3.0 SSI Upgrade Questions

[NoYouRelax]

I’ve done a lot of research here and I am about to bite the bullet on the SSI heat exchanger upgrade, but I need to know to what extent the exhaust system should be upgraded (total scope). There are numerous mentions of HP increase for the 3.0 SC with the SSI installation but I would like to know:

1. Is there a performance upgrade with SSI heat exchanger replacement alone, or should the remaining stock downstream exhaust be replaced too?
2. Can a decent HP increase be realized by keeping the cat converter?
3. If the cat converter is kept in place, what "1 in and 1 out" muffler works well?
4. If the cat converter is kept in place, what "1 in and 2 out" muffler is recommended

Thanks in advance, but it doesn’t seem intuitive to me that the SSI heat exchangers alone deliver additional HP. I am trying to scope this out for the winter projects.

[kodioneill]

Use the search function 3.0 SSI hundreds of posts there.

[James Brown]

ya can't keep the cat converter so if you need this for emission requirements, try something else.
You will need a 2-in muffler of some kind, 1 or 2 out is up to you. Backdating heat system if you want heat

[K Sykes]

The cat won't fit with SSI's. The conventional exhaust sends all the exhaust into a single pipe at the cat. SSI's are a copy of the pre-cat exhaust which sent two outlets direct into the muffler. If you need a cat to pass emissions, you can keep the entire stock exhaust system and put it on for inspection, or tune the car well and hope that the tech thinks the SSI's are "dual cats"

[doublestuff]

NoYouRelax, an important difference between SSI (and stock pre-cat-era 911 exhausts) is that the stock SC exhaust heat exchanger/headers exit towards the FRONT of the car, while SSI and pre-cat-era HEs exit to the REAR of the car. See pics below -
SSI:

Stock SC: (The openings toward the rear of the HEs are for hot air for cabin heat, not exhaust)


You CAN have a system made with SSIs and add two small cats (search for Craig_D's post on his) but it will likely be pricey.

But to answer what I think is your question, if you get SSI HEs, you are going to HAVE to buy a new (2-in, 1 or 2-out) muffler at a minimum (as far as exhaust is concerned).

Hope this helps.

[NoYouRelax]

I performed as many searches as possible here but it was not clear if the existing cat could be incorporated. It became clearer with the above posts. If I go SSI, I am inclined to keep the stock system for inspections.

Thanks!

[NoYouRelax]

I performed as many searches as possible here but it was not clear if the existing cat could be incorporated. It became clearer with the above posts. If I go SSI, I am inclined to keep the stock system for inspections.

May the nut breaking be gentle.

Thanks!

[SCOTITUDE]

no cat with SSI's.
SSi's and a muffler, thats all.
dual in, can be single or dual out.
if you gonna swap for inspections you are going to have to swap the whole exhaust system.
Depending on the inspection laws in PA you might only be a safety inspection (as in NY on old cars) and no exhaust inspection due to year of car.

[boyt911sc]

Bill,

You don't need the catalytic converter for your SSI conversion. We both have SC's and got headers on mine. No problem getting emission sticker annually as long as you don't drive over 5K miles a year you'll be fine and the test is done at a high-end Porsche shop in the area.

Tony

[timmy2]

Don't forget the oil lines that need to be changed as well. One hard and one soft.
Pelican Parts - Product Information: 911-107-739-10-M127
Pelican Parts - Product Information: 911-107-729-10-M127
Read up on getting your lines off the remote thermostat too!

[will hung]

Yeah, you need more than just the exhaust. As Dennis points out, you need to swap out the oil lines as well.

If the car is 30+ years old in PA, you can pass on a visual test. As stated earlier, many techs mistake the heat exchangers for cats.

SSI's are a worthwhile modification for many reasons. The in-cabin heat they generate is insane. As in driving with the heat barely on or with the windows wide open in the winter, hot. The sound alone is worth every penny, the car sounds like a proper sports car. They look cool when you look up under the car and all you see is shiney stainless beauty. And finally the performance. The horsepower increase at the top end is very welcome, but the mid-range increase in torque is very noticeable. My car used to have a step in the power band around 3.5k, now all there is just a steady shove from idle all the way to redline.

[NoYouRelax]

Great information and thanks everyone. I read about the oil lines and I have an existing leaking line anyway. I have a lot of work to do. I started blasting the nuts already.

[NoYouRelax]

For all those with SSI experience, did you keep the O2 sensor in operation and did you install a bung for its new home? It looks like SSI does not come with a home for the O2 sensor. Thoughts or comments welcomed, and THANKS!

[timmy2]

You can buy with or without bung. Get one, you may want it later. I just had one welded onto mine, pain to remove and replace. Just plug it if you don't need it yet.

[will hung]

I ordered mine with the bung pre-welded and plugged it, but that is no longer an option. Most muffler shops can weld one on for you. Just make sure it is at the proper angle and placed on a collector.

[will hung]

You can see the bung in this pic.

[NoYouRelax]

Will and Dennis, Thanks!

[ckissick]

I am selling a pair of nice SSIs that were on a 3.0. It was on a '70 without smog equipment. If don't yet have the SSIs, give me a PM.

[timmy2]

Look at my 'finally back in the game' thread. Towards the end there's a picture of where I had a bung welded on.

[ckissick]

For all those who PM'd me about my pair of SSIs, here's the thread:

(Way more interest now, apparently)

Nice SSIs