bmw dyno day result

[Vixpy1]

dan101smith said:

And here's the graph...

Bloody hell, that ones even worse!!

Again, nothing really wrong with the bhp fig. But the gearing is quite plainly wrong. These engines do not make peak poer at 4800!

I'll dig out what a graph should look like.

[Vixpy1]

I'm afraid i can't remember the details of this car, other than it had minor mods, and was an N reg coupe.

[dan101smith]

Don't suppose you've got a graph for an E28 M535i have you? I'd be interested to see that.

Why do you think that the graphs are so different?

Edited by dan101smith on Monday 21st January 11:53

[Vixpy1]

dan101smith said:

Don't suppose you've got a graph for an E28 M535i have you? I'd be interested to see that.

Why do you think that the graphs are so different?

Edited by dan101smith on Monday 21st January 11:53

I'm afraid i've never done an E28, lots of other M cars, but never an E28

Its because you must tell the dyno what rpm the car is doing at what speed, so it can print the rpm scale at the bottom, and also work out the torque from the BHP it already knows from the rpm of the rollers. Its really really easy to get wrong, I've done it before. If you enter a ratio that is too low, it brings the bhp line down the rpm scale, and naturally this pushes the torque fig up (more bhp at lower rpm = more torque/more torque at lower rpm = higher bhp)

However, its also very very easy to correct any error on the subsequent runs.

[dan101smith]

I see...I didn't spot that on the day, but I have to say I'm a little disappointed that the guys doing it didn't spot it either.

We (BMW5 forum) have been there twice now on group days. Maybe next time we'll come down to Surrey instead...

[Vixpy1]

I should of coarse say i have nothing against DSA.

However, the BMW5 forum would be very welcome at SRR

[lewis328]

i had my standard 97 328 sport on the rollers last week for the first time, max bhp was 189, with 190lb ft of torque, was told engine was running spot on, with no faults etc, i was pleased untill i started to see some of your cars graphs in 200+bhp territory, some modifications are needed i think,

[dan101smith]

anonymous said:

[redacted]

A fair point - to be honest I hadn't really looked at the graph in detail. They sent them through by email about 2 weeks after the day. And it's easy to be distracted by a Sagaris and a couple of M5s on the rollers!

Vixpy - your comment about the setup explains why the torque figure is out, but what about the bhp reading? I know the flywheel HP is calculated rather than measured, but should I expect the RWHP to be accurate? That was measured at 167.5bhp.

[Vixpy1]

dan101smith said:

Vixpy - your comment about the setup explains why the torque figure is out, but what about the bhp reading? I know the flywheel HP is calculated rather than measured, but should I expect the RWHP to be accurate? That was measured at 167.5bhp.

I have no probs with either the wheel or flywheel bhp figs on any of the graphs posted here. A good 328i should do about 195 to 200 stock.

A fair one will be around the 190bhp. So i would'nt get disheartened at all if thats what its doing (the other chap)