Is an 8 rib pulley upgrade really necessary?

[3ponyshow]

How many of you guys are running 400+ bhp with 6 rib setups?

I realize I l live in a high DA area which makes a big difference but...

I'm already running a 3.125" on my centri (3.33" is what Vortech normally equates to 10 lbs). My tuner says I need to upgrade to an 8 rib setup if I want more than 8.5 lbs boost. If I go any smaller I'll lose too much surface area and just slip. I trust his judgement, I just want to hear opinions.

 

[trinity_gt]

How many of you guys are running 400+ bhp with 6 rib setups?

I realize I l live in a high DA area which makes a big difference but...

I'm already running a 3.125" on my centri (3.33" is what Vortech normally equates to 10 lbs). My tuner says I need to upgrade to an 8 rib setup if I want more than 8.5 lbs boost. If I go any smaller I'll lose too much surface area and just slip. I trust his judgement, I just want to hear opinions.

Anyone running a 9-lb KB kit runs a 6-rib setup without issues and are making that sort of power. But this is a twinscrew, not a centri.

Do you smell burning rubber (and not from the back tires... ) during a pull? That's one sign the belt is slipping. Is it tossing belts? Boost abnormally low or varying during a pull?

 

[darkside03gt]

Your dyno guy is full of **** plain and simple. Most people dont see belt slip on a 6 rib till 12 psi or more and I know of more then a few running 14 psi on a 6 rib. The key to running that high of boost is a gates micro v belt and a 3 bolt tensioner timing cover. You can also get your supercharger pulley coated to provide more grip but you will have to change belts more often.

Just to give you more piece of mind I am running 9lbs of boost on my kb 2.1 with ZERO belt slip. Twin scews required more power to turn to there is a higher chance of belt slip when compared to your centri.

Is your dyno guy trying to sell you an 8 rib setup? If he is find another shop because that one is out to steel your money. However if you do want to run an 8 rib setup there is a stickey on modfords in the 96-04 section that will help you put one togeather for cheap using ford pulleys.

 

[3ponyshow]

Thanks for the feed back, guys!

Just to reiterate, this thread isn't about challenging my tuner's credibility. He's nationally known, published on the topic, even been on TV and no, he's not selling anything. Moving on...

darkside03gt: Thanks for the link. I'll follow up.

trinity-gt: No, I don't smell any burning or hear anything. Haven't tossed a belt, (but I'm on the smallest belt I can go). Pull #'s have been consistent, but I think this qualifies as abnormally low.

I know that if I was at a lower DA, I would be running considerably higher boost (The Vortech techs have confirmed that as well). I started to experience belt slip at 325 bhp with a 3.6" pulley, but that was in NY where racing conditions are ideal. Out here, when I added the Power Cooler, the pulley was reduced to 3.33", which as mentioned before, Vortech equates to 10 lbs under normal conditions and pretty much max for what the SOHC was intended to go. A 3.33" pulley got me about 7 lbs here. I dropped to a 3.125" and brought it up to 8.5" lbs.

What I'm trying to determine is, would it be throwing good money after bad to buy yet another smaller pulley (2.9"?) and then another belt (and there's still no guarantee I'm at 10 lbs) or would it make more sense to just upgrade to the 8 rib at this point which is considerably more expensive.