LT5 383?

[vermatrix]

Can i take a 1991 and stroke it out to 383 without breaking the bank? What would I see in gains? Would love to see 500 or so RWHP?

Any ideas? TY

[Paul Workman]

Originally Posted by vermatrix

Can i take a 1991 and stroke it out to 383 without breaking the bank? What would I see in gains? Would love to see 500 or so RWHP?

Any ideas? TY

Ideas? Yes.

Porting, headers, SW X-pipe, phased cams can get you to 510 chp on STOCK cams and stock block.
"383" is synonomous with the std 350 cid SBC mated with a 400 cid SBC's crank (i.e., stroked).
The LT5 has been sleeved to 378, 380, 385, and most recently to 391 cid with the stock crank. 402s to 441 cid LT5's have been done with combination of bore/stroked and either a drop-in (CNC'ed) sleeve gang or closed deck conversion.

I don't know what you call reasonable (price wise), but except for modest 378 cid conversion, upping the displacement of an LT5 is typically a custom job: not a project where you go to a dealer and order up components off the shelf. (Expensive...in other words!)

What specific mods do you have in mind?

[vermatrix]

OK so first, you are obviosly light years above me with knowlege of this. I feel a little foolish.

I am not trying to build a fire breathing beast. In the past I had a few corvettes, now I want to get my ZR1 forever car. Would be a daily driver, for pleasure only, during the summers only. I live in Northern Wisconsin so probably about 6 months out of the year max.

All that being said, I want it to be crazy fast, drooling to look at and fun. Not sure what HP and TRQ numbers equal that. I remember back in the 90's stroking your SBC to 383 seemed to be the thing. I know the LT5 is not just another SBC, but trying to scope out my options.

I was anticipating spending around $6000 or so on her per winter, right now its going to be a 1991.

[TX '90 ZR1]

I take it that you do not have your Z yet?
When you find the "one", go over it and make sure all the basics (fuel,air & fire) are working properly. A stock, well tuned Z is still pretty impressive!
If you want more, start with the low hanging fruit (horsepower). There is a good bit of additional performance to be had for a relatively small amount of dollars.
My '90 was bone stock. All I have done performance wise is a Haibeck "chip", Corsa exhaust, and modified air intake. The difference is noticeable and I can put it back to bone stock in less than a couple of hours.
It has more power than I can reasonably use on a daily basis. More is always better in my mind, but weighing dollars to usability I am good. (For now!)
You can go to gear changes, headers, porting, etc., but I would recommend the "easy" stuff first and see where you are.
My opinion and worth exactly what it cost !!!!!

[Ccmano]

Originally Posted by vermatrix

I know the LT5 is not just another SBC, but trying to scope out my options.

The LT5 is in no way, shape or form a SBC. They share no parts in common especially not the block or heads. A completely different animal. That said, this is a common misunderstanding for those new to the “beast”. Its great that your gaining an understanding and knowledge before you jump in. Paul has already outlined the current possibilities of which there are many, the higher end of which can run in to 10’s of thousands of dollars. If your interested in an enhanced version, in my opinion, any of the Haibeck iterations are fantastic based on your wallet size. The best “bang for the buck” currently appears to be “Pete’s” 391 with an output of about 600hp. Check them all out and as Paul said, 500hp is within relatively easy mods and reasonable expense.
Have fun, keep us posted.
H

[DRM500RUBYZR-1]

If you have not purchased one yet, I would strongly suggest you look for one that already has had the desired mods completed.
As with all cars, when buying modded ones you usually get the mods at pennies on the dollar.
Save yourself by focusing on cars listed on the ZR-1 Net Registry site.
Most are well known to us, and have been maintained, modded, and serviced properly, by enthusiasts who care for them far better than most.
Add your projected first year mod money to your purchase funds, take your time, and you will end up with far more horsepower than your original plan.
Best of luck in your search, and we are here to help along the way.
Marty


p.s. a bone stock ZR-1 will certainly impress!

[EvanZR1]

First off, no you wouldn't do a 383, best option ($/HP) right now is one of Pete's closed deck 391s, which will do right at 600HP. I've got one and I absolutely love it. Having had a couple of ZR-1s with various levels of mods from stock, to ~500HP to fully built 391, here's my opinion:

First off, the car in stock form is a blast, and still a lot of fun even by modern standards. No it's not going to beat everything out there, but it will still surprise a lot of people and is a hoot to drive. I bought my current one planning to take it and have a 500HP upgrade done immediately, but ended up enjoying driving it stock so much that I waited, which unfortunately/fortunately for me led to needing an engine rebuild do to a completely unexpected event (someone in the cars history dropped a foreign object in the intake track, that finally shook loose and got sucked into a combustion chamber).

Anyway, my previous ZR-1 had a ported intake and injector housing and 4.10 gears, and was a beast, and I put long tube headers on it after getting it. The car was right at 500HP, but with the 4.10s seemed even faster. To me, this is the sweet spot for ZR-1 performance, and if what I originally had planned for my current one, and what I would do if I were buying another. Plus if you look around, many of the cars that are for sale will already have some/all of these mods for a very reasonable price. (I wanted a specific color, so didn't have as much choice when I was looking.)

Next step is to build the motor, and right now Pete's 391 cubic inch closed deck motor is the absolute best deal out there. Plus if you're doing a full build, you might as well get the full top end (including heads) ported and do larger cams, giving the car a really nice lope that sounds great, but is still very drivable/streetable. Of course you'll still need the long tube headers with this, and you'll still want 4.10s (that's the next mod to mine).

There are options beyond this if you want to go crazy, Pete recently took the 391 out of his personal car and did a 441 cubic inch. To quote him:

The 391 is freaky fast.
The 441 power feels like it's going to twist the body right off the frame

The 391 runs 132-133MPH in the 1/4 if the 441 runs a lil quicker that's fine but the price of a 441 is double of a 391.

The 391 is a perfect engine big bore short stroke plenty of power.
The 441 is almost useless for the street no traction till like 80mph.

If you were going to go bigger than the 391, do NOT do 4.10s though, as traction would definitely be an issue.

So basically all the work that goes into a 500HP car is reused/needed for a full engine build anyway, so that's a better place to start. Not saying don't do an engine build if this is truly going to be your forever Vette (like mine is for me, although everything's for sale), just that you may be completely happy with a 500HP car.

[Paul Workman]

Originally Posted by vermatrix

OK so first, you are obviosly light years above me with knowlege of this. I feel a little foolish.

I am not trying to build a fire breathing beast. In the past I had a few corvettes, now I want to get my ZR1 forever car. Would be a daily driver, for pleasure only, during the summers only. I live in Northern Wisconsin so probably about 6 months out of the year max.

All that being said, I want it to be crazy fast, drooling to look at and fun. Not sure what HP and TRQ numbers equal that. I remember back in the 90's stroking your SBC to 383 seemed to be the thing. I know the LT5 is not just another SBC, but trying to scope out my options.

I was anticipating spending around $6000 or so on her per winter, right now its going to be a 1991.

I was fussing with SBCs since the 60s, and built a clone L88. But, none of that impressed me as much as the potential hidden in the DOHC/LT5!

For example, this is my "508" hp LT5 (since tweaked a little more). Stock idle, ALL of the accessories work in heavy traffic. You would never know there was a monster hiding under the hood. But, with reground cams and sleeves it becomes a real beast. You've never experienced the torque curve of a DOHC motor, have you? Once you do, you'll likely notice how "peaky" any SBC really is!

https://www.youtube.com/watch?v=y1YFa8ruh8A

[vermatrix]

Originally Posted by Paul Workman

I was fussing with SBCs since the 60s, and built a clone L88. But, none of that impressed me as much as the potential hidden in the DOHC/LT5!

For example, this is my "508" hp LT5 (since tweaked a little more). Stock idle, ALL of the accessories work in heavy traffic. You would never know there was a monster hiding under the hood. But, with reground cams and sleeves it becomes a real beast. You've never experienced the torque curve of a DOHC motor, have you? Once you do, you'll likely notice how "peaky" any SBC really is!

https://www.youtube.com/watch?v=y1YFa8ruh8A

Paul,

Thank you for your insights. As I will be having my local speed shop do the work, How would I order this up? Ask them to regrind the cams and sleeves and they know where to go from there? Is that going to run me more then 6K?

Yes this will be my first ZR1. I am really looking forward to it.

[WARP TEN]

Originally Posted by vermatrix

Paul,

Thank you for your insights. As I will be having my local speed shop do the work, How would I order this up? Ask them to regrind the cams and sleeves and they know where to go from there? Is that going to run me more then 6K?

Yes this will be my first ZR1. I am really looking forward to it.

I would like to discourage you from having your"local speed shop" do this kind of work on an LT5. The LT5 is a special engine that many, many "local speed shops" ruin. They simply lack the specialized knowledge that these require. There are several true experts on the engine, some within shouting distance of Wisconsin, who regularly build LT5s to be highly reliable high horsepower engines. Pete was mentioned above as producing a good value 391, and of course Marc Haibeck (www.zr1specialist.com) has done hundreds of LT5s, his only business. Marc is in Addison Illinois and is always willing to talk with people interested in doing something with the 90-95 ZR-1s. His website includes a variety of options for LT5 upgrades and also provides prices for all the work. Pete is located nearby Marc in Illinois and has done very fine work on LT5s for many years. Both are good guys worth talking with before making any decisions.--Bob