Sneeky smog inspection tricks
 

In high school I remember a guy drilling holes into the bottom of his muffler to allow exhaust to exit via the holes instead of the exhaust pipe. He passed the butt sniff test. I'm wondering if anyone has cut a second outlet into their single outlet P-car muffler to accomplish the same thing. It seems to me that 2 exhaust outlets would mean only half of the exhaust would register on the exhaust emissions test. It also seems that the hole could be easily welded back up after the inspection. Anyone try this?
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Paul
78SC Targa

I know some states look for exhaust leaks, like Virginia, so it would not work there. South Carolina and Georgia do not check for leaks so check where you live to see if you can get away with it in the first place.

From what I have seen the 911s usually have no problem with smog tests anyway if properly tuned. Even without the Cat on SCs, maybe Cererras too.


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Adrian Pillow
1979 911 SC
1966 VW Microbus
PCA - Peachstate Region

How about a huge blower motor in the trunk with a pipe to the front of the muffler. Turn that sucker on when you run it through smog. Manufacturers tried that with those little airpumps running into the exhaust manifold. Just up the ante!

Actually all of my P cars passed California's tests with flying colors. I'm happy to have such clean running machines that run so well.

Dan

Here in CA anyway the sniffer doesn't measure the volume of exhaust, it just samples it. So your mod would have no effect.

Your mod would have the same effect as installing a larger diameter exhaust. The same gases would come out, just at a slower velocity.

Hey maybe that is what all those rice racers are up to!

I removed my cat converter and the P-car passed with no problem. This past inspection, the air pump wasn't working properly and it failed miserably.

I took the air pump apart and plugged the relief exhaust port on the pump to push more air to the exhaust system and it passed.

I need to install a new air pump. So, as you can see, the air pump does make a difference.

Steve

stormcrow, that is weird because my SC passes easily with the smog pump removed. But I do still have the Cat.

The cat will help with emission inspections and that's what it's designed to do. The reason I took mine out was because it was falling apart. There were two cells in there the first one on the inlet side was in pieces, the second one was intact but the honeycomb cells were plugged from carbon. Decided to remove it all.

The cat will help with emission inspections and that's what it's designed to do. The reason I took mine out was because it was falling apart. There were two cells in there the first one on the inlet side was in pieces, the second one was intact but the honeycomb cells were plugged from carbon. Decided to remove it all.

Steve

I have no inspection here in Alabama but I had given this a lot of thought when I lived in New Jersey. I was ready to take one of my scuba tanks inside the car and run a hose to a fitting on the exhaust pipe to dilute whatever was in the exhaust. This would be easy to hook up and to turn on and off. Just a thought.

George
83 911SC Cab/Euro

Relative to the amount of exhaust produced by your car, I do not think supplemental O2 will assist your efforts. From what I remember (laughable) the air pump merely cools the exhaust.

One simple, reversible, FREE bit of sneak is to simply retard your timing, via distributor or chip. Some of my old Turbo Buick friends would burn an extra chip just for emissions for around $45. LOL - now that I think of it, that would impossible for a PORSCHE due to the price people get for chips. BTW - the Turbo Buick chip has some 4500 additional commands over the Porsche, and both cars use the same chip. Talk about highway robbery...
I swear, that LS-1 conversion is osunding better all the time. Hmmmmmmm

RarlyL8 ? - Comments? Muhahahahaha

The air pump does not cool the exhaust. It does not dillute the exhaust. It reburns the exhaust. And it definitely reduces emissions. EGR cools the combustion temps to reduce nitrides of oxygen. This is done by reintroducing inert oxygen free exhaust gases back in to the intake to effectively reduce the amount of burnable mixture, hence the lower combustion temps. This is only done at part throttle cruising, so no power is lost.

The testing station will not pass you if you have big holes in the exhaust because the other gas readings will be off. (Carbon dioxide must be above a certain number or you fail)

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Tyson Schmidt
72 911 Cabriolet