buschur racing dyno evo..
At a 25% loss that is saying every 10 hp you gain at the crank you lose roughly 2-2.5 hp due to the drivetrain, and it just keeps happening no matter how many times you gain that 10 hp. That is bunk and not true at all! The drivetrain is a constant people nothing changes about it. It would be better stated something along the lines of.....at 271 hp there is a 25% loss of power. Which comes out to be roughly 70 hp loss.
If you mod your car and produce 400 hp at the crank. And at 25% you would be losing 100 hp due to the the drivetrain according to that way of figuring drivetrain loss. But, that is not the way it happens. As Hp goes up that % becomes less and less. There is a rotational mass factor or something along those lines that is constant, and when power and torque are up the % of loss to rotate that mass becomes less. Why else did mitsu hollow out their cams. Someone correct me if I am not saying this right. I can think it...but not sure if I am saying this right?
If you mod your car and produce 400 hp at the crank. And at 25% you would be losing 100 hp due to the the drivetrain according to that way of figuring drivetrain loss. But, that is not the way it happens. As Hp goes up that % becomes less and less. There is a rotational mass factor or something along those lines that is constant, and when power and torque are up the % of loss to rotate that mass becomes less. Why else did mitsu hollow out their cams. Someone correct me if I am not saying this right. I can think it...but not sure if I am saying this right?
Last edited by favre95; Mar 20, 2003 at 09:44 AM.
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From: Los Angeles, CA
Originally posted by ShapeGSX
He said "let me get this straight.. you guys actually believe an awd car converted to fwd and then dynoed on a 2wd dyno is going to give an accurate representation of how much power the car puts out?"
I still believe that an AWD car converted to FWD and dynoed WILL give an accurate representation of the horsepower it puts out. People have been doing this for YEARS with AWD DSMs. Until a couple years ago, you couldn't find more than 2 AWD dynos in the United States. Sure you will get less power at the wheels when the rest of the drivetrain is hooked up.
I did not say that Buschur's numbers are correct, or that Shiv's numbers are incorrect. They are just a representation of the power the car puts out to the wheels. It isn't an absolute number.
He said "let me get this straight.. you guys actually believe an awd car converted to fwd and then dynoed on a 2wd dyno is going to give an accurate representation of how much power the car puts out?"
I still believe that an AWD car converted to FWD and dynoed WILL give an accurate representation of the horsepower it puts out. People have been doing this for YEARS with AWD DSMs. Until a couple years ago, you couldn't find more than 2 AWD dynos in the United States. Sure you will get less power at the wheels when the rest of the drivetrain is hooked up.
I did not say that Buschur's numbers are correct, or that Shiv's numbers are incorrect. They are just a representation of the power the car puts out to the wheels. It isn't an absolute number.
What's IMPORTANT is the RELATIVE improvement on the dyno you see after modifications. How hard is it to understand for some of you? The point is that Buschur Racing has shown us very nice power improvements with easy mods.
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From: NYC Kid!
Pruven dynoed the same numbers as Buschur
http://www.pruvenperformance.com/pruvenlancer.htm
This was on an AWD dyno.
http://www.pruvenperformance.com/pruvenlancer.htm
This was on an AWD dyno.
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dynoing any AWD car converted to FWD is just for show and tuning. 
what is the point? if you want an accurate representation of HP you should only use an AWD drive set-up. if you only run the front wheels, you are cutting alot of the HP sapping parts out of the mix. what about the drive shaft, carrier bearing, rear axles? they will all pull the HP numbers down.
who cares what they dyno anyway, just take it to the track and put up some hard numbers!!
what is the point? if you want an accurate representation of HP you should only use an AWD drive set-up. if you only run the front wheels, you are cutting alot of the HP sapping parts out of the mix. what about the drive shaft, carrier bearing, rear axles? they will all pull the HP numbers down.who cares what they dyno anyway, just take it to the track and put up some hard numbers!!
Originally posted by GaryChios
Pruven dynoed the same numbers as Buschur
http://www.pruvenperformance.com/pruvenlancer.htm
This was on an AWD dyno.
Pruven dynoed the same numbers as Buschur
http://www.pruvenperformance.com/pruvenlancer.htm
This was on an AWD dyno.
Erik
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Originally posted by erikgj
So when does 223hp = 254hp? I don't think I would draw any conclusions from that. Different dyno (same maker yes), different setup.
Erik
So when does 223hp = 254hp? I don't think I would draw any conclusions from that. Different dyno (same maker yes), different setup.
Erik
Damn, even I knew that.
Logically, I do not see how a front wheel DYNO would give a less accurate rating of CRANK horse power than a 4 wheel dyno. I even thing it might give a more ACCURATE reading since it does not have to pass through the different differentials and drive train loss can be accounted for.
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Originally posted by Sweft
Logically, I do not see how a front wheel DYNO would give a less accurate rating of CRANK horse power than a 4 wheel dyno. I even thing it might give a more ACCURATE reading since it does not have to pass through the different differentials and drive train loss can be accounted for.
Logically, I do not see how a front wheel DYNO would give a less accurate rating of CRANK horse power than a 4 wheel dyno. I even thing it might give a more ACCURATE reading since it does not have to pass through the different differentials and drive train loss can be accounted for.
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From: Pottstown, PA
Originally posted by Señor Info
I don't understand why you folks believe in the % loss factor. Let's try a little thought experiment.
Suppose some FWD car with an engine crank-rated at 250 lb-ft of torque at 3600 rpm is measured to produce 225 lb-ft of torque at 3600 rpm on a chassis dyno. That's a loss of 25 lb-ft or 10%, attributable to the drivetrain. Now pull that engine out and swap in its place one which produces 750 lb-ft of torque at the crank at 3600 rpm. Do you now expect the drivtrain to somehow absorb 75 lb-ft of torque (10% of of 750)? Why would it suddenly absorb tripple the amount of torque as before when nothing about the drivetrain has changed?
I don't understand why you folks believe in the % loss factor. Let's try a little thought experiment.
Suppose some FWD car with an engine crank-rated at 250 lb-ft of torque at 3600 rpm is measured to produce 225 lb-ft of torque at 3600 rpm on a chassis dyno. That's a loss of 25 lb-ft or 10%, attributable to the drivetrain. Now pull that engine out and swap in its place one which produces 750 lb-ft of torque at the crank at 3600 rpm. Do you now expect the drivtrain to somehow absorb 75 lb-ft of torque (10% of of 750)? Why would it suddenly absorb tripple the amount of torque as before when nothing about the drivetrain has changed?
If nothing else about the drivetrain has changed, and only power increased (for the sake of comparison), then you have the more power going through the same drivetrain... the same drivetrain losses will apply no matter how much power you have. 10% of 100 is 10. 10% of 1000 is 100. Sorta like taxes... the more you make, the more they take.
Unless I'm waaay off here. I would be interested in seeing a good scientific explanation of drivetrain loss % vs. power...
Last edited by Max Rebo; Mar 20, 2003 at 02:44 PM.
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Originally posted by GRoceryTurbo
because you are not measuring crank HP on a chassis dyno!
because you are not measuring crank HP on a chassis dyno!
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I don't see how the drivetrain can physically keep taking away more power when the mass(weight) of it stays the same. Why then if you add more weight like bigger rotors, bulkier axles, and so on...why does it steal more power. It is not physically possible for the drive train to steal a constant set % of power. The drivetrain has a "set mass" from the factory and it will steal a certain % of power at a given power rating. As that power rating goes up the percentage goes down. Kinda like shooting freethrows, if you shoot 100 freethrows and in the first 10 you miss 4 that is 60%...but if you then miss none after that and end up making 96 total your at 96%.
yes, true, but that friction still only has a given value,(of whatever you measure friction in), and left unchanged and power increases you will still lessen the percentage of Power Loss Through the Drivetrain. Not to be rude but, I am still not convinced that a drivetrain takes a certain percentage of power away.