FailedWisdom

I was wondering, which engine combo (400, 454, 434, 427, or 468) would be able to make a broad torque range, and still rev to a redline of 8000. Don't want a big block, just a large small block.

383vett

A larger displacement motor will not need to rev to 8000. The larger cubes means more power and more torque. A smaller displacement motor will have lighter components and can rev higher to make up for the lack of cubic inches. In drag racing, a big block can effortlessly run quick times while a small block has to rev like crazy to run the same numbers.

mike100

A 450 to 500 cubic engine is going to have a hard time making peak hp through typically available cylinder heads whereas a 427 with it's shorter stroke and lighter internals will have a better chance pulling past 7000 rpm using those same heads (and lasting).

yedister

Why would you want to rev to 8000 rpm? This would require at least a 15 degree heads for a 468. it is possible, the main items would be the heads, intake and cam. The cam would have to be bigger than what most people would advise for a car driven on the street but it would be a beast and fun. The link below goes over this topic for a more race only point but there is some good information and concerns in there. I would say build it big feed it the air required, then let the cam be the brain. http://www.yellowbullet.com/forum/showthread.php?t=7949

Beach Bum

Just a few notes, a 454 is traditionally a big block, not a small block, albeit small blocks nowadays can be made to 454 ci, it is not all that common. I'll also say, big cube sbc are typically challenged in the rod vs stroke department, hence rpm range can be compromised in durability and reliability. It is doable though. A 468 is typically just a .030" over bored 454 big block.

427 is popular in both sbc and bbc configurations. Typically a 427 sbc is a 4.125" bore x 4.00 stroke, That bore is the standard bore most aftermarket blocks and stock chevy 400's came with...... but a 427 can also be an overbore with the 3.875" stroke. 434's are typically sbc, with a 4.155 bore x 4.00 stroke. 427 big blocks, while popular back in the 60's and 70's are not popular these days simply because time has passed them by in the cubic inch department. Nowadays, even a 540 ci is considered small in some circles.

All your selections can make a broad torque range. However, 8000 rpm is another issue..... starting with typically hyd valvetrain limitations. Although certainly doable, your streetability would be greatly compromised in building such a motor. I recommend you define your application and you'll get a much better idea of real-world combinations that can help you achieve your goals. I think you might find, that your goals are probably easily reached with an affordable and easy to work with 383.... of which multiple people here are even capable of building for you.

tpi 421 vette

You don't have to rev it to 8000rpm to go fast... especially on a big cube SBC. And your engine will last alot longer if you don't rev it to the moon.

cv67

Check out tpi421Vettes sig, hes living proof of that, no high rpms for him just brute power . Maybe he can put something together for you :

1985 Corvette

I'm no expert by any means but aren't 8K rpm motors the kind where you have to take the valve covers off every week to make adjustments? Valve train which will see 8K rpm on a regular basis is probably worth its weight in gold. Makes my head spin just thinking of the price.

And that's not even getting to the rest of the car. Assuming one put together such a big cube high rev car. From a simplicity standpoint finding the weakest link in the chain becomes very easy. Your chain would consist of two links: the engine and the rest of the car. Guess which one is the weak link?

cv67

Wallet or credit limit which one is weaker

Muffin

Does anyone have the video of a valve spring at 7500rpm I think it was. Posted here some time ago.

FailedWisdom

Thanks, I was thinking of something that will kill at the track and get 9's at the strip with some afr 235 eliminator. Saw those in a hotrod article (http://www.hotrod.com/techarticles/e...ads/index.html), but it might not be as steerable as I want. If you guys have any suggestions on heads, that'll be great. I though Revving high could help on passing, and be fun on weekends.

FailedWisdom

Yeah, He seems qualified. Haha Thanks, those numbers seem alittle lower than I had hoped but definately alot more streetable.

cv67

9s at 140+ is one hell of a street car

Midnight 85

You, my boy, have a LOT to learn. Now before you ruffle up your feathers, I'm not belittling you, it's a known fact that reliability lies in a much lower rpm range than you are looking at. There is no substitute for cubic inches. Build it big, build it simple, and run hell out of it all season.

383vett

Jim (TPI421) can set you up with a great engine combo. He has the knowlege and skill. He can also get you a great deal on AFR heads. He has built many motors for forum members. His C4 would be well into the 9's if he didn't live in 5500+da country. Willie

FailedWisdom

383vette are 421's the only engine he builds, or just his preferable one? And what are the price difference between him and summit? And Midnight, yes I know I have little experience, but i know theres no replacement for displacement. i was just wondering what set up created the best balance of Horsepower, torque and "safe" RPMs

tpi 421 vette

Send me a PM or Email, and we can discuss it. I like 421's and seem to do alot of them, but anything is possible.

383vett

Summit would be way cheaper, but you get what you pay for. At Summit, the motor might be assembled by some first timer right out of high school trying to figure out how to set a torque wrench. Parts are purchased in bulk and put together quickly. With Jim, you've got an experienced engine builder who will check and double check every clearance and machine the parts to race tolerances. The Summit motor may blow after 2 nights. Jim's motor only after the third. Seriously, there is no comparison.

FailedWisdom

Tpi421vette (Jim, if it's alright), what are your experiences with the 421 combo? Is there a price/reliablity benefit?

tpi 421 vette

I have done 421's from mild to wild. A 421 with a baby 222/230 cam old AFR 195's, that made 416 rwhp 440rwtq and got 23mpg, and would pass emissions. And it ran 12.40's with a DA of 7500ft. And on the other end of the spectrum I have done 500+rwhp N/A 421's. What ever you want or can afford!

A 421 with a 6.0" rod will give you a good compression height of 1.0625 and a pretty good ratio for a big inch SBC. And that will help longevity.