SSI's or 74 exchangers on a SC?

VA911 · 02-08-2007, 02:19 AM

I am currently tossing up between a used set of 74 heat exchangers or brand new SSI's. What should i do?
i am after as much power increase as possible but dont want to spend a heap of money on SSI's if i can get the same results out of the 74s'.
what should i go for?
also what sort of muffler should i go with for power. Note this car is a street car and i currently have a 1 in 1 out 100mm monty which is LOUD to say the least.I know i will need to change the muffler to a 2 in 1 out so what is the way to go?

jstgermaine · jstgermaine's Garage

SSI's and a M&K 2 in 1 out. While not the cheapest route, if you ever want to recoup some cost...SSI's sell for close to retail in good used condition, ditto on a M&K.

Zeke · 02-08-2007, 06:18 AM

Well, the M&K will be sorta loud, too. AFAIK, SSI's and stock '74 HE's are very similar, so the performance should be comparable. A stock muffler is ideal for a stock engine, again, AFAIK. This combination would be a much better overall set up than what you have.

If you aren't changing cams or going to carbs and changing pistons, the '74 exhaust might be the best there is for your car.

Others know more, I'm sure.

zotman72 · 02-08-2007, 06:37 AM

I am finishing up this transformation on my '80 SC. The '74 HEs I bought needed a O2 sensor receptacle welded on the left side. Basically you use a hole saw to cut the opening and weld a nut in the hole. I am using a 2:1 OEM stock muffler from my '72 for now and will eventually convert it over to a 2:2 sport muffler. My only concern is that the '74 HEs I bought are a little oil soaked (no surprise there coming off a 2.7!) so I will probably let the engine run a spell before I hook up the 02 sensor. Oh and the SC HEs were thick flange and the '74 HEs were thin, so I just shimmed up the difference with steel washers. HTH.

VA911 · 02-08-2007, 10:08 PM

so should i just go to the second hand 74's. Will i get more power and torque just like stated with the SSI's?
i am a little unsure of what to do at the moment and need as many opinions as possible.

SP2 · 10:16 PM

Bruce Anderson says the SSI's are a performance increase, but that is with respect to stock SC exhaust. Bruce doesn't post here but Steve Weiner does. Maybe you can ask him. I would go SSI though, because they are stainless steel and you will never need to replace them because of rust, etc. I thought the pipe diameters were larger than the stock 74 HE's. I think I saw a photo of that once, either here or in Bruce's book.

You can buy SSI's with the correct thick flange too. I think the hard part will be puttin them on upside down, i.e. with the engine still in.

VA911 · 02-08-2007, 10:40 PM

Quote:

Originally posted by SP2

You can buy SSI's with the correct thick flange too. I think the hard part will be puttin them on upside down, i.e. with the engine still in.

why is this?
Steve..... if your out there what should i do?

SP2 · 02-08-2007, 10:54 PM

Just because it would be hard to get the nuts on, that's all. I found it hard to get the nuts started on the studs, and this was with the engine upside down, so the studs were pointed up.

Steve@Rennsport · 02-09-2007, 12:17 AM

Quote:

Originally posted by VA911
why is this?
Steve..... if your out there what should i do?

Wellll,...by now, the vast majority of original factory '74 heat exchangers have rusted to the extent that they can be unsafe to use due to CO poisoning potential. The Porsche ones had mild steel shrouding with stainless tubing and the outer shell is very prone to pinholes.

If you have the budget and want to do this properly as well as safely, my recommendation is to use a pair of the correct SSI's for your engine as there is nothing better,.......

These will not only keep you safe, but they will last almost forever.

I'm a big fan of Monty Sport Mufflers (with 75mm outlet) for their superior build quality and civilized noise level. The 100mm versions are too loud for my taste.

VA911 · 02-09-2007, 02:17 AM

Thanks Steve,
i currently have stock exchangers on a stock 79sc 3.0, i have removed the cat and have a 100mm monty single in/out. its sort of a bit loud but does sound very cool. I have a problem where the exhaust crossover pipe gasget keeps on blowing. i dont know why.
oh well once i get enough cash up to buy SSI's i wont need to worry about that.
What type of SSI's do i need?

felix_browne · 02-09-2007, 02:27 AM

I went with the 74 style exchangers because they were much cheaper but after 2 years am looking to replace them due to rust. might be cheaper at first to go the 74 route but in the long run would be cheaper if you don't have to replace them again. On top of that when changing them, you run the risk of breaking exhaust studs trying to free the nuts so why take this chance more frequently then you have to?

VA911 · 02-09-2007, 02:34 AM

very true felix.
Did the 74's make much performance gains?
just wondering since you car is the same as mine

wilke3169 · 02-09-2007, 02:42 AM

I have a '79 SC slightly modified, 9.5:1 and 964 cams. I bought a set of SSIs here on the site which happened to come with a Monty 2 in 2 out. Definantly a worthwhile investment. I feel certain I could sell them today for what I have in them, but I can't imagine what I would change to. Keep an eye out, they are for sale on here often. Mine are thin flange. Just take a look underneath and see which you have. I had a turbo guy at our last rally come up and say man i wish my car could sound like that...

VA911 · 02-09-2007, 02:54 AM

cheers kevin,
might put a shout out in the used parts forum. Would like to know exactly what SSI's i need though
if i put some pics of underneath on would you guys know what i need?

wilke3169 · 02-09-2007, 04:32 AM

Fs: Ssi Heat Exchangers & Stainless Muffler, Photos

This is the old thread when I bought mine. The pictures show the thin flanges. Look underneath after looking at these pics it will be obvious to you if yours are thick or thin. I am guessing thin.

VA911 · 02-09-2007, 06:57 PM

ok lookwd under. i reckon the flange is about 4mm. is this thick or thin?

Humm cant resist.. *BIG RESPECT TO THE FLANGE* (the words of Ali G)

island911 · 02-09-2007, 07:24 PM

FWIW, My '81 has the thick flanges. It's good to check; I hear the SC's have both. The difference between thick and thin is big. The thin are about .275" & the thick are .825 thick (about 1/4" & 3/4" for the decimally impaired)

Oh, and listen to Milt and Steve Weiner.

VA911 · 02-09-2007, 07:51 PM

thanks island.
looks like i got the thin flange.
now all i need to do is find a second hand set.
anyone???

Steve@Rennsport · 02-09-2007, 08:24 PM

Nice pics, Glenn.

Can I add them to our archive when someone isn't sure about what they have?

Jgordon · 02-09-2007, 09:46 PM

I dunno about this "hard to put them on" stuff. I put mine on on my back in my garage, before I even got my crawler. Just try to get ahold of a bent wrench like the B&B sets come with. and some beer.