Apologizes regarding posting in the wrong thread then. I saw a title saying dyno results so i was asking if anyone had results that would interest me.

Dang losing 15 to the wheels!! what rims do you have? and is there a link to what happened with buschur?

Two tenths isn't to bad in the 1/4. it definitely be a lot more when it comes to handling. Did you happen to see a noticeable difference in power if you ever dynoed it?

 

Went from stock rims to RPF1's that are 10.5" wide, lol. The rims are actually lighter than my stock ones but my tires, 275 star specs are way way heavier, like 4 lbs per wheel I think.

I am sure there is a link to the buschur one, I will try to find it.

 

I pulled the stock 17" Enkeis on my VIII and put 17" CE28Ns on. Wheel and tire weight per lost 5 pounds per corner. Put it on the dyno right after and gained 6whp, torque rose globally about 4. It's not a farce.

 

My test isn't exactly what your asking, nor was it very controlled, but its close enough...

I kept the same wheels, but went from a very worn set of the stock Advan tires to a new set of significantly heavier all season winter tires. I did virtual dyno runs before and after (same stretch of road, same external conditions). I lost 10-15whp at high rpms and 5-10ftlb of torque near peak.

 

I believe the old adage was 10 lbs. of unsprung mass = 1WHP, pretty sure that was it.

 

But are unsprung mass and rotating mass equal in the context of this discussion? I'm not a physics guy (nor an expert on much of anything) but I think that the reduction of rotating mass would be much more significant than a reduction of non-rotating unspring mass?

Discuss...

 

Awesome! Thanks for the answers guys! Those numbers are definetly a bit noticeable.

unsprung mass can only be related to the discussion through the rims because other components of the suspension wouldn't factor into the gain in horsepower. but mayb the old adage went 10lbs of rotating mass accounts for 1 whp. but then you have to take into consideration where this mass is, for instance on the crank or rim weight.

 

Lighter wheels "could" be weaker too. I’m happy that after a couple of years driving my evo hard, and couple of rubbing against curbs and pot holes my rims still keep a perfect shape. Just a couple of scratches.
Unless you definitely need to gain 1/10 sec in drag racing, keep your rims, get a tune for less money.

 

This isn't a farce. LOL @ the thickheadedness in this thread. Are lighter wheels going to make more power? Of course not. Could more power show up on the dyno from less rotating mass? Yes.

scheides has a thread somewhere that showed how he picked up HP on a dyno by switching his winter wheels/tires to his lighter summer combo.

EDIT:https://www.evolutionm.net/forums/ev...-whp-dyno.html

 

This thread is all over the place, but I thought I'd take a stand on the "drive-train loss" comments on page 1.

From most of the articles I've read, rotational mass IS considered part of the drive-train loss, even though the energy is converted to potential energy, and not simply lost as heat due to friction. I think the rationale here is the engine has to expend additional energy that is explicitly not transmitted to the ground and therefore "lost".

I think a better phrase for this effect would be drive-train inefficiency. Priuses (Priusi?) for example have regenerative braking systems that capture this type of potential energy, meaning not all the energy is lost.

 

in simple terms
will you gain HP... no
will you gain WHP... yes

 

Right

Wrong

An object in motion stay in motion according to Newtons law. Heavier wheels do consume more HP to accelerate, that is correct. But, heavier wheels don't contribute to drive-train losses at steady speed (ignoring road / gear friction and air resistance).

 

Not to be a *****, but you're not even close. Heavier wheels require more energy to rotate at a steady speed just as they require more energy to accelerate. This is why your gas mileage goes down with heavier wheels/ tires, even at steady state speed and your performance decreases and you get less wheel horse power on a dyno. All things being equal, the car with heavier wheels is simply less effecient.

And FWIW, the wheels are part of the drive train which is commonly defined as the stuff that makes the power and delivers it to the road so you're wrong on that as well.

Way too much crap posted in this thread by people who truly have no clue.

And FWIW,

 

+1