2.0 heat exchanger options, SSI vs stock vs ?

[718RSK]

Jon is right as usual, they have the restrictor rings.

Would it be fair to assume that these were fitted as replacement for the earlier recall boxes? Not sure I want to go down the rabbit hole that is called "making early heater boxes", as it would not do my spare time and bank account much good. That said, the outfit working on the mufflers could do these also I am pretty sure. However I do not have a set to use for patterns.

[356rider]

Interesting, mine do not.

[Jon B]

I know that this has been discussed before but my understanding was that Porsche stopped using the original rectangular boxes in early '65 for safety reasons as there were welds internal to the box and they had dealers replace them. So the original 901 boxes were used all the way until the '67 model year? If so, then my thinking was way off. My May '65 car has heat exchangers similar to Joris and they do not have restrictors at the muffler flanges. However, even though the car is unrestored, I question if they are original to the car as one side had a small tab to adapt to the 6mm mounting stud at the bottom of the 901/01 engine as it was in a slightly different location. I was curious about that adapter tab. Maybe it was updated at the dealer early in its life?

Chuck, the replacement of early heat exchangers due to internal welds was initiated in 67.
Carl Bauer posted a bulletin on that here...

https://www.early911sregistry.org/fo...t-system/page5

"Earlier this year, a campaign for the replacement of heat exchangers on Porsche 911 vehicles was initiated."
The bulletin is dated July 67.
Prior to 67, there were no improved heat exchangers to replace the originals with.
You're welcome to post any documents that contradict this timeline.

On the same linked page, I posted a factory bulletin regarding the mounting tabs when installing 67 heat exchangers on earlier engines.

Jon B.
Vista, CA

[356rider]

Jon, thanks for the clarification. No contradictions other than my flawed previous understanding.

[Jon B]

I'm re-posting Service Bulletin M 16/66, from December 66.
It introduced the 901/06 engine, and had updated information regarding replacement heat exchangers for earlier engines.

For Joris and Chuck, I'm curious to know if your heat exchangers have spare part numbers stamped into the muffler flanges, as described on page 2.
I'm not sure if systems installed at the factory had stamped flanges, and I don't know when this practice ended.





Jon B.
Vista, CA

[356rider]

Jon,
The flanges on mine have partial part numbers. 017.00 on left and 018.00 on right. Engine is 9014xx.

[Jon B]

Jon,
The flanges on mine have partial part numbers. 017.00 on left and 018.00 on right. Engine is 9014xx.

Thanks for the photo, Chuck.

So as outlined in the bulletin above, you have 2000S (911S) replacement heat exchangers on your engine.
These were acceptable to use on early engines, but as noted in the 3rd paragraph "...this will result in increased engine power output".

Joris has heat exchangers described in the 4th and 5th paragraph, with "a modified pipe design".
These were first used on 67 901/05 engines, and then distributed as replacements for earlier engines "to keep the power output within the present specifications".

Jon B.
Vista, CA

[356rider]

Thanks for the photo, Chuck.

So as outlined in the bulletin above, you have 2000S (911S) replacement heat exchangers on your engine.
These were acceptable to use on early engines, but as noted in the 3rd paragraph "...this will result in increased engine power output".

Yes, I doubt the dealer was overly concerned if they only had the S replacements in stock as the customer was unlikely to complain about a modest power boost.

[718RSK]

Went out this morning wire wheel in hand. As can be seen in the below pictures mine are 011.01 and 011.02 exactly as Jon pointed out. I think we have found another detail the authenticity and concours crowd can go crazy over. These stampings will be visible when on the car.

I did not know that the first style exchangers were used for such a long time. Always figured they were a 64/ early 65 item but it looks like they were used well into 66/ early 67 and then recalled. The recall could have resulted in either the S type exchangers or the "T" type exchangers. Likely dictated by what the dealer had on stock at any one time. I would surprised if the price (which would be reimbursed by Porsche) would have been different for the two but who knows.

Back to the question at hand, for my car it appears I have three options (before considering aftermarket)
1. Early style exchangers before recall
2. S type exchangers
3. "T" type exchangers

I would still be very interested to learn how the SSI's in terms of cosmetics differ from the S and T type exchangers. A quick review of pictures found online appears to show that they look pretty close, am I right? If indeed so I would probably opt for them, paint them the correct color and maybe stamp the numbers on the flanges to make them look more authentic.

[Jon B]

Joris, thanks for your photos.

Yours are not "T" exchangers, they're 67 Type 2000 heat exchangers, which were also supplied as replacements for earlier models.
If these were my cars, I'd be very pleased to still have the 67 replacements from 53 years ago.
The original heat exchangers were less effective as exhaust headers, and were recalled due to the potential danger of leaking carbon monoxide into the passenger cabin.
The restrictor rings on yours can be removed, or used as they are, if they're still serviceable and can be restored to your satisfaction.

Thanks again to you and Chuck for the part number photos, it's very helpful to document this.

Jon B.
Vista, CA