Power!!!!!

[Sibs Individual]

Hi guys

Excuse my sillyness, but wanted to ask this as I've always wondered but guess have never had the chance to ask......

What do they mean when the dyno guys talk about fly wheel power and on the wheels????

what is the difference between the two?:fencelook:

 

[AdiS]

Essentially, power can be measured at two places on a car.

At the flywheel basically means exactly that - an engine produces "X" power at the flywheel. However, not all of this power gets translated to the wheels. Due to mechanical power losses in the drive train, the resultant power which ends up being transferred to the wheels and on to the road is always less, hence the distinction between power figures 'at the flywheel' and 'on the wheels'.

EDIT: Power figures for cars are generally quoted at the flywheel. So if the brochure says "170kw" then it means at teh flywheel. What you'll get at the wheels will be less. People often talk about 'on the wheels' figures because its more relevant to the real world performance of teh car.

 

[Sibs Individual]

Oh i see! that makes a lot of sense!

Why then do car manufacturers quote power that we will never see from the car?

 

[SP33DYV]

Essentially, power can be measured at two places on a car.

At the flywheel basically means exactly that - an engine produces "X" power at the flywheel. However, not all of this power gets translated to the wheels. Due to mechanical power losses in the drive train, the resultant power which ends up being transferred to the wheels and on to the road is always less, hence the distinction between power figures 'at the flywheel' and 'on the wheels'.

EDIT: Power figures for cars are generally quoted at the flywheel. So if the brochure says "170kw" then it means at teh flywheel. What you'll get at the wheels will be less. People often talk about 'on the wheels' figures because its more relevant to the real world performance of teh car.

Funny that you chose 170kw.

 

[AdiS]

Oh i see! that makes a lot of sense!

Why then do car manufacturers quote power that we will never see from the car?

Because drivetrain loss is not necessarily a constant, it varies. The power figure is a performance metric of the engine, not the car. Thats why we have power to weight ratios, 0-100 acceleration times etc as well to assess a car.

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Essentially, power can be measured at two places on a car.

At the flywheel basically means exactly that - an engine produces "X" power at the flywheel. However, not all of this power gets translated to the wheels. Due to mechanical power losses in the drive train, the resultant power which ends up being transferred to the wheels and on to the road is always less, hence the distinction between power figures 'at the flywheel' and 'on the wheels'.

EDIT: Power figures for cars are generally quoted at the flywheel. So if the brochure says "170kw" then it means at teh flywheel. What you'll get at the wheels will be less. People often talk about 'on the wheels' figures because its more relevant to the real world performance of teh car.

Funny that you chose 170kw.

Hehe In this case its fitting on two accounts

 

[Sibs Individual]

thanks - one more piece of knowledge acquired:idea:

And is it true that cars lose power with the passing years?

 

[AdiS]

thanks - one more piece of knowledge acquired:idea:

And is it true that cars lose power with the passing years?

I think that probably has more to do with how they are maintained than abything else.

 

[Pfw28]

thanks - one more piece of knowledge acquired:idea:

And is it true that cars lose power with the passing years?

I think that probably has more to do with how they are maintained than abything else.

Nothing last forever, power output starts dropping from day one, but so slowly that it can't be measured. Each revolution causes some microscopic wear, no matter how good the lubricant. This process is minimised by good maintenance and lubrication, stable temperatures etc. but never stops, therefore any engine will eventually lose power due to compression loss as clearances increase, followed by oil use and smoking, once wear is at it's limit. :thumbdo:

 

[Sibs Individual]

Damn:nonono:

 

[AdiS]

Damn:nonono:

Sibs I wouldn't worry too much about our engines. They are very strong, as long as you always keep clean oil in them, and maintain them properly, they will always be nice and powerful .