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Dyno reading Question??

RNS11Z

By RNS11Z,
in General Automotive Discussion

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RNS11Z Experienced

RNS11Z

Posted
Posted

On the weekend i dyno'd my car at the Brisbane Autosalon. I Made 260rwkw. Now i had been told it was dyno'd on 8cylinder Shoot mode. Would this make a difference to the power figure reading?? Apparently it can read up to 80rwhp less. Is this true??

A vehicle that i know that made 340rwhp a couple of days before the salon made only 200rwkw on the dyno at the show. So there was something definately wrong.

Thanks

Harun

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Sydneykid Grand Master

Sydneykid

Posted
Posted

Hi RNS11Z, there are different inertia loads from engines of different configuration. In Shootout mode the dyno automatically selects the appropriate inertia loading. Basically it has a look up table for a 4 cylinder, a 6 cylinder and a V8. If the you run a 6 cylinder on the dyno with a V8 inertia loading it will allow for more inertia than the engine actually has. So it will read slightly higher output than it would in a 6 cylinder inertia loading had been used.

Logically there are great differences in inertia loading from a 6 cylinder dinosaur engine (say a V6 Commondoor) and a DOHC straight 6 (like an RB). So I wouldn't worry too much as the 6 cylinder inertia loading may have been just as inaccurate as the V8 one.

Hope that helps

R31Nismoid Grand Master

R31Nismoid

Posted
Posted

A/S dyno's

lol... i made 190rwkw @ 6600rpm on 10psi boost at my usual dyno place and it reads low-ish

at auto salon... on 10psi i had made 210rwkw at 5000rpm (i dont make any decent power till 4500rpm as i got a t04e)

Pity the car was pinging a little and they stopped.

It could've gone to around 240rwkw i reckon as the graph just kept going

:/

just goes to show how different dyno readings can vary really

RNS11Z Experienced

RNS11Z

Posted
  • Author
Posted

True true. Yours read higher then expected. The guy with s15 i know (which had made 340rwhp - 250rwkw a couple of days before it only made 200rwkw). So who knows what was going on. Im just trying to find out wether my results were correct or not. Doesnt really matter as im going back on the dyno very soon

Duncan Grand Master

Duncan

Posted
Posted

While shootout mode may help with more consistent readings, I understood you cannot compare wheel power figures between 2 different dynos, there are a host of differences in setup between them.

The power figures are only really comparable for the same dyno on the same day.

R31Nismoid Grand Master

R31Nismoid

Posted
Posted
Originally posted by Duncan

I understood you cannot compare wheel power figures between 2 different dynos, there are a host of differences in setup between them.

The power figures are only really comparable for the same dyno on the same day.

that is 100%... spot on the money.

IF you wanna compare results you gotta go the the same dyno on the same day.

Otherwise all sorts of variable come into it.

Aahh... if you wanna see, just get a few mates together for a dyno day :)

ANDY32 Apprentice

ANDY32

Posted
Posted

I agree that weather conditions can effect horsepower esp. in turbo cars and therefore give slight hp variance but if you look at the theory of a dyno it shouldnt make any differance what motor is pushing the wheels against the retarder when youre talking hp its hp ,and shootout mode sounds like a wanker term, youve either got it or you dont because hp is hp .One hp in a 1500hp drag car has the same power hp as one hp in a 30 hp zeta.

Duncan Grand Master

Duncan

Posted
Posted

As far as I know, a dyno measures torque not power, and even then it is at the wheels, not the flywheel. The rwkw are then calculated based on the revs (if the operator actually calibrated them too).

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