Euro 3.2 post-emissions heat exchangers and exhaust

[RonCT]

I've read every post I could find through searching and haven't found a definitive answer to my question. Hoping the collective wisdom here can help.

I just purchased a 1985 Euro 3.2 that is tight and strong (1-3% leak-down). PO fitted a Fabspeed 1:2 muffler and Steve Wong chip.

I am backdating the front fenders and bumper and the rear bumper to '73, another Long Hood look.

The car has OEM heat exchangers and cat and now that the car is >25 years old it is exempt from emissions, so the cat can either be replaced with a pre-muffler or removed altogether. The OEM heat exchangers look tired - pretty rusted, so I'm not opposed to replacing them.

If I keep the fabspeed muffler I could cap the passenger side for a more accurate look, but am open to a dual exhaust (both sides, both to the rear).

I want to get the most out of this car and it will be used for street only. So maximum HP at top RPM is less important than low to mid range.

Options as I see them, tempered with advice from some fellow forumites - keep in mind it's a Euro spec engine:

Stick with the OEM exchangers, swap cat for bypass, and keep the Fabspeed with 1 or 2 outlets. This re-uses the Steve Wong chip already on the car. Could also change the muffler for something that might fit / look more correct with a 73 rear bumper.

I have a feeling that if I'm going to replace the exchangers, I might as well also remove the cat and change the muffler for a 2:1 (or 2:2). But would this be a true "exhaust backdate" or do I need something else because it's an 85 but with a 73 rear bumper - or do I need something else because I need an 02 sensor. This could get expensive - replaces everything including the chip. But there is some credit back as the $1,000 Fabspeed muffler probably has some value.

I like the concept of the reduced weight and complexity of buying some new exchangers and a more traditional muffler - and I don't want this too loud. The advice to date is "maximum flow" and a suggestion the B&B 1.75" exchangers would be a good starting point. But then what to put that into...

Thanks in advance,
Ron

[Dan J]

Hey Ron
If you're backdating the car why not use SSI heat exch and Dansk sport muffler?

I'd also back date the air supply hoses on the top of the motor It really cleans up the eng compartment and the heat still works fine

[RonCT]

Hey Dan - I'm somewhat coming out of "Porsche Retirement"!

My first thought was SSI/Dansk and then I started wondering about the chip (sell current one, buy the other Steve Wong version for Euro with SSI/Sport Muffler), how the 02 sensor is handled (if at all), etc. Trying to learn more about this before moving ahead.

I'm thinking with dropping 250 lbs, starting with the Euro engine, and then tweaking things like the exhaust now that a cat isn't required should wake the car up nicely.

[Bill Verburg]

first thing I'd do is find out what motor you have
930/20 or /26 are most likely

ssi will be fine around town, but will restrict top end power, they only have 1 3/8" id primaries and w/ zero overlap smog cams you don't even get the benefit of tuning the pipes

[whiterabbit]

I have had two of these (3.2 ROW) and honestly the cat bypass seemed to add as much power on one car as SSI's on the other. Given the chance again I would splurg on something like LRaleys headers or just go with a euro bypass.

[michael lang]

If its a street motor, I'd approach it with a conservative approach. I'd go with a pre-muffler or cat by pass to allow the exhaust to flow a little more freely. SSI's would be an awesome choice if you wanted to really get the most out of your engine without going to a race header/heat exchanger set up. Then I'd go with something like an M&K which will add to the look being correct, will last forever because of their build quality and have a nice 911 sound to atleast add to the whole experience. Good luck as your choices are limitless.

[RonCT]

I've confirmed that it is indeed a 93020-63F engine, though to federalize the car in 1985 they swapped the OEM pre-muffler with a cat. So the simplest solution appears to be to swap back for a pre-muffler and either adapt the Fabspeed muffler (ie: cap the passenger side outlet) or change-out the muffler altogether. I don't mind spending to replace "everything" and backdate the exhaust, though with an 02 bung, but don't want to be silly either. If new heat exchangers into a 2:1 or 2:2 Dansk sport muffler will give me benefit for street use (lighter weight, better performance), then I don't mind. The current exchangers have been on the car for 29 years and 98k miles (see attached).

Thanks!

[Bill Verburg]

Originally Posted by RonCT

I've confirmed that it is indeed a 93020-63F engine, though to federalize the car in 1985 they swapped the OEM pre-muffler with a cat. So the simplest solution appears to be to swap back for a pre-muffler and either adapt the Fabspeed muffler (ie: cap the passenger side outlet) or change-out the muffler altogether. I don't mind spending to replace "everything" and backdate the exhaust, though with an 02 bung, but don't want to be silly either. If new heat exchangers into a 2:1 or 2:2 Dansk sport muffler will give me benefit for street use (lighter weight, better performance), then I don't mind. The current exchangers have been on the car for 29 years and 98k miles (see attached).

Thanks!

So since it's a /20 swap back the oe premuffler and then use whatever muffler floats your boat

did the install the O sensor circuit when it was federalized?