Z3M Dyno Results
Discussion
john_p said:
At the wheels or flywheel?
For some reason you can't dyno an E46 M3 past 6500rpm - the DSC stops you doing it even if it's switched off!
I think the graphs I've seen were developing 250-260bhp ATW at 6500 rpm ..
Apparentley the E46 M3 gets a bit worried by the fact that the rear wheels are spinning "hell for leather" yet the fronts are still stationary so it limits the revs you can use. Was probably done to try and prevent Tiff from burning the rear tyres out when testing it!
233.5bhp at the wheels, drag 69.5bhp!!, corrected 303.0bhp
Runs 13.7s 1/4s at 105mph (slippery surface with 2.3s 60ft times!) and will run off the limiter at 157mph GPS (160mph speedo)
Most BMWs that I've found dynod run under the specifications claimed - I understand their figures are "test bed" figures i.e. no water pump, oil pump, fan, power steering, alternator etc
Have found a couple of M3 dynos about 245bhp at the wheels which seems about right?
Bet they "fixed" the new M3 so it couldn't be dynod - otherwise we'd find out it "only" has 320bhp, not 343 - LOL!!
P.S. only other "excuses" are 1. they didn't rev it out - the graph was still climbing at 7100 and The Book claims max power @ 7400rpm; 2. there was still wheelspin despite fat man sitting in the boot, anti-slip spray and Nitto 555 Drag Radial (which were smoking!), 3. No "Ram Air" effect on dyno (minimal with standard airbox set up, I guess?)
>> Edited by The Admiral on Monday 17th November 18:21
Runs 13.7s 1/4s at 105mph (slippery surface with 2.3s 60ft times!) and will run off the limiter at 157mph GPS (160mph speedo)
Most BMWs that I've found dynod run under the specifications claimed - I understand their figures are "test bed" figures i.e. no water pump, oil pump, fan, power steering, alternator etc
Have found a couple of M3 dynos about 245bhp at the wheels which seems about right?
Bet they "fixed" the new M3 so it couldn't be dynod - otherwise we'd find out it "only" has 320bhp, not 343 - LOL!!
P.S. only other "excuses" are 1. they didn't rev it out - the graph was still climbing at 7100 and The Book claims max power @ 7400rpm; 2. there was still wheelspin despite fat man sitting in the boot, anti-slip spray and Nitto 555 Drag Radial (which were smoking!), 3. No "Ram Air" effect on dyno (minimal with standard airbox set up, I guess?)
>> Edited by The Admiral on Monday 17th November 18:21
Admiral, your figures sound about right, don't BMW quote PS rather than BHP which would equate for a few percent as well, and if you were getting wheelspin, that must affect results by quite a margin ?
I don't know the reason for the block on dynoing an M3. Apparently if you have a BMW diagnostic computer you can turn off the 'dyno lock'. Certainly on an M3, all the electronic aids are supposed to turn off if you turn off DSC - and if it was ABS why is it a hard limiter at 6500rpm? Very odd.
There have been a lot of posts over at bm3w trying to solve it, and I think the only conclusion so far is to hack the front and rear ABS sensors together on the rear wheels so that the car doesn't know about the differing wheel speeds - or purchase a pair of metal bars about 3m long and bolt the front and rear wheels together steam-train style!
>> Edited by john_p on Monday 17th November 18:44
>> Edited by john_p on Monday 17th November 18:44
I don't know the reason for the block on dynoing an M3. Apparently if you have a BMW diagnostic computer you can turn off the 'dyno lock'. Certainly on an M3, all the electronic aids are supposed to turn off if you turn off DSC - and if it was ABS why is it a hard limiter at 6500rpm? Very odd.
There have been a lot of posts over at bm3w trying to solve it, and I think the only conclusion so far is to hack the front and rear ABS sensors together on the rear wheels so that the car doesn't know about the differing wheel speeds - or purchase a pair of metal bars about 3m long and bolt the front and rear wheels together steam-train style!
>> Edited by john_p on Monday 17th November 18:44
>> Edited by john_p on Monday 17th November 18:44
Hi Rassi!
They use a Maha rolling road - I understand that it measures torque and uses a formula to change this into power. This is measured at the rear wheels. After the full power measurements, the operator lifts off the throttle and the dyno measures rolling resistance and assumes this to be roughly equal to transmission losses.
Different RRs seem to use different measuring techniques, so I guess they're only much use for comparing same car on same RR with/without mods, or possibly different cars on same RR on same day etc... If the cars are turbos, they also apply some conversion factor for intake temperature to compensate for the artificial envirnment of static measurements... More usefully , Star measure boost pressure and air fuel ratios which is helpful for out turbo colleagues
On bm3w there are reports from German tuners who have dynod many E46s saying that they have on average 320bhp ~(corrected) with a range of 318-323 or so which ties in with my estimated 303bhp, I guess.
The results from the G-force dynos down south are much higher, with E46s pulling much higher bhps and the Spanish seem to think the BMW figures are accurate to two decimal places!!
In summary, the at the wheels torque figures seem the most accurate ways of comparing cars between dynos, with extrapolated figures for power at wheels not too bad and flywheel figures more variable.
They use a Maha rolling road - I understand that it measures torque and uses a formula to change this into power. This is measured at the rear wheels. After the full power measurements, the operator lifts off the throttle and the dyno measures rolling resistance and assumes this to be roughly equal to transmission losses.
Different RRs seem to use different measuring techniques, so I guess they're only much use for comparing same car on same RR with/without mods, or possibly different cars on same RR on same day etc... If the cars are turbos, they also apply some conversion factor for intake temperature to compensate for the artificial envirnment of static measurements... More usefully , Star measure boost pressure and air fuel ratios which is helpful for out turbo colleagues
On bm3w there are reports from German tuners who have dynod many E46s saying that they have on average 320bhp ~(corrected) with a range of 318-323 or so which ties in with my estimated 303bhp, I guess.
The results from the G-force dynos down south are much higher, with E46s pulling much higher bhps and the Spanish seem to think the BMW figures are accurate to two decimal places!!
In summary, the at the wheels torque figures seem the most accurate ways of comparing cars between dynos, with extrapolated figures for power at wheels not too bad and flywheel figures more variable.
Admiral,
As you too are the proud owner of a Breadvan, go have a look at the www.z3mcoupe.com/forum/ - a dedicated forum for the M Coupe.
Anders, '99 M Coupe
As you too are the proud owner of a Breadvan, go have a look at the www.z3mcoupe.com/forum/ - a dedicated forum for the M Coupe.
Anders, '99 M Coupe
Great,
The thorny issue of dyno figures again. IIRC the G Force dynos don't use the coastdown technique to estimate a flywheel figure like the maha dynos (not sure how they do it though).
IMHO flywheel figures are not very useful anyway, they are so prone to being overstated, to the point that in the USA tuned car scene hardly anyone even quotes flywheel figures anymore (it always starts arguments).
For the record Performance Bikes magazine always used to dyno all their bikes and some of them were quite a way off the quoted power figures.
Rob.
The thorny issue of dyno figures again. IIRC the G Force dynos don't use the coastdown technique to estimate a flywheel figure like the maha dynos (not sure how they do it though).
IMHO flywheel figures are not very useful anyway, they are so prone to being overstated, to the point that in the USA tuned car scene hardly anyone even quotes flywheel figures anymore (it always starts arguments).
For the record Performance Bikes magazine always used to dyno all their bikes and some of them were quite a way off the quoted power figures.
Rob.
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