mklinger

iTrader: (18)

OK..so I have a Corvette LT1 electric air pump to install in hopes of getting the 7 to pass emissions. The pump has three wires on it, ORANGE, RED, BLACK and what appears to be a ground tab.

For those of you that have done this install, what wires are hot and what's ground.

Thanks for the input.

alberto_mg

i think ccarlisi did it. i think it lasted a few hours before it burned out iirc...

CCarlisi

The second one lasted for even less time

poss

iTrader: (5)

Dublup installed one. I think it is still working well for him.

https://www.rx7club.com/showpost.php...4&postcount=74

Scrub

iTrader: (25)

Where can I find an electric air pump and how much do they cost?

I was under the impression you have to regulate the volage from 12 to 9 for it to work correctly.

DaleClark

iTrader: (55)

The various electric air pumps for cars are NOT designed to run full-time like the RX-7's stock air pump. It just runs for a few seconds on startup to get the cat hot, then shuts off. The RX-8 has an electric air pump that operates in this fashion, with EXPLICIT warnings in the shop manual about running it for more than a few seconds.

IMHO running one at a lower voltage will buy you some time, but an electric air pump just doesn't seem to be a long-term solution. It's likely possible to build one that could be run continuously without failure, but as far as I know that pump doesn't exist.

Dale

alberto_mg

if you want to be a pioneer, i've heard the rx8 uses an electic airpump. that might have a better chance of working.

DaleClark

iTrader: (55)

Hehe, see above post . The RX-8 shop manual states that you can't run it for like more than 30 seconds or a minute, then you're supposed to allow 30 minutes for the pump to cool before running it again. Methinks that won't do the trick.

Dale

Wargasm

I have this pump and I used it the last two times for emissions successfully. I think the red is +12V, the black is Ground, and the Orange controls if the pump valve is open or shut. I think if you wire 12V to the orange and the red, and ground the black, it will run full speed and wide open for you.

I did some testing on this guy, and it gets VERY hot after about 1.5 to 2 minutes. I have a remote switch rigged up and I ONLY run mine for the 2-3 minutes or so that the car is on the emissions tester actually being tested. These pumps will not last for continuous operations.

angelck022

yeah, i did this mod to pass emissions in the state of washington. You need to wire in a switch,as stated above, to turn it off and on. otherwise, the damn thing gets super hot, and I can't imagine it will not last long.
Or wire in a fuse-- put the fuse in when you need it, and disconnect it when you don't.

mibad

I know I don't know squat, but why would it fail? It's just an air pump. It pumps air.
How much air does the cat need and at what pressure? I find it hard to believe that there isn't a continuous duty 12 volt air pump that will do the job.
How much does the vette pump weigh?

sonix7

I think it might have to do with engine compartment heat, air pumps probably can't continuosly run and withstand the heat? I have no idea? I would think there was one out there but, maybe harder than what we can imagine in order for it to work. there was a recent discussion on this very topic. I could find the thread.

sonix7

found it https://www.rx7club.com/showthread.p...+pump+electric

Kento

Ever wonder why air compressor tanks need such big, powerful electric motors? Why can't they use something like those cheap little air pumps that you hook up to your cigarette lighter? Pumping enough cfm (not pressure) to work with a catalyzer requires either a very big pump (like the Mazda OE engine-driven pump), or a smaller one that has to run at very high speeds. Sure, you could probably find a 12V DC motor that would be able to handle continuous running of an air pump at high load, but you can bet that it's going to be one big and heavy **** (and probably won't fit in the limitied space of an engine compartment).
The car manufacturers are trying to save weight and space, so they'll only use an electric motor that will meet the bare minimum requirements. Any electric motor generates heat through its windings the harder it works, and the comparatively small ones used in the Vette probably generate quite a bit. That heat destroys the windings inside the motor in no time.

mibad

I just think the mazda air pump is overkill for what it does. A rotary vane pump could have been built much lighter by a company that advertised they drilled the brake pedals to save weight. I think an electric solution is feasible using the latest brushless motors coupled with a centrifugal blower or rotary vane pump.
I'd rather have a belt driven pump, just lighter!

DCrosby

My stupid questions of the week would be,

1 If you're pumping air (Oxygen) into an area with emission, of couse you're going to get less smog, it's like poking a hole in the exhaust pipe before the cat when you take it to the smog inspector. I know the oxygen helps the cat burn hotter and that helps as well... but we're not talking about continuous emissions here, since we're obviously just trying to fool the smog guy.

2 If on the vette it only works for a short period of time, and then turns off when the cat is hot, why wouldn't that work for the 7 ?? Why does the stock mazda airpump come on all the time below 3000 RPM ??

-DC

Kento

I think it's bulky for what it does too, but there's a big difference between getting a contracted parts supplier to build holes into foot pedals, and getting one to build a lightweight and highly efficient air pump that will last the life of the car for a low enough cost to keep from raising the final production cost. Anyone can say, "it would've been easy to do this", but they weren't there dealing with bean counters in a big corporation when designing this car 15 years ago.
Brushless motors (especially one large enough to run a vane pump; I doubt that a centrifugal blower could be small and efficient enough to work) are hugely expensive, which is one of the reasons why you rarely see them in industrial applications.

Kento

The additional air injection helps with the chemical reaction that takes place on the catalyzer itself. It doesn't "dilute" the emissions enough to make a difference in that manner.
Probably because you're talking about a car that was designed in the early '90's with a fairly simple mechanical pump configuration versus a car designed over a decade later with better technology and materials. You're also talking about an engine that by design is thermodynamically inefficient (the rotary), which leads to more emissions that need to be dealt with, versus a much more thermo-efficient piston engine.

mibad

What do you think of bleeding off air from the turbos to do the job? Too much of a problem to regulate it?
I have a brushless motor in my house A/C that just got zapped by a power surge. It's going to cost $822 to replace it (including labor)

dclin

iTrader: (4)

Huh, that's an idea. Don't know if the air pipe check valve can handle it when the intake path goes vacuum (you certainly don't want a bunch of exhaust in the intake, would royally screw with your idle) - but one probably exists that can, if the stock one doesn't. As for regulating, my wild guess is that the cfm does not have to be precise; just as long as there is enough.

The only other problem is that boost (and therefore flow to the cat) builds at higher revs (at least 2000+ rpms with the stock turbos, usually more with singles), and emissions testing usually covers the lower half of the rev range IIRC. In other words, the effective output range of a turbo based air supply would not match that of the stock airpump - idle to somewhere around 3000rpm.

mklinger

iTrader: (18)

Thanks to all who replied. I hooked up the airpump while having the sniffer up the tailpipe and watched the HC values drop from 1450 down to 110. In NC you just have to be below 200. We than ran the emissions test, and after not polluting the atmosphere for 90 seconds, I PASSED! Perfect. I just ran the power straight to the battery, 12v (though I have read that these pumps like 9V so as to not burn up) and off she went.

Here in NC for 2006, I no longer have to pass emissions, just safety. If any one is interested, the air pump is for sale. It's off a late 90's Firebird. I paid 50.00 bucks for it. I'll sell it for 50.00 shipped anywhere in the lower 48.

Who want's to pass their emissions test next?

Email me if you have an interest. I can take PayPal

dubulup

My electric has run for over 5k miles.

scotty305

iTrader: (2)

^^ ...because you installed a resistor, right?

dubulup

right, the fuel pump resistor...the pump has no problems working from 700rpm-3000rpm