Under Drive Pulleys

[danthaman01 0]

Hey

Where can you get under drive pulleys in NZ? Do they give a good gain in power on the M50 motor?

any help appreciated

cheers

Dan

[320guy 0]

Dont think you will find any in NZ, but you will be lucky if they give you a noticable power increase.

[*Glenn* 854]

The pulleys will make your wallet lighter...dont know what that will equate to in HP gains though

BTW: Seriously, I have a waterpump one here if you want it.... alluminium and FREE

You'll need to get a shorter drive belt for it though

Edited January 21, 2009 by *Glenn*

[briancol 3]

The pulleys will make your wallet lighter...dont know what that will equate to in HP gains though

Glenn, haven't you heard about power to weight ratio? If his wallet is lighter the car must go faster.

[*Glenn* 854]

Check my edits

[Greg111 13]

Can i ask what under drive pullys are? Never heard of them.

[Guest FrantiC]

Can i ask what under drive pullys are? Never heard of them.

Different "ratio" pulleys for like your alternator etc, Good for engines that see higher revs more often. They run the alternator or whatever it is a slower rate than stock.

Edited January 22, 2009 by FrantiC

[Greg111 13]

Different "ratio" pulleys for like your alternator etc, Good for engines that see higher revs more often. They run the alternator or whatever it is a slower rate than stock.

Oh i see. can't imagine it would be that necessary?

[danthaman01 0]

cheers guys was just looking in performance BMW and they listed them as a must do for a m50 after exhaust and intake mods, they were making claims of up to 10 hp

[morerevsm3 7]

on an E36 M3, replace the crank pulley with an E46 M3 pulley, cheap and underdrives all accessories

[No name user 379]

The belt drives the Alternator, Air con and Water pump. The total power required to drives these would may be get close to 5kW in the worst case.

About 80% of this would be the Air con

Reducing the pulley ratio by 10% would reduce this by 10% or .5 kW

Turning the air con off will reduce it by 80%

The magic (lies) is in the marketing the truth is in basic physics and maths.

i make under-drive pulleys for many different vehicles,the alternator can rob 7-12 hp and water pump around he same to which is why race cars run an electric pump and the alternator runs off the drive shaft.

they don't go to these degrees if there wasn't a noticeable gain.

water pump conversion to electric on a small block is worth 20hp at the wheels,cant complain about that.

the other reason apart from power gains( which are real !!) is with the water pump it stops it cavitating at higher rpm to aid cooling.

you notice the gain everywhere not just at high rpm.

so there's maybe something in that magic

every little thing helps when playing with na,smaller lighter etc maybe only 5-6 hp here and there but combined together could at up to a noticable gain.

I'm looking at making my own multi throttle body setup on my m40, i only listen to those who can prove to me certain things arnt worth the gain.

then there's those with their heads stuck in the sand,just cause its a bmw doesnt mean it cant be done