TO SSI OR NOT SSI TIS' the question 76911s

[gliderguy]

I have been reading threads, trying to do homework about

exhaust upgrade. SSI's seem to be coming up alot. Problem is most of the questions are related to the famed SC and not as much mention of my humble middie. Here is a pic of my exhaust. Any suggestions on the best "upgrade" I do not have to worry about any smog testing or vehicle inspection. Looking for A little horsepower bump and nice sound.

[gliderguy]

appealing to the middie "gods"

[Bill Verburg]

SSI was designed FOR 2.4 and 2.7. It will work better in that application than for 3 or 3.2 liter cars.

[dd74]

Do it. SSIs are a great addition to the engine. They give at least ten horsepower more and keep the engine cooler. Bear in mind you will also need a new muffler. SSIs require dual-in-dual-out mufflers. I believe single in single out was the muffler style on OEM 1976 911s.

[dd74]

Originally posted by Bill Verburg
SSI was designed FOR 2.4 and 2.7. It will work better in that application than for 3 or 3.2 liter cars.

Interesting. And what do you suggest for the three liter engine, Bill?

[RoninLB]

Originally posted by gliderguy

appealing to the middie "gods"

you'll love SSI.

then disconnect the dizzy vac retard and set initial to Z1 or full to 35deg.

[Bill Verburg]

Interesting. And what do you suggest for the three liter engine, Bill?

SSI but as the displacement goes up the appropriateness of the SSI goes down. Don't expect the same bang w/ the larger engines as w/ the smaller. By the time 3.2 is reached they are probably not worth the $ or effort except for in some very limited circumstances..

[dd74]

Originally posted by Bill Verburg
SSI but as the displacement goes up the appropriateness of the SSI goes down. Don't expect the same bang w/ the larger engines as w/ the smaller. By the time 3.2 is reached they are probably not worth the $ or effort except for in some very limited circumstances..

So I guess we're talking about custom headers for that appropriateness, right? Unless there's something readymade on the market. Bursch makes a header for the 3.0, I think.

[gliderguy]

So yes to SSI and I will need new muffler? Is SSI pretty much "the way" to go. are there other alternative's? 74 exhaust looks very similar to the SSI. Is the difference one is Stainless steel?

[gliderguy]

Still amazed at the wealth of knowledge that flows from the pelican post.

[ipapilot]

I think a plain header (ie, without heat) would be the only other good way to go.....In ohio that would suck, but in Florida, who cares!

[gliderguy]

She is a summer car. I assume plain headers is cheaper way to go. Looks like 500-600 for used SSI is about right?

[ipapilot]

If you can find them for that, including all the necessary installation hardware for your car, I would go for that option. They may discolor, but I haven't seen a rusty stainless SSI yet
Otherwise, yes, headers would be the cheapest route...

[Rod.911S]

Fortunately, my '77 had the stainless exhaust and heat exchanger conversion by a PO. Everything I've read says to get rid of the thermal reactors -- apparently they create a real heat problem for the engine. The air pump and a/c were also removed so I'm guessing I'm at around the 175 hp and 187 lbs torque of the '74s. Then there's I don't know how many pounds less of fine German steel to haul around.

[dd74]

Originally posted by gliderguy
So yes to SSI and I will need new muffler? Is SSI pretty much "the way" to go. are there other alternative's? 74 exhaust looks very similar to the SSI. Is the difference one is Stainless steel?

I've spoken with some engine builders who believe there is very little difference between the '74 heat exchanger and SSIs. After all, as was said earlier in this thread, the SSI was based on the heat exchanger used with the '74 911. SSIs might be a tad larger in diameter which might mean a tiny bit better top end performance. At least with the SSIs, they will not rust, as was also said earlier.

I have '74 heat exchangers on my '83 3.0. Regardless of what better perfomance could be obtained with the SSIs, I'm not certain there'd be a large horsepower increase between '74 h/es and SSIs. As is, my car revs to 6500 with power, so for the most part, I'm good with the performance the heat exchangers have given me.

With a 2.7, I'd opt for '74 heat exchangers - in good condition - i.e. not rusty - over SSIs, because they are what the 2.7 originally came with.

[RoninLB]

here's a good SSI thread

HELP: The SSI's I bought don't fit my car!

[HardDrive]

gliderguy, have you considered adjusting the ride height on your car? She rides kind of high.

[darkbeer]

Gliderguy...if you go with either the SSI or OEM '74 Hx's, you will first, have to deal with the air injection loop I see is still on your car (per pics). It will be right in the way of the earlier style Hx's....you can get nice plugs for the air inj. holes, red loktite 'um in & you're good to go......that ugly old loop is just dead weight anyway with out the pump-egr, etc.

Good luck !!!

[Bill Verburg]

Originally posted by dd74
So I guess we're talking about custom headers for that appropriateness, right? Unless there's something readymade on the market. Bursch makes a header for the 3.0, I think.

No, 1 5/8" B&B are available for 3.2. The other thing is that w/ late smog cams headers have little to work w/ and a large enought stocker in ROW confi. is as good.

Of course if cams are used as well then the equal length headers become much more efficient.

[Bill Verburg]

I would discourage the elimination of heat. even in a race car.

SSI are an improved copy of the early headers. Their genesis was the poor life expectancy of the oem header/heater box back in the '60s and early '70s. eventually the factory started to use better steel but the SSI business was well stablished by that time and had swithed to being a performance enhancing alternative to the stock single pipe system.

Yes, SSI are more equal length than the '74 back system. This doesn't hurt but neither is it the most critical design criteria.