The Forgotten On

Fine uneven crank loading will wear out the bearings in the engine faster.

Speedtoys

Yes, and we have pictures.

But bearings are easy and cheap to replace.

GregBBRD

An air pump requires such little amounts of power to turn, I'm amazed anyone would bother removing one.

And rebuilt pumps are cheap enough that anyone who owns a 928 should be able to afford one. (Perhaps better said as: If you can't afford a rebuilt air pump, you have no business owning a 928!)

GregBBRD

If the air pump belt load has any affect on the main bearings, you've got other problems.

James Bailey

The 1980 USA cars did NOT have a smog pump......weird but true

Randy V

Any guesses on the horsepower loss, if any, from running a smog pump?

Speedtoys

Between 0 and 1.

It's just blowing a somewhat low stream of fresh air into the car when cold, and into the airbox when the engine is warm.

Not even under pressure.

It helps balance out resting (Engine stop and startup) direct wear on the front main bearing, from the load the alternator belt places on the crank end...and thats a TIGHT belt. The PS pump and AC work the same way.

Porsche makes delete-pulleys for these where regions didn't need them. They should absolutely be used.

Because like I said, bearings and the labor are easily available and cheap.

Air Pump Delete: 92810608002

Cant find the AC delete hardware quickly yet...

vanster

Ah HA! My 80 did not come with a smog pump, Thank you Mr Bailey

Ramp

Deleted mine as part of the WB/TB project. I like having all that stuff out of the way - makes working on other projects easier and it's a cleaner look. Just capped the hard line to the cats so everything can be easily reversed.

technoDave

Just did a trip from L.A. to Ft. Worth in my '91 GTS clone without incident (driving as hard as I dared on Interstate/State Hwys.), and FOUR MILES FROM HOIME, the damn smog pump FROZE and took ALL THREE BELTS, the fan wiring, and I don't even know what else yet with it !!! Mine is definitely going in the "spares" bin! Along with the cats, etc. The car is smog exempt in Texas... But I'll prolly leave the little filter housing by the radiator, as it makes a fine drink holder while I'm under hood. Jes sayin'...

docmirror

Dave, welcome to the forum. And, welcome to sanity, otherwise known as Fort Worth! You escaped intact. Hope you don't have to go back.

Start a new thread, and tell us about your car, and history. Put your location in the signature.

docmirror

BTW, the estimates for the smog pump HP at full throttle is about 9HP. The Euro S4/GT is rated 10HP higher, only due to smog pump.

Speedtoys

Given what it does..that seems like a ton more HP that it really uses. I agree "testing" was done. But I'd be shocked if a 3/8" hand drill cant turn the pump all the same, it's a fraction of a HP.

Id say a S3 mechanical fan sucks up that much HP...10Hp is a -lot-.

It pumps an amazing low amount of air at almost no PSI.

Again, id be more significantly concerned about main bearing swiping on every start from the alternator pull on the crank without a smog pump or a replacement pulley in place.

technoDave

I'm actually from about 1.5 hours S. of Ft. Worth since I retired, in Bosque Co. I just picked the car up last week and drove it home - GREAT TEST DRIVE. I ran with an S Class V8 Benz from Palm Springs to Phoenix (he had an Escort, mine was at home - don't ask...). We ran 95+ ALL the way across with the sunroof open, A/C on and good music from the stereo. Only slowed when he did to watch the red-n-blues givin' out Welcome Cards to the truckers :-).

Thanks for everybody's knowledge and input, and as I get the new addition back together this week, I'll update with a new thread
Cheers,
technoDave

docmirror

I will freely admit to not doing dyno tests, if everyone else will. Along with that, we know that Porsche did do smog pump and non smog pump tests. The results are: Euro rated 10HP higher without the pump. I believe Ferrari also did similar tests, and found similar results.

Interesting side minutia. In 1972, Lamborghini was forced to put smog pumps on it's 4L V12 engine for US market. The engine was rated at 350HP in 68-71. It was rated at 350 in 72 and later. Lamborghini chose an interesting route. They used the same ole smog pump as everyone else, but - they put a AC clutch drive on the snout. At 2600RPM, the tach sensor had a cutout that would de-clutch the smog pump, and produce rated HP up to redline. Apparently, Lambo felt it robbed enough HP at high RPM to stop turning it.
More minutia you say? Well alrighty then. Ferrari uses the same smog pump as all those little Fiats that were imported back in the 70s and early 80s. Ferrari, always looking for that last horse of power swapped out the vanes used on a 2L Fiat engine, and went with half-size vanes, for less power draw. It did the job, just barely but anyone with a 79-86 V8 Ferrari knows, if it's in CA, and won't blow clean, to replace it with the Fiat pump for more air(even though it does nothing once warmed up).

BTW, turning a pump with no front or back pressure is NOTHING like turning it with the vacuum draw through a filter, and pushing the air pressure down 8 small tubes(or in some cases 2, 4, or 6, or even 12 depending).