Tom M'Guinn

I am thinking about getting a factory fit converter from DEC but am having a difficult time confirming which part number fits the 944 turbo. Can't tell if it is PO82603 or PO82609 or PO82609B -- anybody know for sure?

PEvans

I think it is PO82609B. That has a two-bolt flange on the bypass that should mate with your exhaust system. If you know your present cat does not have that flange I believe it is PO82609. I bought one in 2008 and as near as I can tell from my notes PO82609B is the part number. Sorry, I am not positive.

In the pic below you can see the flange on the cat on the right and where it is supposed to mate on the left. My DEC didn't really fit and they had to extend the pipe from the left to reach the flange on the replacement cat assembly.

This is an '89. The front of the car is to the left.

What is your source? I may need another pretty soon.

PEvans

Here is a view of a factory cat, you may be able to see the two-bolt flange a little better, or at least see what the factory one looks like.

PEvans

I just saw your other "downpipe" post. You probably know more about these flanges than I do. In any case, I think PO82609B refers to the version with the bolted flange.

Tom M'Guinn

Yes I am familiar with the change from clamp to flange thanks. My confusion is based on DEC's own site pulling up PO82603 for the turbo, even though other places all seem to point to PO82609 with or with B for the flange. The pictures I've seen of the two also suggest 609 is for the turbo, not the 603. Disappointing to hear yours did not bolt right up though. I'm still working on the right part number and haven't picked a place to buy it yet.

PEvans

There is a DEC catalytic converter offered by Automotion (search for P904975C) that looks like the right one. I am not sure what their numbering represents.

Let us know what you find out.

PEvans

I see what you mean about DEC's site. The search results are different from what shows up in the "application guide" and they may both be wrong. The search results show both the PO82609 and PO82609B for the 944, but don't specify the turbo. The pics look like the same part and it looks like the turbo variant. (I think it is correct -- and I'm sure you know for sure -- that the catalytic converters for the turbo have the bypass pipe, and are nothing like the catalytic converters for the NA)

Tom M'Guinn

Exactly. From the pictures, it looks like 609. I also don't think the n/a had the additional flange issue, so that would only make sense if the 609 were for the turbo. I'm inclined to order the 609b version (from someone with a good return policy).

Tom M'Guinn

Well, I wrote to Calconverter on ebay and they confirmed the DEC chart is wrong, and that the correct part number is PO82609B (or PO82609 without the football flange for wastegate dump tube). So I ordered that part number and am happy to report it appears to be a dead ringer for the factory cat. I will not be able to install it for a few weeks, and will report back then on how it fits. I ended up ordering it from an ebay place called wundercarparts because they stocked it in CA and shipped it free, and had the cheapest price at $518.

PEvans

That seems like a good price. Thank you for reporting. Good luck with your install and the fit. You should ace the smog test, but my experience is you barely get by the one in two years. Keep the warranty paperwork.

Tom M'Guinn

Well, I must say I'm surprised by how little catalytic material there is in the wastegate dump tube -- it's essentially just a little honeycomb plug that fits in the dump tube. Since a good portion of the exhaust goes through the WG during the test, here's hoping that little piece is enough to do the trick. It's fully CARB approved for CA, so I assume it's enough...

PEvans

Oh, you will blow the doors off the first test. You will be totally fine if your car is running half decently. Here's hoping you have better fitment than I did.

Frankly I am happy DEC is still making these things so we can keep our cars on the CA roads.

Dave W.

I'd recommend you remove the new cat after passing the test and store it for the next two years. For some reason the aftermarket cats seem to loose effectiveness after a few years.

Laust Pedersen

I have noticed a functional change in (aftermarket) catalytic converters as a function of production year.

The early 3-way converters initially had a “good amount” of noble metals (platinum, palladium and rhodium), which resulted in a very effective catalytic process and quick warm-up. It had the disadvantage that if the AFR was too rich it could easily melt the honeycomb matrix.

They then reduced the amount of noble metals (current situation), so the meltdown was much less frequent, but the warm-up took much longer and it sometimes is difficult to get it to function adequately. There is an obvious financial incentive for the manufacturers to skimp on the noble metals as much as the law allows.

I now see that there are special California cats.
Does anybody know what the functional differences between converters for California and the rest of the country are?

Laust

Tom M'Guinn

I don't know, but would suspect in many cases the difference is simply the certification and labelling procees (and associated cost).

This dec aftermarket has a little honeycomb stuffed into the dump tube (no bulging canister like the factory) so clearly less catalyst material than stock -- although maybe equally effective compared to less efficient 80's technology? The main cat is about the size of the factory cat, but I wonder how much of the exhaust actually passes through that at low load...?