Quote:
Originally Posted by 1slow370
the problem with the calculation of the vortech unit you posted based on horsepower is that the vortech horsepower ratings are compensated for drive loss so the amount of horsepower it actually bumps is higher than the figure they post. also their cfm values can more accurately be turned back into airflow assuming non apocalyptic weather conditions rather than a horsepower number that is affected by many more variables than just temperature and pressure. the cfm value assumed to be a draw value at average temperature conditions 100kpa, 70degrees Fahrenheit, with a standered weight of air at STP of .0807 lb's per cuft, through the ideal gas law leads you to about 86lbs a minute of airflow. The point of hp ratings on superchargers is that it accounts for the airflow of the unit and the parasitic losses all in one number.
the issue no one is really talking about is that all that crap doesn't matter when you consider that it will cost you a freakin truckload of cash to build a motor capable of handling more than 500hp supercharged so both units will work fine(unless you feel the need to spend almost 10k to sleeve your block then you can care). the gtm stage1 is a good setup that focuses on response which with a centrifugal is key because they are designed to suck balls in this department, and once sam gets the cvtc at least figured out more power out of the stage one unit won't be a problem until you spend the money to build the block then you need an upgrade.
Edit: but if the vvel controller never surfaces (which i'll be damned if it doesn't) then the stage 2 or up pullied vortech are worth the money in order to make up for the airflow lost to the valve overlap.
Also god damn HKS for locking the VPro powerwriter softeware down to needing a dongle (and for being a piggyback in the first place). some of us don't like the idea of having to pay big cash if we wanted to even get our car to the tuner hell two trips and you double the price of the ecu Grr
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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.