I know we wnet through it before but..

Scoobys typically have a power loss of 10% per wheel making 40% transmission losses. a 218 bhp wrx would produce roughly 131 bhp at the wheel and a 261 bhp STI would make around 157 bhp. The actual figure for power loss is probably closer to 38% so you can add a few bhp to these figures.

Frawls
 
I have a read out from my yoke from the previous owner before it had anything done to it and it was 197.5bhp & 103 to the wheels. 48% is a big drop. That was when it was 9 years old and about150,000 on the clock so it wouldn’t be the most efficient of machines
 
[quote author=FRAWLS link=topic=2005.msg18078#msg18078 date=1176304792]
Scoobys typically have a power loss of 10% per wheel making 40% transmission losses. a 218 bhp wrx would produce roughly 131 bhp at the wheel and a 261 bhp STI would make around 157 bhp. The actual figure for power loss is probably closer to 38% so you can add a few bhp to these figures.

Frawls
[/quote]

a 218 wrx makes more than 131bhp at the wheels surley? I thought the % loss was more like 25%..my VZR made 143 bhp at the wheels and that was on a dyno pack not a rolling road which is more accurate..I know FWD losses are less (15-18%) but still you expect a wrx to make more at the wheels
 
Yeah i think 25% is about right my sti was on the dyno and it showed 200@ the wheels. i was just wondering how that compares?
From what i have read on the net multiply this figure by 1.35 = 270
 
If you multiply by 1.35 that means you are factoring in a 35% factor for drag! I've been at about 4 rolling roads and Scoobies always show about 10% power less per wheel so 35% seems pretty close.

Frawls
 
yeah its just when mine was measured with a hub dyno and showed 200@wheels yer man gave me a print off that showed 287@fly out of a standard sti, seems too high that was factoring a 30% loss, anyway i'm not pushed about the calculation i was just wondering if other people had wheel bhp figures to compare
 
I will have next week putting my b4 on the dyno pack at TTM..sure it similar losses..il post up the results..whp and fly
 
[quote author=FRAWLS link=topic=2005.msg18249#msg18249 date=1176399704]
If you multiply by 1.35 that means you are factoring in a 35% factor for drag! I've been at about 4 rolling roads and Scoobies always show about 10% power less per wheel so 35% seems pretty close.

Frawls
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you maybe correct about 35-40% loss but I dont know what you mean showing a loss at the wheels??? sure the reading is taken from the wheels and the fly wheel power is then calculated factoring in transmission losses...only way to get true accurate fly wheel power is to use an engine dyno
 
[quote author=Dagnut link=topic=2005.msg18279#msg18279 date=1176412952]
I will have next week putting my b4 on the dyno pack at TTM..sure it similar losses..il post up the results..whp and fly
[/quote]
Look forward to that thanks, mine was done at TTM as well
 
you can clearly see written on the right of the dyno sheet that the flywheel power is an estimate...200 WHP is a good figure for an AWD
 
I know it's an estimate, what I'm saying is it means nothing because depending what estimate you use i.e 30% 20% 22% you get a differant answer just looking to compare atw bhp.
 
Might be of intrest, I spoke to a couple of people about this who would be failry well up on mapping and rollers and seems AWD losses are grossly exaggerated on the rollers. Due to the fact that the tyres on all four wheels are contacting in two areas on some rollers instead of one on the road which equels twice the friction equels twice the drag. Things like tyre type, tyre pressure tyre size , tyre temperture, gearbox and diff temps / ratio all effect the reading they put out so really means very little.

Ive been told the norm scoob losses (newage) are 20% - 24% and the only way to get an accurate flywheel bhp figure is on an engine dyno. Some rollers are showing near 40% though. From what I hear the Dastek dyno the losses are more like 13 or 14% on a scoob.
 
This was a dyno pack which bolts directly onto the hubs, i dont care about flywheel bhp because as you say its meaninglees, unless you use an engine dyno, and you basically make it up to suit your ego depend on what calculation you use, thats why i want to compare wheel bhp if anyone had readings.
 
[quote author=thedoc link=topic=2005.msg18321#msg18321 date=1176461145]
This was a dyno pack which bolts directly onto the hubs, i dont care about flywheel bhp because as you say its meaninglees, unless you use an engine dyno, and you basically make it up to suit your ego depend on what calculation you use, thats why i want to compare wheel bhp if anyone had readings.
[/quote]

your dead right whp figure is the one that counts, especially on the dyno pack..what kind of car have you got?
 
There are plenty of guys on here that have printouts form the many rolling road days we had at Westward Engineering. Martin Tracy's printouts show a lot more info than the ones posted above and show power and torque at the wheel as well as at the flywheel. It also shows ambient temp, boost presure, max rpms and speed attained.

Unfortunately I gave my dyno plots to my cousin when I sold my car but I think the whp was around 211 but I could be wrong. Since almost no one has access to an engine dyno, a rolling road is all we can go on. The figures vary wildly between dynos but Westwards dyno is well respected and if anything is a little conservative compared to most other dynos in the country.

Frawls
 
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