Jfrahm

I almost took a pic of the steak. I have one of the center idler on my turbo motor but not with the support bracket I feel is needed to keep it fixed in place. That part is under revision, it's working but I think there is a better fitment option. I'll get some pics and measurements when I have something less alpha.

This AM I realized I could have probably gotten the thing running if I'd switched back to the Corvette belt and rotated the eccentric center idler the other way. Much of this is because my test pulley is so small and I also downsized the reversing idler a bit to keep the belt away from the timing belt cover, but it also seems that my guesses/measurements were on the long side.

-Joel.

Lemming

My SC will be back in my hands early next week. I will then be able to test fit the larger SC pulley that Carl sent me. If it works, that will be the basis for sizing the larger crank pulley for racing applications.

Carl Fausett

Tim, I am installing your new pulley on your supercharger for you while its' here.

I can see that the ID of the pulleys were not relieved for the hard-coating.... that is to say they are too tight to slide onto the shafts now.

To those that will receive new pulleys from me this week (they were shipped Friday) please return them to me. I will have to have them bored to the correct shaft size again. When the hard-coat was applied, it made them too small.

I will have them bored out and resend.

Jfrahm

Update: the first running test was a success. I did not have the belt very tight, it can be twisted 90 degrees between the reversing idler and the SC pulley. I saw 1 psi at 2000 rpms and 4 psi at around 3500 before I detected some slip (boost stopped rising.) I did not push it as this configuration is designed to find the left edge of the graph of belt tension, pulley size and traction. I may crank it up with more belt tension next, or move on to working with what I feel is the smallest sensible pulley which will have 30% more contact patch with the belt.

I feel I have proven the configuration works and the traction can't help but be improved.

It's dark out and I'm hungry so I am calling that good enough for now.

Belt tension is not easy to work out with this setup, I may incorporate a jackscrew to position the center idler (old Toyota 3.4L style) or an eccentric for the reversing idler to make life easier.

-Joel.

Carl Fausett

Tim,

your supercharger is finished and shipping today.

The new pulleys look fantastic, I think they will solve the belt slip issue on racers.

edz968s

Carl, I recieved my pulley today, looks good, but I now have to return it for relieving of the centre hard coating?
Is it just reboring to ?? size and can I get it done over here, rather than sending it off to you

Jfrahm

Update: I have not worked on the project but I daydreamed about the bracket a bit and have a few ideas. The issue I have with it, is that it prevents full operation of the belt tensioner. A cure for this could be as easy as routing the belt over the new idler between the alternator and AC, but then the new belt route does not improve crank wrap at all. It is possible to get the belt tight, but it's fussy and inelegant as it is now.

The issue is that when the AC pump gets close to the crank pulley, the belt takes on an inverted teardrop shape and starts to get tight again. A good range of adjustment is needed to get the belt on and then tight, and then retension after it wears in. In my system this requires messing with the eccentric and that kinda sucks.

What I am going to try instead is make a bracket that rotates around the other alternator carriage bolt and use a turnbuckle from the upper one to provide another adjustment point for the belt. The belt can be put on with this new adjsuter loose, then the new adjuster cranked up and locked down, then you ca go at it with the OEM adjuster. You could also do it the opposite way if you like.

It might be possible to fit a spring tensioner down there somewhere and if I am ever at the pick-n-pull I might get one to mess with but not anytime soon.

Here is a pic of v 0.1 of the bracket showing the new idler in a very low position that does not work at all with the Volvo belt. The new bracket would run from the other 17mm headed bolt to the right and the turnbuckle would come down from the upper 17mm headed bolt that is currently holding this bracket in place. This is fitted on a turbo motor for testing so you do not see the belt routing for a supercharger but you get the idea.

Carl Fausett

Ed,

It seems as the the plater left the batch in a little too long and that's why it built up a thicker coat than we engineered for.

The bore needs to be 17.00mm, and I think you will find with the coating it is about 16.98mm

Take a micrometer to your Raptor shaft - maybe your shaft will be a little under 17.00 mm or maybe your pulley is a little bigger ID than mine was here.

If you take it to a machinist, have him bore it to 17.0mm even. If you want to try to install it, be sure the heat the pulley well first and to put a little grease on the supercharger shaft. Line up the keyway or it will never go on!

I am having them re-bored here now - so if you don't want to futz with it, send that one back and I'll get another one on its way

edz968s

There are 6PK 1600mm double sided V belts available, we use 1574mm.
So with the belt tension turnbuckle adjustment, a slightly larger reverse idler and a slightly larger alternator pulley, plus a new s/c head 6 grooved pulley, would that improve belt slip

Carl Fausett

Your still ignoring the size of the crank pulley, and the belt slip will not be fully addressed until you deal with that.

I am making a larger crank pulley for the new Stage 2 kit, THEN we can increase the pulley on the blower also and all belt slip issues among racers will be eliminated (if they are not already eliminated by the new supercharger pulley that we are shipping now.

Lemming

I'll be at Road Atlanta next week and will put mine to the test

edz968s

Ok, just a shot in the dark that double sided ribbed belt are out there, but with your development of the crank pulley and myself a stage 2 kit buyer, look forward to this further upgrade.

Carl Fausett

Road Atlanta will be a good test! Nice track. Very technical, short and twisty. Raced there last year myself.

Lemming

Sure hope the extra power puts me into the 1:35's

SC arrived tonight, turned the volute to the left and got it mounted. Might work a bit more tonight to get some of the IC plumbing done.

Jfrahm

What car does the 1600mm belt fit?

I am at the point of cutting a custom pulley to match the double sided belt profile. I have had some fun with my modded alternator pulleys but got slipping over 4.5 psi. 1.8 psi at 3000 RPMs was interesting though. I am being held back by the extra deep grooved alternator pulleys I have been fooling with, they do not provide enough contact patch with the belt. They only touch about 2/3 of the belt surface.

I have spent little time on the project in the last week but I might get after it a bit more in the next few days.

-Joel.