markr1963

Just had my stock 06 STI dyno'd and it gave 230BHP at the wheels. Is there a formula for calculating the BHP at the flywheel? Just trying to get a handle on whether mine's a good 'un or not.

TIA

Mark

Neilo

sounds pretty good to me if the dynos anywhere near accurate....thats around 300bhp at the crank...

good place to live by the way, might join you soon.

markr1963

300?

Perth's most excellent, as is the rest of WA, especially if you like a drop of wine. A downside would be the daft speed limits.

scoobykevuk

my classic was dynod before i got it and i got the reading/graph is it always measured at the wheels from a dyno then?? mine says max bhp 264???

Neilo

nope, most quote at the fly, which is a calculation of the wheels figure anyway...

scoobykevuk

so does that mean mines roughly 190 at the wheels??? is that good for a uk turbo?

p1mark

go on a 26% loss and you are about right.

[Davey]

26% loss sounds a bit low for a 4x4?

markr1963

26% loss on 230 at the wheels give 310 at the flywheel

That sounds a bit high for a stock STI. Aren't they supposed to be around 275-280?

Mark

p1mark

all the dyno dynamics ones i have seen tend to show 25/26% loss

heres my own graph 405 at flywheel and about 307 at wheels. (26%)

another P1 i know showd 396 and 300.

http://img.photobucket.com/albums/v3...ark/graph3.jpg

scoobykevuk

so is the bottom line at wheels and top at fly?? sorry,its all new to me!!!

p1mark

yep, but as said above its measured at the wheels and then calculated to give a fig at the flywheel.

scooby_matt

Mine made 321 @ fly and 250 @ wheels.
About 22% loss by my reckoning

scoobykevuk

ok so what bout this,its says 264 max bhp but what at the wheels??

http://download.yousendit.com/69F0172016BCFC07

[Davey]

For 2WD I assume?

4WD should be higher.

p1mark

its a P1 Davey.

Thats a variant of an Impreza dontcha know. Them things that cost a fortune to rebuild by unscrupolous specialists.

last time i looked in my little owners handbook it was 4WD

WRX_Rich

iTrader: (5)

pmsl

to add mine 303 @ the wheel 386 @ the fly thats at another dyno dynamics but at scooby clinic

R19KET

You will get different losses depending on the gear used, the type of rolling road, and various other things.

It isn't a fixed % anyway, and the ATW's figure is far better for comparison, but for the purposes of getting a ball park figure, I think 22% is a good average.

Mark.

swtmerce

Hi. Can anyone help please? What about a RWD car showing 420 at the wheels? What does that equate to? Thanks

Fuzz

Depends on the tyres you had on, the pressures they were at, the gear you were in, the oil in the box used, how hot that oil was and how hard it was strapped down, to name but a few.


Andy

swtmerce

Cool, so in other words, any rolling road readout is quite meaningless at the end of the day? Thought that might be the case

p1mark

think that sums it up. useful for comparrison on a day but as figures go ignore them.

we dont use them at work for anything other than emissions, noise and driveability testing as we have shown they are just not accurate enough. all power development is done in climater controlled cells with the engine out.

DutchClutch

230 at the wheels equals 290 at the flywheel.
(230 x 1.26)

R19KET

This is where it gets even more amusing........

If you want to believe there is a 26% loss from flywheel power, you can't take a ATW's figure, and muliply it by 26% to get the flywheel figure.

290bhp - 26% = 214.6bhp.

Working backwards, or forwards, depending on perspective you would need to multiply by 35%.

230 x 35% = 310.5bhp. 310.5bhp - 26% = 230bhp (229.77 for the pedantic

But to be honest, it's all a load of tosh anyway

People worry too much about "figures", when the important thing, is if they're happy with how their car goes !


Mark.

p1mark

echo that

the problem is we make it worse cos everyone (including me) is always banging on about it