http://mazdaracing.com/pulley.htm



dyno sheet here:
http://www.mazdaracing.com/dynotest.htm

from the picture the crank pulley can take 4 belts. that's a big pulley. i only use one belt so i guess i would want their eliminator pulley when it's available.

 

Don't buy underdrive pullies, i've witnessed their destruction, the car ran hot and would always have a dead battery because of them.

 

ran hot??? I have using RB main pulley plus alternator dual belt for almost 20 years with no problem.

 

I the same have both alt and main drive underdrive pullies, never had a problem running hot, and I always used to drive in upper RPMs... both with 2 core rads, and 3 core rads, with an e-fan.

 

I had the RB main and alt underdrive pullies and can never ran hot and battery was fine. Just wanted to see if anyone has installed mazdaracing.com's pullies and noticed a difference

 

This is my first time of hearing something other than bad things about underdrive pullies.

 

i wouldn't buy one thing from Mazdaracing.com

I don't trust Jeff Warner with him stealing other peoples work and saying it was his.

 

Hmm. I think this is what we would call another internet myth. Have you tried an UD pulley? Did any of these people who told you bad things actually try it or were they just making assumptions about it? I would be 99% of these people are just making guesses and assumptions and the other 1% of people are probably just blaming some other problem on their UD pulley... ie. "I just put a UD pulley on my car and my battery died the day after because of it" or "I just put on a UD pulley and I fucked the bearings on my motor because of it"... uh huh.. im sure.. Did you stop to think that maybe that person complaining of battery problems just had an old or crappy battery? And the preson who fucked his bearings.. maybe his bearings were already shot or about ready to be shot. I personally have not witnessed any problems with a UD pulley on a car, usually if there is a problem it is a result of the owners own stupidity...

 

I witnessed it like i said in my first post, he purchased the car with the underdrive pulleys, his car was running hot and his car's battery would always be dead when he tried starting the car. We replaced them with stock pullies and now his car runs at normal temperature and always starts up fine.

 

the answer to your question is hell no!!!
i have had several rx7's come in the shop lately complaining of dead batteries, bad alternators(too much load on the alternator) because of underdrive pulleys. keep in mind these were full street cars with all elec. acc. still being used(radio, ac, heater fan, ecu, etc., etc. ..

Also another problem with the MR pullies is they not only underdrive the alternator but the ac. compressor and power steering as well!!!! so your ac wont be as cold and your power steering will be useless unless you keep the motor revved up!!!

the Racingbeat pullies utilize the stock pulleys for the ac and p/s in combonation with the underdrive pulley

i would only reccomend underdrive pulleys for racecars only with minimum electronics...

 

i have seen this problem too, again on street cars . not on race cars though

 

It takes more power (albeit slightly) to drive two belts vs. a single belt.
Racing Bleat used to offer an underdriven aluminum pulley set that used a single skinny belt, I don't know if they still sell that setup but that would be my choice.

 

No one has really anwsered the topics question. MR claims a 14 HP gain from JUST the underdrive pulleys. Can anyone confirm or deny this claim?

I was checking out the same stuff yesterday. ANd was curious about the same thing.

 

a friend of a friend has an 87 turbo 2, the pulley did 12rwhp on the dyno, we were shocked

mike

 

so... it looks like yes, maybe it does free up that HP, but unless you're racing, don't mess with it.

 

You don't need underdrive. If you can, just take the emissions off, along with the air pump, A/C if you have it, get an E-Fan, and take power steering off if you have it. Those are the most parasitic pieces on the engine. underdriving the alternator isn't going to do much at all since it doesn't put that much load on it, plus with the A/C gone, the alternator doesn't have to work as hard.

In the end, if you don't mind having no A/C then you don't need the underdrive pulley. As stated above, it can eventually lead to no power at all in the form of an overheated engine.

 

ok i have a question.....those underdrive pulleys....which stock pulleys do they replace? cuz when i will have my car on the road im only gonna have the alternator pulley, the crank pulley, the water pump pulley and thats it i think no air pump no a/c no clutch fan.....???

 

never mind it shows the list on the site....is it possible to only buy a few pulleys rather than the whole set>?

 

Your stock e-shaft pulley seperates in half Mr. BiG G, incase you didn't know.

 

I can confirm this, I took off the A/C part of it which only left the air pump and alternator belt pulleys. Same on the '84 engine I have that had the extra pulley for the power steering. Just took off the extra large pulley and put the four bolts back in.

 

mazdamotorsports.com offers an aluminum pulley set for one belt only. crank, waterpump, and alt pullies are aluminum. painted black. cost me a pretty penny but needed it for the racecar.

9600rpm shifts all the time in the bridgeport with stock pullies would cause water pump to cavitate and alternator to burn out due to very high rpms it would be spun.

 

That sounds similar to the RB setup.
Does it use a narrower than stock belt?
I think it was 8mm, but I could be mistaken.
The RB Main pulleys also had additional timing marks that made setting timing to max advance much easier.

 

i dont remember the size but i just use whatever they sell at autozone. thats the stock alternator belt. i have rb dual alternator and main pulley.

 

brad whats the mazda motor sports web site?

 

http://www.mazdamotorsports.com

Need to race to buy parts but two autocrosses a year does the trick.