Quote:
Originally Posted by christian370z
If you are interested in making more power, the Stillen kit uses a Vortech supercharger which is capable of flowing more than even the stage 2 Rotrex unit that comes with GTM. However, people have had hit or miss experiences with Stillen kits while everyone with a GTM kit is extremely happy. Most of the praise that the GTM kit receives is the smooth and easy driveability, linear power and torque output, and a very clean install.
I would say that the GTM stage 2 supercharger is the best FI option out there for the Z as it retains linear and instant power delivery which I feel suits the precise and balanced handling of the car. Turbos can't deliver that experience in my opinion.
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In regards to the Vortech supercharger's flow capabilities vs. the Rotrex, there was a discussion in this thread:
GTM STG 2 SC, when will it be available? regarding that.
The result of that discussion was that while the compressor that the Vortech uses may in fact flow about 2% more air than the Rotrex, the rotating assembly of the Vortech cannot spin fast enough to actually achieve what the compressor is rated at.
About 5 years ago, before we started even developing a supercharger kit, we had a customer with a G35 and a Vortech supercharger kit. As far as I know, we are the only company to achieve over 500whp with the Vortech, and that was using their biggest supercharger (T-Trim). When I say that the rotating assembly just can't handle spinning high rpm, that comes from experience...that supercharger failed 3x trying to push 500whp. When we tried to get the unit warrantied, Vortech came back and said that we were over-spinning the blower...keep in mind that this was on a DE car with a 6500prm redline. The customer finally gave up on the Vortech and went Twin Turbo instead.
The thing about the way the Vortech is rated that people are forgetting is that those blowers were designed specifically for V8 engines with low volumetric efficiency. What this means is that they produce more boost at lower rpm on an inefficient motor. Remember that boost is nothing more than a measurement of restriction. On the VQ motor, the Vortech has to spin higher than it is capable of spinning in order to produce enough boost to make it's rated power.
The Rotrex blower on the other hand was designed specifically for high efficiency engines and is capable of spinning to high rpms with very little parasitic losses. So in essence, you'll never see that extra 2% flow the Vortech is rated at.
I also want to point out that our stage 2 supercharger kit is using a fairly large pulley and isn't even maxed out yet. There was a member who pretty much did every modification under the sun you could possibly do to a Vortech and still doesn't quite make what our Stage 2 kit does out of the box.