383 or 350?

[Achilles]

I've decided that my '86 is going to need a rebuild & was thinking about having the engine rebuilt to a 383. But I talked to a very reputable engine builder in town that suggested since I use this car for Auto-X and Track days @ road course events, I shouldn't do a 383 conversion and just bore the engine out, up the compression & hi-perf. cam. Also, he said the 383's work better w/ carb rather than FI.

I know some of you have 383's, so I was wondering what you take is. I think the L98 has a lot of torque already, and maybe I don't need the additional torque that a 383 offers, since I don't drag race or street race stop light to stop light. I like the low end torque that the L98 offers, but I don't want to sacrifice my top end by over powering for low end performance. Make sense?

Maybe I just need more HP.

 

[Kid_Again]

...on a dollar-based comparison, the cost will be equal whether you rebuild your engine or buy a new gm crate stroker...BTDT

good luck

 

[89sleeper]

I've decided that my '86 is going to need a rebuild & was thinking about having the engine rebuilt to a 383. But I talked to a very reputable engine builder in town that suggested since I use this car for Auto-X and Track days @ road course events, I shouldn't do a 383 conversion and just bore the engine out, up the compression & hi-perf. cam. Also, he said the 383's work better w/ carb rather than FI.

I know some of you have 383's, so I was wondering what you take is. I think the L98 has a lot of torque already, and maybe I don't need the additional torque that a 383 offers, since I don't drag race or street race stop light to stop light. I like the low end torque that the L98 offers, but I don't want to sacrifice my top end by over powering for low end performance. Make sense?

Maybe I just need more HP.

I am confused
You want to bore out the old 350 witch will add cubic inches why not go with the 383 ?
I have a 383 in my coupe (I am not sorry I did) its great
When you mod your engine you need to have the computer chip reprogramed to the changes you made on the engine
Here's a video of mine on the on ramp
http://media.putfile.com/email-size

 

[grumpyvette]

rebuilds on a worn engine normally require a slight overbore (.030 is comon) to true up the bore, adding a 3.75" stroke crank to make a 383 vs just the overbore that makes a 355 with the stock 3.48 stroke and new pistons will cost only slightly less but keep in mind that those extra cubic inches add both low and mid rpm tq but an average of about 35-40hp and 35-40 ft lbs of tq.
its total nonsence saying the engine works better carb vs injection, either way the extra displacement helps, its matching the components(cam,tuning,cpr etc.) that gets you the results with either methoed
stroking the engine to 383 adds power over most of the rpm range and theres NO disadvantage,especially when you consider that all that potential power range starts lower and finnishes higher in the rpm range than the hydrolic cam in the engine can opperate effectively at and that youll shift well under the valve float limit of either engine config.
with the correct cam and compression a 383 can spin up to about 6300rpm,THE SAME MAX RPM that a HYDROLIC cam in a 350 limits you too!
since the stock auto trans shifts well under that rpm, and valve float occures at about 6300rpm with stock or nearly stock components and youll rarely approch that rpm even when racing, stroking to 383 has only advantages

 

[ZumZum]

I think what people here have failed to mention, it's not quite as simple as making your current block into a 383. Your stock TPI is basically designed for a 305 ci engine and is flowing pretty much at its max capacity on your stock 350. Going to a 383 is a lot more cubic inches then your stock heads and intake system will handle, especially with a higher flowing cam. So, with a 383 stroker, your looking at needing some aftermarket heads and intake. Even rebuilding your current motor to a 355, if you upgrade the cam very much over stock, the least you're looking at is also some porting work on your factory heads and some hi-flow runners for your TPI and some porting on your plenum and manifold.
I hoped I've helped instead of making the issure more confusing.

 

[grumpyvette]

a 383 is aproximately 9% larger in displacement, youll reach the same basic flow levels in the intake at aproximately 9% lower rpms and make APROXIMATELY 9% more power .. thats 23-25 thru displacement alone, then theres a 3%-4% gain in boosting the cpr one full point from 9:1-10:1 so that 25 hp is easily 40hp plus when both the increased cpr and increased displacement are combined. .IF nothing else changed.. but youll generally want that new 383 to have a slightly higher compression ratio and a slightly longer durration cam, both mods allow the engine fo make more efficint power slightly higher in the rpm range, what youll find out quickly is that youll have a noticable boost in low and mid range power and the engine seems to run into a wall due to lack of flow only slightly lower in the rpm range because the increased durration allows it to more effectively fill the cylinders even with the increased displacement.
the CRANE 114132 cam is an EXCELLENT match to a ported TPI intake on the early flat tappet L98 engines.wether a 350 0r a 383
its got 210/216 durration vs the stock cam with aproximately 10 degrees less durration
with no other changes but the boost in cpr to 10:1, when you install a 383 stroker kit,a cam swap and porting the intake,& runners, youll easily pull 40-50 more hp MINIMUM, a good set of performance heads can easily add an additional 50hp
and yeah, carefull port and runner clean-up can increase the flow that 9% or MORE

 

[ZumZum]

Some very good and interesting points there Grumpy

 

[Achilles]

Ok, Those are all very good points to consider. So, if I go with the 383 stroker, up my comp. to 10:1 or 10.5:1, add a perf. roller cam (any recomendations helpfull), 52 mm throttle body & Headers, do you think I can get by with the stock heads and intake?

I do have a budget to consider, but I'd like to get close to 300 HP at a reasonable $$ if possible. Otherwise I could go with the ZZ4 crate, but I don't have $3800.00 for that swap.

 

[Achilles]

BTW, I think stock comp. is 9.5:1

 

[vetteboy86]

At least I would have a 3 or some shops do a 5 angle valve job on the heads. You can have them machined to accept larger intake and exhaust valves. The corvette head is a pretty good head, not to match some good flowing aftermarkets, but for a stock car they are good. I would recommend replacing the intake manifold with a bit mouth manifold or something like that. I also put a ported plenum and siamesed runners on my engine.

With the 383 it pulls so much harder the whole way to 120, and probably more. The difference is amazing.

 

[Achilles]

Who did your computer tune and what is necessary to have it done? Do they just need to know your mods?

 

[Moonunit 451]

I've decided that my '86 is going to need a rebuild & was thinking about having the engine rebuilt to a 383. But I talked to a very reputable engine builder in town that suggested since I use this car for Auto-X and Track days @ road course events, I shouldn't do a 383 conversion and just bore the engine out, up the compression & hi-perf. cam. Also, he said the 383's work better w/ carb rather than FI.

I know some of you have 383's, so I was wondering what you take is. I think the L98 has a lot of torque already, and maybe I don't need the additional torque that a 383 offers, since I don't drag race or street race stop light to stop light. I like the low end torque that the L98 offers, but I don't want to sacrifice my top end by over powering for low end performance. Make sense?

Maybe I just need more HP.

Lot's of good points here, but I didn't notice any discussion about the rest of the flow, ie: headers and exhaust. If you are planning on a street legal Cali car from what I've read you got nothing but problems ahead.

Sure you can get some more HP I suppose but, a) I think the engine builder that you talked to is out to lunch on the carb thing, b) you need a better intake, cam and heads to optimise a 383, and, c) headers and a free flowing exhaust are required.

If you are track only and don't have to pass emissions, then the optimal setup from what I've seen is: ZZ9 or 409 cam, MiniRam (or LT1 conversion[second choice]), headers, duals, maybe TB. Then dump weight.

Let's call it close to $10,000 if you do it on the cheap (like I did) 50% + or more retail. Have fun, and do it right --- the first time. BTW I did all the work myself accept the build of the 383 (low compression) which I bought used, the tranny rebuild on my A4 and converter, which I got a deal on, and the exhaust install that I got HOSED on. I also added a D44 for that price. I wanted to cheap out too, but couldn't bring myself to do it (more than I did) once I got started.

Good luck, have fun, and get out your wallet. I couldn't be happier with mine

 

[Moonunit 451]

Who did your computer tune and what is necessary to have it done? Do they just need to know your mods?

My experience is, and no offense to anyone, is, you need a great tuner, and a dyno to get the chip right, PERIOD!

 

[Achilles]

My experience is, and no offense to anyone, is, you need a great tuner, and a dyno to get the chip right, PERIOD!

Thanks for the advice. I don't plan on keeping this a street car so smog is not an issue. But I don't have $10K to spend right now. I may have to settle for a straight rebuild for now w/ minor performance improvements.

 

[vetteboy86]

Well what you should plan on doing is sitting down with a builder and deciding just where exactly the money is. For me it was a little easier because I paid no machine or labor charges, and still ended up with a little over 5k. Mind you this was on the stock heads. I did have them worked on. I plan on replacing the heads in a year or so when I can swing the money. However think about doing the necessary things, like a rotating assembly to make your motor with some more cubes. You dont necessarily have to do heads right now, but I would recommend the new intake manifold. Porting the plenum for now would be a good step, but if you cannot swing the ported runners, do some work on your own.

What I am trying to say is get what is logical and what will benifit you with a good platform in the future. In other words, you dont want to build the motor and put a stock cam in when the money is really no different with a milder cam. This is a good building block.

Good Luck,
Craig

 

[Black Bart]

I've decided that my '86 is going to need a rebuild & was thinking about having the engine rebuilt to a 383. But I talked to a very reputable engine builder in town that suggested since I use this car for Auto-X and Track days @ road course events, I shouldn't do a 383 conversion and just bore the engine out, up the compression & hi-perf. cam. Also, he said the 383's work better w/ carb rather than FI.

I know some of you have 383's, so I was wondering what you take is. I think the L98 has a lot of torque already, and maybe I don't need the additional torque that a 383 offers, since I don't drag race or street race stop light to stop light. I like the low end torque that the L98 offers, but I don't want to sacrifice my top end by over powering for low end performance. Make sense?

Maybe I just need more HP.

After reading this I would suggest talking to a different engine shop the guy you talked to is an idiot.
I totally agree with Grumpy but to really get the potential from the 383 you should change to a better intake and headers. Since money seems to be the problem maybe you could build a 383 and install headers and intake at a later date.

 

[Achilles]

That's all very good advice to consider. And most likely I will try to get the most for my money, starting w/ the rotating assembly. I can do head work and/or intake swap later. Due to additional cost, I just don't want to "over build" the engine so that it forces me into head and intake work in order for it to run right. I'd rather it run effectively with less power, than ineffective with "built-in" power that is difficult to take advantage of or obtain. I do plan on installing long tubes, since this will be a track only car.

The engine builder is very reputable around here and I've seen his work before. I think his advice was just based on a past experience. I know a guy that has an 87 vette w/ a 383 stroker that was built by this guy and he is very pleased with it. So I know he'll build whatever I want. I just have to decide what that is. Thanks again for the responses.

 

[Koop]

look in the GM catalog.

I have a ZZ383 and I'm not looking back! 425 HP 460 pounds of torque. You need modified car or a ZR1 or a Z06 to out run me. My car still doesn't turn or stop but it goes like hell! Aluminum heads...Roller cam and more!

Look at the cost of new before you pay for a rebuild, the new GM crate motors rock.

 

[Achilles]

Ok, after much discussion w/ my machinist, I've decided to go with the 383 stroker. Most likely an Eagle rotating assembly. Grumpy, you are on the right track with what I was thinking for a cam in the 210/218 @ .50 area, maybe in the 475 lift range? Also, I was hoping to go roller, but my guy says I need a roller block, huh? Can't a roller cam go in any block?

Anyway...bumping compression to 10.+:1, long tube headers....

Planning on a 3 angle valve job. So if I mildly port the heads, should I go with the Accel base and runners with a ported stock plennum. Or just port my stock pieces to match my heads? Remember this isn't a strip car. I want to keep my low to mid range torque.

Aftermarket heads are out of the budget.

 

[Black Bart]

Ok, after much discussion w/ my machinist, I've decided to go with the 383 stroker. I was hoping to go roller, but my guy says I need a roller block, huh? Can't a roller cam go in any block?

Yes you can run a roller but like I already pointed out to you that guy don't know what he is talking about and once again proved it with that statement.