I have a Dart Big M block, 4.600 bore, good steel 427 crank, some 6.660 rods and domed 1.245 pin height pistons. My engine calculator says that's a 500 ci monster. Anybody ever tried one? I have an '81 vette to put it into behind an over the counter cast iron Super T-10. Anyone who's ever done much work on a vette knows that the drivetrain, particularly the rear end, isn't known for handing a lot of torque. That's why I'm looking at the short stroke. I also have a set of aluminum heads, 320cc runners. Chime in, guys, I'm all hears. Any speculation about the combo and it's capabilities would be appreciated.

Sounds pretty good to me. I currently run a mild short stroke bbc with decent results. Would love to try something similar to what your proposing.

I've got a deal for you. Ship all the parts to me here in MD, I'll do all the assembly and then install it in my chassis and tweak/tune it for you. After enough passes to prove the combination was worthwhile, I'll gladly return it to you graemlins/thumbsup.gif ...all free of charge to you :D .

Not joking either.

smile.gif Good offer! My dream motor myboty! 500+ inch of spinin' rat! Todd, man, what do you think!? I mean you could go sub tens!!!!! 9.80@ 139!! :eek:

Todd, want to see what you can do with my motor?
4.375" x 3.76" :D

Originally posted by Epistuff:
Todd, want to see what you can do with my motor?
4.375" x 3.76" :D As long as your paying for all the parts (roller cam, etc), then sure...send it down here :D .

If I was to build a motor like being talked about I would strongly consider a 4.625" b x 3.5" s = 470" motor and build her strong as possible and run her just like a little 302 Z- motor with a -754 cam or big Isky solid in her and low gears in the back!!!

I honestly figure that anytime a motor is larger then say 400 inches, it can make enough grunt regardless whereas the little Z- motor was almost too small to produce any simbalence(Sp?) of good grunt..

pdq67

500CI on a 3.76 stroke. I would think that would still be a 550 ft/lb motor. I have never had a 454 that would hook in "street" trim, but always liked the way a 427 would come on at 3500+. I am facing a similiar situation with the 454 block I have sitting in the garage. Although it is still a std. 4.25 bore, a couple of cylinders are gouged deep. +.100 will clean it up. In this case a 4.350 x 3.76. That's still 447 CI motor. In the "Vette" I would think the 3.76 stroke may come on smoother and not kill the chassis. At 500CI, it will still be a handfull.

Go for the extra stroke at 4.25 and get the max cubes out of it or 4.50. More is better. Just my 2 cents.

Rob

I have a second block at 4.560 that's getting the 4.250 crank for a pump gas '56 streetrod truck. I'm gonna call this the big block version of a 302. My mechanic also tells me that short stroke/big bore engines respond to nitrous like nothing else. Don't think I'll need it, but it's good to know. What are you guy's thoughts for intake/carb? I'm kinda thinking a pair of Holleys ought to add something to the WOW factor. Thanks for all the replies and keep 'em comin'.

I think a tunnel ram would be the only way to go! 11:1 compression, alum. heads, large by huge cam and zoomies tongue.gif .
BTW myboty, wherabout are you in Lubbock? I used to live around 38th & memphis. I won't be offended if you want it a secret. graemlins/beers.gif

I'm out close to Lowery Field off 66th between University and 66th.
I either need to try to keep this thing under an L-88 style hood OR I'll try something along the lines of a shaker with a fiberglass breather cover separate from the hood. That's actually the way I'm leaning right now, but still don't think I can go tunnel ram. It's tough enough to see out of a car when you're tilted back at about 23 degrees without having to look around a big intake.

Well then, stick a 3X2 on it. 1125 cfm, and it's open plenum when all the carbs are breathing, dual when the center is. Cool, huh? Fitting, even in an '81.

427,

You run a bored out 427 motor on a street/stock chassis, but I've seen you talk about doing a 496. The 3.76" crank has to be a little easier to launch. Heck, my hydraulic cam 408 won't hook, I couldn't imagine another 100 ft/lb of torque thrown in there. I would think a 500 ci 3.76" stoke motor would still be RPM limited do to piston mass [ unless you were willing to spend the money to get the right parts ].

496 ended up in my flatbed crewcab. I put a lift gate on the back of it and use it to lift and haul engine cores (among other things). That one ended up with 781 heads and a Q-Jet with a 210/218 flat tappet hydraulic roller and will pull like nobody's business. I agree that it would be rev limited, but 7K with a big block still has to be music to a gearhead's ears.

Well the motor definately sounds cool, kind of the opposite of what everyone else does...short stroke over long stroke.
Now im not trying to rain on your parade here but i dont see a factory borg warner holding up.

Originally posted by GRN69CHV:
427,

You run a bored out 427 motor on a street/stock chassis, but I've seen you talk about doing a 496. The 3.76" crank has to be a little easier to launch. Heck, my hydraulic cam 408 won't hook, I couldn't imagine another 100 ft/lb of torque thrown in there. I would think a 500 ci 3.76" stoke motor would still be RPM limited do to piston mass [ unless you were willing to spend the money to get the right parts ]. =
If you consider 8500+ RPM limited then yes I guess the 3.76 stroke is RPM limited & this was almost 30 years ago with stock cranks, L88 rods & TRW pistons before I was aware you "couldn't do this" :D
This was done with regularity with both a 3.76 452" engine & 4" stroke 482" engine & this was not an automatic it was a 4 speed Lenco.
Both engines ran about the same MPH but the 482 ET'd consistantly better by about two tenths
A tic over 150MPH (best was 155) with both 5.13's & 5.38's & a 32" tire,, you do the math ;)

Granted, this wasn't exactly a street car but if you pull about 1000 RPM out if it with a longer rod to get piston weight down I think it would make for a very livable street deal,,, & oh yea,,, rats do sound rather sweet the other side of 7000,,,,,, graemlins/thumbsup.gif

Mike,
I wasn't referring to rpm's as related to stroke, the rpm potential of a 427 is not even in question. I was referring to rpm as related to piston bore and piston mass. I was under the impression that in order to get a reliable motor like we are discussing, the component parts quality will have to go very high. But then you threw the rod length into the equation and this is where things must change. So I would assume this is one of those areas where you are not going to want to hog out the cylinders and try to make a stock 6.135 rod work?

Joe, the 496 I flirt with will be a very low rpm motor, essentially looking like a 1967 396 325 hp. Very different deal. Much like Chris Corwels's motor, desinged to run ok through an M20 and 3.08s. Its not a street/strip motor. It'll be my 'restoration' piece. Which is why I'm willing to sacrifice and use ovals. ;)


RPM limited? I bet GOOD slugs for a 4.5" don't weigh much more than the heavy-arse TRW/GM slugs I was taking to 7300-7400 rpm. And the motor made it for 30,000street miles, almost. And that was a backyard built, stock L88 bottom end motor. But again, don't know the weight of say a SRP/JE in the 4.5 config. TRWs were, what, 745-750?

Ah, slightly heavy, on the JE ( SRP doesnt make them) side, 3.76 X 4.500, using the 6.35" rods weigh in at exactly 700. Not lightweight, but still lighter than the heavy TRW/GM forgings pushed past 8000. An old 6223 or 7118 crank would balance them nicely.

Rods I have are Lunati Pro Mod 6.660, so I get to use 1.245 pin height shelf pistons and I have a line on a Lunati Pro Mod 3.76" stroke crank. Internals will be able to take the revs, IMO

7500 easily IMHO, yes! Only because we did it with much less and drove the engine for 30k!( don't use an HV oil pump, it would have lasted longer!)

This is a "again" an interesting topic. The dilemna of cubes. I was also looking into the stroker motor but wound up using my 408 / oval port combo w/ 3.73's and a 3000 stall. But still want to run the A/C and make it more of a cruiser. There in lies the dilemna a lot of us face. What range to build the motor. I currently run my hydraulic cam 408 to 6200 - 6300 but I have not hooked up the A/C comp yet. My past experience tells me that A/C and RPM don't mix [not that 6300 is that high, but it is alot higher than the 5200 - 5500 the system was designed for]. I am also considering dropping the rear to 3.31's or even 3.08's for the cruise factor. The original post was looking into a 500incher on a short stroke. So the unanswered question comes down to : given a target displacement range whether 450 or 500 CI, which is better - big bore/short stroke, or longer than stock stroke?

This thread got off on 2 directions. Myboty is obviously looking at an all out hipo big bore motor. My experience with Vette's - you are looking at too much motor for a Vette chassis. The earlier cars had even better rear suspensions than your '81. The rear setup in that car is a lite wt housing. The only way I would even try to put a 500 incher in that car would be auto with a tight converter. NOS will hit too hard. If this is going to be race car and you want to change the chassis, that's another story.

Joe, Sir I beleive you answered your own question or at least posed the question properly,

The operating range question, and the overbore/overstroke question. Do higher operating ranges favor the overbore, lower operation ranges favor the over stroke? As a hobbyist, I would comment that , at least GM thought so when they did the 302-class and 427-class of engine, both of which were, in their highest performance trim, 7500-rpm engines. While the SD 455s were still only 5500 redline.
( btw the 496 I'd like to build one day would feel ultimately comfortable in your engine bay running AC and 3.08s. I'm letting the gear ratios dictate the rpm range, so really 5200 is peak. And probably a cam no bigger than the 280/88 mr 4 speed runs in his 454, or maybe a more intense HyRoller equiv.

Originally posted by GRN69CHV:
Mike,
I wasn't referring to rpm's as related to stroke, the rpm potential of a 427 is not even in question. I was referring to rpm as related to piston bore and piston mass. I was under the impression that in order to get a reliable motor like we are discussing, the component parts quality will have to go very high. But then you threw the rod length into the equation and this is where things must change. So I would assume this is one of those areas where you are not going to want to hog out the cylinders and try to make a stock 6.135 rod work? =
No, if I were doing it again I would not use a 6.135 rod & this has nothing to do with power potential it has to do with weight of the piston.
The engines I built 30 years ago I wouldn't consider doing today for the same purpose.

Just saying what can be done when you "don't know any better" :D
Both of these engines ran L88 rods & had pins in them like an aluminum rod to keep the bearings from turning in the caps they were distorting so much.
I used to cut the caps for resizing on an angle to give more clearance at the parting line & the rods still distorted enough to turn the rod bearings. The pin cured it but the pan was off at least every couple of races to check & I also ran M bearings that are very soft.
The 452 met an untimely death after a couple of seasons & a few "test runs" with 5.57's but the 482 was run in 2 different cars, a 69 Camaro & a Vega & sold to a guy that put it in a boat.
The sucker had so many runs it had a slight ridge in the bore :eek:

I feel if you pulled it back to about 7500RPM & kept the piston weight down it should be reasonably reliable.
We are not talking about a Honda Civic here that you are expecting 200,000 out of :D

The big bore engine is going to make more power because of the difference in breathing ability given a decent set of heads like say a 335 or 357 AFR which will show upwards of 20-30CFM difference on the larger bores & this is not anyone's advertised numbers it is fact off my bench back to back testing at 4.310" vs. 4.530".

Drivetrain breakage can be done with a 305 or a 500" engine & it is just something you as the builder need to address if you want to push the parts.
I say build the sucker & fix what breaks,,, one weak link at a time :D

First : to 427L88 - this is Gene right? My name is Joe, I kept getting confused with reading your response - I am assuming you were addressing me as Bill.

Secong : Mike (Wolfplace). My take on your response is go ahead and build whatever you think you want and work out the details of the package as you go?

graemlins/clonk.gif , yes Joe, sorry.

This is an original numbers car and all I'll have to do to the interior is replace carpet. I'd planned to pull the original engine and tranny for numbers/value sake (if I hold it for 20 years, it'll make a difference) and replace it with a strong hydraulic roller cammed 406. I'm thinking that may be the way to go at this point. The aluminum differential is my weak link and the swap to cast iron is expensive. I can strap the caps and deburr it and get it to hold my 406, but the torque of a big block would probably spray parts all over the street. Maybe I should wait until I build my trailered race only 'vette with a 9" and PG. I'd hate to spend the money building an engine that I couldn't beat on and it's not fun to cringe at every high rpm shift, expecting to shell the drivetrain every time. It would be such a waste to have that much hp and tq on tap and not be able to enjoy it. If this car was 2 years older and had the older, stronger rear end in it, I'd go with it without looking back. Still like the combo and will probably build it for that drag-only combo, though. That car should weigh in somewhere in the 2700 lbs range and that easier launching 3.76 stroke may be just the ticket. Keep the responses coming, though - I'm enjoying it.

Originally posted by GRN69CHV:
First : to 427L88 - this is Gene right? My name is Joe, I kept getting confused with reading your response - I am assuming you were addressing me as Bill.

Secong : Mike (Wolfplace). My take on your response is go ahead and build whatever you think you want and work out the details of the package as you go? =
Joe,
Where did that come from??
Your "take" on my response is a bit off.

All I am talking about is the engine & what can be done with it.
If you put it in a car & break stuff as you probably will you need to address those problems.
Got nothing to do with build what you think you want & work out the details as you go.

I don't build cars any more, I build engines & will build what ever a customer wants.
If he puts it in a car that is not capable of handling the power & would assume he would address these problems & I believe that is pretty much what I said & even that was said in jest as the big grin implies :D

I would assume most people on here realize that if you build a real engine & hook it up you are going to break stuff so you build it as strong as you feel necessary & again you fix each weak link as it rears it's ugly head,,, "one weak link at a time" :D

Mike,

I refer to the "package" to include the chassis and drivetrain. I assumed that is what you meant by fixing the weak links one at a time. I addressed this last fall in a thread " How much is enough?". It seems that no matter where I go, you run into guys who are always looking at a new motor combo, but have held off because of other reasons - like chassis, undefined driving goals, etc. etc. I completely understand what you are saying, didn't mean to come off questioning it, poor choice of wording. The reality, I also fall into that category of drivers that has quickly grown accustomed to the power level in my current mill and is saying - ok, 360 - 370 HP was ok. but I think what I really want is a 500 HP mill under the hood, now how do I get there and still mantain practicality, reliability and docile driving characteristics - all in a street package. That becomes the defining means of differentiation for me. Street package has to include: idleing in traffic, running A/C, driven on street radials (that will also work in the rain), suspension tuned for handling curves, not just straight roads.

Tall request to say the least. Or so it may seem.

The original post in this thread lead into a discussion of what would work better in a "81 Vette" chassis.
It really is all about having to make a decision, isn't it. Tough item to tackle - ego/practicality, power/driveability, power/power? As long a men have a pulse, 2 things are eminent - they will always want more power and they will always be checking out the women. Not necessarliy in that order!

Originally posted by GRN69CHV:
Mike,

As long a men have a pulse, 2 things are eminent - they will always want more power and they will always be checking out the women. Not necessarliy in that order! graemlins/beers.gif

And this leads to that other dilemma,,, supporting your local body shop because of checking out the women while playing with your new found power :D :D

Not to mention,, it's really hard to look cool in your ride when it's in someone elses trunk : graemlins/sad.gif

That's why God instilled man with intellect to invent the automotive horn - the equivalent of yelling "fore" right before you hit the guy on the next tee in the back of the head after a really bad slice!

graemlins/beers.gif

Oh and by the way, one advatnage of living on the east coast - it is now dinnertime here - and yes that includes a couple (er few) of the cold ones.

Dug out my copy of Hot Rod's "Hot To Build Monster Chevy Big Blocks" and found an article where they built pretty much this engine. Bowtie block at 4.600, L-88 crank, ported closed chamber rectangular port heads and an Engle solid roller 261/269 @ .050 with .696/.681 lift, topped it with a worked over dual plane intake and aluminum rods. Static compression was 11:1. Dyno results posted in the article started at 4000 with 423hp and 555 ft lbs of torque. Torque peaked at 5200 with 613 ft lbs and hp was still climbing where the chart ended with 700 horses at 6600 rpm's. I know the guy that built it and will give him call in the next few days to see what he remembered about it. I'll try to fill you folks in on what he learned from it and whether or not he'd recommend it for a light car with limited traction.