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Jason · Site Admin

Hey Mike.

I can tell you:

1. Turbos are more efficient than SCs.

2. The greddy kit costs half as much as the pettit.

3. The greddy out of the box can make far more torque and hp than the pettit.

4. Turbos are far more flexable than SC. You can adjust how much boost with a click of a button. You can also adjust stuff like wastegate speed, so power can come on slowly, or come on all at once. With a SC you're tied directly to your engine RPM and a pulley.

5. Turbos are dynamic. They spool up based on exhaust pressure, not engine RPM. Because of that, I can get 10 psi at 3,500 rpm, and keep that 10 psi till redline. With a SC, you get X amount of psi at N rpms. Thus you have to design the SC pulleys system to get lots of boost low, or lots of boost up high - with the opposite side suffering. The best example of this is to watch the DNA SC for the RX-8. It's designed for peak hp. But because of the parasitic drag of the SC on the engine, it makes LESS horse power than a stock RX8 until you're over 5,000 rpm, and it doesn't really make big power till 7,000 rpm. Additionally, whenever you shift, your rpms drop, and you'll lose something around 60 whp till your rpms climb back up!

The only thing the Pettit SC has over the Greddy Turbo is that it will generate more power under 4,000 rpm. After that point, it falls behind. So if you only care about driving around town with a little more torque, the Pettit would be a good choice. If you're doing any competition, you're not going to be under 4,000 rpm, so it would not be my recommendation.

The only SC I'd consider buying is the AFE SC, but they're not available yet. Right now it's a waiting game for Cobb racing to put out their RX-8 reflasher, which will allow FI kits to operate without piggyback fuel management systems.
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Turbocharged RX-8