Warrtalon,

I fully support your statements, the magazine Automovil got 311HP on the European 280HP rated EVO. That also explain the high trap speeds and also the fact that makes in some ocasions more power than a 300HP rated STI.

Agree..

 

You're missing something, though. You can't base the drivetrain loss off the MR's numbers while ignoring the STi's. There is a major difference in the numbers and there's no way the drivetrain loss is that different between the 2 cars. If you use the STI's drivetrain loss, you get 340whp=437.8bhp.

I think it's safe to say that the 05 is UNDERRATED at 276, while the STi may be slightly overrated. You definitely can't base standard drivetrain loss off of what the 05 dyno's in comparison to Mitsu's claimed bhp.

 

they have different scale of "HP" in euro.
a little bit higher than U.S scale (with same engine, same hp)
but not that much...

 

I believe that the drive train loss is much greater than you guys guesstimate. I feel it is around 100 hp on the higher power vehicles.

 

HP= torque x (rpm/5252)

Please explain to me how that is going to change the results if the same units are being used? ...

fromWRXtoEVO and Warrtalon: I have to agree with you guys, I also believe the 05 US EVOs are making around 315HP at the flywheel based on the dyno numbers ... Heck in GT4 the EVO MR is rated at 315HP ...

 

From my understanding of dynos, which I have spent many hours researching, if it was on a Dynojet dyno, it won't be that much of an increase. I think Dynojets add 15-20% to the actual whp number before they print out their new "whp" number. That is why if you put the same car on a Mustang dyny and a Dynojet dyno, the Dynojet number is always significantly higher. I will post up some links to sites that explain it better than I could when I get home.

 

ok awd drivetrain loss is anywhere from 20 to about 25% loss in power. so if u are making 300whp u have about 360-370 crank hp. that is assuming a 20% loss. u have to remember everycar is different. some awd systems only use the awd when the other wheels are slipping, some only use the 2 opposite wheels. as for the evo, if i am correct it uses all four wheels all the time. u start out with a crank hp number ex. 370, then u multiply it by your percentage loss, .20 and subtract the 2 numbers.

370*.20=74
370-74=296whp

now there is no way or at least an easy way that i know of to figure out your specific drive train loss so we have no exact numbers.

 

u cant go by factory ratings. your description is saying that the evo has only about 13% drive train loss. thats not correct as far as i know.the evo is known to be underrated so we know that the 276hp is not correct. i fell like they under rate it for emission reasons. but hey thats just me.

 

Greetings,

Using a dynapack, and having tested over a dozen stock cars, the driveline loss is around 19% to 20%. This percentage can only be used for stock comparisons, since driveline loss stays constant (within 2%) as horsepower increases. It is a common misconception to calculate driveline loss percentage as a variable.

276hp = 218 to 225whp on dynapack = 51 to 58 hp loss in driveline

600hp = 549 to 542whp on dynapack

Using a percentage (20%) would equal a loss of 120hp in the driveline in this example... Unless someone can explain the additional driveline loss due to increased power, I'll stick with my number of hp lost versus using a percentage.

Cheers,

OS

 

Why would it not be a percentage? You are assuming the first numbers are right, but that would mean a 50bhp car would read -1 to -8whp on a Dynapack. Likewise, a 100bhp would read 49 to 42 whp? Not likely. The actual % of drivetrain loss may not be perfectly linear as you increase power, but you definitely can't use the 276bhp vs 220whp as your standard for measurement across the entire range of hp, especially since the 276bhp is known to be underrated.

 

eric, i would ask Chris and Alfred how much power STOCK evo's put down on their dyno, i believe its in the ballpark of 225hp.

then, i believe you can figure out the drivetrain loss percentage and apply it to your numbers.

 

I will do that. Thanks.

 

Here's the link I was talking about earlier:
http://www.germanmotorcars.com/Dyno_...0inertia_1.htm

 

Hey guys,

You can't really use the factory rating of 271 (03 Evo) or 276 (05) anywhere in a calculation for drivetrain loss. You can't assume the 271 or 276 is right. Production cars would obviously have variances as well, ceteribus paribus... Automakers have clearly erred in factory ratings both higher and lower.

The only real accurate way to determine true drivetrain loss would be to dyno the engine only on an engine dyno, then dyno the same engine in a car with a chassis dyno.

Also, some state the drivetrain loss is always a percentage, while some state it is more of a fixed value. IMHO, the latter makes sense if you think about it, because, the transmission and other parts of the drivetrain lose power as heat and noise among other things. Think of conservation of energy. As you make more power, it's probably not going to increase linearly, ie. the tranny doesn't get "that' much hotter, right? However, it's probably not a fixed about (~50 HP) exactly either. As one poster stated, it probably goes up slightly with more power, but not linear. In other words, you can't get an exact value, but you can get a rough estimate. Much like internet bench racing, there are too many variables to consider, heh.

Does anyone know of any actual engine dyno vs chassis dyno comparisons?


Thanks.

FB

 

ceteris peribus = "all else being equal"

so what you're saying is "production cars have variances, all else being equal."

Explain that one.