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Old 01-13-2011, 03:42 AM   #92 (permalink)
1slow370
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Quote:
Originally Posted by Mike@GTM View Post
From a purely academic perspective, I would be inclined to agree with you. However, it has been our experience that Vortech is very generous with their power ratings as it is. Not to mention that their blowers aren't designed to spin at very high rpms. So while the compressor by itself may be able to flow high cfm, the rest of the rotating assembly simply can't handle the necessary rpms and would blow itself apart long before you reach the limits of what the compressor can do. It's a lot like some of the frankenstein turbos you see out there with huge compressors and small, restrictive, exhaust housings. Sure, the compressor may be able to flow 500hp worth of air, but the exhaust housing restricts things too much to ever achieve what the compressor could theoretically deliver.

In terms of needing a motor build, someone else here already mentioned the clinching factor, and that is torque. Given that horsepower is a function of torque and rpm and superchargers make their peak torque near redline, the overall torque they produce to achieve a given horsepower level is not necessarily high enough to require a built motor. Another thing to point out is the G37 TT we built making ~500whp daily with a stock motor and still running strong.
Well i have a few questions about that one as well if 500whp daily is the current safe build mark then i don't see superchargers going much further because you take the 430 available from a stage one kit and tack on the 50-70hp lost in driving said supercharger and the motor itself is actually seeing the load of a 480-500hp turbo motor less about 10-20% for the increased pumping losses and the heat wear on the exhaust side of the head. from what i've witnessed generally you can't push the internals to get the same whp from a supercharger that could from a turbo charger. And it isn't all about torque i would say it is all about cylinder pressures when you're talking about an 11:1 CP ratio. combustion heat and pressure, causing detonation are going to kill it long before the regular torque output of the setup will (not true with the de motors as they had bitch-rods). usually when judging between the two i like to go off system psi and air charge temp, so if the "safe" power level of TT setup is at 8 psi, and the air charge temps remain the same(intercooler and compressor efficiencies obviously), then i wouldn't try to push a supercharger setup much more than 10-20% over that so like 9-10 without more than one guy doing it first. now on the hr motors being able to run more psi safely with tuned valve timing to reduce the overlap, the same levels of power there should carry over between the engines do to the similarity of the build, less the increase in pressures for the half point of compression. Really there are quite a few unknowns on pushing a vhr supercharged as of yet. on another angle though the stage 2 could be worth the price if there is enough of a ceiling above the stage 1 blower and the kit price is close between the two. if an hr can run 14psi safely then it is a good bet that we should be able to get close to 12 with our compression maybe more because our heads have a smaller hotspot around the spark plug. then it is just a matter of making that 50-80 hp cost effective to the consumer in the upgrade price. on the same token the vvel controller would have to cost at least as much as the stage 2 upgrade or people will just buy the vvel controller and see the same gains for less jeopardizing stage 2 sales

It might be better to sell the -91 compressor as a stage 3 upgrade once the vvel controller is completed in that case, and sell the stage one plus vvel as the stage2.
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