A lot of people wonder why Stage Three is what it is and why we stopped there. The answer is that Stage Three pushes certain production engine components to their limit. Going any farther with Stage Three, or adding more modifications to Stage Three, would put us at a horsepower level that would require internal engine upgrades.
For example, the piston (specifically the second ring) in the LSJ 2.0L Supercharged ECOtec engine can not hold any more than 310 horsepower. This is one of the reasons the Stage Three PCM allows for only a 50 shot of nitrous. Once you have the Stage Three 76-mm pulley and a 50-shot, you're maxed out. Anything more would require upgraded pistons and rings. Otherwise, youâd see cylinder pressures that could ruin your piston rings and potentially more. This also creates crank case pressure high enough to blow out the dipstick with extended high rpm use.
The Stage Three kit also puts you at the limit of the fuel injectors. With Stage Three, you need to be extra careful about keeping your fuel system (fuel filter, fuel pump, injectors, etc.) well maintained because even a minor issue could cause a lean condition. If you work through our "rule of thumb" fuel injector calculation tool at 310 horsepower supercharged, you get a required flow of 58 lbs/hr. The production injectors flow 55-60 lbs/hr. As you can see, you're right at the limit with Stage Three.
Many of you wonder why the Stage Three 76-mm pulley is the smallest pulley we offer. The reason is heat. Each incrementally smaller pulley generates more heat, and heat is bad for power. The Stage Three kit includes a two-pass intercooler endplate and recommends a second surge tank to mediate heat build-up. If we were to go to an even smaller pulley, we'd be getting into heat generation that would require things like an exhaust ported head and an ice box.
That's not a complete list of production parts that have reached their limit with Stage Three, but I think you get the idea. There is some reasoning behind our Stage Three kit!
A couple of additional things I want to point out: first, the Stage Three PCM does allow you to push the production valve springs beyond their limit. Stage Three includes the functionality to adjust the rev limiter up to 8000 rpm. However, the engine wonât rev reliably above 7000 rpm. If you want to take full advantage of the high-rpm feature, we suggest upgrading valve springs (at 7000 rpm) and going to neutral balance shafts (at 7500 rpm). Second, the Stage Three kit is off-highway only and has not been emissions certified.
Stage Three includes some features that are not streetable. As our way of emphasizing off-highway use only, the Stage Three PCM will disable your car's air-conditioner. Stage One and Stage Two are street legal and plenty of fun. See your GM Performance Parts dealer for parts and availability and check out flickr for more pictures of the parts included in the kits.
