1G underdrive crank pulley

[CLuTZ]

Hey all, i'm looking at purchasing a buschur racing underdrive crank pulley from the states and am wondering if there's anyone out there (besides you baz) that has an underdrive crank pulley on their car, and how many HP i'd expect to gain from using one on my setup.

Also, the belts- what belts need changing?

Chur


dre

 

[bazeng]

lol dre
they give you the belts you need to change (air con and water pump...
we needed to machine it a little to fit also

pricey unit $350.00 USD for something thats not lighter, just stronger / wont split..

 

[CLuTZ]

lol dre
they give you the belts you need to change (air con and water pump...
we needed to machine it a little to fit also

pricey unit $350.00 USD for something thats not lighter, just stronger / wont split..

I dont think the one im looking at comes with any belts, are you trying to say theres no performance gain at all? Just reliability?

 

[Entaran]

Try the unorthodox racing one. That's more drag style.

Will make some parts of your car a bitch (like the heater/aircon)


Belts are usually supplied, otherwise your mechanic/daz/etc should be able to sort it all out.

Underdrive pulleys on heavily worked cars usually free up about 10-12 KW across the range. This is only applicable if the things being underdriven are actually running (like your aircon).

 

[CLuTZ]

I have no aircon. Apparently only the buschur racing one has dampeners so your crank doesnt vibrate itself to death?

 

[matress]

it'd be an alternator underdrive pulley wouldn't it?
i had one of these on my rx7... to be perfectly honest, i didnt notice a huge difference, but then again it wasnt making much power. if anything it probably revved out slightly quicker.

 

[bazeng]

the buschur racing ones dont actually free up hp by lightening the weight, its probably the same weight

the only difference is that its not cast therefor not risk of it shattering / splitting

underdrive is also a benifit but not for power really, more to do with revving

eg, the pulley is smaller, therefor it would spin the alt / water pump slower
which means that the water pump will flow less at idle, up high would flow more without cavitation (is that the word??)

the stock water pump isn't designed to go to 7000+ rpm, so at this rpm, the water isn't actually flowing, the pump is just make spinning but not actually moving the water if u know what i mean..

so its designed to flow the same amount the pump would flow down low up top..

as for the alternator, buschur claim that the alternator is spinning way to fast already, therefor they slow it down to increase the life of the alternator

thats about it.. no other benifits..

for hp, go for the SOLID ALLOY ones, they are really light!!!
but once again, no rubber = vibrations / harmonics which is believed to cause bearing failure / cracked cranks etc etc...

funny thing is wrx's use the solid pullies all the time without hiccups.. and they are cheap too!

there is a fluid damper on the market for the evo's 1-2-3... newly designed by the US guys... not sure if its compatible with the vr4's, designed with the 7bolt crank, but i dont think there is a difference..

if u want to free some hp via pullies, free up a/c.. the water pump and p/s like i have =)

 

[EVO-00X]

Personally, I'd look at getting the extra HP from other avenues before I'd go spending $$ on pricey items such as these. But thats just my opinion If you have a dead harmonic balancer and need to buy a new one, then yeah buy it as the OEM ones are pricey buggers themselves. But if yours is still in good nick I wouldnt worry about it until you have to :wink: