Underdrive Pulleys

[gt-p]

Hi all, I am doing a feasability study on how many or if any one would be interseted in purchase of an underdrive pulley kit for the AU and BA 6 cylinders, Turbo's included.

They would yeild about the same amount of rear wheel gain as the V8 ones of 8 to 10 kW at the rears and would most likely retail for around the same price of $460.00

Thought I would try the forum for a response before manufacturing these pulleys as it takes a fair amount of resorces to follow it through.

Those of you who own a 6cyl BA or AU would you mind letting me know if something like this would interest you..

Regards,

Barry Batten

[Yoda]

Pardon my ignorance but what does one of these things do? :(

[hypnodoc]

Hi Barry, if they work as well as your XR8 airbox mod you can count me in, Rick C

[Cobra]

Barry,

welcome to the forum

feel free to discuss the possibilities of underdrive pulleys in the forum, but please be careful when it comes to unauthorised advertising (as per the forum rules)

my 2c worth on the topic : for n/a vehicles they can be a good think but (for me) underdrive pulleys and turbos/superchargers generally don't go hand in hand; it is easier to up the boost a smidge then go the pulley route,

purest would say that the power is there for the taking if the rest of the car can take it :lol:

enjoy your time here

cheers

Rob

underpulleys is a term of endearment

[Guest]

What the hell are we talking about here?underdacks on a turbo,WTF

vik

[ms700]

What the hell are we talking about here?underdacks on a turbo,WTF

vik

Underdrive pulleys, if I understand it all correctly, are smaller water pump, alternator etc pulleys that dont put as much "drag" on the motor, therefore allowing some more turning force to be used in actually driving the car instead of driving the accessories.

I think....... im sure someone will correct me if im wrong.

These underdrive pulleys are very popular over in the States on the import honda's and nissan's.

[Benny]

I'm not exactly sure what they are either but I'll have a go.

I think they're light weight pullies for the motor, Alternator, AC etc. I don't think they're any smaller because that would increase the rpm of anything running off the belt.

These sort of kits were made for the wrx and improved throttle response and hp.

Correct me if I'm way off track.

[turbotom]

Just my 2.2c worth, but with a high torque 4 litre 6 cylinder motor, would there be an appreciable difference???

It would be more noticeable in a small capacity (<= 2 litre) lo torque motor certainly, but when you've got 4 litres and 450 Nm standard torque, why waste the money! save up for one of the chip kits. Much better bang per buck!

[Antisocial]

And if they work as we all theorise, the last thing I would want to do in Australias hot climate, where cooling is already an issue is slow down my water pump.

I don't think it would have an effect on the alternator as the stator is regulated and if you reduce the rpm of the alternator the stator feild would increase to maintain the required output and the 'load' on the engine will be maintianed or even increase depending on the efficiency of the alternator at lower rpm. But im no auto electrician and am just guessing..

[bkofoed]

I think you'll find the "underdrive" idea comes from the fact that the new drive ratio is under 1, I.e. 0.8 underdrive pulley will present 80% of the normal RPM to the water pump (or whatever) over the factory design.

Hence lower loading on the motor = free power for no tuning changes.

This would mean _larger_ diameter pulleys on the accesories (or smaller on the crank).

Same principal on overddrive pulleys for factory supercharges, I.e. put more revs in than the factory design and get higher boost that way.

But, see above, would the cash be better spent elsewhere?? perhaps...

BK