Light Weight Underdrive Crank Pulley

[osaenz1]

I install an Underdrive Pulley for a Honda Accord 02 v6 it fits great, I got it from where else Ebay they around $22. Like always I change the belts for a smaller ones the 425k4 and the 450k6. Results better response in the pedal, I haven't check the mpg. Didn't record at the beginning.

[jcart]

Could you elaborate/ explain as I don't understand......lightweight crank pulley means less parasidic (sp?) loss by turning less mass got that but underdrive means bigger pulley diameter???

thanks

jrc

[moda_way]

Just an FYI, it is a well known fact that a harmonic dampner is integrated into the crank pulley of every J series motor that I can think of. The underdrive pulley does not contain this and thus you are risking some long-term bearing damage. Buyer beware. For the gains... I'm not it is worth it.

[osaenz1]

The original Pulley was about 4-5 times heavier and both are all metal no rubber that eliminates the harmonic problems.

[N_Jay]

Originally posted by osaenz1
The original Pulley was about 4-5 times heavier and both are all metal no rubber that eliminates the harmonic problems.

Crank pulleys are often offset weighted to reduce/counter-act vibrations.

Some have rubber isolation to dampen other vibrations.

Lightweight and under-drive pulleys are good for two things.

1) Racing where every last HP REALLY makes a difference,
and
2) "Ricers" who want to pretend then are part of #1 above.

[jcantanixon]

Originally posted by osaenz1
The original Pulley was about 4-5 times heavier and both are all metal no rubber that eliminates the harmonic problems.

Harmonic Balancers can be made entirely of metal. More often than not, they're designed to counteract the forces made on the other side of the crankshaft by the flywheel.

The lighter weight reduces the rotational inertia and underdrive means that it is smaller in diameter, so it turns the other pulleys at a slower rate. Both of those changes produce some performance gains, but sacrifice things like voltage produced at idle, and main bearing longevity.

IMHO, it's not worth the tradeoff in smoothness and reliability. I have no problems with modding a performance vehicle, but our Pilot rarely sees WOT so it's fine as is.

[osaenz1]

Well I have them about 3 years on both of my trucks, no symptoms on any of the two trucks yet. On one I have a Trailer hitch wiring, radar detector, exterior rearview camera, cb radio, ham radio plus a gps system. Non of them have a volt problem, and doesn't dim the lights at the time That I am transmitting on the radios. I am very happy with this mod. And boy I will be sad if something happened on the future with my pilots.
Original I install the pulleys to save gas, and better respond on highways that is doing right now.

[moda_way]

Originally posted by osaenz1
Well I have them about 3 years on both of my trucks, no symptoms on any of the two trucks yet. On one I have a Trailer hitch wiring, radar detector, exterior rearview camera, cb radio, ham radio plus a gps system. Non of them have a volt problem, and doesn't dim the lights at the time That I am transmitting on the radios. I am very happy with this mod. And boy I will be sad if something happened on the future with my pilots.
Original I install the pulleys to save gas, and better respond on highways that is doing right now.

A lighter, same diameter pulley wouldn't lower voltage... only under-drive accessory pulleys would do that. None-the-less, I passed on this for my TSX and I'll pass on this as well, but for the sake of the site, did you take any pics, pre/post install? Do you have data to support gas savings (i.e. months of mgp calculations at the pump, not via the Pilot's computer)? Parasitic loss is a funny animal. I put a lightweight flywheel on my TSX, reducing the OEM weight by 50%, significant IMO, and I saw maybe a 2mph better performance on the highway, so I don't really see a crank pulley doing even 1mpg better. Guess anything helps though, maybe??

[A6Pilot]

In this age when a car manufacturer will sell his oldest born just to raise a CAFE rating by .1 mpg, why do you think the Honda powertrain engineers missed such a simple solution as a lighter set of pulleys? Could it be they just don't improve anything. Even a 1 mpg increase in mileage on a car that gets 20 mpg is a 5% improvement, an incredible amount. What's next, the Turbonator?

You be the judge.

[moda_way]

Originally posted by A6Pilot
In this age when a car manufacturer will sell his oldest born just to raise a CAFE rating by .1 mpg, why do you think the Honda powertrain engineers missed such a simple solution as a lighter set of pulleys? Could it be they just don't improve anything. Even a 1 mpg increase in mileage on a car that gets 20 mpg is a 5% improvement, an incredible amount. What's next, the Turbonator?

You be the judge.

I would agree and add, changing driving habits would increase gas mileage more significantly.