901 and early 911 exhaust system

[preS]

Contact Jim Newton at Auto Associates in Canton, Ct. He bought my last (maybe the last on the planet) NOS 901 Heat Exchangers. He was thinking of reproducing them. They were recalled by Porsche in late 65 or sometime in early 66 and replaced with the heat exchanger that we are all familiar with.

Regards

Jim

That was a smart buy, but wasn’t it a nos from your cabinet and an used set (3 in total)? If it was a nos set than my mind is surpressing my failure

Richard

[vojtech]

Interesting. Don't mean to go off-topic, but does anyone know when the earliest-type manifold was abandoned in favour of something more familiar? Sometime early in 1965? Any factory documentation that records the event? Much appreciated.

Unfortunately I dont have any info about date(or production number) of change.... and I also need this info. But for some cars I definitely need early style exhaust.

[Jon B]

Unfortunately I dont have any info about date (or production number) of change.... and I also need this info...

Answered in post #17:

This original version was used through the 66 model year. It did not have equal length manifold pipes.
The much-improved 67 version was developed for the S engine, and had equal length pipes for improved exhaust scavenging.

When the 67S system was tried on the standard 901/05 engine, it increased the power by 10 PS.
This brought it too close to the S power output, so restrictor rings were installed for the standard engines to reduce the effect!
The restrictors were removed on the 901/06 exhaust systems.

Jon B.
Vista, CA

[vojtech]

Ok

So heatexchangers: will be not so difficult to find....purchase from Freisinger or find some original for 3D scan. Please for next tips who can have it (for me best is Europe location)
But what about Muffler... maybe construction is similar and we can just add heat shield to later style muffler.

Vojtech

[718RSK]

Ok

So heatexchangers: will be not so difficult to find....purchase from Freisinger or find some original for 3D scan. Please for next tips who can have it (for me best is Europe location)
But what about Muffler... maybe construction is similar and we can just add heat shield to later style muffler.

Vojtech

As mentioned, I have an original early style muffler boxed up in my garage ready to be send out. Have not gotten around to it because of Corona but will get going on this project again. Once the shop has looked at it I should be able to come back as I am sure they will want to get a feeling for the demand out there.

[vojtech]

As mentioned, I have an original early style muffler boxed up in my garage ready to be send out. Have not gotten around to it because of Corona but will get going on this project again. Once the shop has looked at it I should be able to come back as I am sure they will want to get a feeling for the demand out there.

Perfect. Can you send me email on vojtech.bejda@autobejda.cz ? I am definitely a buyer of reproduction.

[haul]

well, I am still curious about the cars...
901 in prague?
@biancaneve

br
haul

[one-two]

This original version was used through the 66 model year. It did not have equal length manifold pipes.
The much-improved 67 version was developed for the S engine, and had equal length pipes for improved exhaust scavenging.

When the 67S system was tried on the standard 901/05 engine, it increased the power by 10 PS.
This brought it too close to the S power output, so restrictor rings were installed for the standard engines to reduce the effect!
The restrictors were removed on the 901/06 exhaust systems.

Jon B.
Vista, CA

Hi Jon, many thanks for this. I was under the impression that the very first set of manifolds were phased out in 1965 rather than 1966 - and may even have been the subject of a factory recall. Yet the story you tell is very familiar. Could there have been an intermediate manifold between early-1965 and mid-1966 or am I just confused?

[davep]

Attachment 526996

A later muffler is smooth, these have an additional shield around it w heat insulation sandwiched in between.

So is this purported 914/6 muffler actually one of the very early 911 mufflers?
https://www.early911sregistry.org/fo...-6-muffler-NOS

[StephenAcworth]

Looks like it actually may be!

So is this purported 914/6 muffler actually one of the very early 911 mufflers?
https://www.early911sregistry.org/fo...-6-muffler-NOS