When rebuilding an engine with forged components and a lower compression ratio (8:1) for a turbo setup is it better to stick with a 350ci displacement or increase it to 383? I am kind of thinking it would be better to stay with the 350 because of the massive amounts of torque that the turbo generates.

 

If you are going to put a crank in it anyway, then why not stroke it? 3.75" cranks are usually the same price as a 3.48" crank. All you will need is to have the block clearanced for the extra stroke and the rod bolts, which might cost a couple extra pennies. But if you are looking @ going that far anyway, then the 383 is almost the same price.

 

Traditionally, most turbo shops will tell you that the smaller cubic inch motors like the turbos better, especially if your building a street motor. Race motors get a little bigger, but then Reiger only had a 427 motor when he made over 2400 hp on the dyno with twin turbos. Then again, the Sundowner corvette made over 1200 hp with twin turbos on a 302 sbc and ran 240 mph on the salt.

 

This EcoTec 2.2L 4cyl GM engine seemed to do fine turbo'ed with small cubic inch displacement, made 800-1000hp. And they added this "A Chevrolet 5.7-lites LS1 V8 with this much specific power (horsepower per cubic inch) would be making 2137 hp."

Granted it's a drag race engine, made to last 20-40 runs and runs on some ungodly high octane fuel.

http://www.ny-jbodies.org/forum/libr...ortFighter.htm

 

Generally, you only need to up the displacement if you are going to use a turbo that will have some lag to it. Uping the displacement is kind of a crutch in that it allows the car more bottom end power until the turbo spools up to speed. Or atleast that's the way I've always understood it. I'm sure there are other reasons both for and against. But, for what you pay for a forged 350 bottom end, you can easily spend a few bucks more and get the 383 bottom end.

 

Alright, thanks guys. I will just plan on spending a little extra and going the 383 route.

Right now I am putting a shopping list together to figure out what everything is going to cost.

 

The advantage of more cubes is that you get more HP with the same octane fuel than the smaller one...

I would like to hear why would someone advise to use a smaller displacement engine with a forced induction engine, since all I have heard and seen is that bigger displacement always helps no matter what, with the exception of some nascar engines and their restricted ports etc etc etc... but its "only" 8CIDs, here we are talking about 33cids more... more or less the difference between 396 and 383 and 358vs 350, since most people prefer the 383 over the 396 for longetivity and some other hassles?

Anyways... with boost, the longer stroke will be filled perfectly and thus taking a lot more advantage from the stroke than on N/A

Unless you want to rev the crap out of it.. go with the 383.

 

You can use my game plan...

Dart Little M block with 4.125 bore and an Eagle 3.75" forged rotating assembly. 434 CID (or something like that)

 

smaller engines are better for big power adders because they hold together much better. thats why you see small 4 cyl making allot of hp, like that example listed before. but for your case, i dont think staying with a 350 would be any weaker than 383.

 

Alright, I'll go with a 383. What are some of the most highly recommended brands of parts to use? What about rod length?

Thanks.

 

I'd go with a 6 inch rod, but a 5.85 is good too. As far as brands... what kind of budget are you looking at?

 

This is something that will probably take a year or two worth of saving to get what I want. But I am figuring around 5 or 6k for the engine alone, not including the turbo stuff.

 

Sounds good. My Eagle rotating assembly was around $1700 before I decided to switch to the Little M block, I need different pistons now (along with a block). But something like that would work well for you as well. A nice set of ported heads, and a different cam (the 306 won't work well with a turbo/SC). As far as a turbo kit goes, I believe PTK is what most people prefer, could be wrong though. How much boost are you planning to run anyway?

 

I have no idea on how much boost I plan on running, but I am shooting for 650+ hp on 93 octane pump gas.

Where can I find more information about the Little M block

 

It's a Dart product, so you should be able to find it on Dart's website. The Little M is an aftermarket gen 1 small block so you can't use it as an LT1. Although, you can supposedly make a 454 small block chevy with one.

Here's a link.

http://www.dartheads.com/csblittlem.htm