Eric_Oz_S2

Couldn't you use one of the Dayco ones? There seems to be quite a few sizes available:

http://www.advanceautoparts.com/1/3/...-poly-rib-belt

Carl Fausett

Good stuff Joel.

I'm waiting for the pulleys to comer back from hard coating, I will notify here when I have them.

Jfrahm

I checked them all before:

6060470 Belt Length: 47.05 in - too short and maybe VW profile ribs

6060719 Belt Length: 71.85 in - Too long

6060724 Belt Length: 72.44 in - Too long

607xxx's are 7 ribs, even if you sliced one rib off one is too short and one too long.

605xxx's are 5 rib.

Hmmm, I see now I did not think about using the 6060719 or 724 and putting my idler up where I want. That is in interesting idea. I will check if it is K profile and see how the numbers work. I think the 719 and 724 are Volvo fitment so it should be K profile. They are also quite cheap and the cost of getting one locally is not as punitive as it was for the Corvette belt.

Excellent. Thanks!
-Joel.

Carl Fausett

Just a reminder - we did also explore this option when we were designing the kit initially.
It wasn't easy then, either.

Carl Fausett

Joel, as to raising the location of the idler - make sure you can still get the hood closed.

Jfrahm

I'm not moving the reversing idler. I am either moving the little plastic idler from the kit towards the centerline, or adding an idler between the AC compressor and the crank.

If I needed some more belt I could put a smaller reversing idler on and get up to an inch of belt but that might not be necessary.

-Joel.

Carl Fausett

Then I mis-understood what you meant. My fault.

Carl Fausett

Just in from the hard-coater.

I will try to ship as many as I can today to present owners.

From Post 1002:

Jfrahm

Those look good.

I made some progress today, got the longer Volvo belt and figured out the bracket for the additional idler.
I whipped up a bracket but it might be too long, but I can make another one in 30-45 minutes. I also prepped a pulley for testing. One more wrenching session should have it running with the double sided belt.

There are some options from here on out. Ideally a pulley can get cut to match this belt which has shallower ribs than the stock belt, probably so it does not crack the ribs when it bends the other way.
This means the ideal blower pulley would have shallower and more rounded grooves in it than the traditional K profile.

If the belt does not slip with the typical K profile pulley, great. If it does slip the surface area on the pulley can be optimized.

I should have something spinning tomorrow or Sunday.
-Joel.

mikey_audiogeek

Hi Carl,

Will you be offering the Stage 2 crank pulley on the open market? If so, can you please tell me price and diameter?

Thanks,
Mike

Jfrahm

I broke down and bought a used mini lathe, so I have been playing with that and grinding a tool to properly cut a pulley to fit the belt. I also did some more shaping on the too-small 'mini muffin' pulley I plan to use for some tests. Playing around with the pulley, my impression is that it has a great deal more grip than stock. I do not have a fish scale to measure the force, but I did make an attempt.

Using a belt I'd cut up with a weight on one end, I found it took a lot of pull to slip the belt at a 90 degree angle over the mini muffin (fixed in place) but it pulled easily over the stock pulley. Granted the mini muffin was recently sprayed with oven cleaner which gave it a rougher texture than it might take on when in use. Encouraging nonetheless.

It'll take more work to cut a pulley to really match the profile of the Volvo belt but doing so should increase contact area by 30% or so. If the teeth look like this '\_/' then the current pulley I am using really only contacts the sides of the tooth and not the flat bottom. If the muffin pulley grips OK, there is no reason to bother cutting a larger pulley to match that tooth profile (but I might do it anyway now that I have a lathe.)

The whole point of this too-small pulley test is:

1) Detect slip at an RPM more conducive to staying on the road and out of jail (things happen real fast at 6500 RPM.)

2) Confidence in a too-small pulley makes for a great deal of confidence in an appropriately sized one.

-Joel.

Lemming

Good work Joel.

I noticed last night that the alternator pulley looks to have a similar shaft fitting as Carl's SC pulleys (did not have time to measure it). If this is true, than it would be possible to put one of Carl's larger pulleys on the alternator to help take up slack and to deal with over spinning the alternator once the larger crank pulley is available.

Jfrahm

Yes, the 968 alternator as well as GM and Ford alternators use a 17mm shaft, same as the supercharger. There are lots of cheap options for steel alternator pulleys, you can get them from Amazon or alternator supply houses. Probably a good FLAPS as well. Slowing the alternator down is no problem.

My test pulleys for the SC system are alternator pulleys cut from billet and sold as underhood bling parts.

-Joel.

Jfrahm

Update: I spent a couple hours on the project today and had hoped to have a testable configuration. Unfortunately I got everything into place and found that I could not get the belt tight. I need to move the center idler farther up to use up more belt. This will only take 45 minutes or so but instead I am opting for a ribeye and a glass of cheap, vulgar wine. I do not believe there are any gotchas left at this point, I just have to pull the center idler (aka the crank wrap pulley) and bracket off, take it apart, drill another hole in it and move the idler a bit. I might improve the bracket a bit at this time also but nothing serious.

Still looking good!
-Joel.

Lemming

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