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+--- Thread: Dyno Readings - Facts ! (/showthread.php?tid=2994)
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Dyno Readings - Facts ! - Bobby - 04-01-2018
Picked this up on another site thought it might be of interest, the guy that wrote it supplies a lot of good technical info on the RX8 site so IMO he knows his stuff, others might disagree though !
Quote:I used to work in automotive testing and dynamometers, so here are the facts:-
There is only one sort of dyno that gives you engine power, and that is an engine dyno which has to be directly connected to the engine and used in an engine test cell with strictly controlled environmental conditions.
A chassis dyno (rolling road) will never ever tell you engine power. It measures power at the wheels, and is only really useful for comparing before and after when modifying.
Any engine power figures are calculated (guessed) from estimating transmission losses during spinning down the rollers.
A highly skilled operator can tweak the calculation to get very close to the figure which would be produced from an engine dyno, but you wont find them on your average industrial estate dyno shop.
Many don't even correct for atmospheric conditions (temperature, pressure and humidity).
Dyno Readings - Facts ! - Lexusboy - 04-01-2018
We have Engine test cells at work for the engines and this is were most of the car data is collected from.
Interesting read..
Dyno Readings - Facts ! - FirebirdPhil - 04-01-2018
Can't disagree with the fact that an engine dyno is needed to ascertain actuate HP of an engine, but it is widely accepted that RR's are fine for getting the HP of your average road car, the calculations are usually very close, who has the money to use engine dynos??
Dyno Readings - Facts ! - Asi - 04-01-2018
some good information there.
Dyno Readings - Facts ! - steviewevie - 04-01-2018
Yep, agree with 2tongues. If you go somewhere reputable it should be ok. Sure, you won't get an accurate a figure as if you took the engine out and connected it to a proper dyno, but it's the next best thing in the real world.
As you say Bobby, it's especially good if you take the car back to the same rolling road to compare before and after a mod. I've already got a "stock" figure for my car at Surrey Rolling Road, so I can take it back there and see the "after" turbo figure ! :biggrin:
Dyno Readings - Facts ! - FirebirdPhil - 04-01-2018
Surry RR and SPC's are within something like 0.1 BHP of each other, the only difference is the one at SPC has newer software.
This goes some way to saying that RR's with good operators are fine for your average person.
Dyno Readings - Facts ! - Andy-R. - 04-01-2018
Wouldn't you rather know the HP at the wheels anyway so you know what power you actually have at your disposal.
Dyno Readings - Facts ! - steviewevie - 04-01-2018
Andy-R. Wouldn't you rather know the HP at the wheels anyway so you know what power you actually have at your disposal.
In a way, yes. But the trouble is, manufacturers don't usually quote wheel bhp figures. So your starting point is normally the flywheel bhp.
Dyno Readings - Facts ! - Andy-R. - 04-01-2018
But the flywheel figure is for showing off:laugh:
Dyno Readings - Facts ! - Bandit - 07-01-2018
My IS200 was 128.7bhp at the wheels when standard,
And the Skyline's 257.8 at the wheels, so a bit better :thumbup1: