First of all I'm holding out for the STS rear mount system, because I think it's incredible. Before that though I had considered the HP C4 system.
Found here: http://www.turbochargedpower.com/85-96%20Corvette.htm

The only thing that was holding me back however is the fact that they only mention L98's on the website. I'm just curious if anyone has bolted this kit onto an LT1 before. I wouldn't want to drop that kind of money and it not fit.

I seem to remember seeing something about it in a thread before but I wasn't able to find it again.
Has anyone ever used this?

 

about the STS, compared to HP perf, I am wondering what are truly the benefits of having the turbo at the back:
- Clearance issues.
- Not oil lubricated.
- Long tubes with high lag.
- Air filter exposed to dust and water.

The STS is only for drag uses, compared to the HP perf that allow dayly driving.

But I may be wrong.

 

i wouldn't rule the STS out too fast. they have done very well with the C5 and C6 vettes. also responce isan't as bad as what most people think.

thanks Chris.

 

The STS kit is actually oil cooled. http://forums.corvetteforum.com/show....php?t=1629238

I don't know if you've read through this thread but the STS kit is actually really street friendly, and the clearance is not much worse than a stock exhaust. It's very stealth, so you're packing a lot of power that people can't see.

The rear mount also eliminates the need for an intercooler if running at a low psi.
Also in the tests they felt little to no turbo lag. You don't really lose pressure in the pipes even given the length of them.
One of my main concerns is emissions, as I'm moving back to Cali soon. I want to keep it daily driver legal.

But I digress.. I'm curious about whether the HP kit will fit an LT1. If so then I'll do some price and benefits comparing between the two before I decide.

 

i'm new to corvettes (just got mine today) but i would think that as long as the exhaust manifolds are interchangable with the l98 and lt1 that the turbo kit should be as well. turbo kits are generally pretty universal and easy to make fit. in time i'll be looking into turboing my l98

oh and injectors/fuel pump if included would need looked into

good luck

 

There's lots of factors to consider really. Especially since I don't know how to fabricate my own piping.
Exhaust manifolds may or may not be inter-changable between the L98 and LT1.
But with a preformed to fit system you have to make sure the intercooler fits in its designated spot, the oil lines fit properly.
I talked to a guy that used this kit on his L98, and it changes out your intake manifold as well, so you have to make sure that fits.

I just don't have 5 G's to lay down on something, that I'll have to turn around and have retrofitted. If I'm going to put down that kind of money then I want something that's tried and true ready to go.

 

If I were you, I would wait on this kit. http://forums.corvetteforum.com/show....php?t=1628875 Do a search on HP kits before laying down the money.
On a L98 vs LT1 the manifolds will bolt up, but emissions are different. Also, if you have to change the intake, that is totally different as well. The accesories lay out differently on the motor. You have the ARS and computer box near the battery. Dont know how much any of this will effect the install but there is probably a reason they dont show it for a LT1.

 

Ummmmmm, almost nothing in this statment is true. There are alot of things different between teh LT1 and L98 engine compartment which determines IC pipe routing and how the exhaust gets built. Turbo kits are not generally universal by any means. This is why no one has made a mass produced turbo kit for the C4. They are all one off kits.

The length of the piping would hurt a turbo spool IF the same turbo was used as a front mount application. However, STS uses a smaller turbine setup to compensate for this. If you check out the camaroz28.com website there are a ton of people running an STS setup. While its not an ideal setup, I can not argue with the results. These do very well with stock or slightly modified engines.

There isn't alot of info on the HP kits. There is one guy on this forum that has had one done. The turbo is packaged in the battery area. And this kit is available now, depending on HP delays. While the STS kit is still in production.

Your other option is to build one yourself. But that gets into a lot of complications.

Good luck

 

If the STS is oil lubricated. This is really important, even with low PSI.

Is the pipe lengh long enough to reduce temp and avoid an intercooler ?
Best would be to have a kind of minimal intercooler somwhere at the rear of the car.

Small intercooler + pipe lenght means perfect working temp.

What is the smallest intercooler possible to fit the rear ? possible ?

The guy that have the HP perf did not answered my questions about how it is really working! not good sign for sure.

The only problem left with STS is the air filter that must go somewhere where there is no turbulence and prtotected from dust, water etc...

This is really an issue fr daily driving. May be you can hook it just in the gas tank compartment or somewhere. Any ideas ?

 

with mn_vette. Pre-fab kits for certain cars/engines, are just that. They are built specifically to fit.

I have talked to a guy that installed the HP on his L98. He says it works great. The turbo is placed in the battery space, and the battery is placed behind the drivers seat.

As for the STS:
They did use a small intercooler. I was just saying that with the rear mount it's possible to get away with not using one.
They had talked about building a shroud around the air filter to protect it from water and other road hazards. I'm not really sure what the final verdict was on that issue, but I know they worked it out, and they are working on the test models now.

 

Although I doubt it's an issue in Paris yet, but it may be, for a lot of us in the US the first and last question is: Is there a smog legal version? With ever tightening smog laws across the globe the best made, most efficient turbo kit in the world doesn't do you any good if you can't pass even the initial visual inspection at a smog station. With the new rear wheel dyno test that even sniffs for NOx it's not going to get any better. That's why Procharger has managed to absolutely dominate the C4 segment. Is their product the best? I don't think so, my kit is over ten years old now but I had to reroute tubes and fabricate parts and it has a definite power ceiling on it and well known functionality issues. But, when the smog guy popped the hood and saw the CARB EO number stamped on it I was good to go. I don't want to make an off road only car.

The new rear turbo kit that is in the other thread is said to be going for a CARB EO number, that means it is legal here in CA and in a lot of other states and countries that just mimic the California smog laws. So really, if this is a true registered street car in most places, where you don't want to try to disassemble half the car every few years or know a buddy who can get you a smog or some other scam to skirt the laws, you are pretty much at a Procharger supercharger, or waiting to see if the rear turbo unit gets its CARB approval.

I am hoping it does. I know the local mechanic can read the plate riveted to my P600b and see the CARB # and if it was a D1 - F3 notice it wasnt there, but I seriously doubt he can tell turbo housings apart, thereby allowing me to upgrade my power potential signifigantly without removing it from being a steet car with no registration or smog hassles. The devil is in the details.

 

Exactly!
like I posted earlier.
My biggest concern is passing Cali emissions.
I'm moving back there next summer and I don't want to ship my vette there all the way from Japan, just to have it fail a stupid a$$ smog inspection.
They're pretty strict here in Japan as well, but my GT-R passes just fine.
wish I could bring it home with me.

 

your point is very well exlained and I understand your issues in USA.
Thanks for the infos.

In Europe too we have extremly restrictive polution laws, even more than in USA as they are now based on carbon monoxide quantity not related to cubic inchs. Big power means lot s of carbon monoxide equals higher taxes to pay !

BUT this laws are for regular cars and in France, a C4 vette is not a regular car but it is very exotic. You can see one or two per year on the streets if you are lucky.

We have to go to smog tests every 2 years and you cannot sell a car if not passed for instance.

However, as C4 vette are so exotic and has they do not have any polution references about them, they are much more permisive and allow you to go with your car as, anyhow, there is so few on the roads that they do not care about.

Not the same for C5 and C6 that must follow the rules due to the fact that those newer vettes have been "legaly" imported via General motors Europe. for american cars like 20 years old that were imported only by individuals, this is ok.

I am sure cops will look at my turbo vette saying "what a lucky guy" and will be even more interested to look at this exotic car. This is already the case when they stop me. It is more for them to have fun during their boring day and never give me tickets.

 

I can tell you from my own personal experiance with HP to stay FAR AWAY from them. I can't tell you how much B.S. I went threw with them. If you do a search of the C5 FI/Nitrous forum you will find a lot of people who have had issues with this company. It only cost me $8000 to fix there mess so I could drive my car again and they did nothing to repay me for all I went threw and this was after I paid them $4700. Most guys end up waiting at least 6 months after paying for there kit to get it shipped complete. They tend to ship some of the kit then make excuses for why they can't ship the rest and it is never there fault. The guy who had the L98 got lucky that his car only had minor issues when he got it back from them. I would however ask him how long they had his car before he got it back from them. They had my car over 2 years and I finally had to just go get it from them because they could only give me more excuses as to why they were not done and I found out that some of there excuses were straight up lies!!

 

whaoo !

For my part, I am looking at the most simple and reliable system as I will probably be the only one in France to drive a SC or turbo vette (exept custom drag ones).

Budget is not a problem for me as $ is very cheap at the present time.
Import budget is 8000$ (5000 euros) for vette restauration.

This has to include:
full intake
full exhaust
torque cam
turbo or SC

I think that with 8000$ I can handle it.
intake + exhaust + cam : 3000 $
Turbo or SC: 5000 $

Does not include exterior painting and complete seat and interior restauration that are currently handle by pros in France.

I want my 91 vette to be "new" for next summer.

So far, ATI seems to be the most reliable guys out there and SC seems fairly easy to handle compare to turbos but I must admit the rear turbo story is impressive and "sounds" very good.

If the STS turbo is available next spring I will hesitate a lot between the 2.

 

Thanks for the info Mat.

I don't know how easy the STS system will be to install. It runs along the exhaust path. So I don't for see it to be too difficult. You shouldn't have to do much if any relocating of items unlike most kits.

 

I also heard to stay away from hp,I like the sts system some guys on z28.com want insane power so they like the turbo mounted up front.
the rear mount doesn't have much for lag and it cleans up the engine area. S/C have belt slip issues if you want more than 7 to 8 lbs of boost. pick your poison they all have some disadvantages.

 

that post was without a doubt an abundance of bad wording on my part and i am nowhere even close to being educated on corvettes yet. after reading through this thread i've actually changed over from also being curious about the hp turbo kit setup to being curious about the STS LT1 setup. what modications would need to be made/considered to change over kits between LT1/L98? has anyone fabbed up their own turbo kit on either engines? i will be useing my search button finger quite a bit before referring back to this thread

 

well I have yet to hear a positive story about the HP system. I know of only one person who installed it in a l98, and didn't have any troubles.
But none on an LT1.

I'm beginning to draw a conclusion quickly.

 

I have the Raptor/STS LT1 prototype in my driveway. I just brought it back from STS's shop in UT. It's a 24mpg highway queen and a street monster. Stock engine with 42lb injectors dynoed 407 rwhp and 437 rwtq on our 100k mile engine. Fun to drive and very very streetable...

STS has given their go-ahead for production so the car should leave Vegas next week for pipe documentation and jigging. We will test fit several Mule Cars before the production kit is available. If anyone is interested, we are actively looking for both stick and automatic C4's for test fitting in our OKC facility.

We plan an L98 version which should be soon to follow. I plan on using one for my daily driver...

Cheers,
RH