I have decided to TT my Vette. I went to a local Speed Shop (Dynamic Racing) They only specialize in Mitzubishi 3000 gt's but the owner Matt Monett, if you didn't already know owns the fastest 3000gt in the world, also owns a 1994 ZR1. I thought, "Who, other than the forum, could give me a few pointers. Matt said he would suggest two Garett T4's. I have found some T4's but they aren't Garett. Are all T4's rated about the same? I am looking to get into the 500+ HP range. I want to stroke to a 383 but am willing to just stay with the 350 if money gets tight. Would these turbos get me there. Is it absolutely essential to have fordged pistons, or can they be Hypo. I plan on having a 8.5:1 CR, is this where I need to be or could I get away with more. I want this to be street leagl. Any info and any other tips would be greatly appreciated.

 

A 500hp 383sbc is very possible without all the work and costs associated with a TT install. For the money it will cost you for TT, you can install 18 degree heads with a bunch of other goodies for less money and make tons of power.

If you must have a TT car, then expect to purchase premium parts to handle the added pressures and heat from the turbos. When going to something as exotic as turbos, titanium valves are a really good idea. You'll also need a really good ECU and software to control everything. Talk with others that have done this to get an accurate idea of costs and power levels that come with TT. TT is a great way to make power (much more than 500hp) on pump gas if you can do it & do it right so that it's reliable when finished. :)

Just my2c's :cheers:

 

You won't want a 383 with a turbo, especially if youre using a TPI intake. My Callaway makes 550rwtq!! A 383 would be undriveable, plus you'd need really big turbos to feed it.


[Modified by SurfnSun, 11:42 PM 8/22/2003]

 

Maybe the extra displacement will help with lag.

 

I really don't have any lag on my car.

 

Lag is a factor from having too large a turbo mounted to a specific engine. Many factory turbo cars come with turbos that are actually too small and become restrictive to the exhaust flow hurting performance. Factorys' do this so there is no lag time for the turbo to spool up. There are software programs available to help choose the right compression map & turbo for your application.

Here's just a couple links for more info on turbos :) http://www.innovativeturbo.com/cgi-b...rbo/index.html http://www.turboneticsinc.com/

 

Let me restate that....

When Im in the correct gear, there is no lag. If I let the car out of the proper rpm range then yes I will experience a second or two of lag. But with the gearing and strong torque of the L98, my car almost doesnt even see full boost in first gear. But when you hit second...hang on.

 

Damn, I already went with a 406, and I planned on adding one big Turbo infront of the engine or if I have no room, then twin Turbos this winter. I mean I dont want too much TQ that it wont ever have traction, break drivetrain, uncontrollable burnouts when not needed. :crazy:

If I were to go to a short runner intake like a Carb Style Intake and EFI it. That would help make it streetable no? :confused:

 

Why titanium?

 

with a 406, you'll have to change intakes anyway. A TPI setup won't flow enough to feed a motor that big.

 

SurfnSun, your Callaway doesn't exactly fit the bill of "factory" turbocharged cars that I was speaking of ;) :cheers:

As far as recommending titanium valves for a turbocharged engine: Turbochargers generate exhaust backpressure which anytime you have air molecules compressed (forced to squeeze together) they create heat. Since a turbocharger is on the exhaust side, it's a good idea to have titanium exhaust valves for this reason. The titanium material is lighter so it's easier for the valvetrain to control it is also much stronger & durable than it's stainless steels counterparts.

One thing you'll notice in the aftermarket cylinderhead market is that you can buy them assembled or bare. One reason for this is so that if your building a racecar or extreme hp engine, it allows you to choose the really good valvetrain components of your choice. Many of the "assembled" parts aren't of the quality that these engines require for longevity and durability. :)

 

IMO for 500hp or so that your looking for a TT isn't the most cost effective way to make that much hp, a built short block with a 10-12 psi ATI will do that with tuning no problem. If you planning to go further, a TT might be a good idea, but your realistically looking at $15-20K+ for a TT setup, computer and block unless you can do all you own fabrication... You may want to look into a Callaway TT's car it maybe cheaper and have better resale.

 

Actually titanium valves aren't the best for this application... They have a cycle life; generally on a turbocharged application you'll use a sodium filled valve or if money permits, inconel...

We're looking at a TT 383 project right now; if we keep it mild we're looking at an easy 600 rwhp with boost THERE ON DEMAND... If I decide to go with a little larger set we can easily make 900 rwhp on race gas with the wick turned up. Strokers are actually great for turbocharged applications because their long stroke and additional torque produces more exhaust much more quickly and will put the hairdryer in it's efficiency range a lot faster.

FWIW- I spent 15 hours yesterday dyno tuning my buddy's AWD Eclipse racecar. It's a little stroker 4G63 (that's Ichipussi speak for "big motor") with a T72 Q-trim turbo on it...We started at 182whp with no boost and after 35 pulls had it up to 632 whp at only 28 psi of boost, no nitrous, and only 19 degrees of timing. We need 800 to his 160 in the 1/4 which will put the car in the 8's... We're gonna turn up the wick today and hit the button too; the nitrous will spool the turbo a little faster (it doesn't get to max boost til 7k right now)... But this is a FOUR CYLINDER!!! Imagine what this would do on a V8 that produces a ton more exhaust pressure!
-Jeb

 

First off , thanks to everyone that has responded. Let me restate my gaol here. I am lookng for as much power as I can get. 500 RWHP is what I am after at the minimum. I was trying to be realistic. If it were easy to get all the power you want, everyone would have a 1000HP street driver. My question is really, what size turbos would you suggest? I was thinking of two T4's. I am a machinist and welder so, I can make all the pluming and exhaust manifols myself. Would I need a new computer or can I just get a custom chip made. I was planing on installing two more injectors in front of the throtle body to get more fuel. It would be cheaper than replacing all 8 injectors. Would this be a good idea. I have seen it on other TT vehicles.

 

I would not go the front injectors like the Callaway has. If you put too much boost on there all the fuel ends up at the back of the plenum and leans the front of the motor badly. My guess is you would need a DFI system to proper run the car. Ideally you could run 16 injectors of which 8 are hooked up to an FMU so they fire when the boost comes on, that way you don't have the drivability issue of such large injectors when off boost.

I just had my front injectors cleaned and flow tested, I don't have the exact numbers in front of me but I know they flow 75-80 lbs/hr.

I still stand by my comment about not going with a stroker, especially if youre going to run a TPI setup, but I am no expert. A stroker with miniram, stealthram, or superram. A 600rwhp turbo with TPI would probably be making around 800rwtq under 3k rpm.


[Modified by SurfnSun, 2:32 PM 8/24/2003]

 

:eek: Damn, if someone would go through all the trouble to build it. They could build a TPI style Intake( Bigger RUnners and all) for a BB, run it through a Pro STreet Car, and have 1200HP and who knows how much TQ to go with it, maybe 1600 if SurfnSun is right. And I think SurfnSun is correct b/c THeirs a Forum member with a L98 355CID Twin Turbo and makes about 150+ RWTQ compared to his HP figure. Thats a whole lot of TQ. :crazy: :yesnod:

 

Call Mike Mahaffey at AAM.Ask about some Y2K turbo's.Mike has the fastest full weight street driven 3SX car.3800lb 1.4 60'ft 697AWHP over 800at the crank 10.7mph at 134+.That was like 6months ago who know's now?Check out the web-site " Stealth316.com".

 

uh, have you seen the quad turbo BB that was built? they used what looked like long tube headers for the intake runners. it made something like 2200 hp.

 

probably for a lot less $$$$ you could add a roots style or pro charger supercharger and get that kind of horsepower. I'm building my champagne vette on a draft beer budget (married with children!) LOL So, I opted for the quick-fix.... N20. check out my other mods and follow the link to see my motor! good luck with your project!

 

Whoop-dee-doo. Thats the nature of an L98. Stock my car laid down 211rwhp and 315 ft/lb.