Early Heat Exchangers

Bones · Bones's Garage

ok......this coming year i plan to replace the heat exchangers on my 78 911SC with the much praised early type...i believe these to be pre '73......am i correct and what specific part no.s i should look for as i don't want to be sold the wrong (later) thing...i know the forums here have gone into lengths about this subject but i haven't seen a reference to part no.s....i plan to use a two into two outlet exhaust

Joeaksa · 06:07 AM

Bones,

Considering that you live in the UK, your choices are many. You can still find the old style HE (heat exchangers) from time to time as well as those from SSI, Dankse as well as others. The stock units normally would be a bit less expensive but will always suffer from rust.

Another thing to think about is how long you plan on keeping the car. If you plan on keeping it for a long time, I would go with units made out of stainless steel. The weather and winters in Europe are rough on HE's and using stainless steel would mean that they would never rust out again, a big plus for most people. This also adds value to your car if you were to sell in the future.

All of the firms who make a HE for the 911 have an example of the "early style" HE as well as the 2 into 1 muffler needed to work with this conversion. I made it on my 85 3.2 and it really made the car nice to drive.

Joe

Bones · Bones's Garage

what's so important then about a 2 into 1 exhaust as there are plenty of people offering 2 into two's (which obviously means modifying the rear valance) but technically surely a 2 into 2 is every bit as good as a 2 into 1 so long as it is designed correctly......further thoughts greatly appreciated

Joeaksa · 12-16-2002, 09:33 AM

2 into 2 people are usually looking for a bit more noise and hoping that more power comes with it. You might flow a bit more out the 2 into 2 setup but doubt that it would result in a great HP gain unless you were at full throttle most of the time and the rest of your motor was tweaked already.

Best I can recommend is to keep your eyes open and if you find/hear a 911 whose sound you like, flag them down and see what type of system they have.

I am using the SSI pre-73 HE with a stock Porsche "banana" muffler and am very happy with its performance and sound. Will be switching the muffler out with a used Danske stainless unit shortly but only because I got a good deal on it. If its too loud, the stock unit will go back on!

I do not want to start cutting on my rear valence, so the 2 into 2 is not a factor for me. Got enough HP to make me smile already!

Joe

Superman · 12-16-2002, 10:23 AM

The "two-in" style is the way to go, because of exhaust tuning and backpressure reasons. It's not pre-73 you're looking for , it's pre-75. IN fact the '74 had arguably the best of all Porsche exhaust systems. Equal length headers made of stainless steel. Previous years were all iron, post '74 systems were 1-in 1-out.