llvll4l2c91350

I'd like to remove the AIR pump on my 91 350 to free up some HP. Anyone know if this will have bad side effects besides higher emissions? In other words, will my CATs get damaged sooner than expected or will the engine run differently seeing as the ECM controls the AIR valves?

TIA

jamesbob02

Taking off the air pump lessens the drag on the crank, so naturally there's going to be less parasitic power loss. Honestly I don't know what the actual gain should be, but I felt it after taking mine off. You'll defintely need a shorter belt and will need to re-route it if you didn't know that yet - check out the tech article for more info.

As for the cat, I couldn't tell you, but since you don't seemed to be concerned with emissions, if I were you I'd go ahead and take the cats off too.

Don't worry about the ECM, my car didn't even seem to notice the pump was disconnected and gone.

While you're at it, remove all your AIR system hoses, valve, and the tubes (just cut them off with a hack saw), unbolt them from the exhaust manifolds and fill the holes with some tapered bronze bolts - the guys at Oreilly new exactly what I was talkin about and hooked me up. If they don't know just take one of those fittings that screwed into the manifold, they should be able to match it! And go ahead and cut of the pipe that goes down to the cat, too - its all just clutter if you're removing the air pump.

Hope this all helps!

Iroc n roll

You're engine will not run any differently. The AIR pump, like its name implies pumps oxygen into the cat to aid in the combustion of hydrocarbons. Removing this will increase the possibility of your cat getting clogged. I don't know exactly how much the AIR system prevents this it's there for a reason and that's the reason. I just dropped the cat when I took mine off. Get some flanges welded on a straight pipe, us the straight pipe until its time for emissions, then bolt on the cat and go.

Read the tech article on this site to re-route the serpentine belt. You'll need two 1/2" pipe caps to cap replace the check valves on the AIR tubes. Tie down all the unused connectors and take out all that other related crap like jamesbob02 said. The hard lines are a PITA but they will come out.

llvll4l2c91350

Thanx guys. I just removed it, got the new belt and started it up. The exhaust sound got louder and I felt a vacuum at the check valves. I haven't driven it yet but will in a few. Got two q's though,,,where do I get the two caps for the check valves and what happens if I drive it with the valves open like that in the meantime?

Thanks.

P.S. I don't wanna remove the CAT or the AIR tubes from the manifold cuz there's always a chance I may move out of state and will need to put this stuff back on.

llvll4l2c91350

Also forgot to mention that I have the dual CAT setup so it's more of a pain in the *** to remove and install when emissions testing is required cuz the Y pipes and CATs are all part of one unit.

Iroc n roll

I've never heard of anyone ever trying to drive the car with check valves . You're getting vacuum at them you say? The caps can be bought at any hardware or plumbing store.

As for emissions. Your cat is still there and as long as its not clogged it'll function the same once its warm without the AIR. Make sure to drive your car a bit first. I live in an emisisons state and they never EVER do under hood checks. Not only that but these guys wouldn't know an AIR pump if it bit them in the ***. You're fine taking that thing off for good. I really don't think you're cat is going to clog up all that easily.

Not to get too off-topic but here's my favorite emissions story. I bring my Nissan 200sx to emissions. They take the keys, roll the car up to their little wheel rollers, drop in the front wheels, and wait for the signal. They hook up the tailpipe and as I watch them I think to myself "boy, these *******s don't realize my car is rear wheel drive." Sure enough, he gets the signal and <chirp!> jumps the car foward a few feet. A smack in the back of the head and some spanish swears later the rear wheels were in and it passed with flying colors

doc

Removing the air pump on my '87 was basically a no-brainer. The ECM does not know whether its there or not, at least not on an '87.

You might pick up 2-3HP, but also quicker due to less weight. Like I said, a no-brainer. You have every thing to gain and no down side, unless emissions come into play.

Iroc n roll

A day late and a dollar short Kemosabe.

llvll4l2c91350

Well I just drove the car and you guys were right, the engine seems to run the same. About the performance though it did seem like it made a difference although not a big one. But hey every little bit counts. The crank has less of a load now so the HP has to go up. I should've done this a long time ago. About the check valves, when I took the pump out I also took out the diverter valves but left the rubber hoses that attach to the check valves. That's where I'm feeling the vacuum. I dunno why air is being sucked in there. I would figure it should be going out instead. But I'm gonna go ahead and look for those caps tomorrow. I don't want this thing to possibly turn into a big exhaust leak.

jamesbob02

This is just an idea, but I think they may be sucking air because of the vacuum pull of the air rushing through the exhaust manifolds and cat. If it's not blowing out, I can see it just as easily getting sucked along with the flow. Does this makes sense? I don't know, but it did the same thing on my car before I removed the tubes completely - my dad just put some ducttape and a ziptie over it and it was obvious the tape was getting sucked in. Anyways, glad you like the effects of the mod!

llvll4l2c91350

I think that makes sense. The fast moving air in the manifolds has less pressure than the slower moving outside air therefore a vacuum is created. It don't matter though, I got caps for the pipes and plugged 'em up. Yeah overall I'm happy with this mod. Engine bay looks less crowded and I got rid of some unnecessary weight. Next up for me is replacing the AC compressor with the 1LE pulley, and replacing the manifolds with the much lighter, and more efficient, set of headers.

MdFormula350

i am thinking about doing this mod also. not sure though.

Iroc n roll

I personally recommend it. It's not going to give you much performance at all but un-cluttering the engine bay was worth every minute and more of my time. Even more so because I had a V-belt setup.....that's one less belt I worry about now.

jamesbob02

Dude if you're not concerned about emissions, ditch it. Ditch it ALL. The pump, the hoses, the valve, the metal tubes and all. Your engine compartment will be so less cluttered it is definitely worth it - especially if you've ever had to change spark plugs with the AIR tubes in your way - you know what I'm talkin about! Imagine not having to go through that **** again........should be no question if emissions is not a problem.

Vicious 88 GTA

I am going to be taking the A.I.R. stuff off this weekend...now what size belt should I get and any part numbers for the belt will help.....also...would an aftermarket crank pulley help any? if so how much?......AARON

jamesbob02

Look in the tech article for the right size belt, it's there - HOWEVER, if you put performance pulleys on there it will probably require a different size belt.

You are going to have a lot of guys tell you both ways that the pullies will give you HP or do nothing. I for one think the basic principle of it shows it will increase HP - changing the ratios of the pullies reduces drag on the crank, and reducing drag on the crank will always offer more power, even if it is minimal sometimes. However, this means that you will sacrifice a little bit on your A/C and alternator, naturally, so if you've got problems starting or keeping a charge or you have a high-powered stereo, stay away from performance pullies.

llvll4l2c91350

I've heard more bad than good about underdrive pulleys. I was seriously considering buying a set for my car but decided to spend the money buying other things. I think they become more significant when you only drag race. That's when you need every HP gain you can get without worrying about whether or not my alternator will put out enough charge.

About the belt, it's part #968K6. There's also a pic in the tech article about how to reroute it.

jamesbob02

Yeah thats what I'm talkin about w\ the pullies - I decided against them because I'm gonna be doin big stuff to get HP and don't need to risk losing my charge or A/C, but for an all out dragger I bet they wouldn't have anything but an alternator anyway, so it's not a big deal and getting the pullies would add a little bit if they were squeezing out every last HP and could take that chance. Again, though, I have a friend with a mustang GT that put pullies on his car and hasn't had any problems, he's said they gave him a lot of power, he could feel it.

Therefore, its just a matter of choice and risk.