BrandonsZ Posted November 28, 2005 Share Posted November 28, 2005 I would have been the first to say, "WHAT are you NUTS????!?!?" when I thought of putting a cat on my car but after careful consideration one day as I choked on my own exhaust fumes at a stoplight with a tail wind I decided that my car could use some pollution controls. I drive it every day about 50mi and about 10 of those miles are in stop and go traffic lights. About a month ago as I was tearing up from the fumes (ok so I'm a wimp sue me) I decided to look for a high performance cat. I purchased the MPE-94109 from Summit. I figured it would not only tone down the smell but also tone down the sound (was a bit loud for my taste as well especially between 45 and 55mph where 6th just doesn't feel right and I pop into 5th it would drone like a SOB.) Well, I replaced the glasspack with the cat and immediately noticed the smell was gone, but the exhaust was actually louder then before! A cat and a flowmaster muffler were not enough to quiet the beast. So then I added a spiral flow muffler MOR-94051 and now it's nice. It's still louder than any car I hear on a day to day basis but it no longer drones or smells. Of course I didn't Dyno it, but I did not notice one bit of difference in power at WOT above 4k. We'll see about MPG and I'll report on any change there. It does smell at WOT but instead of filling the driver's compartment with gasoline smell, it is filled with what is remarkably like freshly cooked pepered eggs. Comments? Quote Link to comment Share on other sites More sharing options...
PeterZ Posted November 28, 2005 Share Posted November 28, 2005 Good job. I appreciate cleaner air (and the smell of breakfast). Did you add heat shielding? If your engine was terribly rich you may overheat the cat damaging the undercar and also do internal converter damage. The inlet side of the cat will look like moon rocks. Did you do any pressure gauge readings before and after the cat? I have welded brake fittings on customer's pipes so they can temporarily attach pressure gauges to quantify the amount of pressure drop and determine if the cat is plugged. Saves a bunch of time diagnosing a new problem knowing the cat is clear. Quote Link to comment Share on other sites More sharing options...
BrandonsZ Posted November 29, 2005 Author Share Posted November 29, 2005 Good job. I appreciate cleaner air (and the smell of breakfast). Did you add heat shielding? If your engine was terribly rich you may overheat the cat damaging the undercar and also do internal converter damage. The inlet side of the cat will look like moon rocks. Did you do any pressure gauge readings before and after the cat? I have welded brake fittings on customer's pipes so they can temporarily attach pressure gauges to quantify the amount of pressure drop and determine if the cat is plugged. Saves a bunch of time diagnosing a new problem knowing the cat is clear. Good ideas, if there is a problem I bet I'll hear it in the tone or smell of the exhaust. The way my exhaust is setup, a few bolts and about 5 minutes is all it takes to remove the cat and examin it. If it fails for any reason, I'll have to abandon the idea but I hope not. I'm going to check it after 1k miles. Personally I doubt backpressure is an issue based on the sund it made with just the cat on there and no other mufflers, it didn't sound much unlike having one straight pipe. And there was not even a hint of less power. I'll let you know if anything happens. Quote Link to comment Share on other sites More sharing options...
PeterZ Posted November 29, 2005 Share Posted November 29, 2005 Thanks, I'm interested in the outcome as I haven't installed a cat on a carbureted V8. I'm under the impression that excessive fuel will cause internal overheating and damage over time. The bad cats I have taken off doing regular service work were always caused by some sort of engine management problem. Fuel pressure regulator, engine misfire, etc. I did install a two cat system on a 280Z with a 92 vette engine and they needed some additional heat shielding because they were close to the tunnel. No problems there. Good luck. Quote Link to comment Share on other sites More sharing options...
randy 77zt Posted December 1, 2005 Share Posted December 1, 2005 cat converters where installed to mop up the exhaust if somebody forgets to tune up thier car.it is best if all the hc's were burned up in the engine.if your car isnt jetted /tune correctly the cat will run hot and possably plug up.get a wide band 02 system and use to tune your jetting so the cat isnt overloaded . Quote Link to comment Share on other sites More sharing options...
Moridin Posted December 1, 2005 Share Posted December 1, 2005 cat converters where installed to mop up the exhaust if somebody forgets to tune up thier car.it is best if all the hc's were burned up in the engine.if your car isnt jetted /tune correctly the cat will run hot and possably plug up.get a wide band 02 system and use to tune your jetting so the cat isnt overloaded . I believe they also help reduce NOx emissions too??? Quote Link to comment Share on other sites More sharing options...
BrandonsZ Posted December 1, 2005 Author Share Posted December 1, 2005 I believe they also help reduce NOx emissions too??? Only if it's 3-way I believe. Quote Link to comment Share on other sites More sharing options...
wingnutthehutt Posted March 9, 2006 Share Posted March 9, 2006 The smell of eggs is the cat "firing" It's part of break in. You're lucky it smells like peppered eggs. My parents had a 92 BBC Suburban and with the cat it had from the factory it smelled like Rotten eggs. Quote Link to comment Share on other sites More sharing options...
BrandonsZ Posted March 13, 2006 Author Share Posted March 13, 2006 I have noticed a significant imporvement over the last few months. It only smells now if I floor it or decelerate for a long slow hill in a low gear, and even then, much less than before. I was kinda worried my cat might be getting clogged or something because of that, except my gas smell never came back. Quote Link to comment Share on other sites More sharing options...
Nigel Posted March 14, 2006 Share Posted March 14, 2006 I've had a catalytic converter in my 240Z Turbo for the past 2 years now. My friends and I are amazed at the difference. You don't get out of the car smelling like a refinery, and you can stand behind the car while it's running and not pass out! For $100CDN, it's a cheap way to escape the rolling gas chamber. Mind you, it's not a solution for bad tuning. Nigel '73 240ZT Quote Link to comment Share on other sites More sharing options...
Guest jinsei888 Posted October 22, 2006 Share Posted October 22, 2006 mmmmm....peppered eggs sound good right now! As for the cat, yah I haven't ordered the exhaust yet, but I'm sorta juggling between straight pipe or cat... Quote Link to comment Share on other sites More sharing options...
BrandonsZ Posted October 24, 2006 Author Share Posted October 24, 2006 Well, either the cat is burned in or burned out, I'm not smelling even a hint of exhaust anymore, no gas smell, no cat burning egg smell. It's nice. I almost forgot I used to have a problem. Quote Link to comment Share on other sites More sharing options...
VinhZXT Posted October 26, 2006 Share Posted October 26, 2006 I can't disagree with you with the CAT. I just took my LS1 Z out today with open headers. As soon as I open the door I was overwhelm with the exhaust gas and it made me sick until now as I typed. I definitely have to put the CAT on my car. Otherwise I will not live long driving this car in a stop and go traffic especially this car has side pipes. Quote Link to comment Share on other sites More sharing options...
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