StanAE86

I'm going to be trying to do the "flip the flange" modification to some 993 heat exchangers...for fitment on my 964. I have the exchangers and the cats off a 993 already.

I know people have done this, has anyone used the 993 cats as well? All the pictures I can find on the net (well, actually, only 2 or 3 pics), all skip the cats. I don't want to do that.

With that, does anyone have any pictures they can share with me, where they have cats and the muffler?

This is one company I know of that does these types of mods, but they don't have any pics using a cat:

http://www.instant-g.com/Products/Exhausts/993Exhaust/
http://www.instant-g.com/Products/Ex...Out/index.html

Thanks.

pete000

I always thaught that would be a grteat mod. Not sure if the cats would fit though. Never seen it done.

SimonExtreme

Don't know about cats but I would bet a lot of money that the instant-g set up would be LOUD!

Colin 90 C2

If you look on Pelican, there is a DIY on flipping the flanges.
I recently completed the flange flip and it was pretty easy, although I went through more than a few dremel cut-off wheels. I ended up buying an air die grinder and using diamond tipped wheels that are available from Harbor Freight for less than $20 for the tool and the wheels.
The hardest part was realigning the flanges for welding. Luckily, I had the engine out (still out).

I have been thinking of exhaust sytems and will probably go with compact cats and bullet mufflers.

StanAE86

I heard you can grind out the inside of the pipe to break the OEM weld to the flange? Or did you just cut the pip and flip it?

Thanks!

Colin 90 C2

I ground down the weld on the interior of the flange and the header tube. I think it is a better solution. This way the flange is free to be positioned correctly. It also gives you a better welding area with minimal metal distortion.

StanAE86

Thanks Colin. Let me know when you get the motor in the car and start trying to figure out how to make things fit...I think that will be the hardest part. Right now, I'm thinking of keeping the cats and running muffler bypasses instead. From the way the pipes run, it'd be a J bend into an exhaust tip. I'd rather get busted for no muffler than no cats in California.

964 C2R

"I recently completed the flange flip and it was pretty easy"


Dear Colin,

Do you have any pictures of the result per chance?


Regards, Daniel Saxlid

robmug

What's the benefit of this mod?

SimonExtreme

Don't ask awkward questions!

Gus

more HP

Colin 90 C2

try this link
http://forums.pelicanparts.com/showt...eat+exchangers

I know there is another link on Pelican and I will find it for you.

Here is the definitive thread with awesome pictures
http://forums.pelicanparts.com/showt...hlight=993+hes

SimonExtreme

I have heard this but based on data on other threads, is there really a gain to be achieved?

Colin 90 C2

Apparently most of the gain in hp between the 993 and the 964 is due to the exhaust.
The 993 HE's have a much better flow pattern than the crossover pipe associated with the 964 HE.
Much more like aftermarket headers, such as the SSI's that are popular with the 911SC's.

Plus it gives you the option of true dual exhausts.

SimonExtreme

Well, I stand corrected but looking at the figures Colin has produced, it doesn't seem to be the answer. I had thought it was the varioram but that while it gave an imporement over a 64, when it came to tuning further the 64 system was better.