AquaMetallic94LT1

Has anybody done this to their C4. I am thinking about doing this and putting my own kit together. Just wondering if there are tips I should remember. :hat

ChrisB

Twin is going to be a pita, single would be an easier setup. I was actually just talking to a friend who is thinking of switching over to this setup. A forged 383 w/ billet rods and some custom JE pistons, ~8.5:1 compression and ~18psi (race gas setting) with a t-88 turbo should be good for around 900-1000rwhp with some 300cfm heads and a small cam.

The one thing to consider is tuning. I wouldn't do anything less than a speed pro (now fAST - ref: http://www.fuelairspark.com) with a wideband setup. The stock computer can't read boost - with a supercharger this scales with rpm and you can add fuel that way - with a blower it scales vs. load, and there is no way to compensate for that adequatley with the stock electronics. You *really* need something like that if you wan't to make it fast and reliable.

The real question is - what kind of power levels are you looking for? that will dictate almost the entire setup?

AquaMetallic94LT1

Hmm.... I was thinking more like 550 hp. You can get 18 lbs and 900 rwhp from a single turbo ? Wow. I was thinking I might be able to use the stock electronics with boost controlled retard on the ignition system. Stock MAF tables appear to go up to about 550 rpm. I could try spoofing the ecm and rescale the spark tables to work with a 2 bar map. I guess there is the problem with fuel enrichment under boost vs fuel enrichment without boost.


[Modified by AquaMetallic94LT1, 1:36 AM 8/9/2001]

ChrisB

Stock MAF will max out around 450rwhp in compensating for a FI setup - and fueling isn't very reliable at the peak boundaries of the MAF.

You can get 2000+ hp with a single turbo - just say t-100 . On smaller displacement engines twin's help fight lag - but on a v8, esp. a 383 you will have plenty of exhaust to spool the thing up. I would look for something in the T-60 series - probably the new T-68 if it was for me (which will support up to around 700rwhp for future upgradability - just math the a/r ratio to your setup).

We have been talking about trying to convert the LT1 pcm to a 2 bar map, but the problem is there are so many different tables referenced by map, as well as correction factors which fit into other -tables - not to mention you would have to do at least one hard code patch to compensate for the initial barometer reference. (pcm takes baro reading with key on but not crank/engine running. this determines atmospheric pressure).

with a supercharger you can use the Pe vs. RPM table to scale for boost -and since this is referenced vs. TPS initially (setting PE mode) and then rpm you can pretty much determine the boost. With a turbo you could be at full boost at 2000 rpm, half boost at 2800, etc. There is no way to really program for partial boost, so you would either have to program for full bost anytime you are actually in boost (map at 100 kpa) - and probably wash out your rings/foul your plugs, or run the risk of going lean if you rely on the MAF (which in a FI application (because of the higher BSFC) works to about 450rwhp.

The wideband option isn't a necessity, but makes tuning a snap (you will proably save it's price in dyno time when it's all said and done), but I would consider some kind of aftermarket 2+ bar capable fuel injection a requirement. You could probably get a good deal on an old style accell DFI since many racers are upgrading now - but I would get a emic to tune this on a wideband, as the accell unit isn't the easiest to tune. Speed Pro (fAST) deserves a very serious look if you are serious about this.

For a 550rwhp HP level you can do things much cheaper. A cast eagle crank will really probably hold you up to 700rwhp with the low rpm's a turbo will turn. I would consider H-beam rods, though I-beams will probably be fine for your application.

SRP has a nice 31 cc dish piston for a 383 /5.7 rod combo - with a 55 cc head and a 0.45 quench this would give you around 9.2:1, which would be good for 14 or so psi. To achieve your 550 goal I would shoot for 9.5:1 which would work with a 52cc head and a 0.41 quench. With a corvette 4 bolt main I would give you 600-650 rwhp with this setup with a very streetable camshaft (something around a 219/219). Shortblock would be very affordable, probably around 2500 with H-beam rods (if you start with a vette 4-bolt block).

I think it's an awesome idea, and I have thought about it myself (if you couldn't tell ). The thing would probably make torque like a big block - ~600 ft-lbs and at a low rpm (2500+) with peak hp around 5500 or so.

The other advantage to an aftermarket DFI is if you have a m6 you can use anti-lag features to allow you to build boost while you free-rev the engine. This negates the auto's advantage of brake boosting.

I say go for it, it would be an awesome setup, but again, please consider the speed pro/fAST FI computer!

bill mcdonald

Do you have any plans for it?

Mounting them above valve covers or next to the oil pan?

You know about mounting tubos lower then the oil pan means you need some way to collect the oil out of the turbo and then pump it back into the engines oil pan?

I have been debating this as well.

Need someone to make a kit already! Chris?

By the way chris.

With a single turbo, where does one go about mounting that? And how do you run the exhuast from the turbos opposite side, over to the turbo? Vettes sit pretty low and running an exhaust pipe under the oil pan is not a good thing. Where would you come over at under the car?

Do you sell the speed pro system chris?

ChrisB

Nope, we aren't in the market to produce a turbo kit - as you point out it's just to much of a PITA without a large enough market

Can't tell you exactly where I woudl run a crossover pipe as I would have to look at a vette up on a lift. I definitley would not run the pipe under the oil pan though - using exhaust components for battering rams wouldn't be my idea of fun .

Turbo mounting has a couple of different options - easiest would probably be similar to a supercharger setup, though this would require you to run the crossover pipe up along the front k-member. A single T76 (T77 now I think?) would fit will there - or over the valve cover though that's a more involved route and make plenty of power.

Yep, we sell the speed-pro/fAST system!

LT4POWR

Man!!! Chris B. really knows his stuff. We are lucky to have him.
I think trying to convert to a turbo setup would be a nightmare. My vote is to lower your CR, upgrade the fuel system and go with a big blower & inter/after cooler.

FrankD

ChrisB, what do you mean by this "The other advantage to an aftermarket DFI is if you have a m6 you can use anti-lag features to allow you to build boost while you free-rev the engine."
Can you explain a bit more?

bill mcdonald

Frank, I think you posted on another turbo topic a few months back about a place in Canada that was turboing a 383 LT1? :confused:

Any update on that?

I keep checking the web page but there is no updates, and I cant find any info to contact them.

I really want some turbo(s) on there. I want to make some BIG hp. Woried a vortech would slip, need a cog belt/pullies and there is no room on an L98 for that.


[Modified by bill mcdonald, 1:41 AM 8/10/2001]

AquaMetallic94LT1

For those of you who are novices like myself, get the book I am currently reading - Maximum Boost by Corky Bell.

In my case, I was initially thinking that I would put two turbos and mount them to the exhuast manifolds. From there, I would like to run tubes to a front mounted intercooler. I would also like to position the inlet tubes so they can suck cool air.

Chris - What do I do about passing emissions with an aftermarket computer ?

Thanks to everyone for all the suggestions :jester

Oh yes 600 HP :crazy:

bill mcdonald

Aquametalic. I have read through that book a bit. good book.

I was thinking more detailed when I was asking your plan.

There have been a few discussions on this topic before, I dont know if they would show up in the search or not. you may want to take a look back there.

Heres my take on it.

I have seriously considered this project, the exhuast/turbo fitment and oil sump are the 2 major problems. (aside from tuning)

I have a few pics of a callaway turbo motor out of a car, no way a stock manifold will work. It's outlet is too far forward, and the stock exhuast is really weak by design anyhow, it would need a lot of reworking.

You will need an exhuast manifold built to do it once, and do it right IMHO. I have been reading all the other forced induction boards as well, some F-body guys have had a turbo built exhuast header/manifolds crack after little use, and they cost ~$700.00

I would have 321 stainless manifolds built. question is by who?

Second is, what size turbos will you use? Callaways turbos were actually compact units, smaller in size, I think that means smaller CFM output as well (12 psi?). There is not a whole lot of room down there to mount a turbo, and plumb all those pipes with a large turbo.
I am still trying to figure out how they did the Sledgehammer with twin TO4's. I dont think it was just shove em in there type of thing.

Then you have oil drain back from the turbo to deal with. turbos oil drains by gravity. the turbos oil outlet will be lower then the oil pans oil level. this means no oil will drain out of the turbo and will go into the engine oil pan. so know you need another sump mounted lower then the oil pan. I have a 1/24th model of a callaway which shows the sump mounted by the front by the crossmember.

Now you need to pump the oil from that 'turbo oil sump' back to the oil pan. Callaway used a belt driven pump, it was built into the stock idler arm. (really trick) where do you get this? L-98's maybe replace the smog pump? go electric? Dry sump?
Now the question is what rpm sould the pump spin based on oil pressure flow out of the turbo? Does this matter........ Chris??

Then of course the nightmare of getting clean cool filtered air into the turbo. I thought about cutting some holes about in the front cross memeber where the mono leaf spring is at so tubing can go through. this means coil overs will be needed.

where to mount the intercooler and all that otehr stuff seem pretty easy to me... I am mainly worried about the turbo size/exhuast/oil problems.

Have you any turbos to check and see if they will fit in there?
A buddy of mine picked up 2 for a boat project he aborted. I am trying to get him to get some exhuast housings on them to see what they look like under the car next to the pan size wise.

Anyhow, keep me posted with what you come up with.

ChrisB

This used to be done with auxilary injectors (some rally cars still used an extra injector plumbed in the manifold) - but now the current state of tech is to do it with the primary injectors
What is it? Basically when activated it would supply extra fuel (based on how you program it) through the primary injectors - this fuel would continue to burn in the exhaust manifold and spool up your turbo VERY quickly. I have seen cars (RX-7's) make 18+ psi of boost free-revving like this!



Great book!

FWIW I went and looked at a vette today (LT1) and, well, it will take some very creative work to get a single or twin in there!



Shouldn't be a problem at all - especially since turbo's tend to like smaller (more emissions friendly camshafts). Catalytic converters *may* be required, and they will definitley put a dampner on your boost - but you should still be able to make more boost than you will ever need.



That was the turbotech kit - anything for a vette is going to have to be custom as far as the tubing. If you are really serious a custom set of shorty headers made for the turbo would be the way to go - you could put the primaries exactly where you wanted to mount the turbos. Does the vette have enough hood clearance to so a over the valve-cover setup?



That will end up totally depending on your displacment and hp goals. But you are right, size is definitley an issue.



I would definitleytry to mount the above the pan if you can - but if you can't incon has some electronic scavenger units they are supply with their LS1 twin kit which I think would be the best choice (since it's the environment it's spec'd to work it). I would stay away from belt driven setup's since that adds another layer of complexity/custom fabrication.



I wouldn't worry so much about getting the coldest air possible - the turbo will heat it up quite a bit regardless, and the intercooler should cancel out most differences in ambient temp (relative to ambient of course, which effects it's cooling capacity).


If someone is really serious it is going to take (as bill suggested) someone buying the turbos and just mocking them up and seeing where they will fit.

bill mcdonald

________________________________________ ________________________________________ _________________
I would definitleytry to mount the above the pan if you can - but if you can't incon
has some electronic scavenger units they are supply with their LS1 twin kit which I
think would be the best choice (since it's the environment it's spec'd to work it). I
would stay away from belt driven setup's since that adds another layer of
complexity/custom fabrication.
________________________________________ ________________________________________ _______________

There is a vette that has the turbos mounted over the valve covers. Problem 1 for me, I have a 90. on the 89-91 the AC is a lot larger and is not mounted in front of the passneger head like the 85-87's, it is on the side of it. So to put a turbo there, I would have to remove the AC. :rolleyes:

I dont know what room is available on the LT1/4

but a single on the drivers side might work out.

Heres a link to the pics. http://www.geocities.com/jerrysturbovette/

Also notice the radiator is the straight up design, which has a ton of space between it and the engine unlike our later vettes. :cry

J Z06

Two words "GOOD LUCK" :eek: :eek: :cheers:

AquaMetallic94LT1

I was looking under the hood of my C4 and I see three possible location options:

1. Mount the turbos where catalytic converters are now. This would require special oiling conisderations, fairly long complex tubes to the intercooler, and intake source is going to be tricky to hook up. The engine compartment would be less crowded.

2. Mount them at the front of motor on the sides like accys are mounted.
The engine compartment would be more crowded but the oiling would be easy. Intake plumbing is not too bad. Probably have to lose AC or come up with a very unque way to locate it.

3. Single turbo on passenger side - There is enough room on LT1s to do this. The tough part is getting the exhuast from the drivers side over to the turbo. Its probably going to have to go under the oil pan. No oiling problems with this one. The inlet side would be pretty easy.

notbob

The idea of a turbo corvette is very cool ;) Very cool indeed.

I think everyone has covered the issues that technically it's one challenging bitch to do ;P

The pics of that guys 'Vette engine appear very weird to me, heh looks like he's been custom ghetto rigging that car a lot!!!!!

I keep trying to think about what I want as a goal to do with mine, hehe I love the torque on the L98 and would love to keep that but would like to see a better idle (sorta sucks), and would like a little more mid-range power, as frankly I don't care about hitting 172, but if I can move from 70 to 120 in like a second that would be really cool ;)

Had fun with some kiddies on bikes today, I showed them what driving is really about ;P They tried to keep up with me and tried to pass me but never happened for them, hehe.

Are there any tricks we could steal from a Porsche or an Eclipse as both have very small engine bays and I think the 'vette's has more room then usual ;P

Are there any crazy locations to possibly put things?

I keep wondering what I could do with that hatch area, I want to rip out the carpet and find out wtf is actually all back there, as I'd love to find a way to expand the room back there to fit goodie in.

Raysur

http://www.high-techracing.com/PAGE4TURBOKITS.htm

Check it out they are making an LT1 turbo kit.

AquaMetallic94LT1

Take a look at the C5 kit that Lingenfelter has on his website for ideas on how to mount the turbos etc.

meach13

The pics of that guys 'Vette engine appear very weird to me, heh looks like he's been custom ghetto rigging that car a lot!!!!!

SO YOU KNOW THIS CAR HAVE YOU SEEN THIS CAR???????

THE RIGGING THAT YOU TALK ABOUT CAN YOU BE MORE SPECIFIC! :mad
THE CAR IS TOP NOTCH IT HAS RUN A 11.22 @120 ON ONLY 10 PSI NOT BAD FOR DIALING IT IN

SO PLEASE TELL ME WHY YOU ARE PUTTING DOWN A FAST STREET CAR!!!!!!!!!!!!!!!!!!!!!!!!!!!!

notbob

Woah there buddy chill!!

I just said it looked very weird, I wasn't dissing it at all I just said it looked weird in there compared to most the pics I've seen of C4 engines ;P

Wow.... chill man chill..... wasn't your sister I was talking about or anything...