911 Smog Equipment Removal

I had a few questions regarding the smog equipment. I live in a county where smog test are not done. So I want to remove all the smog equipment. Is there an advantage to this? Or is it not recommended? Oh it's for a 76 911S 2.7. Thanks

Gonzo:

There are propbably three advantages to removing the smog equipment:
1. Weight reduction - all that plumbing is heavy, and it can reduce your sprung weight.
2. Cooler engine - the smog equipment works by catalyzing unburned fuel and byproducts of combustion. The catalyzing process generates heat, thus adding proportional heat to that of the combustion, which as you know is only 30% efficient; the other 70% of heat of combustion is just that - heat.
3. Cleaner undersides - this MIGHT give you better airflow, but it's probably marginal at best.
And maybe 4: removal also leads to a slightly louder exhaust, which some people equate with more power. Since there is less restriction in exhaust pipe, this might translate to better "breathing" and thus give more power. But I think the conventional wisom is that you really have to go back to a 1974-type exhaust system (SSI, for example) to get good scavenging and "better breathing".

Forget the environmentalists objections: one or two Porsches will not unbalance the world's eco systems, and I doubt all those Camry drivers will remove their cat systems. So do it, and enjoy the above four side ebenfits.......Andras

I don't know of a single application where smog equipment is an advantage to vehicle performance - get rid of it as fast as you can. One oil burning junkheap puts out 1000 times more pollution than a well tuned non-emission 911. Don't throw away your original system - you never know when Big Brother will start checking your county.

Ok guys can this equipment easily be removed or do I need a mechanic to do this? Thanks

Just curious, does the '76 have thermal reactors? If so, you will be doing your car a HUGE favor by getting rid of them. Those things absolutely bake the engine.

If you have a catalytic converter instead, you may help the engine a bit by removing it. I think the main advantage to removing it is to reduce heat on that side of the engine. A straight pipe runs much cooler. Also, there is some weight savings, and if you cat is old and clogged, you may get some performance increase. If your cat is in good condition, a straight pipe generally does not help much, if at all.

Getting rid of the other stuff is likely to help mainly by reducing weight, and making the engine compartment less crowded, and easier to work and look at. These things are the smog pump, the air injection system (you'd need some plugs for the heads) and the EGR system.

If you are at all mechanically inclined, you could remove most or all this stuff yourself. I would DEFINATELY keep every piece of it safely tucked away, though. You never know when you might need it again, for a variety of reasons.

Brian

I have read that a 55 Buick sitting in a garage actually produces more pollution than a new car driving down the highway. Colorado has an interesting emissions program. It costs less to have an old vehicle fail than a new one. For those who have to replace a failing vehicle it is cheaper to buy a higher polluting antique than a new, fuel efficient car. Let us know how it goes so we can do it too.

If my memory serves me, the California 76 911S had the thermals and the federal S came with the SC style exhaust without the converter.
The SC style is actually a pretty good set up and there would not be a tremendous advantage or gain in its removal in my opinion.

On an SC 3.0, Bruce Anderson reports that you will gain between 17-22 hp by backdating to the 74 and earlier style exhaust. Don't know what the gain would be on a 2.7, but it is probably something close.

If I didn't have to smog my SC. I would definately spend the money for an early style SSI exhaust system. Have to wait until 2008 here in California!

Brian

[Balisong]

Hello. Digging up an ancient thread here. This is a 76S low mile original car. The engine was pulled to be resealed, time serts, oil tensioners. I do want to remove the smog equipment.
Can you please tell me if this is the SC style exhaust and is this a cat converter? Are these heat exchangers good enough to leave or would SS exchangers be worth it?
Thank you

[Balisong]

Another pic

[darrin]

that is an SC-style exhaust -- difficult to tell whether the cylindrical object to the left of the driver's side valve cover is a catalytic converter or a premuffler -- should be easy to determine by checking the numbers. Given how pristine your engine looks in these pics, I'd personally start "simple" and retain the exhaust, but swap in a European pre-muffler if that is, in fact, a cat.

[eastbay]

That 'looks' like a 2.7 48 state or euro exhaust system, same as SC style. It also looks like a resonator rather than a cat.

Every part in your picture has a part number and date code, look them up in PET or post them here to determine what they actually are.

From the bottom, you have air injectors that can be removed. Will need top side pictures to determine what other smog features have survived over the last 45 years.

Very, very clean, sure that is a 2.7 ?

[Balisong]

Thanks for the info. Pretty sure it’s a 2.7. It was sold to me as an all original car and engine. Unfortunately the COA did not list the engine serial number.
Here’s a pic of the topside.

[stevie 77 930]

Beautiful car and very original ! The only true smog gear on your car is the air injection system with the air pump in the engine compartment and the "spider" (black tube) with the air nozzles screwed into the exhaust ports.

On the exhaust, as others have mentioned, this is the 48 state/euro exhaust with a "pre-muffler" (not a catalytic converter). This exhaust is reasonably decent without getting into replacing the entire exhaust system with a "early style" exhaust with a 2 in 1 out muffler.

Please post more pictures of this beauty Love the Pirelli CN36 tires

[Balisong]

Thank you very much.
The car is amazing but almost too refined on the exhaust note. I was sort of hoping a decat would wake it up a bit.
Of course I will be extremely selective in making any changes to the car and there will be no permanent changes made.

[Balisong]

One more pic

[stevie 77 930]

The car is stunning !!!!
I would leave it as is.... but if you are inclined to do so, your only other exhaust option is to use a '74 and earlier style exhaust.

Its a 3 into 1 heat exchangers and 2 into 1 muffler. Remove the air pump, air injection tube and injectors. Be sure to plug the holes left by removing the air injectors

Here's a photo I grabbed from our host.

[Balisong]

Thanks again!

[eastbay]

Originally Posted by Balisong

Thank you very much.
The car is amazing but almost too refined on the exhaust note. I was sort of hoping a decat would wake it up a bit.
Of course I will be extremely selective in making any changes to the car and there will be no permanent changes made.

Check out just doing a 1 in 1 out sport muffler, lots of SC and 3.2 guys happy with that setup, lots of threads

[Balisong]

I have a little more info. Here’s a pic of the muffler and the Gillet item which I don’t know if the Gillet item is a cat converter or bypass.
The muffler appears to be a stock Bischoff and must be the original muffler based on the date code.
Google won’t tell me what this Gillet item is though. Still hoping to wake the sound up a bit.
Thanks