View Full Version : S/C Pulley & Belt Help

10-08-2006, 04:40 PM
I have read several of the posts on this board concerning the correct size, whether or not to use the upper/lower pulley, slippage, etc. But I still have a few questions that I hope you guys using the pulleys can help me with.

I use my cobra pretty much as a show car it has only has about 1600 miles, but I would like a few extra HP for those Sunday drives. Currently I have Magnaflows cat backs and a JLT CAI.

I have decided that I want to go with the 3.1 or 3.0 pulley, but only if I can be sure that the belt slippage will not be a concern. I have heard that the Reichard Racing (RR)pulleys grip pretty well so I was thinking about using that.

Anyone out there using the RR pulleys that can verify?
Are there other upper pulleys that prevent slippage?
What is the best size/type belt for a 3.1 pulley?
How much would an idler pulley help reduce slippage?

Any help or suggestions would be welcomed. Thanks!

10-08-2006, 11:28 PM
I know this is not much help but the only answer I can give you is, some slip and some don't. Some folks run RR pulleys and Gatorback belts and still need the extra ildler. Some are lucky like me. I run a 2.80 cheap $30 pulley and Gatorback belt with on extra idler (just replacer the stock ones) and have no slippage. I would think if you are going with a 3.1 pulley you should be fine without an extra idler but there is only one way to find out for sure.
Just make sure you get a good dyno tune for it. :thumbsup:

10-09-2006, 08:49 AM
IMO, it's not worth the pulley if you go any higher than a 2.93 upper. you'll only see minimal gains with a 3.0 or 3.1. If you get the upper and snub idler, you'll more than likely see no belt slip, but it's hard to guarantee that. With the 2.8 upper, it'll put in the 450rwhp-470rwhp range, some see higher, just depends on the weather. LFP, Billetflow, and Reichard racing make great pulleys. Let me know if you need any pricing.

10-09-2006, 12:11 PM
That is some really good feedback guys, thanks. I think I will start with a 3.0 pulley and see if I notice any slipping. If so then it sounds like adding the tension pulley might fix the problem.

I decided on a 3.0 just to be on the safe side of things. I definetely do not want to overtax the motor or supercharger.

Are steel pulleys better than aluminum (as far as less slippage). If so who makes a good steel pulley? Any recommendations for a good belt? I have heard the gatorbacks are good, but tend to slip worse than others.

Thanks again.

10-09-2006, 12:55 PM
I have not heard the gatorbacks slip worse. I heard the opposite. :( I run the Gatorback with no extra idler on a 2.80 and do not have any slip. The thing about the Gatorback is they do make a whistling noise.

10-09-2006, 12:58 PM
most use aircraft aluminum...gatorback belts are good, but we've had success with Dayco Polycogs as well...

10-09-2006, 04:48 PM
I used to run a 3.1 aluminum upper without the traction grooves cut and once in a while it would slip when getting back in the gas after an aggressive up shift. now I run a 2.9 with the traction or no-slip grooves plus an upper idler. I really wanted to retain the stock belt cover for the stealth effect, but since then, I have made alot of other mods to the point that you can't help but know it isn't stock. I should also mention that I was and still am running a gatorback belt. I've heard of a magazine test where they used a 2.8 steel upper pulley with the Gates or stock style belt with no idlers while experiencing no slip. if I had read that particular article prior to my current mods, I would have tried it and if it slipped, Iwould have gotten the upper idler. this car they tested ran in the 11's. You also mentioned you didn't want to tax the hell out of your blower by running to much overdrive. Just to let you know, my wife and I just got back from a 2500 mile vacation in our 04 cobra running the 2.9 upper with no extra noise or heat or problems of any kind the whole trip. if I didn't have as much time and money into my existing combo I would have started out with even a smaller upper pulley and saved the money I spent on the 3.4, 3.1, and the 2.9 I,m running now. I also tested the mielage and is just the same now as when the car was new, around 22-25 mpg, the boost- bypass valve is to credit for this. I also did the long tube headers and full exhaust and I would recomend the headers to anyone. they were the biggest pain, but they are the coolest mod so far. have fun improving your ride! go with the steel upper and gates belt, let me know what happens.

10-13-2006, 09:04 AM
I have used the Reichard Racing pulleys on both of my last Terminators, with great success! You should be able to use a stock belt with a 3.0 upper, especially if you get a snub idler to prevent belt slippage. This should incerease your boost level by a few pounds. Good luck with your choice!:thumbsup: