why? [Exhaust Question]

72 four door · 01-14-2003, 03:56 PM

ok can someone tell me why the early heat exchangers help produce more Hp for the sc and is it worth doing [changing oil lines and such.

masraum · 01-14-2003, 04:10 PM

they are well designed equal length headers, basically.

I would think it's worth it, but I couldn't say for sure.

Someone else surely will.

pwd72s · 01-14-2003, 04:21 PM

Beware if you make this change in a smog sniffing state that doesn't allow it....otherwise, yes, you'd experience a power gain. The early 911 heat exchangers design was the most efficient factory 911 exhaust...period. It was discontinued because Government felt it could design cars better than engineers...

TimT · 01-14-2003, 04:30 PM

The early header are equal length as mentioned above.....It is a tuned exhaust that breaths easily and also contributes to better filling of the cylinders. Therefore more power

Randy Webb · 01-14-2003, 04:40 PM

"It was discontinued because Government felt it could design cars better than engineers..." -- Well, that's just stupid. CARB & EPA set limits on pollutants. They never designed cars or any part of one. PAG couldn't comply and still have high efficiency exhaust (at least for quite a few years).

pwd72s · 01-14-2003, 04:51 PM

Quote:

Originally posted by Randy Webb
"It was discontinued because Government felt it could design cars better than engineers..." -- Well, that's just stupid. CARB & EPA set limits on pollutants. They never designed cars or any part of one. PAG couldn't comply and still have high efficiency exhaust (at least for quite a few years).

Shoulda known I'd hear from a lover of big brother...okay, the government set the limits, then the Porsche (and other) factory engineers had to design around them. Happy now? The fact that the high efficiency exhaust went away is evidence enough...I try, I really do...but I have trouble embracing the notion that big government mandating standards for all is the best path. I guess you're right...that makes me stupid.

72 four door · 01-14-2003, 05:30 PM

Thanks guys also what about the oxy sensor ? and do i use a cat?or by pass I live in jersey But have ways around things.

pwd72s · 01-14-2003, 05:42 PM

I'm now passing you on to the SCWDP guys...hope they weigh in. With my early car, I didn't know what an oxy sensor was, until a friend with one got stranded in the middle of a Utah desert when it failed...

speeder · 01-14-2003, 06:30 PM

Others have pretty much explained the benefits, basically these motors breathe a lot better w/ early style exhaust, realistic HP gain from switch of heat exchangers/muffler is 15-20HP. Also they tend to run cooler w/o catalytic converter+ it's a much simpler and cleaner looking arrangement. Also easier to do certain maintenence tasks, like valve adjustment on left side.

Is it worth it? Hard to say for everyone, if stock exchangers are rusted out it is a no-brainer since then they would need to be replaced anyways, but if you have a nice stock SC that runs perfect maybe not. SSI heat exchangers, (stainless steel, beautiful pieces, last forever and 3 days), are the gold standard in aftermarket parts for 911s, IMO, they are true equal length headers made better than original parts, look awesome and improve heat in car to boot. A cheaper alternative is some good used '74 HEs+ '74 muffler, but switching to new SSIs+ 2in style muffler and changing oil line is approx. $2Gs. That is about $100 per HP. Hope this helps you.

Doug Zielke · 01-14-2003, 06:39 PM

Quote:

Originally posted by speeder
...... SSI heat exchangers, (stainless steel, beautiful pieces, last forever and 3 days), are the gold standard in aftermarket parts for 911s.......

Couldn't have said it better myself, Denis!

72 four door · 01-14-2003, 07:18 PM

wow boy are they sweeet

Tim Walsh · Tim Walsh's Garage

now here's a question for ya.. is it worth it to replace the my post '75 exhaust on my 73 2.4? It's not rusted out but it sure isn't original.

pwd72s · 01-14-2003, 08:50 PM

I guess my question is why anybody would want to put a '75 exhaust on a '73...

speeder · 01-14-2003, 11:03 PM

Doug, Lookin' sweeeet! Looks like a Dansk sport (larger outlet), and Sachs Power Clutch? When does it go in? Sure looks ready. Can't remember, did you switch cams? Hope mine looks that good, but it should. I'm doing basically identical job. Removed lower studs and split case today, driving up to Lake Isabella to Competition Engineering tommorow to pick up heads, rockers and cams+ clean cases, etc. in his hot tank. Should be a fun and educational trip. Hope to see some gnarly J. Woods motors there. Then plan on an assembly party this weekend, w/ some Pelicanheads, will post pics.

Once again, looks great! It's kind of fun, other than paying for everything, no?

KTL · 01-15-2003, 06:19 AM

It's a shame such sweet looking headers are going to turn brown. I guess you could polish them once a year and they'd stay like new?

Of course you could ceramic coat them, but that's a little pricey and sometimes the work is a little sloppy.

I had some headers done and was not too happy with the finish around the most important places. Those being the mating surfaces of the flanges. Had to smooth them a bit with an abrasive wheel. Still, they look nice.

You're definitely making the right choice with the SSI's. They look really nice and fit just like the factory intended. Maybe even better.............

RickM · RickM's Garage

What a beautiful site!

Deeks · 01-15-2003, 07:41 AM

Wow KTL that is stunning. Do you have a lot of spare time on your hands

or is it a new system ??

boyt911sc · boyt911sc's Garage

Doug Z,
That's an awesome piece of machinery you got there. I have an SC 3.0 liter engine and I'm thinking of installing an SSI or pre-74 exhaust sytem. While I could easily locate SSI exhaust units, I'm having difficulties getting replacement part for the oil circulation line. Did you fabricate your oil line (as shown on your pic)? Could you direct me where to start looking? Thanks.

Doug Zielke · 05:29 PM

Quote:

Originally posted by boyt911sc
........ Did you fabricate your oil line (as shown on your pic)? Could you direct me where to start looking? Thanks.

No fabrication required.
The Porsche part # is: 911 107 739 10

**You may note in the image, the black patch where the oil line crosses behind the engine. In my installation, the line was quite close to the rear of the case. Although it was not actually touching, I wrapped the line with a bit of neoprene rubber sheet at that point, just incase.

HawgRyder · HawgRyder's Garage

The reason for all the controls...oxy sensor...computer regulated injection....EGR....spark retard.....etc.
Mostly because the government...and then the manufacturers...know that most people will NOT maintain their engines!
So....they pile on the automatic controls to reduce the bad emissions even when the owner has not changed his plugs in the last decade.
The least poluting engine is a well tuned high horsepower one.
If you are pulling all the HP out of the gas going in...there is almost nothing left to come out the pipe.
We are to blame for the present day situation...collectively we have neglected our engines....and invited the government to protect us from ourselves.
Another case in point...seat belts...why?...if we were all competent, careful drivers...we would not need them.
Oh well....back to work on my old early 69...with no pollution controls.
Bob