400-430 bhp at the fly wheel equate to at the wheels?? on a 2wd saph

 

2wd?obviously less losses than 4wd but there are arguments as to the amount actually lost.
ill guess that 400 youd be seeing 360 at the wheels maybe?

 

hmmmm so really i need around 350-360 atw in order to get 400+

 

at the wheels i rekon for 400, 340-350

 

hmm thats my next step.

aiing for 350 atw

 

i made 408 atw and 473 atf. a standard new fiesta st done 3000 miles ran before me and made 1 hp less than ford state atf.

 

thats nice power

 

I reckon you lose about 25-35 on a FWD, between 35 and 50 bhp on a RWD car. About 80 on a 4wd.

I think any more smells a bit bullshitty to me, thats a lot of energy turned to heat.

 

so say around 40bhp loss??

 

think of it in % terms, the more power the more loss.

Given on half decent powerish manual rwd motors 50ish bhp


the saf mentioned above lost 65 bhp.

 

Volkwagen Beetle. Rear Wheel Drive. 32bhp as standard. So, if RWD cars typically lose around 40-50bhp, regardless of the power they make, I presume this Beetle won't move, since it's making -8bhp at the wheels at best?

Transmission losses are proportional to power.

In answer to the question though, a RWD 200SX made 350ATW yesterday on our Dyno Dynamics RR, which was just enought to top 400 estimated Flywheel horsepower.

 

makes my 310bhp about accurate also, and it was the same dyno (not the same premises)

i lost bout 53bhp but its an AUTO so loses more!

 

so really there is no real method to working it out?? its guess work basicaly? as to many factors can cime into play

 

S13 or S14?

Spec?

GT30?

 

Its NOT a flat out percantage though, same as its not a fixed number.

Things just dont work like that.

Its more of a fixed number, plus a bit of %.

Or in fact, who cares, its a SWAG (scientific wild ass guess) and its totally and utterly irrelivant to performance, and only good for showing off to other nobheads who care about a number which doesnt affect a cars performance at all.

 

100% guess work. Read FF issue 258 for my 6 page very in depth dyno article for far more details.

 

I think it's harsh to say it's a guess. A guess makes it sound like it probably isn't anywhere close. Dyno Dynamics have proven that they can get within a few HP of engine dyno results (if those can be taken as gospel, which in all honesty, they can't as there are as many bullshitty engine dyno's as there are chassis dyno's)

 

will do Stu

 

im more on wheel power but i wanted to know what kind of fly wheel power i would be gettin

 

i think you have your answer mate

 

Mine made 376@ wheels, 442@ fly..

 

the overall transmission loss from flywheel to tyre/road interface is not directly proportional to power at all.

some transmission losses maybe (like in the gearbox where more power through gears gives a proportionately higher thrust loading)

others are not, like in a rwd you may have losses due to a centre prop bearing. that does not change with power - but could change with speed

one of the biggest losses is the tyre/road, or usually worse, the tyre/roller interface (particularly if the test vehicle is strapped down with a downward force on the driven wheels). it is usually true to say that cars with more power generally have wider tyres that have a higher rolling resistance (which is part of the 'transmission loss'), so this is where the myth or assumption that more power = more losses probably comes from

in addition, cars with more power tend to run longer gearing so the wheel speeds are higher on the rolling road - again increasing the losses

quite right

i would say that based on some experimentation and experience it can be more of a 'guesstimate' than purely guesswork

 

Lets settle on an "Educated Guestimate" shall we?

 

 

Wheel figures are were its at.

Unless your using an engine dyno.

 

you cant argue with stu at msd he knows his stuff and thats that. he said to me my car is a good 450 after mapping and made 470. i think some rollers are better than others run a healthy low miles standard car is my view to check if rollers are near enough. then use the same rollers as you tune i think thats the best anyone can do without taking there engine out

 

mine made 373@wheels i estimate

415-420 at crank

with more to come for 2008

 

i only want around 350-360 atw for now..dont want to get bored of that and have no where else to go

 

Pump your tyres up a lot more so you have more power at the wheels!!
tabetha

 

 

People tend to use percentages, but this goes out at high and low power outputs.

Most accurate way of going from ATW to Fly is add 10 and divide by 0.88
Tried and tested way, and better than just saying 10%.

342 ATW would be bang on 400 Fly with this method.

Still not 100% accurate, but cuts out the conversion guesstimate of course.