ok i've been wondering this for a while now: lets say if 2 cars get the same WHP (but one car heavier than the other) on the dyno then that should mean the two cars should be just as fast as each other on a straight line (same driver, same suspension , same structure ridgity of chassis) right ? The weight advantage only comes in when the cars are on the corner ....where the lighter should be able to be corner faster....

then it should also mean that on a stock ITR if u get lets say 168WHP and if u remove some weight out of the car then u should be able to achieve higher WHP (with everything esle still the same except weight) and corner faster...

am i getting the right idea? someone please help


[Modified by Tiwe, 1:40 AM 12/8/2002]

 

Weight benefits both straight line acceleration as well as in cornering. 2 Cars with the same WHP, the lighter one will accelerate faster.

Removing weight from your car does not increase horsepower.



[Modified by mattymatt, 1:44 AM 12/8/2002]

 

humm but i thought the weight of cars take effect on DYNOs??
if weight dont affect WHP of cars then how come when u have 4 ppl sitting in ur car u will accecerate slower than if it was only u in the car? so removing weight wont add WHP but adding weight will lower WHP ??? that dosent make sense to me...

 

Look, you've got the same amount of power in either case, but with 4 people in the car the hp/lb is lower, and therefore you accelerate less quickly.

Do me a favor, sign up for physics next time.

 

...

think about physics.

your engine output has NOTHING to do with being effected with weight of the car.

your actual speed and acceleration has a direct dependency on your engine output and correlation with mass.

welcome to physics 101 n00b

 

weight has nothing to do with whp numbers. the motor is producing a certain whp. let's say a 180 whp integra weighs 2600 with driver, the 180 hp motor only has to pull that 2600 pounds. When you add more people into the car on a road, not dyno, the hp numbers are still the same because the motor is still the same. the only thing that is different is the amount of weight the motor needs to pull. more weight to pull for the same hp motor= slower acceleration. just because you accelerate slower, it does not mean your whp numbers will change.

On the dyno, weight makes no difference because it is just testing the power of the motor. the only thing that would be relevant to this post is that lighter wheels = more horses on the dyno.

 

ahh i see .....sorry cuz i used to think WHP means the amount of power that gets transfered to the ground by your car (not engine) so weight takes effect on WHPs...sorry for being a noob

 

NO , weight does not affect WHP!

WHP = constant

Weight changes (with 4 lard asses)

VW Cabrio passes you.

Get the picture?

 

hehe frustration ownz j00

 

Lets not forget the importance of torque and more importantly gearing, as it plays a large role in how the car will accelerate.

 

will rotational weight affect WHP? or is this what guys have already been pounding this guy for... it won't affect WHP.

 

Remember highschool physics?
F=M*A

Therefore:
A= (F/M) <--- Acceleration is bigger the more Force you have, and the less Mass you have.




[Modified by jond, 1:22 PM 12/8/2002]

 

Yes it will show up on the dyno. Specifically lightened flywheel and light front wheels will show up on the dyno.

 

for H-T peeps and the physics lessons.

 

I guess that's why engines produce more power on an engine dyno

Of course I am just kidding.

 

Rotational weight DOES NOT affect WHP, but it will nevertheless show up on a dyno because of an inherent flaw in the way the dyno works. The dyno measures how fast the car can angularly accelerate a big weight. Unfortunately the car also has to angularly accelerate its own rotating parts. This will slightly affect how fast it can accelerate the big weight. The car is not making more power.

If you dyno the car in first gear this will have a greater effect than if you dyno it in fifth gear.


[Modified by Lsos, 9:34 AM 12/10/2002]