Do lightened underdrive pulleys increase engine power?

[gen2 CRX]

As the title states, do lightened underdrive pulleys increase engine hp and torque?

[Limbo]

slightly cos the drag is less than OEM. You might get 1-2kw if your lucky
The only bad thing is that cars are built with heavier pullies to use as balancers and absorb vibrations . If you change to an underdrive pully it usually put more vibration into the engine, causing early wearing of engine.

This is usually only for people looking at getting the last bits of power out of the car.

I myself wouldn't do it, there are better ways to make power

[JohnL]

As the title states, do lightened underdrive pulleys increase engine hp and torque?

No, it won't increase engine power, but to a very slight degree reducing pulley mass will remove some parasitic drag from the engine. This will only be seen when accelerating, it will make no difference to top speed. The affect is similar (but FAR less) than fiting a lighter flywheel (most probably not noticable). For what it will cost you I'd think you'd be a lot better off putting the money toward something that will make a real difference, like a lightweight flywheel.

PS Just noticed you said "underdrive" (not just "lightened"). This will also reduce parassitic losses, but again I think the affect will probably be very slight.

[kayot1k]

just get rid of your PS and AC if your seeking hidden power.
underdrive pulleys no, crank pulley yes

[black200is]

in short, no. The same way a flywheel will not increase power.

It will change the way the power is delivered most certainly, but will not increase top end power.

But imo still a very worthwhile mod on an NA car.. which is all about lightning power delivery and super sharp throttle response

[Sexc86]

When your doing a all build... everything counts ... all small percentages add up just like weight reduction...

When getting light weight pullies.. ONLY DO Accessories... Alternal/PS/AC... Never change your Timeing Pully away from OEM honda, aftermarket light weight timeing pullies have been proven time and time again to chew your timeing belt at accelerated rates.

my 2c.

[Sexc86]

search on hondatech mate... i have been down this road as i have lightweight pullies.. AEM make them, and was their specific responce to my question... why no timeing pully " faster wear of the timeing belt" i dont know how or why. But thats also what plenty other gurus say on hondatech / turbod16 as well.

[string]

Your engine will not produce any more power, however less energy is now required to spin up the little pulley so you have slightly more energy for other acceleration duties thus increased performance.

Now that little pulley is 10cm diameter max, and weights shit all. 1-2kw equivilence, no chance. You'll never notice it purely from a reduced rotating mass context. Underdrive, maybe.

[bennjamin]

Your engine will not produce any more power, however less energy is now required to spin up the little pulley so you have slightly more energy for other acceleration duties thus increased performance.

Now that little pulley is 10cm diameter max, and weights shit all. 1-2kw equivilence, no chance. You'll never notice it purely from a reduced rotating mass context. Underdrive, maybe.

whatever "difference" in power - it will be ACROSS THE BAND so hardly noticeable. Your engine might rev alittle more freely - but better off either removing the accessories ( PS/AC) or simply installing a lighter flywheel.

Note , all these mods are worthless if you have subs in the back , or big rims

[TODA AU]

Never change your Timeing Pully away from OEM honda, aftermarket light weight timeing pullies have been proven time and time again to chew your timeing belt at accelerated rates.

Perhaps some manufactures claim this, but I'd have to say I've never seen or heard of this.
Are you talking about the crank pulley or the belt drive on the crank?

Regarding crank pulleys,
I don't rate the stock balancer too highly for high rpm applications.
We generally change to a fluidamper or Ati Damper on engines that see sustained high rpm.

The benifit is to the oil pump & the engine bearings.
We don't use lightweight alloy balancer replacements.
Yes, the fluidamper or Ati damper is heavier than stock.

[black200is]

honda spend millions on R&D to make sure all their components work, and work with other components. So if the difference is minimal, it makes little sense to bother changing something.

OEM is generally the best way to go for these sorts of things IMO. Aftermarket bits for such important parts can often be more hassle than benefit

[panda[cRx]]

adrian i've seen the belts chewed up on 3-4 cars with aftermarket pulleys in the last 2 years. i'm surprised with your experience and expertise you have never seen it (that's not sarcasm)

judging by the cars i have seen with them fitted i would not recommend it, it's not worth any gains you MAY get