JohnnyG35

which is better? ATI, Vortech? or Greddy Twin Turbo kit? which is more reliable? main goal is atleast 350RWHP.

Eagle1

iTrader: (2)

All three are excellent if properly installed, tuned, and cared for both in terms of maintenance and driving style (thrash it and you break it).

The two sc units you list are centrifugal design, which means they use a turbine wheel like a turbo, they are just belt driven instead of exhaust gas driven. This means parasitic loss to drive the belts, a characteristic jet engine type whine, immediate response (turbo lag is nowhere near the problem it used to be, especially with a twin set up, but it still is present), and lower gas mileage than a turbo. They are a bit lazy in bringing on the power(3000rpm+), like a turbo, when compared to a positive displacement blower such as a Roots/Eaton type or a twin screw Lysholm type. But like a turbo they keep building power well past 6000rpm on this motor.

Prime difference between the ATI/Vortech is that you tap the oil pan for the Vortech while the ATI has a self contained reservoir, and they use different fuel managment systems and pumps. Fuel management for the sc units is the big issue, so do your research carefully there, and tune it properly.

If you are going to track it, I would get the supercharger. Throttle responsiveness, smoothness in bringing on the power, avoiding turbo kick in a turn when you are at the adhesion and handling edge of the car...these are only some of the reasons for that point of view. If you are going to keep it on the streets, then I would get a turbo. Quietness, better mileage and absense of the need for that throttle precision are some reasons. If you are going to street it, but want immediate power, then get a roots type blower, which brings on power fast but tops out at 3000 rpm to 3500 rpm, and actually trails off a bit after that. I like both applications, it just depends on how you want to use your car.

The biggest issue is how much power you are seeking and why. You say you want at least 350rwhp, and I think you really need to be saying up to but not more than 350rwhp, at least with these or any other FI units on stock internals. Once you pass that level of stress you are playing with major failures with this motor. If you want more boost, you have to build the engine with forged internals. The combined cost of the FI unit and the rebuild take you to another level of cost. You might at that point want to consider a vette or other type car that will deliver that level of performance, because it will be comparable in cost, if not cheaper.

I have tuned my unit to approx 350rwhp and 326lbft torque and run it there since Sept./Oct. of 2003. Eight track days and 16,500 miles of trouble free joy. Everybody, and I mean everybody, that I know that has boosted their cars on stock guts to more than that has broken the motor when they pushed it hard, either deliberately or inadvertantly. There is absolutely nothing magic about a hp/tq number. For any car or motor. What is important is power with reliability for street or track. You cannot go beyond the specs for what you have in there. But then I just hate having to walk home picking pieces of toasted piston/rod from my liver.

The car has great bones for modifications. Have fun.