WonPutt

SSI is a company in Northern California (Novato or San Rafael) that makes stainless steel tuned heat exchanger/headers for various cars. I believe it is short for Stainless Steel Inc, or some similar derivative of that. When 911's changed to meet emmissions in the US in the mid 70's the HE's went from same length pipes to unequal ones, thus causing a less efficient exhaust system, robbing HP from the engines.

Bill Verburg

For those with larger displacement engines starting around 3.2 liters and up B&B 1.75" headers allow the engine to breath freely at higher revs. here's a pic of the B&B on a 3.6 transplant in a 76 Carrrera chassis. Stock heat is retained, though the quantity of heat is less than ssi or stock. The difference on a 3.6 over ssi is remarkable.

WonPutt

Great pic! How loud is this? I've been told the dual out is WAY loud when going with a header system. Why is this B&B better HP wise than the SSI? Why is the heating worse?

Bill Verburg

The muffler is A Fabiani ss header muffler. Joe supplies it with the 2.5" ss tube and tips. You get to cut and weld the pipe. The advantage is a near perfect custom fit relatve to an off the shelf muffler. Yes, it is a bit louder than a Borla(we coincidentaly did a comparison this morning). I don't know why the heat doesn't seem to be as effectve as the SSI which I previously used.

Ed Bighi

I had SSI's on for a few years and tried on a variety of different mufflers. I did feel a hair more hp at the best of times but it seemed to be at very, very high rpm's, and no real world change in torque. 3 years ago, I wanted an easier time at emissions so I went back to stock exchangers. But this time I had the shielding removed and jet-hot coated them. I put in a cat test pipe and a completely gutted factory carrera 3.2 muffler with stock the stock single outlet. Other than the amazing sound, I am maybe 4 hp shy of where I was at with the SSI's at the best of times. So if I were to do it again, I would not even bother with them. I am no longer the devotee of SSI's I used to be once I found ways of gettting the hp very close to SSI levels. After playing around with both types on the dyno, I found that the SSI's due to their equal length made a hair more power at the very top of the rpm. But midrange my car is right on now. Also, both exhausts did not even nick the lap times as much as 23/30 torsion bars did. I am a realist that drives like a madman with a deathwish at the track, so small hp changes like that don't make sense to me any more.

Joe@Fabspeed

Independently tested and published data by Bruce Anderson & others on 5 different exhaust systems on a 3.2 Carrera showed that SSI headers and a sport (loud sport muffler) made virtually the same high midrange RPM power to top end power that a catbypass pipe/european premuffler & dual outlet sportmuffler did on the same 3.2L Carrera on the same dyno. (+/- 1hp at 6000rpm). The only advantage of SSIs headers was low midrange TORQUE OF 11FTLBS @ around 2000rpms. Otherwise the graphs were almost mirror images. Either system over bone stock is an improvement. However, a Catbypass pipe and dual outlet muffler will save several thousand dollars of parts and installation cost from the intial acquisition to annual Remove & Replacement at emissions time. No headers in the world are exactly equal lenght. Lastly, there are many more factors about an efficient exhaust system that are much more important than primary pipes that are close to being equal lenght. There is cheap bolt-on horsepower available on all 3.0 & 3.2 Carreras without major expense. FYI the primary pipe size is too small and collector design is poor on SSIs for 3.2L Carreras. Do you waht the very fastest & cheapest & lightest BUT LOUD race TRACK exhaust is for 3.2 Carrerras?

Darrell Erwin

Ed:
What do you mean when you say you removed the shielding from your stock heat exchangers? Is that the heater boxes so you efectively turned the heat exchangers into headers? Thanks for the clarification.

Paul Brewer

[QUOTE]Originally posted by Clark Griswald:
[QB]Wonputt

. Each pulse of gas has mass, and as it moves down the pipe it develops inertia.

This is a really good explaination of gas flow in an exhaust system. However, I wish to make one small correction.

Inertia is an expression of the energy it takes to accelerate a body which has mass and is at rest. Momentum refers to the energy a moving body has which is dependant on it's velocity and mass. Therefore the exhaust gases have momentum.

Ed Bighi

Darrel, what I removed where the heater boxes. When I had SSI's years ago, I did the same thing. I have no use for the heater boxes since my car had everything stripped out of it. They look just like headers now.

J richard

Having just gone through the process of "detuning" the mods on my RS to pass the arizona smog test I would advise looking into CA requirements in your area. (unless this is a track only setup or you have the patience and $$$ to swap out components every year or so.) It can really be a pain. I have had the Bursch setup, I didn't care for the fit on the 3.2 carrera, the B&B system fits like factory and sounds soooo gooood...

Ed Bighi

Is your RS the red one with the different wheels that I last saw at the South Mountain autocross. If it is, it sounds great. We all like the way it sounds. My car is the real loud silver sc.