Black91n/a

I was thinking about removing my airpump and adding one of the dual sheave alternator pulleys and I'd like to know if it'd be worth my time. I already have a summit rpm switch and a ACV blockoff plate, so all I'd need to get is the gasket, a dual sheave pulley, a belt and an electric air pump and do a little bit of work. First of all, is there any increase in power from removing the airpump and ACV on an S5? Secondly, if I use the racing beat pulley with a 20% underdrive how noticable is the drop in electrical power (i.e. will I be able to crank the stereo while driving with the high beams on with the wipers on etc)? Also how noticable is the increase in power with the underdrive? I've seen posts from people using cheap pumps bought at walmart or wherever but I'd question the reliability of the pumps under constant load. Have those with these pumps had problems with them overheating/burning out under constant load (ie having the 5/6 ports always on during constant high rpm use)? Also how much power would a pump draw from the alternator?

Thanks for your help.

NZConvertible

Not that you'll be able to notice. The air pump uses very little power.

You'll drop the alternators max output from 80A to ~64A. With a lot of electrical stuff running you run the risk of flattening the battery. This is a pointless mod for a street car. Get a stock-diameter double-belt pulley.

You'll gain ~0.5 peak hp...

5-10A would be realistic.

Note that you don't need any rpm switches for S5's. You use the 6PI and VDI signals from the ECU.

Black91n/a

Ok thanks, I was thinking that it probably wouldn't do much, but it's worth asking as it wouldn't be too hard to remove.

Kenteth

My expereinces with it:

Finding a 5/6 port pump that can withstand the abuse and keep the amps low is pretty dificult. I went through two air pumps before just calling it quits and wiring the ports closed until I can design something that might work more permenant.

However, I have removed the air pump, a/c, and p/s, and went efan. When the aux ports and VDI worked together, I could VERY easily make power to redline and beyond. When the ports worked stock and all belts were avail, this could still happen, but it wasn't as easily done.

Now that the ports are wired closed (for driveability reasons) I can make power to abuot 6500 where it really starts to run out.

Is it worth it?

It takes me about 3 minutes to change sparkplugs, the engine bay has 4 times the room, it looks alot cleaner (well... at least alot more open) and people always comment "That engine is tiny."

The tradeoff: No aux ports without rework. No power steering (doesn't bother me, I'm used to it), and No A/C (sucks in the summer).

Black91n/a

Interesting, does anyone know what kind of electric pump will stand up to the engine bay heat, not draw too much power, not make too much pressure and stand up to constant running (kind of a tall order). The ford lumbar pump sounds good to me, dows anyone have specs for it (ie how much pressure does it generate, how many amps does it draw, is it reliable)? Also where would one get a dual sheave alternator pulley that's stock sized (or could you just weld two stock ones together (unless of course it's aluminum), or could you just bolt two on together using a longer bolt? My car already has no AC. I'd be hesitant to remove the PS, I know it would be alot harder to manouver the car at very low speeds, but a manual rack has slower steering and I don't think I'd like that either, so for now anyways I'll be keeping the PS.

MRX_Rotary

I have an '91 N/A too... I used the Lumbar Pumps to activate my ports. They come insulated. Even so, they are usually mounted too far away from anything that generates any decent amount of heat. I also wired in a set of LEDs in my dash to show that the pumps are getting power. They don't seem to draw too much power (I used 18 gauge wire and it gets plenty of power if that helps). I attached a wiring diagram....

As for the dual belt alternator pulley, I just got one from Higgi that fits my FD alternator. (Very nice, BTW) He sells pulleys for FC alternators too. They are stock size, not underdrive.

http://rx7cz.net/shop/

Black91n/a

Thanks, I acually just found a place that sells stock diameter dual belt alternator pulleys.

http://www.rotorhead.ca/detail.php?adid=2

$23 shipped, pretty cheap compared to others.

Black91n/a

After doing a bunch more reading it seems to me that it's really not worth the trouble to remove the airpump. There's no real HP benefit, and it'll cost money. I'll maybe do it sometime if it fails, but for now I'm going with simplicity and reliability (plus I may have to emissions test my car some day if I decide to bring it with me to university, or if I get a co-op job in Vancouver).