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Dynapack rolling road



Took my car to a rolling road today to see how she was running. First time iv been on a Dynapack rr, remove the front wheels and it just bolts to ur hubs. Can some one tell me, is this a better way of telling you the TRUE bhp/torque for your car????
 
  ITB'd MK1
it's no better or worse because people still apply guestimated loss figures.

Hub dynos do tend to give an "at the hubs" figure that's a lot closer to the flywheels figure. Often this is forgotten and normall rolling road loss numbers are applied. for example, if on a rollers you're seeing 30-35bhp losses, on a hub dyno, you'd see more like 10-15bhp losses.
 
I got 224.9 bhp at the hub and 199 of torque. The lad who tested it said there is a loss of 35 bhp compaired to flywheel hp.
 
the only real advantage is elimination of slippage.

you cant get wheelspin on a hub dyno simply.

only a problem on high power stuff though really, more so turbo cars with aggressive power delivery, which can be difficult on twin drum rollers.

for a stock 172 you should be fine on either system :)
 
what mods you got? how did they work out losses ?

My clio's supercharged, as for losses he told me there was a 35 bhp loss from flywheel to hub????
I know there is a loss of 16% through the gearbox on normal rr. Just seemed mad how it was tested, with no wheels on.
 
i thought the torque was high for the hp. i take it you dont rev very high? or torque drops sharply at high rpm?

The car revs to 7100, never really take it that high. But on the last rr i went to, the torque drops off fast from just over 6k. This time it was tested , i told him only take it to 6.5k because of this.
 
not sure i understand what your asking?


but to make hp, you need to carry tq as high in the rev range as possable. you dont need much torque, but you do need to keep hold of it as long as poss.


i.e a car that makes 200lb/ft@ 8k will make 304hp.

a car that makes the same 200lb/ft, but only holds it to 6k will make 228hp.
 
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no probs :)

heres 1 of mine from 2 weeks ago, note not much torque really, but quite high revs, makes good hp




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