Why not just build a 347 with better rods/pistons? Look in the forced induction threads and most people you see are running 347 or 370ci. Personally I would ask them what the advantages/dis adv are to larger ci on forced induction. No offense but most of these guys are talking n/a. And how much hp are you looking for? Just run more boost... haha. If you went stock stroke then you could save an extra 7xx on a crank. JMHO but good luck with your build!!

 

good point with your turbo a forged 347 would be the deal.
http://www.schwankeshortblocks.com/S...rt%20Block.htm

a complete 347 iron short block for 1799.00, iron for high boost and the low price thats would be hard to beat IMHO.

I posted a link because i know they were a sponser and i think they still are..........if not my bad

 

First- whats your budget? Second I will agree more cubes are better then less, so if you can build a 408 for the same price as a 383...why not...Lastly to the people who say a 383 cant be built.....guess again....i make 530+/470+ and run 10.70's @132 in the quarter with my combo....cam is a mild vrx5 cam...but my engine isnt a budget build....no expense or option was not considered when being built.

 

You would have made more with an equally planned 408, lol.

 

check out this SS LMR did 408 rear mount 88mm turbo made like 733rwhp and you can drive it on the street ive personally seen this car has a killer sound to it and the motor has ported 6.0 truck heads on it. 9 sec street car with AC
https://ls1tech.com/forums/texas-mem...ght=LMR+camaro

 

i have yet to have found a 408 making more hp/tq with a similar cam.....

 

I dont get too caught up on dyno numbers, but im sure there are plenty out there.

Since you obviously like to get caught up on numbers, ponder on this.

Your motor makes 1.389 RWHP per cubic inch.

An equally efficient 408, would make ~567rwhp.

There are a ton of factors that come into play, and its next to impossible to get an apples to apples comparison. However, more cubic inches (especially when that displacement is gained from a larger bore), will ALWAYS allow for greater power potential in a N/A application.

I cant believe people are still arguing this. This is about as bad as the uneducated old time hot rodders that sit around and talk about how they would rather have a "rappy de-stroked motor" like its some sort of secret recipe to take down the competition.

 

sorry...it does not work out that way....and sure dynos vari..but i put down 10.77 @132 at the track with a full weight c5- extra stereo crap...amps etc... and 4 point bar etc...and i still get 28 mpg on the highway and 20 in the city...

and three weeks ago while leaving worcester, ma....ran from 30-150 side by side with a new zr1 and he didnt pull me.....the owner came over last w/e at paul masse vetteacular and told me he was flat foot wot in his zr1 and could not come around me.

 

Im not debating that you car runs well, and makes good numbers. Im simply stating that you would have made even more with a 408.

 

What's the stroke length on a 383 compared to a 402 LS2?

 

Same, 4.00 inches.

 

the only 383 to make more power was Tony Mamo's and he was using a solid roller..and he only made 10 more peak hp...... when you increase bore and or stroke rotational mass increases...this is why your theory that i would have made more power is flawed....

 

You may gain a very very slight amount of weight from a piston that is .10 larger in diameter.... HOWEVER.... you gain the ability to run a larger valved head, which more than makes up for it (assuming you plan your combination accordingly to take advantage of that).

There is no doubt that you have a very stout 383... it probably DOES perform better than most engines that are larger displacement.... BUT if you would have put that kind of research and knowledge into a 408, you would have made more power. That the simple truth.

Ask anyone in any form of drag racing.... in a N/A application you run as many cubic inches as allowed in the class. No one has ever had a 400+ inch motor and thought "I think we could go faster if we dropped a few cubic inches and went with a smaller bore 383"

When i was going through the process of deciding what sort of combination i was going to do, i also considered all the options. I was set on doing a 408, but then i got a call from my engine builder, who said "Why not go 418... it would use a 4.1" crank instead of a 4"... its free displacement and will make a little more power".

Im really not intending to get in a pissing contest with you, but its simply ignorant to think that there is an advantage going with a 383 vs a 408.

 

Well Im in the process of buying the 383 assembly. I have the stock heads off my LS1 with dual gold valve springs. Will this work with my 383 Im running short on funds. Machine shop said maybe to mill them.. I dont know much about this. I will be boosting with the sts, will my stock heads work or should I let the machine shop do some work to them. Going back with new pushrods and rocker arms

 

if your going to run boost, the only thing i would do to the heads is polish the chambers ( you can do this yourself...not hard only a couple of hours work) ...thats it..no reason to deck the heads and raise the c/r as your hairdryer will do that quite well.

 

I'm doing the 383 build with forged rotating assembly ported 853 heads and ms3 cam with turbo 350 and 4500 stall. Should be interesting. But not cheap.

 

with the stock heads and the -15cc pistons I chose the builder said it should put me around 9.7 - 9.9:1?? That sound good for boost, also how much you think will be safe with all the callies forged goodies and a good tune. So no reason to get headwork??

 

First time out with my 383....5.76@124 on a very conservative RPM tune. I'm happy as hell!!

 

I have a iron 370ci and I got it mainly (from LME) due to price. After having it for 2.5 years I can say that if I had to do it again I would have got an alum block (being NA).
But seing you are going Turbo route, I would go the 370 way.
You'll save on crankshaft cost and can put that towards nicer heads.

 

The reality of it is: Do you want to pay some local machine shop (who may or most likely, not have experience with HP LS1 motors), make countless trips there, dragging along your motor, dropping off ordered parts, etc? Or do you want something the same, (or larger) from a reputable LS1 builder, there are plenty on here who know what they are doing with this engine.

Imo, I would research who you think is the most reputable, and get something from them, sell the motor you have, and have piece of mind knowing you have something that will last.. Having a local place doesn't mean **** when it comes down to waranty.. Most places aren't going to back it up when you are pushing it like you want to. Good luck.