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. ;)

Great info, Mike. Thanks. Would the Stage 1 SC benefit from VVEL tuning too?

I was soo set on getting the GTM TT kit but this stg.2 SC + VVEL tuning really has sparked my interest. Of these 2 set-ups, which do you guys think will be more reliable in the long run?

I experimented with my intake / exhuast variable timing on a different platform, the 'blow through the engine' comment is actually very well decribed, I have actually noticed the totally different sound of the engine combined with the drop off in power when this is happening as compared to an optimzed I/E cam set up.
My vehicle was running single turbo at 25 ish PSI but hell what a difference a properly balanced system can make to the TRQ hit and hanging on to that power up top.

Very interesting stuff

Absolutely. That is shown with the 350Z HR Supercharger kit we did. We made more boost with the same pulley and more power as well (487whp) simply because we are able to tune the exhaust and intake cam phasing to match the supercharger on the HR motor.

In terms of reliability, the key is proper engineering, proper installation and proper tuning. A properly installed and tuned GTM supercharger kit will be just as reliable as a properly installed and tuned GTM TT kit. We do our best to ensure that our systems are engineered properly and that they perform as advertised. When we do encounter an issue, we get it fixed properly and get you back on the road ASAP.

In terms of which system will be best for you, that depends on personal preference. I personally love turbochargers and was hooked that first time boost came on and set me back in my seat. For some people (like my wife), that scares the living crap out of them and they'd rather have the smooth, linear power delivery of a supercharger. Not to say our supercharger won't set you back in your seat, or that our TT kit isn't smooth. The power delivery is just different, just like fish is fish, some like it cooked and others like it raw.

Also bear in mind that our TT kit is scalable, so if you ever get tired of 500+whp, you can always get more. :D

Thats great info Mike, Had no idea one manufacturers CFM could be different than another manufacturers measure of CFM.

Damn, makes my decision even harder, lol will the stock block be able to handle 500+hp, the reason I ask is because the car is my Daily Driver.

Christian and his TT G37 was running a good amount over 500+ to the wheels daily driven and his car is holding up great.

^Thanks man, good to know. It really seems like GTM is at the forefront of 370Z tuning & forced induction. :tup: I'm looking forward to seeing any new goodies that come outta GTM in 2011. Mike, any word on GTM long tube headers? ;)

So if I were to get a stage 1 kit, is there any more power to be had out of that C38 Rotrex unit in the form of a smaller pulley or is the stock pulley it ships with already maximizing the blower's efficiency?

I guess there is no plan in the works for the new SC + CARB certification? I was considering stage 2 because I was hoping it would be possible to revert back to something CARB certified easily once that time comes.

The pulley that ships with the kit is the maximum boost pulley. It's rated for 14psi, but our motors only see 8psi of that.

Thanks Staples, that is good to know. With the adjustability with the VVEL controller allow higher boost on the same supercharger after adjusting overlap then?

Bingo :tup:

Why does the motor only see 8lbs? Intercooler and piping?