whp to bhp

[zilo900]

Hey, Does anyone know what the hp would be at the crank for me. i just got dynojet on the car and it came up with 318 whp. and its a gsx. thanks

 

[Ultimatedsm]

Mathamatically you just add 20% to your Wheel horsepower. Your making roughly 382 BHP, not bad at all.

 

[tstkl]

dude, no one knows the actual drivetrain loss for sure, 20% doesn't make much sense for cars that have really high outputs.

 

[Ultimatedsm]

dude, no one knows the actual drivetrain loss for sure, 20% doesn't make much sense for cars that have really high outputs.

You forgot I said "ROUGHLY" 382HP. A 2G DSM puts down around 175WHP and Mitsubishi claims they make 210HP at the flywheel. That is about a 20% difference.

Another thing, I don't get what you mean it doesn't make sense for really high outputs?? The AWD drivetrain loses the most power compared to FWD or RWD. There are too many moving parts which adds to more friction between parts etc.

Having that said, 20% is a good number to go by roughly, it isn't exact thats why I said roughly in the first place.

 

[tstkl]

once you get into higher hp number, it doesn't make sense that you lose 100 hp to move the same parts you had to at lower power outputs. In my opinion, percentages can't be used to find bhp, and also, bhp is just useless in general, its really only for people who are idiots and don't believe how fast your car is, yada yada yada.

 

[Jaraxle]

In general:

Divide by .85 for fwd
Divide by .80 for awd

So 318awhp is roughly 397.5 at the crank. Pretty serious on an evo 16g. How many psi did you have to push to get that ?

-Jaraxle

 

[2gGSX]

If you guys actually want to understand how drivetrain loss works, read through posts written by "Ted B" in this thread http://forums.evolutionm.net/showthread.php?t=197929

For those who are lazy to read, this should generally summarize the important part of the thread:

Higher hp means that the drivetrain is accelerated quicker, so Andrew is correct that higher hp = higher drivetrain loss, simply because it takes more power to accelerate the drivetrain at the faster rate of a higher hp engine. However, higher static drivetrain losses do not automatically equate to higher percentage of engine output.

The load of turning the drivetrain is small in comparison to the load of moving the mass of the vehicle, especially at speed. Therefore, the more power the engine makes, the lower the percentage drivetrain losses comprise of the overall load. Despite the fact that a 600bhp car accelerates the drivetrain at a faster rate than a 300bhp car, the drivetrain loss of a 600bhp car should be significantly less as a percentage of engine output than the drivetrain loss of the same car with 300bhp, simply because pushing the vehicle mass at the rate of a 600bhp car requires much more power than turning the wheels faster in space.

From what I can understand, he is saying that the rate of increase for static loss due to the wheels turning at the speeds which a 600 bhp car can turn them (drivetrain loss) increases at a much slower rate than the increase in overall power.
He backs this up by pointing out the fact that it takes more power to move the entire weight of the vehicle down the track than it does to overcome the static loss. Thus even though the 600 bhp car has more static loss, it is still moving down the track faster than the 300 bhp car (which subsequently has less drivetrain loss since it moves the wheels slower overall).
From this you can provide support for the argument that overall power of a car increases quicker than the static loss, and thus the overall percentage (static loss/overall power) of drivetrain loss decreases as you have a higher powered car.

If anyone has any ideas on this please comment.

 

[Jeremoose]

If you guys actually want to understand how drivetrain loss works, read through posts written by "Ted B" in this thread http://forums.evolutionm.net/showthread.php?t=197929

For those who are lazy to read, this should generally summarize the important part of the thread:
From what I can understand, he is saying that the rate of increase for static loss due to the wheels turning at the speeds which a 600 bhp car can turn them (drivetrain loss) increases at a much slower rate than the increase in overall power.
He backs this up by pointing out the fact that it takes more power to move the entire weight of the vehicle down the track than it does to overcome the static loss. Thus even though the 600 bhp car has more static loss, it is still moving down the track faster than the 300 bhp car (which subsequently has less drivetrain loss since it moves the wheels slower overall).
From this you can provide support for the argument that overall power of a car increases quicker than the static loss, and thus the overall percentage (static loss/overall power) of drivetrain loss decreases as you have a higher powered car.

If anyone has any ideas on this please comment.

I have no useful comment, but a damn fine read. Thanks

 

[silvah_gsx]

A good starting point would be just 210-175 (35), and add that to whp number if you're not much higher than stock. Either way, your car doesn't care about bhp, it cares about whp...bhp is really just a marketing tool, so that you can quote an inflated power number.

 

[Jaraxle]

On the evolution.net site. Trinababe summed it up:

"The numbers are all running through a calculation... it will never be accurate. There are way too many variables. Dynos are made to compare results on the same dyno. They should never be used to compare to another dyno because they just simply will never be the same."

-Jaraxle

 

[zilo900]

Thanks for all the replies, the car was tuned by AMS, running 100 octane and tuned to about 27 psi.

 

[Jaraxle]

Did you run a cat or no ?
Without a cat what is the lowest boost you can run ?
I have a similar setup to yours, and I run a 3" turboback with a cat.
Without the cat, my boost runs wild. Since I only have a 20psi gauge I'm not sure at what psi the party ends. With the cat, I can run any boost I want between 13-20psi.

-Jaraxle

 

[zilo900]

i have no cat, just apex n1 downpipe. the greddy profec spec 2 is controlling the boost and it works great. all my mods are updated in my profile if anyone wants to see what else its got