A/C and Air pump performance hits
 

Has anyone discussed what performance gains can be had by removing the A/C and emissions equipment on an '82? I live in Michigan where there is no automobile emissions testing.

Also, when looking for headers all of the manufacturers state "For racing or off-road applications only". Is this just to cover their butts in the eyes of the EPA?

RE: A/C and Air pump performance hits
 

You could pull the A/C belt off but you won't notice anything, even with the A/C and A.I.R. belts removed you would be lucky to see 1-2 h.p., I would not change any of the emmissions on the 1982 'cause it's going to send results back to the ECM and at the very least give you a "check engine". If you want to get rid of any of your A/C parts let me know, I'm in Ann Arbor and will be working on the A/C in my '78 when I pull the motor.

RE: A/C and Air pump performance hits
 

I thought that the air pump simply pumps air into the catalytic converter. How will the ECM know about it?

RE: A/C and Air pump performance hits
 

I'm not positive but I think the A.I.R. on the '82 also injects air into the exhaust manifold, if this is true then the oxygen sensor will most likely read rich.

RE: A/C and Air pump performance hits
 

GOOD answer. You're sharp.

RE: A/C and Air pump performance hits
 

There are also little pipes inside the exhaust manifolds that get the fresh air to the head of the exhaust valve. If you disable the AIR system, the heat will melt and mushroom the ends of these pipes and you'll have to cut them to remove from the manifold. I learned this the hard way in my younger and more impulsive days.

RE: A/C and Air pump performance hits
 

I'm not understandin' this one there, 73...

Can you explain this just a little differently? Do you have a schematic?

RE: A/C and Air pump performance hits
 

Hey cwb, 73shark is describing the steel nipples that carry the A.I.R. air deeper into the exhaust manifold, their aimed at the port in the head to maximize the oxidation process of the gases. The stainless steel injector manifold mates to the exhaust manifold with inverted flare fittings and seats the flare to another short nipple inside the cast iron exhaust manifold. This is about as well as I can describe it.

RE: A/C and Air pump performance hits
 

Wow. Thanks for the information! After tracing the lines from the pump, I saw that it also feeds into the air filter housing. I figure that the pump can't be too bad if it's giving the intake a little positive pressure.

RE: A/C and Air pump performance hits
 

I believe that you'll find that the air pump draws from the filtered air from your air cleaner, not push air in. (this line is inside your filtered area)Although a hose from your air cleaner does draw air from your valve cover, through the pcv valve inthe valve cover,to burn internal engine gasses. (this line is outside your filtered area) :)

RE: A/C and Air pump performance hits
 

Yup. I've seen this plumbing before, but didn't know what it was.




So they won't dispel heat if there's no flow???

So put on an underdrive wheel in the pump? Keep some flow, save power...

RE: A/C and Air pump performance hits
 

Why would theAIR pumpneed filtered air to go into the exhaust plumbing?

Yes, the other line would need filtering, to go into the crankcase, for Positive Crankcase Ventilation, but the other?

RE: A/C and Air pump performance hits
 

Thanks 78buckshot! Couldn't have said it better. :D

RE: A/C and Air pump performance hits
 

Looks like we all agree on the A.I.R. and it's operation, if you disable the pump your not going to see one bit of performance improvement, if it were mine I would leave all of the emission controls on and concentrate on getting it back to stock so that you can diagnose it better. The other option I would consider given the somewhat poor performance history of the twin TBI would be to gut the factory EFI and go with either an after-market injection system or carbueration, this way you wouldn't have any interference or need of the emmision controls.

RE: A/C and Air pump performance hits
 

I think you missed it...
The filtered air is to protect the pump, that draws air from the filtered side of the air cleaner, the line from the pvc valve draws air from the crank case, to burn gasses from the inside of the engine. This air is filtered, to keep particulates out of the intake system.

RE: A/C and Air pump performance hits
 

I would have sworn that air was blowing out of the tube from the air pump to the unfiltered area of the air cleaner assembly.


What gives?

RE: A/C and Air pump performance hits
 

O.K., I'm goin' to back up.....
The Air Injection Pump, with an integral filter, compresses the air and injects it through the air manifolds and tubes into the exhaust system in the area of the exhaust valves. The fresh air helps burn the unburned portion of the exhaust gases in the exhaust system, thus minimizing exhaust contaminations.
A check valve prevents exhaust gases from entering and damaging the air injection pump, as back flow can occur even under normal operating conditions. So, IMO, you should not have air blowing into the air cleaner from the smog,or air pump.
I took this direct from my manual. I'll detail more, if you feel it will help. :)

RE: A/C and Air pump performance hits
 

There is also a vacuum controlled dump valve that dumps most of the air under high vacuum conditions like closed throttle. This prevents exhaust backfiring. There's a muffler on the back of the AIR pump that is the dump exhaust. Maybe that's the air he's referring to.

RE: A/C and Air pump performance hits
 

How does the air pump not affect the air/fuel ratio the O2 sensor is measuring? The volume and oxygen content would change with environment, rpm and pump wear. Therefore, the emissions system could not expect (subtract) a constant or linear adder of oxygenresulting from the pump.

RE: A/C and Air pump performance hits
 

That's a real good question Batmobile, something that I don't have the answer for. As a test, you could pull the belt off and run the car on a city/highway test loop and see if the computer has any complaints.

RE: A/C and Air pump performance hits
 

I won't venture a guess here. I'll take some time and look it up later today. Hope I can find an answer for ya. :)

RE: A/C and Air pump performance hits
 

To maintain good idle and drivability under all conditions, other input signals are used to modify the ECM output signal. These input signals are supplied by the Engine Temperature Sensor, Vacuum Control Switches, Throttle Position Switch, Distributor, Manifold Absolute Pressure Sensor, and Barometer Pressure Sensor.
Does this answer your question? :eek:
There is a whole chapter on engine emission controls in the manual I have.

RE: A/C and Air pump performance hits
 

Wow Dave, thanks. I think it might answer the question about the effect that the A.I.R. has on the ECM, no mention of it in the description.

RE: A/C and Air pump performance hits
 

Well there's a lot more, just tryin' to be more to the point at hand.
I really hate this stuff. Used ta be ya set the points, timing, plug gap, and tweeked the carb a little. Oh how I yern for the good ol' days. :eek:

RE: A/C and Air pump performance hits
 

Your in the process of bringin' the good ol' days back to life with the Starship, somehow I'm thinkin' it ain't gonna' have EGR,AIR,EFE, catalytic,ECM, ect.

RE: A/C and Air pump performance hits
 

Have what?!?!? Wash your mouth out with Penzoil! [:'(]:D

RE: A/C and Air pump performance hits
 

I thought that might wake you up, Can't I use something a little more palatable, like Quaker State or Valvoline.

RE: A/C and Air pump performance hits
 

I use Castol GTX 10-30. :D

RE: A/C and Air pump performance hits
 

I use Castrol GTX 10-30. :D

RE: A/C and Air pump performance hits
 

This weekend I conformed that the air pump is blowing into the unfiltered side of the air cleaner. Therefore, if anyone believes this is abnormal, speak up!

The exhaust has been modified so that the tube that formerly went to the catalytic converter was eliminated and crimped shut. I don't know if this is going to throw off the air system and possibly affect my air/fuel ratio since there is more oxygen blowing into the exhaust manifold. Any thoughts?

RE: A/C and Air pump performance hits
 

I meant to say, "This weekend I confirmed...."

RE: A/C and Air pump performance hits
 

I'm goin' to read a little deeper, and let ya know what I find. It doesn't make sense to me that it would blow into the intake, but I'll try to find out for ya. I'm not real sharp on smog stuff, that's why I have the manual. I have to deal with that "Schmidt" here in Reno, and usually let a mech figure it out when it's time to do a smog check. I should do the preliminary stuff myself though, I'd save a few bucks. :D

RE: A/C and Air pump performance hits
 

Here's what I found.
The A.I.R. pump blows air into the exhaust manifold, near the exhaust valves. There is a check valve in the system. You can remove the check valve and blow through it, toward the exhaust manifold. If you get air flow when you blow though the other way, the check valve is bad and should be replaced. I don't find any indication of the pump blowing into the intake at any point, under normal operating conditions.
In case you are interested, I got my manual from Ecklers. It is the 1980Corvette Shop Manual.
A really good book to have on hand. :)

RE: A/C and Air pump performance hits
 

Starship covered it pretty well. The only connection to the intake was forvacuum to the air diverter valve that released excess air from the pump upon deceleration to prevent exhaust backfire due to an oxygen rich exhaust. If you have air going into the intake manifold, air cleaner, or anywhere but the exhaust manifold, something's wrong. At least base upon the '73 hookup.
A factory manual is a very good thing to have if you are going to maintain these cars. ;)

RE: A/C and Air pump performance hits
 

Thanks for your time and the info!

RE: A/C and Air pump performance hits
 

That's what CF is all about, helping each other out. ;)
You are very welcome. :)