Advice on exhaust backdating for my SC.

[chrisp]

I can't remember the recommended backdating for the exhaust on my '83 SC. I remembering it being somewhere around 17 hp but for the life of me I cannot remember if it was a back date to the late 70's pre-SC cars or if it was to an earlier exhaust like the '74.

Also, I think there are a couple of related projects that go along with it like some oil lines having to be changed.

If any of you have dont this I would like some answers to the above. Thanks for the help. I searched and couldn't find anything.

[stlrj]

Considering the cost and hassle invloved, not to mention the marginal gains in hp if any, why do it? I guess you know it wouldn't pass smog either, if that is of any concern.

In my humble opinion, the SC exhaust is a work of art in its symmetry and functionality with less back pressure than those who would detract realize.


Cheers,

Joe

[VincentVega]

I recently installed SSI's and a dansk 2 in 1 out muffler and am very satisfied. The car has a little more power, a lot more heat and runs a little smoother, although I am not sure exactly how to explain that. In my SC there was a nice bump in power from about 3k up.

[RSupdate]

Fyi...If you can get a copy of BA's porsche performance handbook, he clearly states that on a 3.0 SC engine backdated with SSI'S and a 2 in, 2 out sport muffler, they (Bruce Anderson & Jerry Woods) were able to get 20 add'l HP on dyno readings.

Of course this is only of any worth if one thinks Bruce Anderson is credible.

Cheers.

[crashmy911]

Headers with two in one out or dual out makes a big difference.

[rdane]

The gentleman who answers the phone at SSI says two in and either one out or two out makes NO difference at all on HP gain for the SCs.

YMMV but I have to think he has a clue.

[osidak]

I have SSI's installed on my Euro 78 SC with a Factory 2 in 1 out muffler. I noticed right off the car has more pick up and seems to rev much freer with this set up as opposed to my Stock exhaust with a euro pipe. I think the dollars are very well spent and I highly reccomend this upgrade. I also like the new exhaust note.

[II6]

I second that. I also have ssi's and noticed the same improved
response, and no more headaches from my old rusted out original pipes. And it's lighter too.

[s2per]

By all means, do it. Either the SSIs or the '74 and earlier stock exhaust makes a big difference. I've done the conversion on two 3.0 cars now, and can't imagine the car without it. Try a single 3" outlet muffler, too.

[chrisp]

I would like to keep my heater controls. I have seen way too many people pull off the track because of fogged windshields to go without a heater. Plus it's still a street car (and track car) for the time being.

So will just putting the pre-'74 exhaust give me the Bruce Anderson numbers? I had read about this in his book but could not remember the details, specifically which exhaust set-up and whether or not the heater was compromised.

And then there are some oil line issues as well right?

[rdane]

SSIs in a pre '74 set up give you heat and the HP numbers with even a factory muffler according to SSI`. If you are back dating a post '74 car, yes you'll need two oil lines. They will run you under $200 new.

[RSupdate]

Originally posted by rdane
The gentleman who answers the phone at SSI says two in and either one out or two out makes NO difference at all on HP gain for the SCs.

YMMV but I have to think he has a clue.

ILMAO...!!!!! Surely you jest!!!

In light of the fact that the stock exhaust on the 3.0 does not comprise of all equal length exhaust tubes (headers a'la SSI's or '74 -> earlier) going into a collector (3 into 1 on each side) that equates to increased back pressure because the exhaust pulses from each cylinder are are all fighting to get down the exhaust out of sequence, at nearly the same instant, instead of those same exhaust pulses exiting in a logical repeating sequence.

I think I trust Bruce Andersons 30+ years of hands on experience building 911 engines as opposed to calling up someone at SSI who sez that their product, does not help the performance of a potential customers car... dumb. (a.k.a. killing a sale)

Don't get me wrong...I have SSI's on my 3.2 and short of the smog nazi's here in CA confiscating my 911, would never dream of taking them off......I love 'em the power increase was just plain undeniable compared to the factory exhaust.

I personally think if you own a 911 you owe it to yourself to at least borrow a copy of Bruce Anderson's Porsche performance handbook. Read it. It is not the end all gospel, but it will most certianly point you the right direction with proven nuts & bolts hands on experience and the coresponding results.

Good Luck !!

[rdane]

The comment was in the context of "two in" mufflers for the SSI and either "one" or "two" exhaust pipes out

I have Anderson's book. Even SSI suggests you read Anderson's book. I also talked at length with SSI on recommended mufflers to use. Let me quote, "in numerious dyno tests over years we have seen no signifigance difference in hp or performance gain between single or dbl outlet mufflers, other than the noise." There was no one recommended performance muffler either. The least amount of effort to fit is the Monty which gets a reserved recommendation for that fact.

The point was, you want SSIs, but the muffer isn't going to make a lot of difference.

By the comments posted the SSIs with a single outlet muffler is a excellent performance system and avoids some of the noise.

[Gunter]

SSI's will not take away heat. I found that they actually add heat.
The biggest headache is not installing the SSI's, it's the oil lines. Especially the connection to the auxillary thermostat which requires special crow foot wrenches. I ended up going with oil lines, and fittings, from Caterpillar Industries. We left the auxillary thermostat alone and welded/soldered a fitting into the existing line right underneath the oil tank. Consider buying the ready-made oil lines from Pelican and let a professional do this because it can be tough. Opening the barrel nuts on your existing system requires heat and a special loooong Allen socket wrench. You would also need a different muffler. I went with a custom-made 2in/1out 'Flowmaster' and love the sound.
There is also some modification on the sheetmetal, and ducts, nessessary. Try and find someone in your area who has done it. Would I do it again? YES. Did it add HP and better performance? YES. But then, I don't have to consider smog issues here. The SSI's do have a threaded hole for the OX sensor. With everything, it'll cost you well over a thousand US.

[island911]

Originally posted by RSupdate
ILMAO...!!!!! Surely you jest!!!

. . .

I think I trust Bruce Andersons 30+ years of hands on experience building 911 engines as opposed to calling up someone at SSI who sez that their product, does not help the performance of a potential customers car... dumb. (a.k.a. killing a sale)

. . .

So John, If I have this right, you are saying BA's speculation hold more weight than SSi's testing of different mufflers. (?)
To my knowledge, SSi is NOT (yet) selling any mufflers. Leading me to conclude they may have some unbiased dyno #'s for the various muffler configurations.

Furthermore, BA's speculation of SSi's on an SC come from testing of a tweaked 3.2 liter SC . . . .and THOSE dyno numbers . . .."provided by SSI." (page 142 BA's Perf Handbook, 2nd Ed)

edit: =>(apparently BA trust SSI's numbers)

[RSupdate]

Island, I have to say I stand corrected here, you are correct.

SSI did indeed provide the performance dyno data. and it shows some, (b'twn 2500-4000rpm) but not much improvement when adding SSI's and a stock early muffler.

BA goes on to suggest that when using SSI's and a dual out sport muffler performance gains of 17-22 hp are probable for the 3.0 SC engine, (probably need a custom chip too?)and that they dyno'd a 3.2 and got only 13 add'l hp, but this reduction is due I understand because the tube I.D. of the SSI's is near the upper limit of it's ability to keep up with the exhaust gas volumes of the 3.2.

Anyway thx for correcting me,always open for education!




cheers!

[Wil Ferch]

More data...
As some said...the SSI route ( stainless version of the pre-74 factory set up) should net you 17-22 hp on an SC...something less like 13 hp on a 3.2 for less than-optimal header size. However, from a 3.2 viewpoint, this 13-15 add'l hp can be duplicated fairly easily with a stock header, substituting cat for real Porsche pre-muffler, and a chip. Downside? Torque at mid range not quite as good as SSI. Upside? No oil lines to change out. Easily converted back to cat for annual smog checks. Similar peak hp.
BTW....dual-out vs single out does have hp improvement ...but small...maybe 1-3 hp. Depends also on size ( 2.5-3-4") for the outlet.
--Wil Ferch

[chrisp]

Ok so if I throw smog legal into the mix what are my options to extract more hp via exhaust tweaks to my SC?

I didn't realize (but would have if I thought about it) that the '74 set-up was not smog legal.

I like the SSI products and appreciate the level of effort they go through but do not like the price to participate. I know everythign costs money but I don't need anything glamorous or anything that will last a lifetime all I want is 17 hp (and smog legal if possible...but maybe I don't get the 17 via a smog legal set up). OEM quality is fine with me. I have other places to spend the $800 that SSI's will cost.

maybe I am trying to get blood from a rock or something like that. As always with this forum, I have learned a ton.

[juanbenae]

i was under the impression that you could not get or use a chip in an sc cis system? is this correct?

[Jdub]

'78:

That is correct: the SC has no brains.

Oi,
John