any body know anything about the physics behind a rolling road?

im thinking of building one im 99% certain i can graph a torque curve and im just about to start working out how to calculate a power curve

but if anyone has any knowledge it will save me the hassle of learning physics again!

thanks
wayne

I hope you're well insured

What they are supposed to do is run the car in aech hear to find out which produces the most BHP, they run it in that gear from 2,000 rpm to the rev limiter 'cruising' at different rev intervals fro a few seconds i.e. 2,000 3,000 4,000 and so on.
When the limiter is reached they then back off, leave it in that gear and let the car slowly come to a standstill, while its doing this it works out the transmission losses and then hey prseto you got your figures.
The transmission losses work out the power at the flywhel and the power at the wehhels.

The hardest thing about rolling roads so i've been told is calibrating it everytime you use it to make sure its spot on.

My Car is now for sale, A total one-off, head turning bargin!!!​

Oh forgot to add have a look here for more info, sorry they talk about Ford Crapris
http://www.fordcaprilaser.co.uk/rolling_road_article.htm

My Car is now for sale, A total one-off, head turning bargin!!!​

hmm i wont be calculating power at the flywheel at all
just bhp at wheels as this is what i will be directly measuring

the dyno wont need to be calibrated every time as there is no variable involved with the harware itself
anyway im not expecting perfect results just something for me and friends to mess about with

thanks for the link cento

At Stanford Hall, the bloke ran it up through the gears to 30mph in 4th, nailed it, then raised the revs in stages with his remote control, allowing them to settle, and doing a plot.

Git plotted power right into the red even though I asked him not to. [!]

His figures were well wrong though.

Pete.
Cinq sporting 1242cc
Cinqs&Seis Yahoo group
Clubcento

so his remote could control the revs of your car?

Yeah, kinda. It had an 'up' and 'finished' button on it as far as I could tell. Looked like he pushed the 'up' button to increase the road speed in stages on the rollers. Ran it up to 7000 revs and 93mph in 4th, the git, with no big fan at the front like you're supposed to have, either.

Pete.
Cinq sporting 1242cc
Cinqs&Seis Yahoo group
Clubcento

sounds more of a cowboy then i will be

hmm i wonder how that works?
the car should be turning the road not the other way round
did he clip ought onto the accelerator cable or anything?

bit dangerous not supplying the engine with air is it not?

Doesn't take into account wind resistance though, so it won't be an accurate measure for fuel consumption or top speed, don't wanna leave it on there too long and run up the miles

Cinqmeister
Alias: BIG BROTHER
http://www.channel9.tk
'94 Cinquecento Basica (USA Spec) 0,9l

Yeah seemed to be cowboys, rollers were way out, wish i had put mine on there may have broken the 100bhp mark!

My Car is now for sale, A total one-off, head turning bargin!!!​

<blockquote id="quote"> face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Blue Seid Boy
sounds more of a cowboy then i will be

hmm i wonder how that works?
the car should be turning the road not the other way round
did he clip ought onto the accelerator cable or anything?
<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">

He had this computer screen display, when he pressed the 'up' button the rollers allowed the road speed to rise, I'm guessing until he let go, so that he could control the intervals on the graph. This was done in several stages.
He just kept his foot mashed to the floor on the throttle, had nothing connected to the engine at all so the bhp and torque figures are taking into account 'guesstimated' tranny losses.
Guesstimated badly too, he said I had 89 bhp and 118 lb/ft torque (poo) and my mate with the VanAaken turbo cinq (which we know has 85bhp) he rated at 99bhp.

Pete.
Cinq sporting 1242cc
Cinqs&Seis Yahoo group
Clubcento

<blockquote id="quote"> face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Donz
bit dangerous not supplying the engine with air is it not?


<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">

Yes. Bad practise.
Had my head been screwed on right and not baked by the sun, I should have probably insisted on the bonnet being open to get fresh air to the induction kit, mine relies on a certain amount of ram-air through the intake scoop in the bumper to get cool air in.

Pete.
Cinq sporting 1242cc
Cinqs&Seis Yahoo group
Clubcento

D'oh!

I invested in a haynes manual today... why haven't I got one before now?? They're so damn useful! :I

Cinqmeister
Alias: BIG BROTHER
http://www.channel9.tk
'94 Cinquecento Basica (USA Spec) 0,9l

Just look out for anything in there that says 'simply'.
It's the kiss of death on any job![xx(]

Pete.
Cinq sporting 1242cc
Cinqs&Seis Yahoo group
Clubcento