i am in the process of building my setup and am stuck on the best route for me. i have the stock lt1 out of the car and am woundering if i should go forged 383 or 355 with a supercharger or turbo. i dont know if the extra cubes will help that much. i think it might cost more for me to go the 383 just because i would like an aftermarket block if i went that route. my goal is 500+ hp and am woundering if i can make that safely on just 355 or would i be better off going 383, i know with 355 i will be able to rev it higher with suporrting mods. i just dont know to stick with 355 or 383
thanks

 

Turbo 355, N20, 12 bolt rear, TC (if auto), clutch (if manual).

 

Definitely 383.

Most say that a T-76 isn't enough turbo for a 383 and a 355 will make more power. Unfortunately, I found this to not be true. I just blew up my turbo 383 and converted to a 363 (4.060" x 3.50") to supposedly better match the turbo. At 13 psi boost, I dropped from 604 rwhp down to 572 rwhp. I'm certainly kicking myself for doing that!

Mike

 

thanks for the input guys

 

Forged 355, smallish (226/236) cam, ported heads, S-Trim should get you 500rwhp.

 

355ci + T67 (or T70) turbo = 600rwhp with a manual tranny and 13-15psi.

No aftermarket block need for anything under 1000rwhp from what I have read.

 

Yea, forgot to answer that part. Big Rick has gone 8.0 at 170+ using a stock LT1 block, though splayed and filled. 1250 rwhp through an auto.

 

well for my goals as just a quick street car you think its nessecarry to go 383. what if its almost the same price. the thing i liked about the 350 was that i have valvetrain work and could safely rev it up to 6500 and i herd it wasnt a good idea with the 383 cause of the stroke

 

If you want the extra power offered by the 383, then do it. If you don't mind having 20 - 30 hp less, then don't stroke it. Personally, I really wish I had kept my 383.

As far as rpm range is concerned, the 383 will move down peak hp by about 200 rpm, but make more when it's there. Don't worry about rev capability. People run 383's up to 7500 all the time. If it has decent parts, it'll be fine all day long at 6500.

Mike

 

383 not worth the extra money in my opinion...500rwhp is easily attainable with a 355. in the end your power is going to be limited by your turbo setup, not your engine displacement.

 

Here is my opinion:

383ci isnt any more expensive then a 355ci. My 383 done by HPE was $150 more than a 355ci setup (cost of clearancing the block). The maor difference is the size turbo you can run. I would not run a T70 on a 383ci because it wil not be as eficient as a T76. A T76 will have more lag. For 500-600rwhp, he can run a T67 or T70 on a 355ci and spool fast on the street...big turbo isnt needed.

My point is based on a hp goal, you can run a small turbo for fast spool. A small turbo will be more efficient on smaller cubes.

 

if 500hp is his goal, a 383 will be more expesive becase he can still use his stock crank with 500hp, instead of upgrading to a 3.75 crank. pistons are also cheaper in the 355 flavor, not much, but every penny adds up

you also have to factor in longevity, a 383 has such a high stroke:bore ratio, it will wear quicker on the inside/outsides of the cylinder walls, and you will have to rebuild sooner. ive heard as quickly as 20k miles the bores being out of round on a long stroke motor

and about the turbo, a single t70 will spool almost instantaneously on either 355 or 383, and will support about 600rwhp, so i think that would be perfect size turbo for either motor...

but then again, im partial to the t-70's, i like em so much i bought two

 

True about the stock crank. I was assuming forged pieces for both setups.

The T70 actually made 700rwhp@14psi on an sts ls1 346ci z28. A T67 or T70 will spport 600rwhp no problem. Just remember hough, the more inefficient air, the hotter the air.

 

very true about effiecency/heat, but with modest goal of 500rwhp, plus the cost of a t70 vs. t76 and 355 vs. 383, ide really lean toward 355/t70 with a nice obx or similar FMIC, 24x12x3 can be had for about $200, and should adaquately deal with the heat from a single t70

 

I agree...small cubes with small turbo = 500rwhp easy.