whats better(sorry about these questions not very go with engine mods, aside the air intake and exhaust system) to underdrive or not to underdrive that is the question? i drive at med. to high RPMage(above 3000rpms most of the time).

it kinda funny cos my car doesnt burn off oil or anything at high RPMage havent had to fill it since the oil change 2000miles ago!! normal car would burn it quicker!!

 

The fact that you don't burn oil is probably due to non-functioning MOP components either injectors or the pump itself. I voted not to underdrive.


Santiago


EDIT: You don't have true duals dammit!!!!!!!!!!!!!!!!!!!11

 

The reasons why underdrive pulleys are not recommended for street cars has been discussed here quite a few times.

 

True duals, means you have a single exhaust pipe for each rotor... if you have cats, that means you also have a cat for each rotor, and of course since there would be two exhaust pipes running from the engine back, you would have two mufflers as well.

True duals doesn't mean you have a dual muffler cat back system.

 

unless your racing. underdrive are terrible for the street, you'll F up your waterpump/cooling system, and your alt wont charge properly at idle like it should

EDIT. SO i guess true duals would be the way to go than eh'?

 

I have lightened, but not underdriven pulleys on my Impreza, do any manufacturer's offer these for RX-7s?

 

Yes if you have the money. They are the best sold. But just wait till he shows up talking his single ****. He never responded so **** him.


Santiago

 

Stop Postwhoring!!

Anyways, I have underdrive pulleys. They were on the car when I bought them so i really didn't mind. I relly don't mind them. The power that I got(before my engine blew) was great,but i never had i dynoed, nor do i have anything to compare it too. The deal with the alternator not charging properly at idle isn't really an issue, but then again i don't spend that much time idling. Over all if i had the choice to switch to stock, I have to say that i would not.

 

I have used the RB dual pulley system for two years now and never had any problems with the charging system or the water pump or cooling system, i would say go for it-- chris @ Spd racing

 

thanx guys for the input on this issue. I dont know much about the engine mods aside the basics(exhaust system/intake), but i will take somethings in consideration!!

to the rx7guy true duals is not the subject here, its " to underdrive or not to underdrive so go bark up another tree or start a post on that stuff!! to some peeps dually's out the back is true duals(basic equipment one on each side of car)!! ive heard some peeps say it true, but read the whole signature and tell me what u read!!PEACE!!

 

I have an Unorthodox Racing Underdrive pully on my 86 N/A and i have also had no probs with my cooling or alternator, i bought mine on ebay for $120 new. i noticed right away how much quicker the car revved and had much better throttle response while driving. i say try and see if you like it then you can decide.

 

for those of you out there underdriving get a water temp gauge. i'm considering underdriving and going to a dual belt and removing the air pump buit i'm ton going to do it untill i get a good temp gauge to REALY insure that my cooling sytem is still doing its job

 

I did although address the main issue discussed in this thread. I voted for you not to underdrive your pullies. If you are sure about the fact that you stay in the high RPMs then you may get away with it but I don't see how that much money is worth it. In the end its your cash bro.


Santiago

 

what is the purpose you are doing this mod. HP GAIN or just to have a mod?

 

I voted to underdrive em. I've got the RB pulley and I havent seen a single problem due to em.

 

Underdriving the pulleys makes them spin slower so they put less drag on the engine. Less drag on the motor= more power at the wheels.

 

plus i alway drive above 3000 RPMage, some peeps say underdrive if u drive at high RPMs'. So that why ERAUMAZDA(should read the post closer)

 

I know what underdrives achive.

They will under drive the alternator: Providing a slower charge to the battery

They will under drive the water pump to prevent pump from cavating. Those providing less flow through your water cooling system.

 

second, I read the post clearly. Just because u drive over 3,000 rpm is a horrible reason to get underdrives.

 

Yea, underdrive pullies are really meant for people who like to take it to the track. Alot of time is spent at higher rpm's. The underdrive pullies are there so the waterpump doesn't cavitate.

 

So your idle is set at 3,000rpm?

Underdrive pulleys are for race cars that are only at idle before the race, and do not have headlights, stereos, or other large electrical drains when at idle. If you want to waste your money on something that is going to give you 1 horsepower and knock your alternator off line at 750-800rpm idle causing your battery to die, and under-flow the engine coolant when you are stuck in traffic possibly resulting in a blown engine, then go right ahead. Afterall, it's your car, and it's your money. If you don't like people telling you it's a dumb idea, then don't post a thread asking for opinions. If you want some nice dress-up parts for your engine, there are lots of STANDARD-sized pulleys available with various colors and designs. Example:
http://rx7cz.net/pics/pulleys/

You should be down nearly a quart by now, which means the MOP isn't working. The time bomb is ticking. I hope you have about $2,000-3,000 handy for a rebuild.

 

whay about an underdrive pulley for just the water pump and not the alternator? would that be ok? even though it does slow down the coolant flow does it slow it enough to make a real huge difference?

 

The Mazda engineers determined the size of the stock pulleys based on the requirements of the engine during conditions of street driving. The stock radiator is minimally effective as-is, and I wouldn't want to have my car sit in stop & go rush hour traffic with a reduction pulley on the water pump. Those who live in rural areas with little traffic, and few traffic lights or stop signs, would probably do fine with a reduction pulley. An upgraded radiator would also help. Those who have a race-only car NEED a reduction pulley to keep the coolant flowing at an efficient rate during sustained high engine rpms.

BTW, I have seen a 13B burn up just sitting at idle. It does happen. Also, as many of you may already know, the stock FC temperature gauge isn't very responsive, and sometimes doesn't indicate a problem until it is too late.