pullies, tensioners and belt sizes

[Race1Mopar]

Hey guys,
I have a question for you about pulleys, tensioners and belt sizes. The question is about my custom setup on my Dodge, but it's one one of you may have run into.

Problem: The gatorback v belt I run is a 114.5" 8 rib belt. I get about 3000-4000 miles out of it before I have to change it out due to belt slip. I really need an 8rib belt between 13.75 to 14" long but I haven't found one, don't believe anyone makes one.

Should I:
1) calculate my operating max rpm for each accessory and increase the size on the accessory that can most take the additional size, ie rpm, or should I
2) search for a pulley I can mate to my tensioner that is a larger diameter or
3) does anyone know of anyone that makes custom tensioners?
or
4) an option I haven't thought of?

Thanks
Joe

 

[JeffBoyette]

You mean between 113.75-114.0 inches?

 

[JeffBoyette]

Part number Metric Ribs Length Outside
4081102 8PK2800 8 110.25 111
4081124 8PK2855 8 112.375 113.125
4081145 8PK2910 8 114.5 115.25

 

[JeffBoyette]

If the tension is too tight it will wear/break faster than when its slipping. You can verify slip by boost loss. Just because you have rubber dust on the pullies dont mean its slipping. Not sure your custom setup, but if you have a spring loaded tensioner you cant really increase the tension by going with a shorter belt. If its a manual tensioner you need a way of measuring the flex of the belt at the time of install and after a few thousand miles to determine if the belt is stretching. This can be done with a straght edge between two pulleys and a micrometer or ruler.

If you verify that it is slipping, try getting a larger tensioner pulley only if your configuration will provide more belt wrap on the supercharger. Your supercharger has more load than all the other accessories combined, and any wear from slip is caused from that pulley alone. Changing accessory pulley size will only help if it increases the amount of belt wrap on the supercharger. You can also try to increase the diameter of both the supercharger pulley and the crank pulley by the same ratios to give more surface area without changing the rpm. This will also increase the speed of all the accessories and give a slight increase in parasitic drag and power loss.

Another option is to send your supercharger pulley off to be knurled or coated. However a few supercharger companies suggest not using knurled pulleys, doing this and it will void the warranty. Verify with the Vortech. They also advise against using the gatorback belt (Kenne Bell being one of them) Although it does tend to run cooler, it has less surface area contact with the pulley resulting in more slip.

 

[Race1Mopar]

You mean between 113.75-114.0 inches?

Sorry about that, yes I mean 113.75 to 114 inches would be the right size for me. 114.5 works but there some tension, not as much as I'd like. It works for a while but after 3000-4000 miles with 500rwhp the belt starts to slip on throttle stabs and aggressive kick downs.

Joe

 

[JeffBoyette]

Try part number 4081124 or 8PK2855
Its 112.375 113.125 inches

 

[Race1Mopar]

If the tension is too tight it will wear/break faster than when its slipping. You can verify slip by boost loss. Just because you have rubber dust on the pullies dont mean its slipping. Not sure your custom setup, but if you have a spring loaded tensioner you cant really increase the tension by going with a shorter belt. If its a manual tensioner you need a way of measuring the flex of the belt at the time of install and after a few thousand miles to determine if the belt is stretching. This can be done with a straght edge between two pulleys and a micrometer or ruler.

If you verify that it is slipping, try getting a larger tensioner pulley only if your configuration will provide more belt wrap on the supercharger. Your supercharger has more load than all the other accessories combined, and any wear from slip is caused from that pulley alone. Changing accessory pulley size will only help if it increases the amount of belt wrap on the supercharger. You can also try to increase the diameter of both the supercharger pulley and the crank pulley by the same ratios to give more surface area without changing the rpm. This will also increase the speed of all the accessories and give a slight increase in parasitic drag and power loss.

Another option is to send your supercharger pulley off to be knurled or coated. However a few supercharger companies suggest not using knurled pulleys, doing this and it will void the warranty. Verify with the Vortech. They also advise against using the gatorback belt (Kenne Bell being one of them) Although it does tend to run cooler, it has less surface area contact with the pulley resulting in more slip.

That's a log of great advice Jeff. Thank you.
I can tell you that the tensioner is not providing the same tension as before the supercharger add. The "travel" on the pulley is short of where it used to be therefore giving me less tension on the belt. One of the reasons I'm only running 6lbs of boost is that I am already on the smallest supercharger pulley (2.7 I believe) and largest diameter crank pulley. Everything is built to hold more boost but I need a new pulley setup to do it. I plan on running these until I can cog it later this year or early next year to get more boost.

Looking at everything, I have room to change everything except the sc and crank pulley. I never thought of the Gatorback belt as having less contact, and can't remember why I thought they were better at belt slip. Which belt do you recommend?

Joe

 

[Race1Mopar]

Try part number 4081124 or 8PK2855
Its 112.375 113.125 inches

I know the 112 won't work but I'll give the 113.125 a try.

Thanks
Joe

 

[JeffBoyette]

Did you try the 112.375. It is 2-1/8' shorter but may be within limits of your tensioner. The automatic tensioner will have less tension at full extentions, and more tension at contraction. They have used concentric coils to help reduce this difference, but it is still there. If it is the stock tensioner it may have lost some of its resiliency. You may try to just swap it out for a new one and see if that is an improvement.

As far as the gatorback, it was designed with those notches to give the belt a little more flex, and to create turbulance and it spins reducing heat. The heat makes the belt brittle, crack and wear over time, so just keep the belt cooler makes it last longer. Too much tension causes the belts to wear more quickly,and stretch causing inconsistent tension throughout its life.

An 8 rib, 113 inch belt is going to be more difficult to find. Goodyear, Dayco, and Gates are my preference in that order.

You can get you a can of CRC Belt Conditioner. Everytime you stop to fill up a tank of gas, or go to the dragstrip, Take this out from behind the seat, and spray down the belt and pulleys. It will extend the life of your belt and reduce slip.

 

[Race1Mopar]

As an update, the 112 didn't fit but the belt conditioner works great with the 114.5. Thank you!

 

[JeffBoyette]

Great man, glad to hear it. Just give the belt a light fog everytime you top off the gas tank and you should get a lot more life and a lot less slip from your belt. Don't overdo it and you won't have much sling and build up.

 

[Race1Mopar]

Jeff that sht is like GOLD!!! The most boost I had gotten before was 6lbs... well this morning I hit 8lbs and could do it on command. To me this is about 60 extra hp at the wheels (We calculated I get 30hp per lb of boost at the wheel) so as you could imagine she felt like a beast this morning.

Did I mention thank you!
Joe