Well as a few of you might know I am getting my engine streetported and such and while Im doing it I want to know what other things to throw on it while its out. And was on the forum and saw a post about Underdreive Pulleys. My question is are they really worth it?
And since Im asking that is there anything else you guys would get?
Im getting a new radiator, act s/s clutch with 9.5 flywheel, Mazdatrix short shifter,... more things to come with more money but what else would you guys recomend?

Thanks

 

Anyone? lol

 

electric fan

 

Yes theyre worth it!!! Even just for the fact that they underdrive all the accessories, making them last longer, especially on a high revving motor. But they also add some throttle response, and a little bit of hp.

 

Cool thanks guys which ones are the best ones and were to get?

 

I have the RB main and dual alternator pulleys. About $110 for both. www.racingbeat.com

 

Can you just add the pulley on a stock NA or does it have to be street ported?

 

You can put it on any FC. Youll notice it more on a stock on, I think.

 

IMO, they're NOT worth it for a street car. The accessories will last longer only because they're not doing as much work. Your alternator is charging less (don't we complain these don't charge enough?) and your water pump will flow less (who wants that?). Any hp gains are only going to be seen at high rpm, but a street car spends a tiny fraction of it's time up near redline. As for the power gains, considering just the alternator, an 80A alternator that's 85% efficient and 20% underdriven will gain you 0.3hp at high revs and only put out 64A. The rotational inertia of a pulley is tiny compared to the rest of the drivetrain.
On a race car that spends most of its track time above 5K, these are worth it, but not on a street car.

 

I agree. Your accessories were designed to operate at a certain speed. If you don't want to use your accessories then simply remove them. Also note that sometimes the underdrive pulleys are difficult to install, and I have known more than one person who damaged their engine by attempting this conversion. Unless you are getting your engine balanced, clearanced, etc., and you plan on running at 8000-9000rpm on a regular basis, I suggest that you save your money for something better like a good aftermarket EMS.
http://www.mazdatrix.com/faq/pulley.htm

 

I agree completely with the alternator idea, but not the water pump. Water pump cavitaion occurs at high rpms, this is bad. I would only ever underdrive the water pump, not the alternator.
I read that the best water pump would run off an electric motor at a set speed, not based on rpm. Coolant cools best a certain speed, where the ratio of amount of coolant moving by a point to the amount of time for the heat to diffuse into the coolant reaches its peak.
The pump would wear out faster due to running faster than it would at idle, but never reach the full speed that it would at redline, so less wear there. Depends on your driving, I guess.
Sean

 

This is the race vs. street issue again. Yes, coolant does cool best at a certain speed, but you do not want maximum cooling on a street car. In fact, those of you who watch NASCAR will notice taped-up radiator inlets because race engines run best at a certain temperature, too. I know that you guys have noticed that your engine runs pretty crummy when you first start it in the morning, and I'm sure that you would not want it to run that way for the rest of the day.

 

i have a 91 T2 with the air pump disconnected (although not removed yet)

would this be worthy to get? http://www.rx7.com/cgi-local/2catalog.cgi?cat=3&part=1

 

I think this would only be required in you've built your engine to rev higher than the stock redline. Mazda would have selected a pulley size that is suitable for those revs and (hopefully!) doesn't cause cavitation.

 

Control of the cooling sytem is the responsibility of the thermostat. The pump should be driven at a speed that can provide maximum cooling capacity, with enough hot coolant sent to the radiator by the thermostat to maintain the correct temperature and the rest recirculated through the engine. The thermostat should maintain that balance.
NASCARs and other racecars tape up cooling inlets because they take in massive amounts of air compared to a road car due to sustained high speed.

 

Ive used the RB pullies for 6 years. I've never had a charging or cooling problem --even when I lived in Texas. Yes, the money is better spent elsewhere, but if he's adding all those other components, he might as well do the pullies too.

I noticed a small improvement to throttle response when I instaled them, he'll notice more with the aluminum flywheel. I've had them on both stock and cars with aluminum flywheels, and they make more of a difference on the lightweight system. (The pullies will reduce a greater percentage of the motors inertial rotating weight. )

While your doing the pulley, I'd install the thermo pellett replacement plug behind the front pulley as well. It's one less thing to worry about.

 

FINALLY!&nbsp If you're looking for more power, you money is better spent elsewhere.&nbsp The pulleys are designed to keep things from blowing up rather than making more power...

My experience...&nbsp Alternator pulley is fine.&nbsp DON'T run the alternator AND underdrive main pulley on the street.&nbsp This is not enough charging power for your FC.&nbsp Unless you got a "ringer" alternator that puts out top 5% of spec, most alternators out there are tired.

From Racing Beat...&nbsp The water pump can handle bursts up to redline no problem.&nbsp The water pump WILL cavitate on CONSISTENT high RPM use over 4kRPM.&nbsp Don't believe it?&nbsp Keep the revs over 4kRPM and watch the temp gauge climb after 10 minutes...




-Ted

 

I run only the main pulley for just this reason. The alternator needs all the revs it can get, and I still have the air pump.

 

Well with all your post I think im not going to go with it. Thanks for the good feedback guys.

 

The only reason I got mine was because I was ordering from RP and they were running a special that if you ordered more than so much that shipping was free, so since I was ordering an exhaust, it was actually cheaper to order the pullies too. weird huh? I saved like $15 by ordering the pullies...

 

HAHA Nice!

 

NOT WORTH IT.

 

I was thinking about getting the waterpump pulley since atleast once a week my car is driven really hard for a long period of time (no I dont drag race). I run at a "track" and my rpms are always above 4k rpms for like 10 minutes at a time. With this type of driving would the waterpump pulley really do more good than harm?

 

Thiers always the 3rd gen alternator conversion.