Why is my power down

[thexav]

Power is down in my car. We went for a rolling road day the other week and I only got 140bhp peak.

What should I do/check? With an induction kit I thought I'd be at least at the 170/180bhp mark.

 

[turbonutter69]

Was that at the wheels or at the flywheel?

 

[thexav]

I suppose it was at the flywheel, I never asked. What do rolling roads usually measure?

 

[turbonutter69]

Depends where you get it done.
When I took my mums Scoob I was ready for scrapping it when it ran only 176 bhp.
But then asked the guy about it and that reading was at the wheels which is why it was low.
Flywheel power was around 230-35bhp.
If yours was 140 at the wheels then it's roughly about right for the car.

 

[stamford]

That figure comes close to the at the wheels figure tbh. Check what they set the readings for.

 

[Yugguy]

It's usually measured at the wheels and then a calculation done which uses knowledge about the average transmission losses for the model of car to work out the flywheel reading.

It might say it somewhere on your printout?

 

[HDi fun]

The flywheel power is calculated from the roadwheel power. At the end of the run the operator declutches but leaves the car in gear and from this the transmission loss can be accurately determined.

 

[thexav]

My mates were winding me up. They all got Flywheel power figures and left me with wheel figures. I was able to keep up so I didn't think I was that much down on power.

What are typical tranmission losses then so I can work it as a flywheel figure?

 

[Big Fat Fatty]

IIRC, it is 12-15% for two wheel drive cars and 20-25% for all wheel drive.

 

[pgarner]

can be much higher than what bff has said, and gets worse the more power you create so theres no way of telling you exactly how much of a loss there is

 

[HDi fun]

Power is down in my car. We went for a rolling road day the other week and I only got 140bhp peak.

What should I do/check? With an induction kit I thought I'd be at least at the 170/180bhp mark.

Like others have said, this is probably roadwheel power that's been quoted. If your car was down to 140bhp or so at the flywheel it would be running very very badly indeed - you'd spot it on startup with rough idle and with heavy fuel consumption. It would also feel totally spineless in general driving.

 

[SLEEPER]

Tell your mates they are the ones with the wrong figures.

ATF is no good to anyone apart from pub talk - you dont drive around with the flywhell touching the road.

At the wheel is all that counts but people give flywheel figures cos it sounds more.