I want to upgrade my '78 SC with a set of SSI heat exchangers and I have a few questions that hopefully some of you out there can help with.
1. My car is California spec and has an EGR circuit. Is it OK to simply dis-connect it and plug it up? (I have already dispensed with the air pump)
2. What is the best silencer/muffler to use. I like the idea of a Dansk twin outlet setup -will it be unbearably noisy on long trips?

 

The SSI's will be a nice set-up on your car. I assume your car is not subject to any clean air (emissions) testing. Since you have already removed the air pump, you should also remove the air injectors (from the old pump) and plug them with a suitable bolt, etc.

You will have many muffler options, but you need a dual inlet muffler that has inlet flanges that match the SSI's. Check this out before you buy a muffler.

I personally like Dansk mufflers. On my 1977 911 (Euro spec), I have SSI's and a Dansk dual inlet, single outlet sport muffler. That setup gives the car a very nice performance boost and a nice sound. I also have a Dansk SS Sport muffler (single outlet) on my '84 Carrera. The Dansk Sport muffler is louder than the stock muffler, but not offensive. At cruise speeds it's quiet.

My experience is that dual-outlet mufflers tend to be louder than single-outlets. Check out the archives here and on Pelican's BBS for info on muffler noise. Some aftermarket sport mufflers are very loud.

Bruce

 

Thanks for the reply. Yes I have blocked up the air injectors - my main concern now is what to do with the EGR circuit (which I think was only fitted to Cal-spec cars like mine). Emmissions tesing is not a problem for a '78 car here in the UK. We have a very strong classic car lobby here which ensures you can run just about anything on public roads

 

I can not help with the EGR circuit. I purchased my '77 911 in Germany, so it never had the air pump/EGR circuits or thermal reactors (UGH!).

Hopefully, someone on this list will have first had experience with removing the EGR circuit.

Just as a hunch, could it be as simple as unplugging the EGR wiring harness?

Regards, Bruce

 

I'd have to agree w/ BER. I have a Dansk dual outlet muffler bolted to SSI's, and it is loud for long trips, but not buzzy. My $.02

 

I guess it depends on what you mean by "upgrading" - do you want to increase performance or have an exhaust system that will last longer? If you want more power then the SSI system allows the engine to breath better and hence provides approx 10 - 15 hp but at a price - noise. Even with a Dansk box the noise will be greater than with the standard system. Dansk do a full SS system that replaces the Porsche system (Euro spec)which is life lasting but also keeps the noise at an acceptable level. The drone which sounds great to start with can get wearing over time. Depends on how much you use the car and for what purpose. That's my 2 cents. It's a lot of bucks either way so the decision needs to be well thought through.

pjc