Vortech Belt slippage?

[skidad62]

I added a new Vortech 3.12" pulley (6 rib) on my V2 SQ SI trim on my 03 GT. I was running a 3.33 pulley.

With the new Vortech Maxflow bypass valve and Procharger intercooler on I was looking to step up to about 13 lbs of boost and get things spinning a bit earlier.

I went to get a Goodyear Gatorback belt in 108.0 inches (running the stock crank pulley) which is 1.0" shorter than the belt I was running with the 3.33 - but locally Goodyear does not have a warehouse anymore and shops don't carry them. I settled for a Dayco belt and crossed by fingers.

I got 12.5 lbs of boost my first conservative run with all the timing pulled... made 401 rwhp (on 91 octane which is all we can get here) but after that it dropped to only 10.0 lbs of boost on all other dyno runs.

I think it must be belt slippage?

We dialed things back to conservative timing and got the A/F all smoothed out but she's only showing 394 rwhp and 386 rwtq. Then on the roadtest she was surging as the power comes on. Seems to confirm the belt slipping?

We're having a Gatorback shipped in for next week to swap belts and try again.

Anyone else have issues with the 3.12" 6 rib pulley?

Sound like slippage to you? Any thoughts or recommendations? Prefer not to swap to an 8 rib set up unless really necessary.

Thanks

 

[acerasuolo]

got a dyno chart?
...im running a (6-rib)3.12" on my t-trim and boost is strong

 

[LS1PUSSOUT]

yea i never liked the dayco belts. I had good results with Gates. Those are the belts that come with the vortech kits. Although mine is sqeaky until it gets warmed up. You shouldnt need an 8 rib setup to run that pulley.

 

[skidad62]

got a dyno chart?
...im running a (6-rib)3.12" on my t-trim and boost is strong

I have a chart but I haven't scanned it yet.

 

[acerasuolo]

I have a chart but I haven't scanned it yet.

if the end rpms look like this www (<--- not suppose to be a link, just wavy lines) thats generally belt slip. they will also just start to drop off like ur running out of rpm. another sign is after a few miles u can run ur finger inside the belt ribs and see if any black dust comes off. thats an easy sign of slippage.

 

[AntiHeightPunk]

i would go 8 rib thats when i started to need it

 

[rubber duck]

I run a 3.12 RR Ultra Grip pulley with a Gatorback belt. If you're running a non-slotted pulley you're going to get some slip, and the belt will eventually shred from it. You can then run a pulley like mine and still have to change belts from how hard a slotted 3.12 pulley is on a 6 rib belt. The only real solution is an 8 rib conversion or get good at changing belts. I'm good at changing belts for now.

 

[Furinox]

+1 get a RR pulley and stay away from the gatorback belts. I talked to the guy at RR and he said the gatorback belts are not that good. Something about them being made out of an inferior material for the past couple years. I would think those belts are crap anyways because of the way they are slotted. Those slots mean less friction surface.
I'm running a 2.9 RR 6 rib pulley with an autozone belt(only brand in the size I need) and I get no slip.