Question: Smog pump question

[34 Vette]

I would like to change out the belt driven smog pump on my 89 and replace it with an electric pump. I'm building a street rod using the 89 as a donor and I am having a space problem, the pump and bracket interfer with the hood side panel. Is it possible to simply replace the mechanical pump for an electric? Are there any control issues or is it a simple electric switch on when the engine is running?
Does the ECM want a signal? Should there be a lag between engine start and air flow from the pump? Is there a tech book that would answer some of these issues?

Thanks,
John B

 

[boomdriver]

I would like to change out the belt driven smog pump on my 89 and replace it with an electric pump. I'm building a street rod using the 89 as a donor and I am having a space problem, the pump and bracket interfer with the hood side panel. Is it possible to simply replace the mechanical pump for an electric? Are there any control issues or is it a simple electric switch on when the engine is running?
Does the ECM want a signal? Should there be a lag between engine start and air flow from the pump? Is there a tech book that would answer some of these issues?

Thanks,
John B

yes actually, it is a signal issue that would be the problem.
The mechanical uses a valve system thats operated by vac & ecm signal,. to either use the pumps air in the cat, or send it to the manifold or waste it. The pump is always running sending air somewhere...
The electric system only uses the pump during startup and warmup for a brief period when fuel enrichment takes place. After that, I'm not sure that it ever runs.

I suppose that the diverter valve signal that would normally send air to the cat,. could be modified with a relay, add a power source for the pump, and use that to "trigger" the electric pump. The pump would not have to run constantly, I'm guessing, only when the ECM would be opening the diverter valve and the other air valve that keeps the air or dumps it.

So, it could be done and make it legal, as far as I can see..

What was the question?

 

[vetteoz]

I would like to change out the belt driven smog pump on my 89 and replace it with an electric pump.
I'm building a street rod using the 89
Does the ECM want a signal?

Do you need the AIR system to be legal?
If not can easily be deleted for a cleaner engine bay without use of the $200 pump eliminator pulley normally required on the TPI serp belt setup
Ask me how

If you need it ,could get a elec pump from a LT1 that performs same function.Can be mounted anywhere
http://cgi.ebay.com/ebaymotors/1993...ptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories

There is no feedback signal to the ECM that pump is working ; only the changes it sees through the O2 sensor
As AIR primarily runs on start up engine would not be in closed loop so would not be reading off O2 sensor anyway
Operation can be taken out in a custom tune which you will probably need for your app

 

[Hib Halverson]

If you are building a street rod with an L98, I'd eliminate the entire AIR system. It's removal will not affect engine performance and taking all that stuff off will make your installation easier.

 

[34 Vette]

Thanks for the responses. Sounds like the pump is outa here! Next thing to resolve is belt routing but since I've got soooo many things to resolve this can be back-burnered. The reason this question came up now is because I'd seen the elect pump on e-bay.

Thanks,
John B

 

[Schrade]

Looks good...

Where's the electric pump?

Is this a belt tensioner mounted to the alternator? Spring, or screw, with the break in the middle? Does it also have the regular pulley tensioner?

No fiberglass on the headers? The exhaust cools quick, and the cooler gases get heavy to push... Plus the heat stays under the hood!

 

[Jeb]

Ask me how

How?

 

[vetteoz]

How?

If you are not running A/c compressor

You buy a std rotation "short" SBC water pump (71 -82 Vette ) ( Vette serp drive has reverse rotation pump )
Ditch the AIR pump and buy / make a brace for the Alt
Can mount brace off one of the head holes as shown above , off intake hole as shown below or come up off one of the WP bolts with a curved home made brace
Some have used the redundant long back brace off the TPI Denso A/c compressor and just slotted one end to give adjustment
Belt tension is adjusted via the Alt brace as on old skool engines.

Must rework or custom make a new back brace for Alt
If you are running headers then need a longer one back to a stud in front of # 3 port

Reuses all stock TPI pulleys
Because OE Vette pump is slightly longer than the " short" pump ;may require a thin washer / shim between pump flange and WP pulley to obtain correct belt alignment.Check belt alignment on install
New belt typically 54" - 55" long depending on where you position Alt
With the AIR pump gone there is a range of locations, closer to the head or out near the suspension as with stock

My 383 spins past 7K with this arrangement; never had a belt problem

 

[vetteoz]

Is this a belt tensioner mounted to the alternator? Spring, or screw, with the break in the middle? Does it also have the regular pulley tensioner?

No idler
Belt tension by adjusting Alt position with the March adjustable heim jointed brace shown
Belt runs Alt - WP ( over not under ) - PS pump only

No fiberglass on the headers? The exhaust cools quick, and the cooler gases get heavy to push... Plus the heat stays under the hood!

Not mine, just a clean install to show TPI AIR pump delete

Where's the electric pump?

No pump