zeiss150 Posted January 18, 2011 Share Posted January 18, 2011 Hi Guys I just bought a Catalytic converter that I'm going to put on my 72 240z and I'm wondering where is the best place to put it. I have an L28 with 2.5 inch exhaust all the way back. The cat is 13 inches long and 4" deep 9 inches wide. Any suggestions? Thanks Matt- Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted January 18, 2011 Share Posted January 18, 2011 Generally, engineers want to get the cats to light off as quickly as possible so they usually place one as far forward as possible. Quote Link to comment Share on other sites More sharing options...
zeiss150 Posted January 18, 2011 Author Share Posted January 18, 2011 So between the 2 into 1 and the next straight section? Will it fit there? Or should I just put it as close to the engine as I can fit it. Anyone done this? If so PICTURES PLEASE! Matt- Quote Link to comment Share on other sites More sharing options...
jc052685 Posted January 18, 2011 Share Posted January 18, 2011 Just put it where the cat would go on the 280z. Should be somewhere in the tranny tunnel. Quote Link to comment Share on other sites More sharing options...
t-tom Posted January 18, 2011 Share Posted January 18, 2011 Can I ask Why you would put one on your Z? Quote Link to comment Share on other sites More sharing options...
Dan Juday Posted January 18, 2011 Share Posted January 18, 2011 The sooner it gets hot, the sooner it starts convertin'. So yes, the closer to the motor the better. But, you knew someone would ask, why are you putting a cat on a '72? Quote Link to comment Share on other sites More sharing options...
jc052685 Posted January 18, 2011 Share Posted January 18, 2011 (edited) He is probably dieing from the fumes.... Which btw, if your car is not running 100% then it will just kill the cat in as fast as a few days... Edited January 18, 2011 by jc052685 Quote Link to comment Share on other sites More sharing options...
zeiss150 Posted January 18, 2011 Author Share Posted January 18, 2011 In answer to the question Why would I put a catalytic converter on a 240z... the answer is ... Because I'm tired of smelling like exhaust. And its worth the 3 BHP that I will loose to not smell like exhaust when I get done driving my Z. My Z is running great. It doesn't even smell that bad... but I don't want any smell. I heard they came from the factory smelling like exhaust... so why not put some tech into getting rid of that problem. My Cat should be here in a few days I'll post up some pictures of where I place it. Matt- Quote Link to comment Share on other sites More sharing options...
BLOZ UP Posted January 18, 2011 Share Posted January 18, 2011 (edited) Cats are actually one of the best devices to reduce emissions, IMO. You can get high flow ones and not feel dizzy at stoplights as well as pollute less. I'm no enviromentalist by far, but I will accept that cats and EGR have pretty much made cars pollute much less than they used to. Why, now, they keep focusing on more stringent standards for cars instead of the bigger industrial polluters is for another thread... The best place is as close as you can get to the valves, without worrying about fires... Edited January 18, 2011 by BLOZ UP Quote Link to comment Share on other sites More sharing options...
kiwi303 Posted January 19, 2011 Share Posted January 19, 2011 Has anyone taken a turbo manifold and made a turbo flange to Cat pipe, mounting a slimline high flow cat on an NA car where the downpipe fits on a turbo car? Quote Link to comment Share on other sites More sharing options...
Tony D Posted January 19, 2011 Share Posted January 19, 2011 Poor fuel control will kill that cat... Do yourself a favor and put an AFR meter on it, and insure you are at 14.7 under a majority of conditions, you will kill it. A catalyst is a pass-through device, it is NOT a 'scrubber'---if your AFR is correct, you will have no HC to make your eyes water. The ONLY time a catalyst is operational is during transitions (acceleration, WOT, decel if you don't have fuel-cut like EFI does.) If you idle or go down the road and get fumes and smell exhaust YOU ARE TOO RICH. And you will burn up or overheat that catalyst in short order if you don't fix that first. You don't slap it on and make it all better. Fix the problem, don't bandaid it! If you smell fumes, you are not 'adjusted correctly'! Quote Link to comment Share on other sites More sharing options...
2eighTZ4me Posted January 19, 2011 Share Posted January 19, 2011 Nor is your cockpit sealed off. The majority of the fumes sneak in through a bad hatch or taillight seal. I'd be checking those "lower cost" items first before stuffing a cat under there. You can also get a 90 degree exhaust turndown to point your exhaust at the ground. It makes a WORLD of difference. Quote Link to comment Share on other sites More sharing options...
ezzzzzzz Posted January 19, 2011 Share Posted January 19, 2011 A proper tuneup goes a long way to reducing noxious exhaust fumes. Don't forget the fuel tank vent hose seals, antenna drain hole seal, spare tire drain hole seal and those seals in the rear hatch itself. Also, if you run rich and overheat the cat there is a chance of setting fire to your car. Sounds kinda silly but those cats can get glowing red hot when failing. Imagine lighting off the undercoating or years of oil accumulation under many of these Z's. Many vehicles have temp sensors to warn of a cat overheating to prevent cat damage and possibly worse scenarios. Quote Link to comment Share on other sites More sharing options...
t-tom Posted January 19, 2011 Share Posted January 19, 2011 That was kinda my point Tony...putting a cat on is not going to fix the problem. Quote Link to comment Share on other sites More sharing options...
BLOZ UP Posted January 19, 2011 Share Posted January 19, 2011 A proper tuneup goes a long way to reducing noxious exhaust fumes. Don't forget the fuel tank vent hose seals, antenna drain hole seal, spare tire drain hole seal and those seals in the rear hatch itself. Also, if you run rich and overheat the cat there is a chance of setting fire to your car. Sounds kinda silly but those cats can get glowing red hot when failing. Imagine lighting off the undercoating or years of oil accumulation under many of these Z's. Many vehicles have temp sensors to warn of a cat overheating to prevent cat damage and possibly worse scenarios. A floor temp light, like on my 77 Cali model... Quote Link to comment Share on other sites More sharing options...
BLOZ UP Posted January 19, 2011 Share Posted January 19, 2011 The ONLY time a catalyst is operational is during transitions (acceleration, WOT, decel if you don't have fuel-cut like EFI does.) What? No it's not. The cat is operational all the time (once warmed up). They don't just convert HC, but also NOx, and CO. They work most efficiently at removing all 3 of those very close to stoich. They overheat when they have too much fuel that burns off in them. They are less efficient for various emissions at non-stoich. levels. Quote Link to comment Share on other sites More sharing options...
Tony D Posted January 21, 2011 Share Posted January 21, 2011 That was kinda my point Tony...putting a cat on is not going to fix the problem. You gave no reasons, just asked a vague question. Not really cricket here. If you want to make a question like that, and 'know' the decision might be a poor answer for something else, you should say so. From his verbiage in the post it seems like he didn't understand the function of a catalyst. My 73 tested out the tailpipe CLEAN to better than 1983 CATALYZED STANDARDS with only carb adjustments and a properly operating AIR system. I don't know how much 'better' he thinks it's going to get when a 73Z with a 71 SU and Exhaust manifold with functioning AIR will pipe CLEANER than the specifications for an 83. That's damned clean! A cat would work on my car ONLY if I RICHENED it up and then that would produce the HC EXCESS needed to start the converter, and sustain it's operation. The only reason cars with catalysts operate at 14.7 AFR is to provide FUEL for the CATALYST to let it work when needed. You can get JUST as clean on HC/CO simply with carb adjustments and AIR without putting a flaming hot brick next to your transmission. Emissions controls are sorely misrepresented and misunderstood. The ignorance surrounding them is phenomenal. Educate, when possible rather than just punctuate... Quote Link to comment Share on other sites More sharing options...
Tony D Posted January 21, 2011 Share Posted January 21, 2011 What? No it's not. The cat is operational all the time (once warmed up). They don't just convert HC, but also NOx, and CO. They work most efficiently at removing all 3 of those very close to stoich. They overheat when they have too much fuel that burns off in them. They are less efficient for various emissions at non-stoich. levels. No, they do not! They utilize the excess hydrocarbons in the exhaust stream to keep to an operating temperature to scrub excess HC and CO from the exhaust stream during transients. Early catalysts such as found on early cars were not really 'three way'---the EGR and timing did a majority of the NOx cleanup, as well as lower compression. Run a catalyst on a dyno with ANY modern car at WOT for a while and watch that catalyst overheat and melt down. They are NOT meant to clean up exhaust ... They are meant to clean transients. Later cats (OBD2 timeframe) do more things. But early bricks are very limited in their scope of cleanup. The reason they are 'effective' at stoich is that NOx is at it's minimum near that point. In reality, the best way to run the car is lean, on the verge of lean misfire where CO and HC levels are almost nonexistent (but NOx is very high)... Then you run a NOx specific catalyst. This is what large industrial engines do as they have a constant load and don't have transients to worry about. Quote Link to comment Share on other sites More sharing options...
rayaapp2 Posted January 21, 2011 Share Posted January 21, 2011 (edited) In answer to the question Why would I put a catalytic converter on a 240z... the answer is ... Because I'm tired of smelling like exhaust. And its worth the 3 BHP that I will loose to not smell like exhaust when I get done driving my Z. ... You think a properly working cat is going to ROB power! HAHAHAHAHA Riddle me this... How does adding heat into the exhaust stream going to slow the system down and rob horsepower? The answer is: its not. The catalytic reaction will have a much higher temperature at the exit of the cat. This heat actually DRAWS more exhaust into the front of the cat creating a low pressure situation which will helps clear your combustion chamber when the exhaust valve opens... which is what a good header is suppose to do! Can we say GAIN! But you say and in whiny voice "But its a restriction! Look at the substrate... its a honey comb it must be a restriction!". Eat the Physics of Thermal Dynamics says I. 3HP loss... maybe in your jaloppy. No, they do not! They utilize the excess hydrocarbons in the exhaust stream to keep to an operating temperature to scrub excess HC and CO from the exhaust stream during transients. Early catalysts such as found on early cars were not really 'three way'---the EGR and timing did a majority of the NOx cleanup, as well as lower compression. Run a catalyst on a dyno with ANY modern car at WOT for a while and watch that catalyst overheat and melt down. They are NOT meant to clean up exhaust ... They are meant to clean transients. Later cats (OBD2 timeframe) do more things. But early bricks are very limited in their scope of cleanup. The reason they are 'effective' at stoich is that NOx is at it's minimum near that point. In reality, the best way to run the car is lean, on the verge of lean misfire where CO and HC levels are almost nonexistent (but NOx is very high)... Then you run a NOx specific catalyst. This is what large industrial engines do as they have a constant load and don't have transients to worry about. Im afraid Tony is right here. a two way Cat will take CO and O2 and make CO2, as well as take HC + O2 and make more CO2 and Water... which gives you your catalytic efficiency by reading CO2 percentage. A TWC three-way-cat, which is what ALL OBDII vehicles have and some older ones now, will do something different. It will take NOx and strip the oxygen off in the first bed call the "Reduction Bed" and leave you with O2 and N2. The second bed known as the "Oxidation Bed" Functions much like a two way cat and reduces the same emissions as a two way cat, but doesnt usually require an extra "air" line for 02 as the striping of the NOx will provide the needed O2. Now if the thread starter lives in California and procured the cat after Jan 2009(effective law date) through a legal channel he has a TWC as per the law and it meets OBII criteria for certification and will have a serial number on the cat(It would also have been expensive). If he has an older cat or is not subject to California laws he most likely has a two way cat. Now on to the implications of installing one of these on one of our antiquated L series. Using either a two way cat or a TWC on the L series isnt the best idea. The ZX EFI system is adequate, but barely. The early L-Jetronics for the 280z dont even have an O2 sensor to make sure the mixture swings to keep the cat happy and require a 30+ year old system to be in good working order for that cat to stay alive. This WILL require a gas analyzer NOT a wideband to calibrate the system correctly for any long term use. Carbs... its been done, but its not worth the time IMO. To lean and the cat burns up. To rich and the cat burns up. Cats like a rapid swing from lean to rich to lean to keep the catalytic process going and not just a chemical reaction. Chemical reaction = BAD maybe even car fire! Carbs just cannot provide this swing in AFR. Thats just one physical limitation, and there are more. The key point to pickup on is that you CAN adjust the carbs and IF all the factory emissions equipment is in place and functioning you can drastically reduce the smell. Lets not worry about seals for the moment. If you had no hatch and no drivers door and all the seals in the car were out(which would leave you in the exhaust stream in a Z and I would know) you would still have no offensive smell from the car with stock SU's and all the original AIR system, AB valve, and throttle lift plunger installed and properly functioning. Years of wear and tear as well as all the garage mechanics that think "that smog crap must come off its robbing me of power" have left you with stink! Did I miss anything? Or is this one dead? Edited January 21, 2011 by rayaapp2 Quote Link to comment Share on other sites More sharing options...
rayaapp2 Posted January 21, 2011 Share Posted January 21, 2011 (edited) Cats are actually one of the best devices to reduce emissions, IMO. And that is the line of thought that has resulted in the Jan 2009 law that mandates all Cats be ODII certified. Techs that just replaced cats to clean up emissions for a smog gave the rest of us new headaches because of their lack of diagnosis and understanding of the whole system. Lets just slap another on it will clean up the emissions.... yeah for what 2 weeks. Guess they will be buying a new cat in 2 years... or 1 if Gross Polluter. The best way to reduce emissions is to get a complete and efficient burn of the A/F mixture in the chamber. 90% of the emissions devices revolve around this statement. Catalytic Converters and AIR being the 2 I can think of off hand that do not. More along that thought process by Tony Poor fuel control will kill that cat... ... And you will burn up or overheat that catalyst in short order if you don't fix that first. You don't slap it on and make it all better. Fix the problem, don't bandaid it! If you smell fumes, you are not 'adjusted correctly'! Fix the Problem... Dont Band Aid it! Edited January 21, 2011 by rayaapp2 Quote Link to comment Share on other sites More sharing options...
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