I hear that wheel horsepower matters more than regular horsepower so i was wondering what mods i can do to increase my wheel horses??

 

wow...that is some hard fail right there...

 

most engine mods will increase whp. i say most because not everything is tuned after install so you may not see a gain.

 

well... wheel HP is like your true HP compared to HP to the crank, when you increase one your increase the other.

HP power to the crank

WHP power at your wheels.

you looking just for some basic bolt ons or do you want to boost

 

for now just some bolt ons

 

Basically simpley put wheel horsepower is the byproduct of flywheel horsepower (actual engine HP) after going through the drivetrain.

Due to rotational mass and other factors, there is power loss in the drivetrain components so once the force gets to the wheels it has been effected.

I win :D

I wonder if lighter wheels increase WHP? I think it makes sense, haha.

 

basically, the amount of power and engine alone makes is called BHP (brake horse power) and the amount of the power generated by the engine is called the WHP (wheel horse power).

the reason for this is because power is lost through accessory drives, flywheels, transmissions, drive shafts, transfer cases, brake rotors, wheels and tires.

so increased BHP will naturally increase whp because the more power the engine makes, the more power the car can send to the wheels.

the only way you could increase whp without increase bhp would be to just lighten and remove as much rotational mass as possible, like light weight flywheel and crank, water pump and alternator pulleys, and lighter wheels and tires and brake rotors and such.

and conversely, adding rotational mass causes a loss in whp, like big brake kits that weigh more than the stock brake components, and those idiots who put giant chrome rims on their cars and think they are cool.

 

you can do the basic bolt on's such as intake, header and exhaust

 

weight of rotating components has zero effect on hp. It only affects the speed at which you can change rpm (how fast it can rev) which does affect performance, but not power output. An inherent flaw in a lot of wheel dynos is that they measure power based upon acceleration... which in effect shows a measured increase in power. However, true power is measured at steady state, not while accelerating.

And to be correct, HP is just horsepower, it is not specific to where you measure it. BHP is brake hp, or hp at the crank. WHP is wheel hp, measured at the wheel. Frictional losses throughout the drivetrain cause a loss in power (mostly through the release of heat). Most manufacturers of cars specify HP as the BHP of an engine.

The above explains why adding rotating mass does not decrease power. Power loss has to result in another form of energy.. in other words, heat when friction is involved. Rotational inertia serves to store energy. When you release the throttle, this energy is fed back into the system, so no net power is lost due to this. While a car with a heavy flywheel takes longer to increase in rpm, it also resists a fast decrease in rpm more.

 

LOL

 

okay, so it doesn't increase power, the added weight would really hinder your acceleration and braking and handling, thus reducing weight of these components would increase performance via having a better power to weight ratio. and as you said since dyno's measure power based on acceleration, it would show an increase in power now wouldn't? not disagreeing with how you say power should be measured, but yeah, whp would be up, but not accurately i suppose...

 

The issue is that acceleration based dynos are incorrect in measuring that type of change as an increase in power. So power is not up. Acceleration can be improved by significant reduction in rotating mass.. that isnt being argued. But power output is not increased. So an acceleration based dyno is basically saying that the cars ability to accelerate has changed.

The power to weight ratio (which is different than the effect of moments of inertia and rotating mass) also affects acceleration, but does not make any change in WHP either. The same power is applied to the wheels, but the car is lighter, so it is quicker.

 

okay, but lastely, would bypassing something like the a/c increase whp slighlty? or is there just no way to increase whp without increase bhp?

 

 

oh goodness.. i'm too old for this...

 

Removing the AC would increase power. AC is a parasitic drag, and removing it would improve power to some degree. Technically the power to the crank is the same, but you are losing some due to the load the AC and other accessories place on the crank. So the net power output is decreased.

Our AC system actually draws very little when off, but there is some loss there.