Will SSI's add much more?

[bship]

I have been contemplating adding SSI's but also have other things I would like to do. Last spring I completely gutted my CAT( no smog testing here) and added a 1 in 2 out Flowmaster. I love the sound and immediately noticed a quicker reving engine. I feel like this mod did increase my HP but don't know how much. I am wondering if going to SSI's and a 2 in 2 out muffler will add that much more than what I have already received from my current mods? If so how much do you think? Any feedback would be greatly appreciated.

Thanks
Scott

[JackT]

I had a test pipe with a 1 in 1 out performance muffler and just switched over to SSI's and 2 in 1 out muffler. Big difference. It revs faster and I can feel more power all the way through the RPM's. I have no idea what HP boost I gained.

[RoninLB]

SSI seems to make a cleaner running engine

[911nut]

I did a back-to-back test between a test pipe and a gutted cat. The result was the cat is sitting on a shelf in my garage. Car felt like it was tied to a tree with it on.

I didn't go the SSI route. Instead I gutted my muffler, replacing the glass packing with two baffles. This freed up the engine nicely but it wasn't an "OmyGod" change. The last step was to disconnect the O2 sensor and richen up the mixture, which really brought the car to life.

If my finances would have allowed it I would have gone straight to SSI's at the time. Now I'm not so sure that SSI's would give me the bang for the buck that I would expect.

I have an acquaintence who actually removed his SSI's and did the gutted muffler thing. He said the HP change was equivalent between the two mods.

YRMV.

[North Coast Cab]

Paul,
So you're running a test pipe and a muffler with baffles? Can you give more details on the muffler, whet you did and how you did it?

Thanks, John

[911nut]

John,
Sawed the muffler into 3 pieces with all of the plug welds remaining on te center section. Cut all of the plug welds out and removed the perf pipe and packing.
Made 2 baffle plates and welded them into either end and then welded the ends back on to the center. Sounds great (like those V-12 Ferraris on Victory by Design) and the lower backpressure really freed the engine up.
Wish I had documented the job with pictures

[Oldporsche]

Somewhere back in time during the last century, I attended a workshop where Chuck Stoddard was one of the guest speakers.

He said, to feel it in the seat of the pants, you needed a hp/torque increase of over 10%.

David Duffield

[ubiquity0]

Originally posted by old_porsche
Somewhere back in time during the last century, I attended a workshop where Chuck Stoddard was one of the guest speakers.

He said, to feel it in the seat of the pants, you needed a hp/torque increase of over 10%.

David Duffield

I think if you spend enough money on a mod you'd be able to 'feel' a hp increase whatever you did

[North Coast Cab]

Paul,
I'm alittle bit of an exhaust novice so exchuse my ignorance. So you cut open and completely gutted the mufller. Then you made two baffles. What exactly are those, what do they look like, and how'd you do it.

John

[Steve W]

Maybe this pic can help Paul explain a little better about what he did:

[North Coast Cab]

Hey Steve, have you ever put your car on a Dyno?

Anyway, Thet looks like a lot of work. Also, if I fail smog then I won't have the old stuff to put back on.

John

[TMR]

I don't have any Dyno results; however, the official "butt-o-meter" indicated I had a noticeable difference after adding SSIs. It felt like a different car. One of my first mods and glad I did them!

[Steve W]

John, no dyno test yet, but my butt tell me my car is pretty darn quick, even compared to some of the guys cars who come by with their SSIs, ported heads, TBs, ExtrudeHone, etc. Perhaps one day. . . .

[no substitute]

So what's the consensus here? Is a test pipe as good as SSI's and a Dansk, or nearly so?

[RoninLB]

Originally posted by no substitute
So what's the consensus here? Is a test pipe as good as SSI's and a Dansk, or nearly so?

it would help if your signature had your model

[no substitute]

80SC, but it was asked as a general question for those who have gone this route. TIA.

[Steve W]

Depends on your model. SCs have smaller diameter heat exchangers than the Carreras, and notice a greater improvement in power and throttle response. On the Carreras, SSIs with a stock style muffler will have less top end hp than just a premuffler with a sport muffler conversion. However if the SSIs are combined with a free flowing sport muffler, the SSIs will have about a 1-2 hp advantage at the top end over the premuffler/sport muffler setup, and more midrange torque.

[911nut]

Originally posted by Steve W
Maybe this pic can help Paul explain a little better about what he did:

OK.
Cut the two ends off of the muffler and leave the center section with all the guts in it. All of the guts are held in place by a series of plug welds between the shell and those pipe supports. Cut the plug welds out and remove the guts. Take the end piece containing the inlet/outlet pipes and cut the outlet pipe back to the shell (on the inside).
Now take an end piece and trace the cross-section twice (since you will need two baffles) on 1/16 inch plate steel. Cut your baffles out. The baffle for the inlet/outlet end will need a hole for the inlet pipe to pass exhaust through. Then cut 10 to 13 7/8 inch dia. holes around the inlet hole. Take the other baffle plate and cut 13-15 7/8 inch dia. holes in it.
Weld the two baffle plates into the center section in approximately the position where you see the those pipe supports. Weld up the holes where the plug welds were and weld the ends to the center section.
Install and enjoy.

[autobonrun]

I drove my 79SC with test pipes for about 17 years before adding the SSI's. My opinion is that the real HP increase comes from the SSI's more so than changing the muffler. The Dansk definitely changes the sound and personality of the car. I have a dual out Dansk on my car now with SSI's. Makes me smile every time I get out of the car even though I've had them on a couple years now. I've attached a link with the performance test results based on use of a Gtech Pro.

Performance Test done - SSI vs Stock SC

[Schrup]

Autobonrun, did you ever post your audio recording? I will soon be installing the same exhaust & would love to hear yours.