[zeeshan]

ripp's numbers are looking like bs even if they are BHP numbers, they are off by like 50hp. a gt 5speed makes what 200bhp? and they usually put down 170whp? that's a 15% transmission loss.

that means it takes the transmission/axles/whatnot 30BHP to RUN.

now say you modified your car and you put down 270WHP on the dyno. the transmission loss STILL remains at 30hp. therefore you are making 300BHP.

transmission loss is CONSTANT.

 

[TheFranchise]

i would think its near constant but not exactly linear. more stress and heat are generated in higher horsepower applications in the transmission therefore, more loss.

 

[Tearstone]

Yeah drivetrain loss is measured in % more less than anything else.

My car, I put down 270whp with 25% drivetrain loss which guestimate = 337.5bhp

Rulez is putting down 295whp with 15% drivetrain loss which guestimate = 339bhp

I only use our two cars as a comparison since they are nearly identical as far as setups are concerned.

 

[zeeshan]

i would think its near constant but not exactly linear. more stress and heat are generated in higher horsepower applications in the transmission therefore, more loss.

what kind of stress are you talking about and what heat? can you explain what you're trying to say? it's can agree to "very near" constant. but it won't be off more than 5-8hp.

 

[zeeshan]

Yeah drivetrain loss is measured in % more less than anything else.

My car, I put down 270whp with 25% drivetrain loss which guestimate = 337.5bhp

Rulez is putting down 295whp with 15% drivetrain loss which guestimate = 339bhp

I only use our two cars as a comparison since they are nearly identical as far as setups are concerned.

tuning in a boosted application can make two cars with an exactly identical setup put out different numbers. same with different dynos. a dyno jet will put out different numbers than say a dynapack. etc. so can temp, atm pressure and few other factors. this has nothing to do with drivetrain loss not being constant.

with the %theory, a mustang that just put down 1000whp with say a 20% loss is actually making what 1200hp? i don't believe that at all.


the only way you can tell how much transmission loss have is by comparing your car with a chassis dyno and then an engine dyno. this has been done locally. transmission loss is constant.


also when you get close to maxing out your turbo. it flows what 47lbs/min. that should make you a max of 470BHP. for a gt 5 speed you will be putting down 440whp.

not trying to start an argument here, just stating things i've personally expierenced/seen. % transmission loss is a common mistake

 

[Tearstone]

tuning in a boosted application can make two cars with an exactly identical setup put out different numbers. same with different dynos. a dyno jet will put out different numbers than say a dynapack. etc. so can temp, atm pressure and few other factors. this has nothing to do with drivetrain loss not being constant.

with the %theory, a mustang that just put down 1000whp with say a 20% loss is actually making what 1200hp? i don't believe that at all.


the only way you can tell how much transmission loss have is by comparing your car with a chassis dyno and then an engine dyno. this has been done locally. transmission loss is constant.


also when you get close to maxing out your turbo. it flows what 47lbs/min. that should make you a max of 470BHP. for a gt 5 speed you will be putting down 440whp.

not trying to start an argument here, just stating things i've personally expierenced/seen. % transmission loss is a common mistake

Seems a little strange that our bhp numbers are so close together when our setups are nearly identical, and we dyno tuned on the same day :dunno: But I'm open to a better explanation. :agreed:

Chasis dyno, you mean where the engine is removed from the car and attached to a dyno?

Does anyone have anyone know if a definitive calculation on converting whp to bhp?

 

[zeeshan]

chassis dyno being the dyno which you guys used to measure whp

i wish i could provide you guys with the proof a ford escort cosworth whp vs bhp exact same mods

i just have a hard time understanding how mustangs that make 1000whp are requiring a transmission that needs 200hp to run! hehe. that transmission would be melted to hell ;p

 

[Tearstone]

chassis dyno being the dyno which you guys used to measure whp

i wish i could provide you guys with the proof a ford escort cosworth whp vs bhp exact same mods

i just have a hard time understanding how mustangs that make 1000whp are requiring a transmission that needs 200hp to run! hehe. that transmission would be melted to hell ;p

I think of it as throwing an anchor out the back of the boat sort of loss. It's not that it takes 200whp to run, but the potential to make 200whp is weaked or held back by all the drivetrain.

 

[npeifer]

I understand what you guys are saying. I have always understood it to be a % but I could be wrong I guess ? I thought that car and driver, motortrend etc always used a % ??

 

[npeifer]

I think of it as throwing an anchor out the back of the boat sort of loss. It's not that it takes 200whp to run, but the potential to make 200whp is weaked or held back by all the drivetrain.

That is a good way to put it Russ.

 

[zeeshan]

i just talked to a couple of tuners, they said that "it's definately not percentage loss" and not constant either. "very close to constant" as he said ;p

 

[Tearstone]

i just talked to a couple of tuners, they said that "it's definately not percentage loss" and not constant either. "very close to constant" as he said ;p

Interesting, I would like to learn more about this. What is the reasoning behind why they feel that it is definitely not a % loss?

 

[zeeshan]

cause they've tested it using an engine dyno and chassis dyno

 

[TheFranchise]

i just talked to a couple of tuners, they said that "it's definately not percentage loss" and not constant either. "very close to constant" as he said ;p

hey thats what i said!

 

[00Z]

This is very interesting. I bet there is a formula, where you are near a constant loss, but variables are there to compensate for amount of power displaced, say with a 1000 hp Mustang, linear plus a bit to include the extra power strain and heat, etc... strain on the transmision (what, maybe 40-50 hp loss total...?).

 

[Tearstone]

cause they've tested it using an engine dyno and chassis dyno

Tested it with various boost levels?

 

[pacoslant]

good read http://www.superstang.com/horsepower.htm

 

[zeeshan]

Tested it with various boost levels?

this guy usually builds motors and runs the best boost possible in the turbo's efficiency range.. so i guess he tested the theory with various boost levels

i'll soon have my motor on after it's built, i want to test this theory out for myself by throwing it on an engine dyno while it's off the car.. and then chassis dynoing it