New M&K Prototype masterpiece for 3.2
 

I was talking to Ben at M&K a few weeks ago about possible exhaust systems for my 3.2L Carrera restoration project. I had just rebuilt my 3.2L engine with 77K because it was burning a quart of oil every 350-400 miles(bad valve guided). I put in new rings(alusil cylinders), 964 cams, extrude-honed intakes, MK 1in /1 out muffler and a SW chip. The car runs and sounds great. However, I felt my stock heat exchanges and stock cat were too restrictive. Ben started thinking and came up with a great idea, remember, I live in the Peoples Republic of CA, so California emissions is the 800 lb gorilla. We decided to go with SSI's because I need heat and liked the quality of the headers. We decided to install two 300 cell cats in parallel and plug into a MK 2 in / 1 out muffler. I am using the single outlet muffler because I do not want something too loud. Hear are some preliminary photos. I would like to state that I talked to many shops about custom fabricating a high performance header/cat system but Ben was the only one who would not only agree to do the job but also call me back and do the groud work to source the cats and other materials. Ben is by far one of the best Porsche specialist to do business with. His customer service and help is a 11/10. Please comment.

Note: These are preliminary photos during the fabrication process. The final welds have not been set. I do not have a total cost of the system yet, however, it is much cheaper than the GHL system.

http://forums.pelicanparts.com/uploa...1204083798.jpg
http://forums.pelicanparts.com/uploa...1204083819.jpg
http://forums.pelicanparts.com/uploa...1204083836.jpg
http://forums.pelicanparts.com/uploa...1204083864.jpg
http://forums.pelicanparts.com/uploa...1204083884.jpg

Wow, that's some nice work!! Post a .wav file when you get it on the car please:D

Great Solution
 

I have a '79SC and also live in So Cal so I have been reluctant to dump the existing heat exchangers for SSIs because I was not keen to swap out the whole system prior to the smog test. However, this solution with the little cats could push me over the edge. I hope he keeps notes....
Kevin

OK, you have cats, and will probably pass the sniffer test. But, will this pass the visual, and will the State of California approve those cats for "on road" use? Therein lies the real rub, IMO.

I can pass Texas emissions, which aren't lax in any way, but it is the visual in Cali that had me worried in my move back there.

Ditto.
What's the significance of "300 cell cats". Are these less restrictive than 'normal' stock cats, or 100 or 200 cell cats? Are they louder? If so, how does this dual cat system compare to a stock single cat? (loudness, emissions, etc)

its a pre obd 2 car so a visual check isnt a big deal, you can pretty much do what you want. I hope it passes smog for you man, its getting bad these days with all the new regulations being added, Im not even sure if that will pass a sniffer test anymore though. keeping your "stock" exhaust and having your "hotrod" one on the side is the way to go. Labor is cheap compared to re-inventing the "right" parts to get through. good luck with it, those are some nice looking ideas.

here's another possibility if you want SSI's and a cat. not an off the shelf thing but instead a 1-off deal. a good custom shop should be able to make you something similar.
http://forums.pelicanparts.com/uploa...1204102824.jpg

Ben does his magic again :)
Looks like a design that could be interchangeable with street adapters, so you can run without the cat's on the track...

Is there any concern about the heat from the cats and their proximity to the cam housings?

I don't think the one cat after the Bursch muffler will do much for emissions, and I wonder if it will pas visial? I'm under the beief it has to be upstream of the muffler to do it's job with hot gas?

Well these cats are certified for CA and I will be sending the reg cards to Mark when done. He will also get street adapters so no cats. You do have to have the cats as close to the heads as possible to work properly.

As to heating up the cam /chain boxes that should not be an issue

A cat has to reach a certain temperature to do much good. The further from the exhaust ports you install the thing, the cooler the exaust gases get. It might be enough to pass a smog test, hard to say without trying it. It might depend on the model year tested, as the standards got tighter as the years passed.

One thing I'd suggest is changing the piping between the cats and the muffler, to reduce the sharp bend aft of the cats. I don't know what the muffler looks like inside but if possible, I'd change the angle of the inlets and try and get one 45 degree bend between the cats and the muffler, instead of the sharp S-bend shown.

Interesting project.

JR

+2 for Ben! one for the 79 and one for the 88!
Great service and support!!

MK masterpiece
 

I have passed the CA smog test twice before with this car. That was before I rebuilt the motor(was burning tons of oil). I am certain the new cats in parrallel will be more efficient, cleaner burning than the sinlge old cat. My only concern is passing the visual. I posted recently asking people where a good shop was in Orange County were I could sort of blow by the visual. I am certian my car will pass the exhaust gases test. Also, the bends in the exhaust are of little concern to me as far as performance goes.

part of the reason for this project was to be able to use any muffler so as bolt on as possible. the s bends will slow flow but to be honest there will be test pipes in here most of the time..

As to passing smog. I know allot of people that pass with no cat's..:)

Hmm,

Let me put on my salesman hat for a minute. Why not let the "bolt on part" relate to the compatibility with SSI heat exchangers, which you wouldn't want to start procucing yourself anyway. Make the rest of the system a custom set-up, with the cats, test pipes and muffler compatible with each other and not your standard muffler.

The way I see it, there are two types of cars, those that need to be smogged and those that don't. Those that don't get tested don't need this system and those that do likely don't already have one of your 2-inlet mufflers (if they do, they are gluttons for punishment, to be swapping exhaust systems each time they test.) Worst case, a guy that already has your muffler could sell his old one on the Pelican board, it wouldn't last long...

Just thinking out loud....
JR

I would not quite agree with you there. Here in Sweden there are now new regulations from some organisers that competition cars must run with a cat during racing. So on my SC, I would need the cat set-up when competing, and not when driving during off the track - so for me a modular system would be nice.

Damn, I am so glad I no longer have to suffer through emissions testing here in Illinois.

If you re-read what I was saying, you'll note that what I proposed was modular, with cats and "test pipes" interchangeable as needed. The difference was whether or not it would be compatible with his previous mufflers, or not. That was an assumption he was thinking would be important, but I think it doesn't matter much.

Hey, it's not up to me. It's Ben's deal.

JR

This is a nice idea; GHL has been making their version of heat exchangers with sport cats and dedicated muffler for a while. But ben's version uses SSi's and a stock inlet muffler= much better

The issue with this set up is heat. You are basically installing 2 very hot ovens right next to the chain boxes and lower valve covers. Gaskets and seals will be fried in short order.
Some serious thermal protection needs to be employed to protect the engine

Keep working on it Ben. I will be in line for a set up once you solve the heat problems