Pakisho

And how much time under boost does the car see? Im assuming turbocharged cars spend alot more time under boost than the SC'd cars, due to the turbo spooling fully by a certain RPM.

Mine supercharged, and I see Vtec and above quite seldom, come to think of it. Id say maybe 0.5% of my driving involves the car being in vtec.

Pathetic, I know.

How about you?

modifry

Overall, probably less than you. My typical 240 mile drive would require over 2 minutes of boost to make the 1% mark, and that's a lot of time to spend in boost on the street.

If you're in VTEC, you're definitely in boost, but at WOT my Comptech is producing boost at 4,000 rpm, well below VTEC range, so it depends on throttle position too, not just rpm. (Boost in this case meaning anything above atmospheric).

So what do you mean by "boost". Anything above atmospheric? Or any time where manifold pressure is higher than it would be on a non-FI car? Running at 7k and part throttle may not be above atmospheric, but it's for sure higher manifold pressure than a non-FI car would see under the same conditions. So while the car may not see >1 atm very often, you probably run near 1 atm more frequently, which is equivelent to running WOT on a normally-aspirated car.

Jason00S2000

At least 33%

xviper

If you consider that a NA car shows quite dramatic "vacuum" most of the time, when you have a S/C on it, it will be "boosted" anytime the engine is running much above about 3000 rpm. So, given this definition, mine would be under boost MOST of the time.
But if you are only talking about blasting to redline, then I'd say mine is "under boost" 1-2% of the time.

cjb80

Just because a supercharger produces pressure at 3000 rpm doesn't mean it's boosting. The pressure has to get past the throttle body, so you'd have to have enough pressure build up before the throttle body that any crack of the throttle body would allow more air past the throttle body than the motor could eat.... which is basically impossible

I would say that my motor is in boost maybe 10% of the time or less.

Given that my motor is lower compression, I would say that 2-4 PSI of pressure would yield the approx same compression ratio as a stock motor.... if that makes sense. Any time I am in vacuum there is less stress on the motor than a stock S2000 motor.

Chris

modifry

[QUOTE]Originally posted by cjb80
[B]Just because a supercharger produces pressure at 3000 rpm doesn't mean it's boosting.

xviper

[QUOTE]Originally posted by modifry
[B]I agree.

modifry

[QUOTE]Originally posted by xviper
[B]
I might be missing something here but if my highschool physics serves me correctly, 1 ATM is 14 lbs.

xviper

[QUOTE]Originally posted by modifry
[B]And yes, even if you don't go above 14.7 psi the SC is supplying more air than a NA car would get at the same rpm and throttle setting.