Im trying to figure out weather i want to stay with a standard displacement SR IE:355 or go stroker. The heads will be LE3 stock castings. The cam duration will be in the 250's intake, 260's exaust and mid 600's on the lift on a 108-110lsa. Per my research I realy dont think I'll make more power going stroker veresus staying with a 355. the only advantages im seeing are more power under the curve and a little more torque if I go stroker. On the other hand if i stay standard displacement I wouldnt have to worry about sideloading on the cylinder walls and I could spin the motor to 7k more reliably geometrically+the cost. Im looking to have my static compression around 12:1 and a dcr of about 9.0:1. We have 93 and race gas here so detonation shouldnt be a problem. I want to trap as close to 130mph as possible as i dont really care about et . So what do you guys think stroker or 355 for this build?

TIA

 

I prefer the broader power curve of the stroker motor....I have ~15K miles on my 396 and am currently shifting at 6800...rev limiter set to 7000

 

So you think the power will be peaky with the 355 or just not a broard as with the 383?.

 

If your going to spend the money to spin one 7k+ go with the extra cubes, especially if the car is heavy, 3400lbs+, the extra TQ will really help out.

Randy

 

Shammon - Why would you not step up to more cube's ? "Quote John Lingenfelter" It's free torque - torque follows displacement. You will be spending close the same amount of money for parts.

 

Go with the cubes. I know some dyno tests show no hp improvement, but I think those combo's just didn't have enough air flow to support the cubes. With LE3's and a big SR, it'll make more power.

A local engine shop does alot of dirt track motors and dyno's all sorts of stuff. It's rare that a 350/355 breaks 600 hp, though some of the ultra-exotic $25k mills make 650. 383's and 406's will make 630-640 with pretty basic parts. 434+ makes up to 800.

Mike

 

I see were both of you are coming from, I just wanted to make I dont end up with some mismatched combo.

 

Don't go .030 over with the pistons with the longer crank, if your worried about the thinner cly. walls.

 

All an engine really is, is like a really big air pump. The more air you can suck in the more hp it will put out. Having more cubes will most definitely help in this department. As they say, theres no replacement for displacement.

 

as long as your heads can flow for the extra cubes your good. That is the area you will need to research.

 

I'm sure there is a formula for calculating required airflow for specific engine combinations. For instance, if my heads flow 270/197 @ .600, and work pretty well with my stock bottom end, how would I find out whether they will be sufficient for a 383 with a larger cam?

 

Good question, I dont think ive seen a formula for that.

 

I have almost the same problem though I have LE2 setup. Let someone throw some light on it..
How the power curve will change with stroker? Will peak HP affected or not? I imagine that peak HP will stay the same but on lower RPMs? Is that true?

 

the est req'd cfm for a 355 is 791cfm and the req'd cfm for a 383 is 853 all assuming u going to the pcm limit of 7Krpm and for kick's a 396 is 882cfm...

as far as figuring out if your heads move enough air i'm guessing you would have to divide that by 8? i don't know..

 

I agree with all of the above and have owned a 383 before but my old 355LT1 is hard to beat. I know I could go a little quicker with a stroker but there is no way it would hold up the way my current combo does. I pulled the engine in December and it had been in my car for over 2yrs, over 150 passes, over 40 n2o runs at the track and it looked perfect. I changed the rod bearings b/c it had detonated a few times while testing 175HP n2o with pumpgas. I even thought about putting a stroker crank while it was down but I like the reliabilty of this engine. JMO Later Clint