Whats the deal with the HP on the DYNOs and the 222HO stock..
the dyno says we got avg 190HP to the wheels? But our specs say 222HP stock,
Is there an equation to cal HP to the wheels from stoc HP?

Roger

 

Drivetrain losses account for the loss. Most cars lose about 20 percent of the 'flywheel' HP by the time the dyno measures the 'wheel' HP.

 

What medicsonic said... so you can say that dyno HP is the real or true HP. Who cares what it makes at the flywheel? What matters is what it makes to the wheels.

 

That's true.

And in addition to that most manual transmission cars will only lose about 15% of the flywheel horsepower at the wheels compared to 20% for an auto. And in addition manual tranny's are usually around 100lb or so lighter than an auto, and they generally have an extra gear. So all that is why a manual is usually quicker than an automatic in an otherwise identical car.

The Acura TL-S/CL-S guys used to stop over here and go "we have 260HP and you only have 222HP so " but they haven't stopped by recently (I think I scared them all away finally).

But it was funny because even though they have 260HP, with their 20% loss through the auto that comes out to 200 fwhp (front wheel horsepower) while a manual Maxima makes 222 HP but comes out to 190 fwhp, only 10 less than the Acura. After you throw in the 250lb of extra weight in the Acura it turns out that a 5th Gen Maxima 5-spd with LESS power is actually faster than an Acura with 38 MORE HP at the crank...heh heh.

Well that doesn't make the Acura guys very happy. Oh well

 

If you install big (18" or 19" rims) on your maxima, or any car, does that lower the HP at the wheels? because in my college physics class I seem to remember that the moment of inertia of the wheels has to do with the square of the radius (meaning you lose a lot more torque on bigger wheels)

am I wrong?

 

Yup...rotational intertia.

And unless they're Volks or RH's or something that light, 18" and up are bricks.

 

So, what's the big obsession with getting huge rims?

BTW, who has info on the tightest looking rims with the... tightest budget?

 

looks, improved cornering ability..... they aren't meant for drag racing though

 

Agreed. Different strokes for different folks.

 

Steve

I've seen a wide range of dnyo results. I've seen it go 10-20% with sticks and 15-25% with autos. I think on average you are right on though.