CAT alternatives - punch out... straight pipe. 1980 SC

[heimtun]

Any thoughts regarding the CAT on a 1980 SC?
TIA,
Wayne

[Oh Haha]

It depends on if you want/need to keep the CAT for any reason. Do you plan to sell the car at any time? The next owner may need the CAT.

I have the factory premuffer which works well with my Flo-Pro muffler. A test pipe will probably be a bit louder depending on what muffler you install.

What is the goal for the car? Track? Street?

[Jdub]

Any broken material inside already (I mean, a LOT)? If so, maybe it is a candidate for a poke through. If not, put it aside and do as I did by purchasing a pass-through pipe, with new gaskets and possibly new nuts and bolts. Bring to a muffler shop and have them simply R&R the nuts and bolts. Then go home and pull the Cat for the pass-through in your driveway with new gaskets.

[heimtun]

t depends on if you want/need to keep the CAT for any reason. Do you plan to sell the car at any time? The next owner may need the CAT.

I have the factory premuffer which works well with my Flo-Pro muffler. A test pipe will probably be a bit louder depending on what muffler you install.

What is the goal for the car? Track? Street?

Thanks Wayne!
No plans on selling the car. Good thought re next owner potentially needing the CAT - I'll keep that in mind.
You mention a factory pre-muffler - does that replace the CAT? If so, could you provide part number and/or sources.
This is a street car with some DE.
My thoughts re CAT are three fold - first, I need to find a small exhaust leak that a mechanic suggested might be one of the exhaust joints, second, the CAT very well could be getting a bit clogged and third, it would be nice to have a little throatier sound - not too loud though.

[Arne2]

I've tried both a pre-muffler and the stock cat on my 3.2, couldn't tell any difference for normal street driving, other than the foul smells (from the stuff the petroleum companies are pleased to call gasoline these days) when the pre-muff was installed. So I run the cat now to clean up the odors.

Track use may be different, you might notice a small improvement at high RPMs.

[heimtun]

Originally Posted by Arne2

I've tried both a pre-muffler and the stock cat on my 3.2, couldn't tell any difference for normal street driving, other than the foul smells (from the stuff the petroleum companies are pleased to call gasoline these days) when the pre-muff was installed. So I run the cat now to clean up the odors.

Track use may be different, you might notice a small improvement at high RPMs.

Cool, thanks for the info Arne.

[Bob Kontak]

Originally Posted by Arne2

Track use may be different, you might notice a small improvement at high RPMs.

A little more rumble at lower RPM's - it's favorable. Power addition on a stock US SC? Sure, but you won't need to upgrade your brakes, if you know what I mean.

I bought the fabspeed pre-muffler. Main issue was the copper gaskets the sent with it. Would not seal where they met the cat upstream. I think I used two stock gaskets and know I used some locally bought muffler goop to seal that joint.

[merlinfe]

I found a used Euro pre-muffler and had a shop weld in an O2 bung. Install was relatively painless except for the rusted in bolts on the cross over tube for the exhaust.

The sound is phenomenal compared with stock. I have a custom magna flow set up for a muffler.

Performance wise, there was a very slight loss of low end torque (1500-2100ish) but power came on earlier and was felt evenly through out the rev range. The car also seemed to rev easier up to red line. Its more of a zing now than a slow build up. My CIS is tuned pretty good at this point, so this may help.

As far as fumes go, for me, there are none to speak of but I'm using Ethanol-free mid grade unleaded as per the owners manual. I don't know if its available in CT.

Its pretty easy to switch back to a cat and sell the parts you buy if you don't like they way it turns out as long as you find used bits.

Good luck,

-Steve

[heimtun]

I'm using Ethanol-free mid grade unleaded as per the owners manual. I don't know if its available in CT.

It is available... quite pricey though.

Thanks Steve & Bob

[Jdub]

This is what I am using: Bursch Catalytic By-Pass.

[911SauCy]

Originally Posted by heimtun

It is available... quite pricey though.

Thanks Steve & Bob

I'm jonesin' to know where?

[Arne2]

Originally Posted by heimtun

It is available... quite pricey though.

Here in Oregon, ethanol-free is only available in 92 octane premium, and despite the recent drop in gas prices still runs over $4.50 per gallon. My car is reasonably happy with the ethanol-infused stuff at not much more than half the price, so that's what it gets.

[Oh Haha]

My premuffler is the factory installed unit with no 02 hole. Except for the muffler my exhaust is stock for a ROW SC.

I didn't see any HP gains but it sure sounds good!

[heimtun]

Originally Posted by 911SauCy

I'm jonesin' to know where?

I'm pretty sure some of these stations carry VP Fuels.
Locate Mercury Gas Stations | Mercury Energy
Let me know if you find it there.

[luyckxglen]

guys Bursch Steel Cat By-Pass, with Oxygen Sensor, 911
(1978-89) works for the carrera 1985 right?

[blpetry]

I'd take it to a muffler shop and have them remove the CAT so it can be inspected, then you'll know what you have. If its good, I'd throw it back on and run it. If its plugged or the catalyst is crumbling, you can either gut it or get one of the bypasses.

My car had a gutted cat what I bought it, and I have to say if replacements were less expensive, I'd run one. The car doesn't smell bad, but you do have an odor in the exhaust when its warming up.

If you do go to an exhaust shop, order new gaskets and bolts from our host before you go.

[RarlyL8]

M&K Bypass Pipe versus Pre-Muffler.
Add this and chip to correct the AFRs and you get a similar increase as seen in an SSI conversion.

[heimtun]

Originally Posted by RarlyL8

M&K Bypass Pipe versus Pre-Muffler.
Add this and chip to correct the AFRs and you get a similar increase as seen in an SSI conversion.

Thanks for this info! I've got a 1980 - not sure that there are any options for different "chip". Am I missing something?
Thanks,
Wayne

[CCM911]

As said before, do not poke through the old one unless it is bad. Just buy a test-pipe (I've been "testing" for about fifteen years now). You never know when you may need the cat.

[blpetry]

Originally Posted by heimtun

Thanks for this info! I've got a 1980 - not sure that there are any options for different "chip". Am I missing something?
Thanks,
Wayne

84 and up models have different engine management and can be "chipped", sadly our SCs and earlier models cannot.