Belt size for LT4 blower 2.5 pulley
 

Hi guys, Im currently pulling down my LT4 blower from a 2.75 to a 2.50

I know that the 2.5 pulley is the stock size however considering that in order for the LT4 blower to be bolted on the LT1, spacers are requiered. My brain says that the stock ZL1 belt wouldnt fit, correct? Since the blower will be sitting slightly higher than where it would sit on a LT4 engine....

I currently have a 2.31 pulley and belt (which I never used) but I was told that the belt might fit on the 2.5 pulley... thoughts??

P.S lower pulley is the stock ZL1. So I would now be at 2.5 griptec high and stock low.

Thanks in advance for any help... I would like a green belt also.

I had the same issue, went through 2 belts trying to find the right size for my eForce with a 3.25" pulley. No I have a good starting point for all other sizes

The stock belt is 82.87 K080828RPM RACING MICRO-V or you can go to gates site and look at the closest fleet runner HD green back belts and do the math.. pretty simple once you know the OEM size length. All you do subtract the pulley sizes to find correct length. Once you have that give them the number at Orileys and all the number will be similar but the endings for like fleet runner will be HD on the end.


If you used the ICB adapters they are 1/2 thick then, seems like your 1/4 or .250 taller now.. the stock belt maybe close enough!

Thanks so much for that data. It actually seems exact.

I currently have on my car 2.75 pulley with a K080839HD belt which is 2130mm

If I substract 2.75-2.50 = .25
2130mm - 25 = 2105

The stock belt you state (K080828RPM) is exactly 2105mm.

So based on the current belt I have been using on my 2.75, the stock OEM belt should work fine when I put the 2.50

your math is a bit off

3.14*radius squared/2 will give you the difference in belt size. You have half belt wrap on the pulley.

OK im lost again.

you need a 13MM shorter belt going from a 2.75 to a 2.5

2117 MM belt

K080825HD 85550112 K080825HD FLEETRUNNER MICRO-V 8 K 82.59 2098MM
K080830HD 85550326 K080830HD FLEETRUNNER MICRO-V 8 K 83.19 2113MM
K080834HD 85550351 K080834HD FLEETRUNNER MICRO-V 8 K 83.46 2120MM

Ended up using the K080830HD belt... I liked the fitment with it.
I was tight to fit on... but once I started the car the idler sat back to its place...

That’s the belt for the LT1? I thought most people using the LT4 blower conversion were swapping the lower pulley instead of the blower pulley. Looking forward to your results with this setup.