Dyno testing

[CharlieHorse 0]

anyone know where i can get this done in liverpool or somwhere near by

[dazzyvr6 0]

dubsports not to far away from liverpool

[dr_mat 0]

Anyone have any info as to how reliable wheel dynos are?

It strikes me that the correction for transmission loss is much greater than the actual variances that are reported between different engine mods.

When you're losing 48bhp to transmission loss, how can you realistically claim that you've gained 8bhp by doing xyz?

That said, it's a good way to annoy your mates down the pub .. "I got 201.1 bhp and 192.7 lbft so nerr".

Of course, the one thing you can rely on is the actual *shape* of the torque curve.

[Henny 0]

yeah, that's how I've always seen rolling roads... who gives a damn what you got on XYZ's road, when in a group session you were 20BHP lower down than everything else and had just enough torque to pull the skin off a rice pudding! ;)

 

I want to see a nice torque curve for my engine, that's nice and flat thru the whole rev range and had a nice BIG number to go with it! ;)

[andycowuk 0]

mmmm rice pudding :-P

 

isnt the torque measured at the wheels? the BHP figures are the ones that are subject to the rolling roads pinch of salt calculations?

[scruffydubbers 0]

torque and power aways cross at 5250rpm, this must pay apart in the calculations

[dr_mat 0]

There are torque losses through the drivetrain as well as power. The power (force) measured at the wheels is translated back to the torque-at-flywheel figure, which is the headline grabber.

The power graph is then simply calculated from the torque curve and the engine revs.

[andihaz 0]

As Dr Mat said all power is, is the torque multiplied by the engine speed in rad/s. Thats why having a nice flat torque curve is best as it gives a solid increase in acceleration, as the power is increasing smoothly, as the engine RPM rises.

[g60bv 0]

as i under stand it, if the torque and hp dont cross at 5250 then the rollers are twicked and the out put is no good, as the equation is based on this, ?

[dr_mat 0]

Well it's a pretty stupid roller if the torque/power doesn't cross at 5250... given that one is calculated from the other..

They can still be out though, even if the lines cross.

[g60bv 0]

i've seen peoples power graphs, whicj have shown them to have much more power than they should, and the cross is about 5400 - 5500, wird.?

[Joe M 0]

Not really wierd at all, it will depend on what units are being used. Power is usually in bhp but sometimes its measured in PS. Same with torque, unless its bhp and lb-ft theres no reason for it to cross at 5252.

[Henny 0]

there's also the "fudge factor" for the losses in the gearbox that will account for the graphs not crossing at 5250 rpm... :?

[kvwloon 0]

Thought it was rather odd that my standard 16v recorded 183Bhp on the rollers at Inters! :shock: Think I'll disregard that figure! Still, the main thing is the curves were a lovely profile, I suppose, with the horsepower climbing steadily and the torque a nice long flat curve. That's the main thing, right?