque and a very nice motor for the street. Please make sure he puts ~150lbs seat pressure on your valve springs to keep the HR cam happy with the blower at peak rpm. They have a habit of pushing the intake valve open and causing a big BOOM! in the intake if you dont...

I think you motor will have about 500+lbs torque at 2000k with a torque curve almost as flat as Kansas. It is a perfect motor for the intended build, but if you ever get hungry for more, you will wish you had a little less compression, little bigger heads and a little bigger cam. Usually you just change the pulleys to make more power on a roots blower, but with gas, that motor won't like a lot more boost and will definitately need high octane race gas and more conservative timing. If you ever want to swap the pulleys and make the 100 extra hp that you refer to, I would suggest limiting static compression to 7.5-7.8:1.

mike

 

[M.Apesland]

I guess i should have also stated that i was looking for a 6-71 sized blower as i was told that an 8-71 might cause more heat on the streat and is just a little to big for the intended use, i was thinking the whipple W200R would be a good choise as whipple does rate it to 900hp. that and the W305R is pretty dam expansive.