Catalytic Converter Location

[blueox]

Is the location of the converter important for it to work properly? I've been looking on the net and I can't find what I'm looking for. I would like to keep using converters on my truck when I put on my dual exhaust but I want to relocate them about 2 feet further back so they aren't tucked in right next to the transmission.

Does anyone know the minimum exhaust temp they need to work properly? Or is there a minimum amount of heat they need to work properly?

Thanks in advance for any info.

 

[IZwack]

yes it does matter.. and the government requires it... this is from the Dynomax website:

Furthermore, the EPA has issued the following installation requirements:
2. The converter be installed in the same location as the original converter.

Here read this page from the Gateway Clean Air Program titled "Using, Installing or Buying Aftermarket Catalytic Converters" :
http://www.gatewaycleanair.com/mechanic/air5_6/catconv.htm

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[blueox]

Thank you that is exactly the info I was looking for. Kind of a bummer, I would like to retain the converter but I don't want it next to the tranny.

 

[tweakedlogic]

I always move mine around when I get the exhaust done. ( have have several vehicles). I usually remove two of them, and replace it with a high flow of some type. Check your local rules and ask around. If you live in Cali, don't do anything.

 

[huskyfan23]

Why does it matter if it's by the transmission or not?

 

[IZwack]

and replace it with a high flow of some type.

damn, i woulda replaced them with a lower flow.. ... ... of some type. i mean think of the back pressure.. thatd be tight talk about force times distance!

Why does it matter if it's by the transmission or not?

it doesnt really matter if its beside the transmission .. but what does matter is how far it is "downstream" from the engine... the temperature needs to be right in order for optimum oxidation/reduction to happen... mainly of nitrogen dioxide/monoxide.. and carbon monoxide..

 

[huskyfan23]

I'm just wondering why blueox sees a problem with it where it is.

 

[IZwack]

he wants to move it back.. i dunno if his reason is the same as mine.. but ive been thinking of the same thing cauz the cat is one of the lowest thing under the SOHC engine... or at least thats how it is in my SOHC engine.. with a relatively low break over angle (even with a tid bit of lift), the cat looks like it can be ripped right off... one thing that ive been thinking of, if u have a BL, is to route the exhaust between the body and the chassis ahahah! thatd be funny but that way the cat would still be at the right distance... i mean if uve got a 3" BL, thats 3" u can work with, though i guess that heat would probbably seep in to the body at some point, but hey, thats what ceramic materials are for!

 

[prozachappy]

I can't speak for blueox, but on long road trips I have always had problems with my M5OD getting so hot that the floorboard gets warm to the touch...and my feet actually get hot too! I've tried everything from synthetic, to balancing the driveshaft. Nothing seems to help, and as you know heat kills a tranny! I have often thought about re-locating my cat to see if that helps. I mean even with the heat shield it still radiates a s$!tload of heat and sits like 3 inches from the tranny.
b-4 you ask...its not the tranny cause I'm on my third and they have all done it
The exhaust has also been pressure tested...it's not plugged, cat is fine. I really think that there is some heat transfer going on from the cat to the tranny! I dunno...JM2cents.

 

[IZwack]

I've tried everything from synthetic, to balancing the driveshaft.

hey just wondering what expected from balancing the driveshaft in terms of the heat problem...

here try this for fun :
http://www.centralhobbies.com/building_materials/paint/

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[prozachappy]

well...after I started noticing the heat threw the floorboard on long trips, it was shortly there after that my original tranny blew. After the second tranny was put in, I was still getting heat threw the floorboard so I knew it wasn't a tranny problem. Something was causing it to run that hot in 5th so I tried synthetic oil and that didn't help. I thought maybe I was getting heat transfer from the engine, but I would literally pull over everytime I started feeling my feet get warm, and check everything out. Engine would be fine, not to hot. I noticed that the tranny would get extremly hot (ie floorboard and feet) only in 5th at high speed and on long trips. It would get really hot, then cool down for awhile, then get really hot again...and cool down...over and over. I would also notice a slight vibration in the vehicle any time this occured. So I started to think maybe the tranny heat was due to some external force. First thing that comes to mind is u-joints, driveshaft, and rear differential. So I popped the diff cover, checked everything and changed the fluid. Changed u-joints (dana's) had the yoke inspected and balanced the driveshaft. My thought was that somehow 5th gear was being overworked by the driveline. Didn't help! So on to the next theory...ie cat converter sitting a few inches from the tranny. BTW...my second tranny lasted less than 5000 miles before it blew (when it was hot/and on a long trip). On my third now...under warranty... and it still gets extremly hot in 5th on trips. I ask the tranny guys about the cat, and they said they doubted that was the problem. Okay...well if they want to keep rebuilding my tranny for free every 10k or so...thats fine with me! My only other thought is that my tranny case is warped to the point that its causing added friction and heat. Who knows...my money is still on the converter though

blueox: sorry to jack your thread :roll: I'd actually talk with some exhaust specialist about relocating your cat if your set on it. I could be wrong but umm...as far as know your cat could sit anywhere as long as your o2 sensor is moved also to compensate for the added distance. The cat just converts the gases to a level the government has deemed a safe level. Technically you could remove the cats completely and the truck would run fine....you just wouldn't pass smog

 

[TheRookie]

A cat MUST be in rougly stock location. Legaly and technicaly. AS stated earlier legaly it must be there. Also as stated earlier it needs certain temps to be most efficient. Moving it will change this.
Before you post about something you dont understand atleast take time to read the posts above you as some of them actualy know what they are talking about. Dont remove your cats. Its just stupid

 

[Creager]

it wont hurt the tranny. there is nothing in there thats not as hot, if not hotter then the cats already.

Plus, the warmer the oil is, the better it lubricates. (As long as it’s not TOO hot! But if that were the cause you have bigger problems)

But just a thought, there is probably something you can do to the PCM to adjust to the position of the Cat proportional to the engine. That’s a long shot, and probably more work then its worth.

Prozac, i dont think your problem is cat related. If you are for sure it is, make sure the heatshields are still on there. If not then that could be your problem, but i doubt it. I think your trannies are just being rebuilt by the wrong people.

 

[huskyfan23]

It will run fine without cats, think you maybe quoted the wrong person. I don't see what's stupid about removing the cats?

 

[Creager]

whoops i just read it wrong

Before you post about something you dont understand atleast take time to read the posts above

im guilty haha

it will work technically. from what i understand on the 4.0 motor your sacraficing all that power when you do it.

with a 5.0 on the other hand... different story.

 

[IZwack]

Plus, the warmer the oil is, the better it lubricates. (As long as it’s not TOO hot! But if that were the cause you have bigger problems)

most ATFs are supposed to be kept at 180 degrees F or lower.. beyond that, ATF starts oxidizing rather quickly (goes from red to brown with the addition of oxygen).. and then it starts to varnish and gum up on parts (like the valve body) .. in addition, at near 250 degrees, most "soft" parts in the transmission (seals) start to harden up. its worth noting however that even normal dirving conditions can easily push ATF temps beyond its limits.

 

[huskyfan23]

I've done it and can say the X feels quicker. I never dyno'ed it though (spindlecone can't attack me now! )

 

[Creager]

most ATFs are supposed to be kept at 180 degrees F or lower.. beyond that, ATF starts ozidizing rather quickly (goes from red to brown with the addition of oxygen).. and then it starts to varnish and gum up on parts (like the valve body) .. in addition, at near 250 degrees, most "soft" parts in the transmission (seals) start to harden up.

and the cats hit around 600F?

hrm

i still dont think the heat from the cats will absorbe through inch thick aluminum. It probably could cause problems like with the rubber caps near the shift rails on a manual tranny drying up. i dont think convential heat from the cat would heat up the tranny...

what about all them gears in the trannies? those dont heat up past like 150?

i was applying my information from differential gears which are known to hit well up near 500-600 degrees.

 

[IZwack]

and the cats hit around 600F?

Yeah thats true.. and its at least that.. the catalytic process starts at about 500 to 600 degrees F.. but it goes way beyond that.. normal operating temps hover around twice this number.. around 1200 degrees F.. with a stream of unburnt fuel/oil, or even coolant (antifreee) for that matter, temps can reach around 2000 degrees F. a few degrees beyond this and the converter element starts melting inside the cat.

i still dont think the heat from the cats will absorb through inch thick aluminum... i dont think convential heat from the cat would heat up the tranny...

Yeah this all depends on how close the converter is to the transmission.. i mean if its like a few millimeters, then yeah transmission's housing will heat up quite a bit and very quckly ... but if its a few inches, then it might take a little longer time... remember that a converter can get VERY hot depending on the reactions taking place inside... the worst situation is probably when the vehicle is just sitting in traffic with little or no airflow over the cats, so that the converter's energy is just being radiated directly to the transmission.

what about all them gears in the trannies? those dont heat up past like 150?

no clue what is exactly the temperature of the gears, but my guess would be just a bit higher than the ATF.

I've done it and can say the X feels quicker. I never dyno'ed it though (spindlecone can't attack me now! )

When you dyno it, please post the chart.. that would be interesting to see what the numbers are with a converter and w/o a converter.. one thing tho, at some points on the power curve, some engines will actually produce more power with a converter ... and per say, for those who deviate from the pavement, most off roading engine speeds are usually very low on the rpms (unless of course u run the Dakar.... or the lesser so called "Baja"... PPFFFT, whatever that is.. AHAHHA!)... ive always thought about building a rock bugy with like a 12hp lawnmower engine.. just geared really really high... cauz after all, its really all about traction, power is nothing as it can be achieved by gearing and thats almost infinite after youve gone through the transmission, transfer case, a Klune, and the differential.

 

[Creager]

on top of thangs once again, my man, DR. IZ!