SuperCarrera

Does anyone in this group have specific dyno. information on how much horsepower is lost in a stock (very early model year) 964 catalytic converter?

I've been told that the later (1995) 964 cats only cost a few H.P. (less than 5) but I'd really like to know the figures for my 1989 C4 cat. (my understanding is that the early 964 cat is different than the later version)

Any input or guidance would be most appreciated.

Thanks...

MelissaM

Tim,

I don't know how much h.p. is lost with the stock catalytic converter. I have read Bruce Anderson's comments that the 964 exhaust system (not just the cat) isn't very efficient power-wise, but that he hasn't found a good aftermarket solution.

You mention the cat. in the '95 cars. Are you sure they weren't referring to the 993? The 993's exhaust system is more efficient than the 964's.

I don't know if the catalytic converters changed during the 964's production run, but I'm sure someone on this board will chime in.

-- Melissa

Adrian

Dear Melissa,
There are different cats but this is an individual national requirement. All the cats in the USA 964s are fundamentally the same. The total loss from flywheel to wheels on a C2 is 15% and a C4 28%. A cat bypass can give variable advantages but around 4HP at the flywheel is sort of average on its own. Some claim up to 8HP. This would put original cat losses at around 3 or 4HP. Nothing major.
Ciao,
Adrian
911C4

SuperCarrera

Thanks Melissa and Adrian...In regard to my comment on the later cats -- I guy I know with the same supercharger set-up I have in a 1995 C4 had his dynoed with and without the cat and he reported a loss of only 4 H.P. (right on target with Adrian's information) so a cat-bypass was not considered a worthwhile modification.

However, when I asked him about my set-up, I was told that his car had a later, more high performance cat than the early 964's (?).

Adrian, do the figures you're quoting refer to a specific year?

Bill Gregory

Catalytic converter info: 964's with option M150 don't have cats, as that option is "operates with leaded gas". There are two catalytic converters, one for Japan and one for everyone else. There was one used up to 1990, one for 1991, and one used for 1992 on. Both the to 1990 and 1991 cats have been superceded by the 1992 cats, for both Japanese and non-Japanese markets. One of the big accomplishments in the 3.6L 964 engine was that they were designed for the catalytic converter in all markets. The cat is a metal monolith converter, as opposed to prior ceramic converters, with one benefit being to allow better flow through. Hence lower hp loss.

There are racing and other high flow converters available. FVD comes to mind as one vendor that sells them. As a related aside, Joe Fabiani of Fabspeed says bypassing the cat will actually lose low and midrange torque, which you get back to some degree at 5000 rpms and higher.

Herbie

Excuse me Adrian: 15% for a C2 and 28% for a C4 are intended as power lost in the trasmission ? It's a lot of power!

Richard H

Herbie,
That's right, a ball park figure. Some state even more.

Richard.

GP964

Hi there folks,

On a Mustang Dynn, with cat 206hp and w/out straight pipe 219hp. Adding a custom chip 233hp and plan to dyno w/ my new Autothority MAFS w/ custom calibrated chip. Feels smooth and alot stronger.

Thanks

George Stevens

Here in the UK it was not a legal requirement to have a Cat fitted until January 1993

As my RS is a 1992 model I have had a de-cat conversion with a Roock ECU chip.

My car was only putting out 220 bhp as the old cat was blocked, after the conversion it is now producing 270 bhp and with only 1200kgs feels sensational.

below is a picture of it's first outing at Goodwood circuit.

Adrian

Dear Herbie,
My figures are not ball park figures they are actual data gathered from all over the world. I have dyno reports from over 50 964 owners from C4s to RS3.8s. Them is factual figures,
Ciao,
Adrian
911C4

PS: I forgot to add. Switzerland also has its own kat version. In fact Switzerland has its own complete exhaust system. Only parts actually show up in the parts catalogue. The rest was installed after delivery to AMAG.

Roland Kunz

Hello

The catalyc convertors changed within 92 and also later in 94. 92 versions are the same ones used with the RS and have a bit more flow but much more heat resistance. The lambda probe and catalyc case changed as well.

Grüsse

SuperCarrera

Thanks to all again for the helpful input and information...

Pietro

has anybody ever seen how a M150 version stock cat-bypass looks like? I have read elsewhere that some reported even power losses by simply emptying a stock catalyst and I was wondering if the stock-empty-catalyst is anything different from a stock-catalyst-emptied.
MF Gruesse!!!
Pietro

n1ne11

Wow, this is an old one.

I have a swiss 964, but I am not sure about delivery in Switzerland at the time or in DE/FR? Thought there is an AMAG stamp in the book (Replikat). When I made an Options request on Stuttcars online, I found out my car was delivered with Option M150, which would be:

150 Operates with leaded gas (without catalysator)

Is it possible that this is a proof it was a originally delivered Swiss car? Did they order all their 1989 911s with this option, because they would modify Cats/exhausts after production chain anyway?

Wondering, if someone knows the answer! (also if someone knows the answer to how recover original color code of a car...). Thanks!

Railmaster.

I remember a lot of family saloons had their engines enlarged with 100 cc to compensate for the catalytic converters when they were introduced so around 3%?