Vehicle & Technical > Defender

Rolling road

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dreadnought110:
:? My point exactly!!

90DV:
How does a rolling road work out the figures anyway?? Because don't they work out the fly wheel figures, if so how is this done???

Porny:

--- Quote from: "90DV" ---How does a rolling road work out the figures anyway?? Because don't they work out the fly wheel figures, if so how is this done???
--- End quote ---


That's the problem.. a lot of Dyno's use different calculations!!!

Lets see...

Chav A - Has a nova.

Takes it to rolling road place X.  They do a bit of tuning, and give power outputs.  He makes 100bhp at the wheels... Chav is chuffed.  Brags to his mates.
Some of his mates reckon they use a better rolling road, so off he goes to rolling road place Y.  They put his nova on the rollers and his modified 1.2 shopping trolley makes 33bhp.

Chav A now thinks that the Rolling Road Y is naff and they don't know what they are doing... carries on boasting about figures from Rolling road place X.

The difference... the formula used by place X is very unrealistic - but has the effect of making them sound very good.

Place Y, uses a more accurate method - but some customers are not happy with the results!


And this does go on!!!


Have a read here: http://www.pumaracing.co.uk/power3.htm for how the calculations are made.


Ian

ian_s:
hmmms, i'm confused now,

reading the stuff on that link, he says that the transmission losses are a percentage of your flywheel BHP. but a more powerful engine will lose a smaller percentage.

what i am getting at is: would the transmission losses be the same in bhp lost for my old 2.25 diesel and my 200tdi?

ian

dew1911:
That´s a brainwave I had earlier - The figures you are reading off the Brochure are more than likley Engine figures, where as the rolling road could be giving you the power leaving the wheels.

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