Matt Lane

Got underneath my new-to-me project 1986 the other day, and noticed it has a Cargraphic catalyst like this one. Nice shiny Cargraphic labeled heat shield too.

Wonder how many Euro 911's would have had one of these installed? Any thoughts on the performance degradation vs. stock no-catalytic converter?

Cheers

Matt

Amber Gramps

I'd gladly give up a bit of performance to not have to smell untreated exhaust. I had my cat off years ago and ended up giving away the bypass to a fellow rennlister. Raw exhaust is just something that I had forgotten about and don't miss.

Drisump

Quite a few I think, the "gray market" cars had to comply with many of the regulations upon entry into N. America. My Euro probably had it when it entered the US but before I got it, it was removed. Cheers

Matt Lane

Any idea what this does to performance on the Euro 3.2? I know there was a higher HP spec due to the higher compression. Wondering if anything is being sacrificed with the addition of the catalytic converter (besides the smell)!

Cheers

Matt

Bill Verburg

for MY86 there were 2 normally aspirated 911 engines
930/20 RoW 170kw/231hp, eng # 63G 00001-10000, cr 10.3
930/21 US, J, Australia, Sweden, Switz. Option code M298 152kw/207hp, eng # 64G 00001-10000, cr9.5

biggest diff is the cr and O sensor on the /21, tuning parameters too of course

check the eng #s to be sure what it was originally, lots of the 231hp(/20) versions had a cat added when they were brought over to North America

Matt Lane

Thanks Bill, will check.

The transmission is definitely original (with the Euro cooler). Assuming it is the original Euro engine, anyone know the performance difference between running as originally designed (no cat) vs. adding one?

Best,

Matt

Bill Verburg

Again, some of the Euro cars had the M298 option, you want to see if it's a /20 or /21

the /20 just ran in open loop mode all the time, the /21 was only in open loop at WOT, the rest of the time the signal from the O sensor controlled mixture and timing.

If it's a /21 w/ an add on O sensor it depend on what mods were done to the DME to use the O signal,

for the most part the main performance related things are going to be fuel mileage related, the /20 will likely get somewhat better mpg do to tighter mixture/spark control and max performance at WOT where the lower cr and poorer exhaust flow come into play

Matt Lane

Thanks Bill, will check the engine code to be sure.

Car was a Porsche Bremen delivery, serviced all its life in Germany, and based on the records, the Cargraphic cat was also added in Germany later on (90's). I assumed as an addition, not as a replacement, but will see.

Cheers

Matt

Mondrian

IIRC the difference between euro (231) & US (216) is around 15 but as already mentioned engine internals were also different - I expect the cat would account for at least 10 of that i would expect that the chip would also need to be changed/remapped accordingly.

theiceman

think 10 is very generous, Porsches have always used high flow cats which provide very little detriment to HP.

would be interesting to get a factual before and after dyno run though.

Matt Lane

In my case, it's not how much to gain - it's how much may have been lost.

The cat is not stock, and I can guarantee there was nothing done to the chip to account for its installation on an engine map that was not designed for it.

Cheers

Matt