Supercharger belt science & the gates new RPM belt...

keltymd said:

From what gates says that is your problem. They don’t stretch so you don’t want that level of tension on them. The reason for high tension is to account for belt stretch.

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I have the tensioner 80 percent from max but the belt is not tight. I moved the top idler pulley to the c position which is the highest position. That took some of the tension off the belt and allowed me to run a 5mm shorter belt. A friend has the same setup a d logged of 10k miles on it problem free.

i have yet to snap an rpm belt of have any issues with one

Thanks for all the input guys. What i take from this is that the belt isn’t a problem its the proper tensioning of it that’s critical . Terry can you give me some input on what to tension my new rpm belt at with my Procharger Stage2 set up as it is very different from the roots blower set ups mentioned in this thread!

beefcake said:

i have yet to snap an rpm belt of have any issues with one

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On a stick car with a 2 step or auto ?

I had a rpm belt on my whipple 10rib and used it when I put a smaller pulley on , and the tensioner was about 50% but I had belt slip, so I got a green belt, put 60-70% tension on it and belt slip is gone

yeah it would seem to me that at 20% on the tensioner you are asking for belt slip. Might be on on a 10rib. Seems counter productive. I might try another one after breaking on at launch last year but I didn't know about the tension thing. Seems like something pretty damn important that they should really advertise more.

keltymd said:

From what gates says that is your problem. They don’t stretch so you don’t want that level of tension on them. The reason for high tension is to account for belt stretch.

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Just for information I had mine 80 percent plus and the car has just idled in the garage. I read this post and loosened the tension of the belt. Now it has a "timed" squeek that goes away after a bit of idling. It did it again today again, so I attempted to make sure the pulley bolts are tight. when I went to tighten them, the pulley actually spun and the belt stayed in place. This would make me think that with less tension this belt WILL slip if tension as described in this post.

I've seen 3 broken RPM belts on local cars. My whipple kit came with one, so I ran it. Idler manual tensioner in the middle and the normal tensioner also in the middle. No belt slip to note on a 3.625 pulley

I've seen a lot of guys with snapped RPM belts. Juice isn't worth the squeeze. I'm at max blower speed on my D1SC with a regular Gates Green belt with no discernible slip. Don't see the need to mess with what works.

Barrel said:

I've seen a lot of guys with snapped RPM belts. Juice isn't worth the squeeze. I'm at max blower speed on my D1SC with a regular Gates Green belt with no discernible slip. Don't see the need to mess with what works.

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What pulley setup and RPM do you have?

I just ordered another belt. Should have got a green one to try. Part # and price? Part # 101054RPM Is for my rpm.

kcc0521 said:

What pulley setup and RPM do you have?

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4.0 pulley spinning the blower at ~62k RPM at 7500 engine RPM. I've got about 50 half mile passes on this belt and about 5k street miles.

Edit*

Just to add for calculations:

8" crank pulley diameter (Stage 2 3FRDR-002 pulley for ATI 918047 damper), 4" blower pulley diameter, 4.1:1 step up ratio, 7500 engine RPM = 61.5k blower RPM.

Barrel said:

4.0 pulley spinning the blower at ~62k RPM at 7500 engine RPM. I've got about 50 half mile passes on this belt and about 5k street miles.

Edit*

Just to add for calculations:

8" crank pulley diameter (Stage 2 3FRDR-002 pulley for ATI 918047 damper), 4" blower pulley diameter, 4.1:1 step up ratio, 7500 engine RPM = 61.5k blower RPM.

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How much boost are you seeing?

A little over 18#.

I did not have any trouble with the RPM belt on the street. Once I went to the track it came off twice. The belt did not snap, but it did slide the adjustable idler pulley as far as it could go and release the tension it had on it. The first time I thought "OK I just didn't have that tight enough". The second time, I am switching back to the signature series the Whipple kit came with and seeing what happens.