GTM STG 2 SC, when will it be available?

Mike@GTM · 01-11-2011, 01:52 PM

Quote:

Originally Posted by RCZ

Not to stir the pot or anything of the sort, but it may be a tidbit of info that can answer your question. Last time I looked into it, the SC unit Stillen uses flows more CFM than the GTM stage 2 unit. Considering the stillen kit doesnt need an engine build, I think its safe to say you guys wont either. Again please for gods sake don't take this comment out of context.

Did someone mention CFM in a forced induction thread? That is one of the most misleading measurements you could use when talking about forced induction. If you were discussing carburetors on a naturally aspirated hot rod, then CFM is appropriate because we can all assume you are talking about atmospheric air density. However, since we're discussing compressed air, CFM is useless for comparing performance unless you specify air temperature and pressure (assuming you know what to do with that information).

What you need to be comparing is mass flow rate in either kg/s or lbs/min. That takes things like compressor efficiency, pressure ratio, etc. into account. As far as I can tell, Vortech does not publish their mass flow rate for their superchargers, whereas Rotrex does.

However, Vortech does rate their superchargers on horsepower. Since horsepower is a function of air and fuel combustion (among many other variables), we can calculate the maximum mass air flow rate of their supercharger using a old rule of thumb that'll get you pretty close. For every 1lb/min of air flow, you get about 10hp.

On Vortech's website, they say that their V-3 Si Trim blower pumps 775hp worth of air. Therefore, that should be roughly 77.5lbs/min of airflow (give or take).

The Rotrex C38-91 flows .63kg/s of air. 2.2lbs/kg yields 1.4lbs/s. 60 seconds / minute yields 84lbs/min. Which is about 840hp worth of air, which is way more air than the Vortech.

Now, just because these blowers are capable of flowing a buttload of air, doesn't mean you are going to see that power on a dyno graph. Another intelligent individual already mentioned one reason, and that is the supercharger consumes power to flow that air. The other reason you won't see that much power is VVEL has so much overlap at high rpm (where the blower is pushing the most air), that a significant portion of that air is blowing right through the engine.

So, at the end of the day, our stage 2 supercharger combined with our VVEL tuning solution will make a lot of power. So much so, you'll want our traction control system too.