Exhaust efficiency question

[Ruben911]

I have a 1976 911s which has a factory exhaust system and thermal reactor bypass tubes ( 3 into 1). My muffler has two inlets and one outlet nozzle. Is this similar to the 1974 style setup which is supposed to gain some additional HPs. Or is the 3 into 1 pipe inefficient in handling the exhaust. I have been considering getting SSIs but I'm not sure if my current setup is optimum already. Any feedback will be appreciated. Thanks

Ruben911
1976 911s 2.7L

[Clark Griswald]

The thermal reactor bypass tubes are not at all like the early heat exchangers or SSIs. They don't even come close to providing the same level of performance boost. They do however help to reduce operating temperatures.

If you want and performance boost and feel what that engine should have been, get the SSIs or the early exchangers. You won't be dissapointed.

[Ruben911]

Thanks Chuck,
One more question. I live in So FL and don't anticipate using cabin heat even in the coldest days (today it is fairly cold 45 deg, but high of 70 expected). Is it better to replace the bypass tube and heat exchangers with just headers, or are the SSIs a better performance package. Also, is there a better muffler than the stock muffler (2 in 1 out) which is still acceptable for street use from a noise standpoint. Thanks again.

[Superman]

LIving in the North, and knowing that any Southern car might be asked to tavel through cooler country at some point, and knowing that air hoses and sheet metal are not terribly heavy, I wonder why most ordinary motorists would choose to lose the heat. My very competitive 914 friend went to plain headers, and he freezes on the way to each autocross. I wonder if it's worth the ten pounds he likely saved.

The type of muffler you use will not impact performance. It is the equal-length (SSI style) exhaust pipes/manifold you need.

[Drago]

Originally posted by Superman
LIving in the North, and knowing that any Southern car might be asked to tavel through cooler country at some point, and knowing that air hoses and sheet metal are not terribly heavy, I wonder why most ordinary motorists would choose to lose the heat. My very competitive 914 friend went to plain headers, and he freezes on the way to each autocross. I wonder if it's worth the ten pounds he likely saved.

The type of muffler you use will not impact performance. It is the equal-length (SSI style) exhaust pipes/manifold you need.

Super,

The same thing, albeit reversed, could be said for the air conditioning that both you and I are removing from our "Northern" cars.....

That's still not stopping me from pulling the AC out of mine this weekend. I figure the weight savings to be in the 25-30 pound range though.

[RoninLB]

DRAGO...I agree with Super again. Removal of AC and you can open windows and sunroof. Closing windows in non heated 911 will not warm car very much. Removing AC blower and wireing from smugglers box in luggage comp is fun job. Enjoy. May I suggest Bombay Sapphire or the tune "eve of destruction"

[Clark Griswald]

For a 2.7 that is otherwise stock, the early exchangers or SSIs will do just fine. Headers won't get you anything extra.

I would keep the heat. A low of 45 can be pretty chilly. I live in Nocal which is also pretty warm, but I would ditch the heat on a street car.

[Ruben911]

Thanks to all for the feedback. I must now decide whether to spend the money and get the SSIs or opt for the headers. I have seen headers advertised for around $400 whereas SSIs are twice as much. Anyone knows what the best source for SSIs are and what are the preferred headers. Thanks again.

[Superman]

Again, I respect anyone's decision to go with headers, I just don't think it would save much weight, and no exhaust outperforms the SSI, according to my understanding.

Also, there is no question in my mind that the AC system weighs considerably more than 25-30 lbs. The compressor alone probably weighs that much. Also scheduled to be removed are the hoses (about 20 feet), the condensor under the deck lid, the condensor under the nose and the evaporator (wherever that is), plus the crap in the smugglers' box, the dryer and the blower. Altogether that's probably going to ditch 70 lbs.

Plus, if my plans for backdated exhaust pan out then I'll be perhaps under 2500 lbs, wet.