Sport power run.....

[he30]

Had the car on the dyno today in preperation of the 6 branch fitting.( For those not follwing the thread ''cheap six branch'' by gra325i. Have to say, quite pleased with the results, as she's putting out bang on, if not slightly more than book. Dyno was fitted direct to the hubs so no tyre loses etc, and run up around 6 times to get an average. As explained 2 whhel drive cars would expect to lose around 45-50 bhp in transmission loses, so a cracking result really


Results.....

[he30]

Big thanks also to Chris Wright (BOFFIN) who did the power run for me an his last day of working there!

[maxfield]

Does that come to about 173hp at the flywheel?

I'm a little confused on the torque though

[he30]

Me too, peaking at 4000 rpm?i can only presume it's the zone wild chip? dyno's confuse me a the best of times....

[bazza93]

so its not a standard sport then ( zone chip ) i thought it was standard was quite impressed until then

[maxfield]

I was thinking of the 500+ lb/ft

[he30]

so its not a standard sport then ( zone chip ) i thought it was standard was quite impressed until then

Sorry should have said, zone chip, bbtb.

[fuzzy]

50bhp transmission losses? . shouldnt be anywhere near that i thought. 10-15% in a 2wd.
im also confused by the 575.3lbft of torque

[oldroydsr4]

normally about 20% give or take a bit.

50bhp is alot

[he30]

I'm going on the figures given, 45/50 2wd and around 70 for 4wd.

[M3Compact]

575.3 Lbft?

[BOFFIN]

Sorry Howard, I gave you the wrong graph.
The power graph is correct, however the torque graph represents the tracktive torque at the hubs. I.e the torque of the engine when amplified by the gear ratios in fourth gear. The correct graph will take into account the combined gear ratio of the diff and fourth gear which I think equated to around 3.856:1
So if you divide the tracktive torque by the gear ratio you get the torque at the hubs;

575.3 / 3.856 = 149.2 lbft

Will get you the correct graph next week.

As for the transmission losses, you guys are quite right 15 - 20% is usually what I use in my head (sorry Howard I should not have quoted a figure of 40-50 hp for a car of this power), however we try not to quote flywheel figures because it is only an estimate when compared with the accurately measured value of the power and torque at the wheels. Besides which, what you have at the wheels is what you have, so really there is no point in worrying what the flywheel figure is other than to compare with other quoted flywheel figures. I wish everyone would just use at the wheels figures, it would make things simpler (for me). Manufacturers are coming round to the idea very slowly.

Sorry for the confusion guys, I hope this helps.

Christopher Wright.

[maxfield]

Americans use wheel figures.

Thanks for clearing the torque up

[M5pilot]

Something not quite right there.

Peak power does not come in at 4500 rpm no matter what chip you use.

If the rev limiter was hit then the tacho should show 7000 rpm and not 6200rpm. Sounds like incorrect tacho hub speed calibration. This would explain the incorrect torque figure to some extent but I just cannot see how 500+ lb.ft was measured.

I hate to say this but that dyno run is something that cannot be taken seriously unless the operator can explain what exactly is going on.

130 bhp at the wheels is quite good.

As a comparison, Barry's sport which made 175 bhp did 140 at the wheels. Ant's 180 bhp 325i did 145 at the wheels.

Sal

[he30]

Something not quite right there.

Peak power does not come in at 4500 rpm no matter what chip you use.

If the rev limiter was hit then the tacho should show 7000 rpm and not 6200rpm. Sounds like incorrect tacho hub speed calibration. This would explain the incorrect torque figure to some extent but I just cannot see how 500+ lb.ft was measured.

I hate to say this but that dyno run is something that cannot be taken seriously unless the operator can explain what exactly is going on.

130 bhp at the wheels is quite good.

As a comparison, Barry's sport which made 175 bhp did 140 at the wheels. Ant's 180 bhp 325i did 145 at the wheels.

Sal

See explanation above???