Rolling Road Dyno Sheet
Discussion
I thought i'd share my Rolling Road experience i had on Saturday by showing you my Dyno sheet.
Now i'm not sure that the readings are correct for the mods that have been undertaken, i think they are a little optimistic at best. But i dont know how these things work but i thought you boys would be able to offer some comment.
Now i'm not sure that the readings are correct for the mods that have been undertaken, i think they are a little optimistic at best. But i dont know how these things work but i thought you boys would be able to offer some comment.
Well,
I've got a Corsa Pace exhaust on, and complete new intake system, the power duct thingy and hose, and hurricane intake thingymebob, but i wouldnt have expected that kinda improvements.
No they didnt strap the car down, they did the front whell drive cars but not the rears, imagine if that slips off at that kinda speed
I've got a Corsa Pace exhaust on, and complete new intake system, the power duct thingy and hose, and hurricane intake thingymebob, but i wouldnt have expected that kinda improvements.
No they didnt strap the car down, they did the front whell drive cars but not the rears, imagine if that slips off at that kinda speed
Hi,
Does the p-eng figure show the power at the crankshaft? I notice in the US, they quote rear wheel horsepower, so would that be the p-wheel at 272? Does that mean you have almost 400 crank horsepower but the drivline loss is 127.5, or 31.9% loss? Is the torque figure at the wheels or at the crank?
The reason I ask is that I had my ZR-1 on a dyno here in Germany, and the dyno machine output was similar, ie 4 lines on the graph. My German is not great, so I was not sure if my results were showing power at the crank. If so, my ZR-1 is missing a few ponies at the crank.
Does the p-eng figure show the power at the crankshaft? I notice in the US, they quote rear wheel horsepower, so would that be the p-wheel at 272? Does that mean you have almost 400 crank horsepower but the drivline loss is 127.5, or 31.9% loss? Is the torque figure at the wheels or at the crank?
The reason I ask is that I had my ZR-1 on a dyno here in Germany, and the dyno machine output was similar, ie 4 lines on the graph. My German is not great, so I was not sure if my results were showing power at the crank. If so, my ZR-1 is missing a few ponies at the crank.
KGV said:
Hi,
Does the p-eng figure show the power at the crankshaft? I notice in the US, they quote rear wheel horsepower, so would that be the p-wheel at 272? Does that mean you have almost 400 crank horsepower but the drivline loss is 127.5, or 31.9% loss? Is the torque figure at the wheels or at the crank?
The reason I ask is that I had my ZR-1 on a dyno here in Germany, and the dyno machine output was similar, ie 4 lines on the graph. My German is not great, so I was not sure if my results were showing power at the crank. If so, my ZR-1 is missing a few ponies at the crank.
I think you are correct by saying the flywheel/crank ouput is 399, and the driveline loss and tyre loss then converts down to 272 bhp at the wheels, its a high loss through the gearbox and tyres but i dont know what it should be?
The torque figure is at the crank also i believe.
>> Edited by b3any on Monday 4th October 12:46
jaytee368 said:
Now, I'm not close to being an expert on this topic but I have witnessed this going around several times on the ZR-1 Net.
Based on my observations from there, you have a HUGE driveline loss.
The talk I have seen seems that most agree on a loss of approx 18%!
Thats what i thought, so whats gone wrong?
Ah ha... Well that's where we come back to my admission to not being an expert!
I can see only 2 options here, perhaps get back to the folks that you went for the dyno run or with a bit of luck, someone more knowledgeable on the topic will chime in here.
There is at least one good thing, the BHP at the crank is very good and the torque is healthy too.
Are those values around what you hoped for?
In any case, good luck.
I can see only 2 options here, perhaps get back to the folks that you went for the dyno run or with a bit of luck, someone more knowledgeable on the topic will chime in here.
There is at least one good thing, the BHP at the crank is very good and the torque is healthy too.
Are those values around what you hoped for?
In any case, good luck.
jaytee368 said:
Ah ha... Well that's where we come back to my admission to not being an expert!
I can see only 2 options here, perhaps get back to the folks that you went for the dyno run or with a bit of luck, someone more knowledgeable on the topic will chime in here.
There is at least one good thing, the BHP at the crank is very good and the torque is healthy too.
Are those values around what you hoped for?
In any case, good luck.
Well i was hoping a knowledgeable person would tell me the score.
I was expecting between 360-370 if i was very lucky, which is why i think its not quite right.
This is a rolling road dyno, so the 'base' figure is power at the wheels - that's the one that ought to be closest to the truth. The flywheel figure is calculated from the power at the wheels and the transmission loss, so there are more possibilities for error in that figure.
Were any other cars tested at the same time, and did they also show higher than expected transmission/tyre losses?
Were any other cars tested at the same time, and did they also show higher than expected transmission/tyre losses?
A test of a 2002 Camaro SS is a good comparator but the difficulty is that GM have always lied about the true power output of the LS1 which probably generates a lot more than the claimed 325bhp. The rear wheel horsepower on that was 317bhp at the back wheels so the losses shouldn't be that high if the base figure is correct. I seem to recall a 1998 C5 vs Trans Am comparo and the rear wheel horsepower on those was abot 260-270 stock.
Andrew Noakes said:
This is a rolling road dyno, so the 'base' figure is power at the wheels - that's the one that ought to be closest to the truth. The flywheel figure is calculated from the power at the wheels and the transmission loss, so there are more possibilities for error in that figure.
Were any other cars tested at the same time, and did they also show higher than expected transmission/tyre losses?
Some of the standard cars were very accurate according to the book figures, within 3-7 bhp. So are we saying that the wheel output is most likely correct but the crqank output has been guesstimated a little high?
>> Edited by b3any on Monday 4th October 20:16
>> Edited by b3any on Monday 4th October 20:18
The dyno chaps can be quite clever. They take measurements used to accelerate the rollers and also deceleration readings and that's how they calculate the drag through the drivetrain (I think). On the US forums they often talk about 40-60 bhp losses via the gearbox depending on if it's auto or manual so I think that's probably a reasonable assumption of likely losses.
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