Ive recently got my LS1/YSi running but have a couple of issues.

I have 12 rib pulleys although currently only using a 6 rib belt. But when I fit the belt on the inner grooves, once driving ( I assume at high rpm's ) the belt travels to the outside of the pulleys.

There is good belt wrap, and its a manual tensioner, which is secured pretty tight. There wouldnt be any real slippage issues yet for all the power/boost Im running.
The grooves appear to be inline with each other as best I can measure.

I assume this means the blower pulley and crank pulley arent running true along the same plane ? even if the grooves appear to be in-line ?
ie, the blower needs tilted back a bit ? Does that sound right ?

Ive already tore one belt due to this, so something is up. Bracket flex wouldnt be a major issue, although it does move a little bit when tensioning.

Thanks, Stevie

 

Why not find 12 rib belts and focus on how they work?

You might have bracket flex, or stuff is not lined up. How much tension do you really have?

 

AT the minute I dont believe I can actually get a 12 rib in the length I need ( 64" )
I have ordered a couple of 10-ribs, but Im still waiting on them, so in meantime I used what I can easily get which is 6-ribs.

As I say, the grooves appear to be in-line as best I can tell. But, I did have to put washers behind the bracket when assembling as without them the SC would have been tilted backwards at an angle. It seems I may have went too far, although at a glance it looks ok.

So bracket flex, or having the blower slightly tilted ( in same way as bracket flex due to too much tension ) would cause this problem ?

 

I can remove or use thinner washers from behind the bracket at the PAS pump ( area circled ) which would move the blower head in the direction indicated.

I assume this is what I need to do ?

 

I had a few issues, but the big one was bracket flex when we put all that tension on it.

I added a custom strut brace.

But if you can run a 12 rib I'd just experiment.

 

6rib stuff can slip at 9psi.

 

I'll try spacing it and see what happens. I'll maybe set it at a bit of an angle, so it pulls straight when tensioned.
I dont honestly believe it is slipping, but I only have 50-60 FI miles on it anyway. Datalogs seem to show a smooth enough boost rise.
Hopefully the 10-rib belts will arrive soon. The guys getting other stuff for me, so will be shipping it to me in one go.

Unless you are aware of anyone who makes a 64" 12-rib ? I could work with 63.5-64.5 if needed.
I also have smaller pulleys being made, so when I'm ready to use them, could maybe drop to a 63.5 or thereabouts. Ive tried searching online, and I cant find anyone who makes them those lengths.

 

I can tell right away the pulleys aren't aligned, maybe its the way the photo is taken or the angle of it. space the blower out a little more.

 

I noticed last year that I would lose my belt at the 1000 mark on a lot of runs. I was not sure if it was walking off the entire time or if my shifts had something to do with it.

On my 136mph run I had belt slippage, it was only a peak of 14psi. Next pass I threw the belt halfway in the run.

Remember my strut pics?

 

When I initinally fitted the bracket, I had to place washers behind it, between it and the PAS pump, in order to align it with the crank pulley. I thought this a bit crap, but visually it appeared true. Under tension it will pulll towards the crank a bit.
Unfortunately I dont have room for a strut brace in front of the crank, although there would be room at the blower.

Perhaps if I lost the extra 2 ribs on the crank pulley that will never be used, it might give me enough room.

How deep actually is the strut brace ? From face of pulley, to end of bolt/stud ?

Ive tried removing a washer, but havent tried it on the road yet. If anything when sitting free it looks a little bit tilted back now. That might help things.

Are there any tools around to check alignment ?? I did see a pic of someone using a lazer a while back ?

 

Might need to check the alignment. My belts would walk a bit on the dyno too. If they walk on the dyno they will walk on the street.