Redvette_22

In having purchased my 72 Vette a short time ago, and the engine needing work, I'm thinking of either going with a 355 or a 383 short block. I'd like to have some input from people who have made either change and the "good" and the "bad" from either choice. My car will be occasionally drag raced, but I'm not sure how far I want to go on the powertrain. At this point I'm not planning on changing the rear end gears (3.08 ratio) but plan on doing a 3000+ converter, and maybe (this is a BIG maybe) an Edelbrock Top End Kit with retrofit roller cam. I've been told that the 383 is not the way to go, but the recommendation is from a person who has never had a 383 dual purpose street car, so I don't really put much credit in that appraisal, which is why I'd like to get recommendations from people who have done a 383 over a 355.

BKbroiler

The only disadvantage of a 383 versus a 350 is the 383 might cost more to build. Otherwise, the 383 is the better engine. More power, especially low end, which is great for the street. I have a 383 in my car, TH350, 3,000 stall and 3.73 rear. I have run as quick as 12.15 on drag radials. It has a mild cam and excellent street manners. You'd be hard pressed to do that with a similar 350.

76Rat

You know the old saying "there is no replacement for displacement" It will help with that 3.08 rear

C3 Stroker

Go with the 383 (been there, done that)...you'll feel better with the results. About the 3,000 stall converter, don't just install it on general principle, let the cam of the new engine combo determine if you need it or not......especially with a 3.08 rear.

fishslayer143

The 383 will produce more torque.. torque is the most important thing in a street performance engine .. you will not regret it

Khibbs

I'd agree with all of the replies already and I'm thinking of a 383 for my next build as well. I'd be curious as to what reasons you were advised not to build a 383 over a 355.

cv67

w/fishslayer

torque is what pulls a tall gear and pushes ya back in the seat
Its not the sheer ci so

Sometimes you still hear "Oh shorter stroke high revs are better...watch xxx piston speed" sure bud!

There are good enough parts out today where you can run more stroke and get rpm if you want it without worrying. My only regret was getting rid of my 400 block and not doing a 421

Match your parts right youll have a blast...BBC like torque in a SB package everything bolts right up!

NewbVetteGuy

$3,895 430 hp / 450 ft lbs; 4 bolt main 383, roller cam with a very streetable 221/226 cam: http://blueprintengines.com/index.ph...ecs-bp38313ct1

IF you're going with a 3,000+ stall you can go bigger with the cam and you'll get more HP.

2 1/2 year, 50k mile warranty.

You could save $300 and go with a flat tappet version, but that's $300 well spent, IMHO.




Adam

81corvettevortec

I went through this years ago when I rebuilt my motor. For some odd reason I thought "keep it as original as possible". Even if that was the case, not a single person would ever be able to tell without dropping the oil pan.

The cost difference is minimal and I think it would be a waste to not go with the 383.

Sincerely,
The guy that went with a 355.

AboveTheLogic

383 over 355 any day of the week. I am quite happy with my roller 355 build but I know that a 383 would be even better.

76CSRvette

I went with a 355 biggest mistake ever for a few hundred more get all the extra tq and hp plus the sound. It was fun in the beginning but now i gotta go supercharger or try and blow the engine and rebuild it again.

Torqued Off

What's the question? If you can make it 383, its a no brainer.

jb78L-82

I have a 355 L-82 with a roller cam maximizing mid range torque, AFR 180 CC aluminum heads, 10.2:1 compression, 1 3/4 inch Long tube headers and love my engine BUT I did the 355 primarily to get the maximum power I could get using as many of the OEM components as possible (OEM reconditioned L-82 rods, OEM reconditioned L-82 forged crank, L-82 aluminum intake, L-82 oil pan, OEM dual snorkel cold air intake etc). The L-82 engine block numbers match the L-82 OEM 4 speed, Vin # etc. I wanted to keep it as much L-82 as possible.....Does the engine make great power for the street with 3.70 gears? Yes.

If none of these factors matter, then 383 is the way to go. If the engine grenades tomorrow, I would install a 383, no question.

With all that said, a properly built 355 will pretty much match most 383's! Here is a pretty mild 355 with AFR heads and roller cam that makes 425 HP @ 5,800 and 440 torque at 4,600 RPM and 429 torque at 3,800 and no less than 382 torque even at 2,600 RPM.

http://www.superchevy.com/how-to/148...-engine-build/

A 383 will make about 20 ft-lbs more torque than a properly built 355. The question is does 20 ft-lbs matter when you are talking about 450 ft lbs of torque? I'm good with my 355.

ajrothm

No reason to NOT build a 383... NONE... Spend the extra $300-500 and do the 383.

Don't choke it down with too small of a head.

cv67

you have a good running 350 good parts selection
imagine another 40 lbs of torque! Youll feel that.

Agreed. System starts at the carb goes to collector make it al match youll be happy
Stroker can use more head than one would think

Kubs

That actual cost of the engine components to rebuild a 350 vs a 383 is almost negligible. The 383 will make more torque which can be felt at street speeds.

The shorter stroke, higher piston speed comment does hold true under certain conditions. If you build a short stroke high rpm engine, you need to change gearing to keep the engine in the higher RPM where that engine makes power. The gears need to be closer together in ratio and more of them. It won't feel very powerful on the street though because it needs to be revved.

The 383 is the best option for street feel and not having to change gears like you mentioned, and it will cost pretty much the same as building a 350.

Torqued Off

I hope this does not hijack the thread, but if you had that engine that Superchevy did, and simply made it a 383, would it still work. I have most of those same components, except a Comp Camp HR270, which is a dual pattern cam with slightly less lift. I think about the day to make my 350 a 383, but would not want to buy new heads, new headers, etc.....so would I gain much with simply a 350-383 gain, keeping these other components.?

NewbVetteGuy

I question your 20 ft lbs estimate; you're comparing a well built 350 to a "meh" built 383. Not really a fair comparison.

Your quoted estimate of a 425 hp / 440 ft lbs 350 is 1.21:1 hp per cubic inch and 1.26:1 ft lbs / cubic inch; a 383 built to the same ratios would be 463 hp and 482 ft lbs

--OR +38hp and +42ft lbs.


Getting the same ratio on a stroker- which by definition has the same bore but a longer stroke is slighly harder on the HP side, so 39hp increase is probably slightly overly optimistic. On the other hand maintaining a 1.26:1 ft lbs / cubic inch with a stroker motor is definitely doable. I'd say a 42 ft lbs increase is a more accurate estimate of the difference; it's more apples to apples comparison between a well-built 350 and a well-built 383 with the same ratios anyway. -We're talking about a roughly 10% increase in cubic inches going from a 350 to a 383.


Adam

NewbVetteGuy

Great question! As long as you're starting with good heads with good flow, mostly what you want to change would be the duration of the cam --you increase the duration of your cam to give more time to fill the larger cylinders. A larger cam in a 383 will have the idle characteristics of a smaller cam if it were a 350, too. So essentially cams just act smaller when in a 383.

It's also worth noting that the intake port size of heads are rated to flow up to a certain RPM on a certain displacement- if you take 180cc heads that are rated to up to say 5,800 RPM on a 350, they might run out of air at only 5,500 RPM on a 383 (note: I just completely made these two numbers up as an example; they're not real numbers; JUST an example of the phenomenon.). You'd probably be better off with larger intake port heads like 195cc or larger on a 383 if you want to keep pulling to 6,000 or 6,000+ RPM. The intake port size and cross-sectional area are correlated to where in the curve you want your power. -The old-school advice overly focuses on intake head port size when it comes to torque, there are now some fairly large intake size heads that have huge low flow numbers and great torque- they have the added bonus of continuing to flow at high RPMs on larger cubic inch motors.

One more thing to possibly investigate if going from a 350 and putting in a stroker crank is that hypereutectic pistons are rated to safely move a certain distance in a certain period of time; as they're physically moving more distance than when they're attached to a normal 350 crank, you sometimes need to be careful about high rpms which may cause them to exceed their max safe RPM. (The way they rate them is weird; IMHO, they should just be rated for xRPM in a 383 crank with 5.7" rods and everyone would understand the limits.) -So I guess the morale is that there's more than just a recommended limitation of no power adders and no NOS with hypereutectic pistons; there's a max RPM. If you use them in a 396 or 406 stroker the RPM limitation is even lower because it's actually a distance over time limitation.


-I've looked into this stuff because I'm planning a new top end in my 79 L82 and I realize at some point the bottom-end is going to need to be refreshed and as I'm going to have to fork out some $$ to a machien shop I want to go 383 then and I don't want to have to buy anything a 2nd time that I don't need to buy a 2nd time. I went with 195cc Profiler heads and retrofit hydraulic roller lifters for this reason. -If/when I need to redo the bottom-end I'll put in a Scat cast 383 stroker crank and new forged rods and pistons and swap for a bigger cam that's more appropriate for a 383 -the 195cc Profilers will let a 383 keep breathing to 6,000+ rpm (I don't want to kill the poor girl so rev limiter at 6,200) and hydraulic roller lifters can be reused with a new cam although if a few years have passed I'll probably replace the heads' springs at that time, too. (and my special snowflake FIRST intake will need to be ported to support the air requirements of a 383)




Adam

NewbVetteGuy

To answer your question more directly, you could certainly leave the top end components alone and just go with a 383 stroker crank for the bottom-end. You'd see big torque gains, but you would be missing out on some of the possibility for increased HP if you don't go with a longer duration cam. -If your heads have more flow at higher lift you could just go with higher ratio rockers for a tiny boost, but you'd be better off with a larger cam. If you're talking about the Comp Extreme Energy flat tappet cams, though I wouldn't go with larger ratio rockers, though as the exhaust close is already too fast and you're likely to end up with valve bounce if you accelerate it even more with high ratio rockers. (If you're already buying $1,500-$2,500 worth of cranks, pistons, rods, gaskets, and bearings a new cam isn't a huge cost.)


Adam