You are correct on the hp loss but it is so small. In my opinion(and again, its my opinion) I would rather not be stranded some where in the middle of the night(if my car was a street car) or when you only have 3 runs on a set coarse and you are on you last run and you only need 1/100th of a second to win and you snap a belt. I do use Mazda belts. Im just saying, its worth the little hp loss to me.

Wankleguy,

In your defense though, we have dynoed a motor with alternator and without. Without alternator, we gained 8hp!!!!!!! The problem without running the alternator, you run the risk of not starting when it is your run and missing the race........I speak from experience.

 

where do you get one of these lightweight main pulleys??

 

I wasn't aware that my position on this subject needed defending, but thank you anyway.

 

I have also raced a 13b in an RX3 for years using a single belt and never had any slippage or breaking belts. Dual belts mean one is more likely to slip as they age and stretch. Check your belts regularly and replace as they age.

 

If you want to buy dual sheave pulleys for the looks, that's fine, but they are a waste of money if you are simply going for function. Yes, a single belt will slip if you remove the air pump (due to the incredibly small contact area), but you can add something called a "yoohoo" belt between the water pump and main pulleys that provides about 10-times the contact area and costs nothing more than the price of the belt itself (~$5-10). It is a 3L220 -- that translates to 3/8th inch wide, 22.0 inch long standard V-belt, available at many fine autoparts and hardware stores. You just put it over one pulley and start it on the other one, then turn the engine over by hand (or wrench) to "walk" it into the groove. Perfect tension. I use one on my peripheral port 13B GRM Challenge car, which revs to over 11,000 rpm, with absolutely no problems in the 8,000+ miles I have driven it. Thank Rob Golden at Pineapple Racing for cluing me in to the "yoohoo" belt.

BTW, the real problem with dual sheave pullies is the impossibility to equalize tension between the belts due to slight flexing of the alt shaft, as well as the accessory mount. To keep the outside belt from slipping, you have to overtighten the inside belt, leading to wear and tear. Not a big deal, but why spend the money for an inferior solution (unless you like the look)?


--
Blake Qualley

 

Great idea! I had heard the term "yoohoo" belt, but was not clear on it until seeing your pic, thank you. Rob has helped me out with information many times over the years, also. I hadn't considered the possibility of uneven belt tension, but that's a good point. I suppose I should also point out that the extra length imparted by the dual belt pulley could cause more alternator shaft runout, placing more stress on the bearing.
But yeah, they do look cool.