Underdrive pully????

[66Sprint6]

I saw an ad for underdrive pullies and how they can help make 15 hp...yadda yadda. Anyways, I was wondering what underdrive pullies do and can we use one on our 200??
Matt

 

[StrangeRanger]

Underdrive pullies slow down the belt-driven accessories on the front of the engine. They're good for 5-10 HP. They will reduce the alternator output and water pump output at idle but will cost little or nothing at higher revs. They are generally worthwhile, especially if you have changed to a numerically higher rear end ratio as they will reduce the accessory speeds to something closer to original.

Most sets consist of a smaller crank pulley to slow the belt down and larger water pump and alternator pullies to further reduce the speed of those devices.

 

[addo]

A smaller crank pulley would need a new balancer... Maybe one (the idea of a kit) for Az to check out?

 

[Anonymous]

These are also used to slow down belt driven accesorys for saftey. When you spin a motor up to 8000 rpm when the factory figured on 5500 max, you might explode an alternator. Though rare, it has happened, althogh a belt usually thows off first.

 

[Lazy JW]

This is a common modification for air-cooled VW's that are raced at high RPM. It is sure death for a daily driver VW though, at normal speeds the fan turns too slow.
Joe

 

[66Sprint6]

Hmmmm, wonder if it would benefeit our inlines any? Might be somethin for someone to look into and then let us know what heppened, lol.
Matt

 

[Asa]

This is a common modification for air-cooled VW's that are raced at high RPM. It is sure death for a daily driver VW though, at normal speeds the fan turns too slow.
Joe

electric fan?

 

[SixFoFalcon]

I have a VAK on my SHO. VAK stands for Vacuum Accessory Kill. It is basically a switch that kills the accessories (A/C compressor, alternator and power steering) under WOT. It gives most of the benefits of UDPs without the negative side effects, since it only operates at WOT, which is the only time you really need it. However, it would only be useful for killing the alternator on most older cars, since it is really just an electrical switch.

 

[Lazy JW]

This is a common modification for air-cooled VW's that are raced at high RPM. It is sure death for a daily driver VW though, at normal speeds the fan turns too slow.
Joe

electric fan?

I never really thought about it before, no reason why it couldn't be done but it would require a serious fan. Bugs don't enjoy the free flow of frontal cooling air through a radiator at cruise speed.
Joe

 

[Asa]

Bugs don't enjoy the free flow of frontal cooling air through a radiator at cruise speed.
Joe

i know they don't, dad has a VW Bus
maybe i'll suggest it to him one of these days...

 

[falcon fanatic]

I suppose one could use the motor from a regular electic fan, attach a pulley and drive the motor cooling fan that way. It would probably work better than stock as I seem to recall my VW squareback overheating easily in heavy traffic on those hot L.A. days since the fan turns slowly at low engine speeds. I wonder if you could attach a rheostat that would vary fan speed depending on head temprature.