Cogs Or Insanely Tight 10 Rib?????

**swc** · 09-12-2005, 02:08 PM

Hi Guys,

We have a bit of a delimma with a belt slippage issue. YSi-Trim running a 10 rib 2.95 blower and an 8" Renegade crank with the driver's side Renegade thick plate type brackets along with a strut tower-to-head unit brace. Several months ago on the dyno I tried a 2.75" Reichard pulley and although boost peaked at 23 lb, within 2 pulls it shredded the belt--our dyno operator suggested we go back to a standard 2.95 pulley. This is where we are at now.

We have had our blower pulley aluminum nitrate meadia (I believe that was the term the shop used) blasted to give it a slightly rough surface (similar to Vortech's "Improved Traction" pulleys). Boost peaked at 22 lb and then rapidly slipped back to 10. And yes, belt dust everywhere Had the belt not slipped I'm convinced that we would have gotten our 25-27 lb that it should have made. I haven't tried wiping down the belt (Dayco) with VHT but , although it would help a bit I don't think that it would solve the problem totally.

I'm at a loss, I honestly do not think that we could possibly get our belt any tighter--this has got to be hard on the snout of the crank, even though it is a billet steel piece. On one hand this is putting undue stress on the carnk but switching to cogs will stress the crank and blower when the throttle is closed at the stripe (track). Personally, I think that cogs will be the lesser of two evils. I am going to talk to Vortech tomorrow and ask their opinion. What do you guys think??

The only thing that we have'nt tried is runnig a strut from the crank pulley to the head unit--Kurgan is making one but only for the 8 rib set up. It would take a fair ammount of fabricating to modify it for our 10 rib. Both our tuner and Kurgan told us to avoid cogs but, what is harder on parts considering how much tension we are putting on our belt?? Personally I am to the point that it's really a toss up whether to try a 50mm cog setup or sell off the blower and go the turbo route. What is my YSi, bracketry, pulleys and a 1 7/8" Kooks headers worth these days?? Looking for any opinions.

Really Frustrated

**BLOWNBY** · 09-14-2005, 12:00 PM

Vortech makes the strut support to connect the SC and the crank and they work nice. I noticed about 2 psi loss when note using this. Or you can have ASP make a custom larger Crank pulley so you can run a larger SC pulley as well. I also had ASP make me an 8.6 crank. You need a remote WP or the meziere 311.

**Pro Stock John** · 09-20-2005, 02:14 PM

I am running a strut brace custom designed for me by Bob Kurgan (Kurgan Motorsports). It runs from the head unit to the crank. It uses pilot bearings (I think that's what they are called).

I went from making 17 psi with 2.85/8.00 pulley combo to 21.5psi. I would need to redesign my tensioner if i wanted to run a 2.75 since I would not have enuff belt wrap to make it work.

I went 9.61@144mph on a 1.49, 3450 raceweight with 18psi in the middle of July.

**stevieturbo** · 09-27-2005, 06:19 PM

DONT tighten it too much !!!!!!!!!

I just knackered the bearings in my YSi by doing exactly that. I have a 10-rib gates, and lots of belt dust. I was seeing some slippage a day before I was due to travel to a race event. So I tightened the belt up... a tad too much it seems. By time I got home, the bearings were shot. That was like a 500 mile round trip.

I was very very lucky in that Vortec have repaired this without charge to me. I should hopefully have my unit back next week.

I might look into re-desiging my tensioner pulley to see if I can get a bit more belt wrap. Im on 8.25"/3.15" at the minute, although will be dropping to a 3.0" when I upgrade to 382ci.

**BLOWNBY** · 09-28-2005, 07:45 AM

Originally Posted by stevieturbo

DONT tighten it too much !!!!!!!!!

I just knackered the bearings in my YSi by doing exactly that.

So your bearings took a $hit..Huh:weird: Well at least your getting them replaced free.

**Pro Stock John** · 09-28-2005, 09:18 AM

That's why I run that strut brace with my blower setup.

**stevieturbo** · 09-28-2005, 11:14 AM

It is something to consider. But I barely have 3/4" clearance between my rad and crank pulley for a strut brace.

What sort of depth does a strut brace require ?

**BLOWNBY** · 09-28-2005, 11:18 AM

Your gonna need more than 3/4". Plus you need a crank modified to hold the plate where the bottom of the support mounts.

**stevieturbo** · 09-28-2005, 11:29 AM

What needs modified on the crank ? Any pics Ive seen, looks like a round adaptor will bolt to the front of my crank pulley, to which the strut bolts on.

**Pro Stock John** · 09-29-2005, 09:41 AM

I think it was called a pilot bushing.

**BLOWNBY** · 09-29-2005, 09:50 AM

There is an adapter plate that sits in a ~7" Diameter- 1/8" deep grove in the pulley and is held to the pulley with 8 little counter sunk screws. Your typical pulley won't have this provision. You need at least an 8" pulley (vortech's pulley's have this provision).The plate has the pilot bushing on which the strut bar mounts to.

You can see it here.

**BLOWNBY** · 09-29-2005, 09:55 AM

Here is how the strut mounts to the plate. You should figure it out from this.

**stevieturbo** · 09-29-2005, 11:34 AM

This is my front pulley.
http://gallery112848.fotopic.net/p8886908.html

Although its ribbed now, rather than cogged. It looks like a Vortech compatable setup as far as the strut brace is concerned.

Would it be possible for you to measure clearnce required from front of pulley to radiator for the brace ? I doubt I can get enough room....but who knows....