Anyone using a HI Flow Cat ala Dansk?

[NY65912]

Getting ready to upgrade the exhaust on the 85 911 widebody over the winter, I'm thinking of using a Dansk Hi Flow Cat as opposed to a Euro pre muffler with a Dansk 1 in 1 out ss muffler. Anyone have any experience with this combo? I want more hp but not a helluva lot more sound. Any thoughts are welcomed.

(PS: I did a search)

Mike

[NY65912]

Sorry, but Bump.

[Steve W]

Mike, most of the guys using the high flow metal cats are in Europe, where the car's taxation rate is based on the emissions level of the car. EU1 taxation rate would be for a stock Euro that was later retrofitted with a aftermarket ceramic cat and replacement 207 hp DME, while EU2 has a lower taxation rate and would apply to a stock 3.2 with a factory installed ceramic cat. With a very efficient, high performance metal cat, with longer catalyzing monoblocks, it may be possible to clean the exhaust even better than the stock ceramic cat and allow a car to be rated EU3, an even lower taxation rate.

Bernd Andritzky an engineer at BMW and myself dyno tested a lot of performance modifications and chip coding variations for a stock 89 Carrera and that included dyno comparisons between a standard European premuffler, a high performance aerodynamic metal cat, and the stock ceramic cat. What we found was that a European premuffler and a high performance metal cat both delivered the same hp gain over the stock ceramic cat. Because we are both engineers, we have computed that the premuffler and metal cats by themselves are good for 6 hp. Installing either on a stock Carrera will net a 8 hp gain, because a stock Carrera is extremely rich above 5000 rpm. The increased flow by installing anything that increases the exhaust flow, will serve to reduce the excess fuel mixture further, adding the 2 hp difference. That is why just adding a sport muffler also improves peak high rpm power.

If your objective is just to improve performance, a premuffler with a freer flowing sport muffler is a lot less expensive and produces no real additional sound level difference over the stock cat. If you want to meet emissions, and have the bucks to spend, then by all means go with the metal cat with sport muffler. Your will gain with either combination will yield 12 hp alone on just on these changes.

[NY65912]

Stevw W.

Thanks for the idetailed info Steve, just to let you know the exhaust I'm doing is a prelude to ordering a chip from you. I figured I might as well do the exhaust before I order the chip, unless you see it another way. I think what I'll do is install the Euro pre muff and the Dansk 1 in 1 out muffler, I'm trying to get as much power as possible without that much more engine noise. I do want more sound, but not enough to stop the wife from wanting a ride.....(hey wait not the worse thing)

Any recommendations would be appreciated.

Mike

[Rot 911]

Mike, I have a Dansk euro premuffler, new in the box. I bought it to put on my '86, but have now decided to go with the SSI back date. If you are interested in buying it let me know. $260 plus shipping.

[Sonic dB]

Good thread...this SportCat, along with Steve W. chip may be the answer for my car...