Hahahaha.... You know way less than you think partner.


N/A power / 14.7 * boost + N/A power


That will get you within 5% in most cases.


14.7 psi is doubling atmospheric pressure. 2x the air = 2x the power. You said 6-8psi so I went with 7. That should add within 5% of half of the motor's N/A power which is 140.


140+70=210


140/14.7=9.52

9.52*7=66.4

66.4+140=206.4hp


I rounded up. Now get off my sack scrub. I thought this was common knowledge. You can even use it on the 1000hp cars and such.

Doesnt matter. None of that proves shit. The size of the turbo matters a lot more.

I could throw the smallest turbo in the world @ 7psi, and only make like 150 to the wheels. I know you're going on an average gain, but you cant assume that.

It's within 5% most of the time.


If he is boosting the stock motor in his DD one can assume he isn't going to hang a GT45R on it just to run 6-8psi. That wouldn't be efficient or make any sense.


So, assuming he puts a proper sized turbo on it for what he is wanting to do and it is properly intercooled to bring the IAT back down within 10% of his N/A IAT it will make within 5% of that formula. I've never seen a car that fell outside of 10% difference unless it was measured on a dyno with a fucked up calibration.


Go ask Phil Thomas and Paul Major. It's the same formula they use to get a rough calculation and they are making over 2000hp in their Drag Radial cars.

True, most DD's dont run GT45R's.
I've seen 100% stock b18b's running about 8-10psi putting about 250 to the wheels.

I've also seen stock bottom ends handle up to 350 to the wheels.

What kind of tires were they on when they were dynoed? Was the intercooler sprayed? Ice on the intake? SAE corrected? It's easy to make a dyno read what you want it to read. If everything is calibrated correctly and no dyno tricks are involved that formula is going to put you very close.

Unsure about the dyno, but I know one of them got it tuned at a place in Mass called like JE's Garage or something like that. Its apparently a reputable dyno place near Boston.

chassis dyno's can still be very inaccurate, and many dynos out there will read low or high when outside a specific range. 8-10 psi is also more than 6-8. the other thing is if he's planning to use the car as a DD and keep the motor stock, he's probably not going to run any bigger than a T25 or T28. GT30 at the absolute largest. 210 sounds very very accurate.

8-10 is more than 6-8, but I'm talking whp, FMX was stating bhp.

BHP and WHP have a direct correlation.

If a car makes xx BHP and xx WHP, raise the BHP and its going to raise the WHP by the same percentage most likely.

Drivetrain loss would stay about the same.

yeah, 210bhp sounds accurate. like i said, chassis dynos can be very inaccurate. they either cater to a lower hp bracket of customers, so its adjusted to read on the high side to make people happier, or their average customer bracket is over a certain mark and their dyno is never adjusted for anyone else that rolls in.

for example, there's 2-3 dynos in vancouver that get used to tune on. one reads typically low, and the other typically read high. you can go do 3 pulls on the low reading one, then 3 pulls on each of the higher ones. wanna know what the average difference in power readings are? 15-20%. truthfully i've grown not to trust chassis dyno numbers. engine dynos are much much more accurate.