Dyno graph autopsy - stage 2 vx220 turbo

[Pumaracing]

In what respect?

[R8VXF]

Engine rpm not mapped to dyno rpm. Have had that happen to me before.

[Pumaracing]

Give the boy a banana. Finally. The simplest most obvious most frequent dyno error there ever has been in the history of chassis dynos. The operator has mapped the engine rpm to wheel speed in one gear, probably third, so say 12 or 13 mph per 1000 rpm and then run the car up in another gear, probably 5th.

Looking quickly online for VX220 gearing it's 1.71 times higher in 5th than 3rd.

So when the dyno thinks the engine rpm is 2500 it's really 4272. The torque curve is correct albeit at the wrong rpms but the power curve is all 1.7 times too low. Peak power is really 134 x 1.71 = 229 bhp.

And yet an entire thread about why didn't the dyno guy rev the engine out. Of course he bloody did. He was just too stupid to set the parameters up properly in the first place.

[R8VXF]

Just having a whiskey instead of a banana right now

If I hadn't seen this myself only a month or so back, it wouldn't have clicked. Symptoms are the same though, under revving and under powered. As BHP is torque * rpm it kinda figures

[Richyvrlimited]

Pumaracing said:

Lol. No!

You're obviously much more experienced than myself, but I've never encountered AFR's of 10:1 on normal petrol as good, its excessively rich is it not?

I can't comment on the dyno stuff as I have absolutely zero experience. But from the AFR's being that rich i'd have said that the rest of the map was suspect too?

[Pumaracing]

Yes it's rich at the top end and no doubt costing a few bhp but not almost 50% of the engine's real output.

[Richyvrlimited]

Pumaracing said:

Yes it's rich at the top end and no doubt costing a few bhp but not almost 50% of the engine's real output.

What I was getting at is if the fuelling is that far off, its likely other things are too i.e. timing

[R8VXF]

Richyvrlimited said:

What I was getting at is if the fuelling is that far off, its likely other things are too i.e. timing

Fuelling can be that bad on a factory tune tbh.

[Paul.B]

Not his Dyno sheet?

It looks like a Diesel car to me hitting the limiter

[Clark3y]

10:1 is rich but it isn't absurd for a turbocharged engine, excess fuel is commonly used to help reduce temps and to fend off detonation.