theoneinthedark

Hi fokes

got a lightened underdrive crank pulley, and i must say im impressed with the effects

any bad points about them ?? its lost 2.6lbs on the drive by doing this swap, so a sizable gain of about 6bhp not bad for 40 quid

Anonymous

changing pulley doesnt effect the engines bhp figures but cant effect how much is lost driving the ancileries

theoneinthedark

well apparantly every 1lb you lose in wieght you gain an everage of 2.7bhp on the wheels, because there is less weight to have to rotate

sort of like running 19's then going back to 15's if you get me? well thats what i was told

Anonymous

No, thats not true at all, you could strap a 1 stone pulley onto the front of your engine, stick it on the rollers and hold it at 4000rpm and it would have exactly the same bhp as it did before

which is just like 15s and 19s

theoneinthedark

thats shocking, cant believe that shop fed me that bullshit, however it does seem to rev up a bit quicker?

dojj

iTrader: (3)

i have never understood how making smaller pullys made you more power
if you've got s amleer pulley then, by default, the other stuff it's turning doens't work as effectivly, and so, by defualt, has to work harder, making any gains provided by the pulley made smaller innefective at best, and, at worst, damaging to the rest of your car

if you want to make things do less work you make the pulleys bigger on the items you want turning, redusing the amount of effort that is needed to rotate those anciarlies
if you half the rotational speed of your alternator will it still produce the same amount of charge?
what about the power steering pump?
will it affect the water pump flow also?

make it bling by all means to make the riciprocating mass lighter to give you less power losses, but also be aware that certain engines will incorporate a harmocin balancer in the cranck pulley and you may get vibratiosn in the eingine by removing the one fitted

Anonymous

smaller pulleys are about allowing you to rev the engine higher without overspeeding the water pump or alternator, on a normal rpm road car they are of no use.

weight saved off the engine roughly translates to a multiple of that weight saved off the car.

So losing 2 pounds off the pulley might equal losing 20kg off the car in first gear in terms of acceleration (and then less in subsequent gears of course)

I personally wouldnt be able to notice it, but if you can then maybe your arse dyno is more accurately calibrated than mine, or maybe you are imaganing it.