catalytic converter placement

[RootBreaker]

Ok so if someone theoretically put catalytic converters on his truck to try and pass inspection... how close to say a fuel pump can one be? i know they get extremely hot inside.. how about outside?

so this theoretical idea would mean a cat about 2-3" from a electric fuel pump.. is that a bad combination????












and yeah my 78 got dual cats last night.. i woke up and there they were installed...


but now i have to figure out why someone (cough cough) would put it next to the fuel pump... maybe cuz there is no other room for where it is.....

side thought is to cut the exhaust and add a extender in there putting the cat farther back.. but that defeats the purpose doesnt it? it needs to be close to the motor to work?????

 

[CGT80]

A cat has to get very hot to work well. It is often recommended to run a vehicle for 5+ miles at a decent speed to warm up the cat before getting a smog.

Putting the cat closer to the engine keeps it nice and hot. Most vehicles I have looked at have heat shields above the cat, to keep the floor of the vehicle cooler. I would not put a fuel pump within 12" of a cat, if I could help it. My truck and K5 both have the fuel lines on the opposite side of the truck from the cat.

My exhaust guy also said that putting the muffler too close to the cat will cause the muffler to fail early due to the amount of heat and the expansion and contraction of the metal due to heating and cooling so often.

I have also read that an electric fuel pump should be at the level of the bottom of the tank or even lower. I thought about running one on my truck when the mechanical went out, but I didn't have a good place to mount it and I scrapped that idea. Of course my truck is carbed and a good mechanical pump will give it all the fuel and pressure it needs.

 

[Rockslammer84]

^^^^^what they said.

 

[Fordum]

You can insulate anything from anything if you work at it hard enough. But if your cat is that close to the fuel pump, you better have an aluminized vacuum bottle around the pump..........

I would suspect it would be a lot easier to move the pump than the cat.

Extend the lines, and either move it forward or back. Plus, move the line either outside the frame, or pack lots of insulation inside the frame where the fuel line is close to the cat.

 

[Rockslammer84]

Yeah you can insulate it but the important thing to keep in mind is that the cat is not going to work the way it's intended to work because the exhaust gases are going to cool through the pipe and not get it hot enough to become efficient. That's the real problem with its location, I guess the truck blowing up would be bad also. I would move the cats to avoid both problems.

 

[RootBreaker]

Yeah you can insulate it but the important thing to keep in mind is that the cat is not going to work the way it's intended to work because the exhaust gases are going to cool through the pipe and not get it hot enough to become efficient. That's the real problem with its location, I guess the truck blowing up would be bad also. I would move the cats to avoid both problems.

The cat on drivers side is closer to the header... Passenger side is cosmetic.. Was going to mount it right behind the muffler so inspection doesnt gripe that i was only running one.. Then was going to remove them both if i pass.... But now trying to make it permanent....


Oh yeah my only concern is blowing up.... Hah

I failed emmissions 6 times... So i just want to pass..... They r making it harder and harder for a carb vehicle to pass.....

Sent from my Epic 4G Touch using Tapatalk

 

[Rockslammer84]

What state are you in? In Maryland 20 years or older doesn't need emissions.

 

[K85 Octane]

fyi: my cat is just about right under the driver's seat or right next to the transfer case. That is the stock location, stock heat shield position, and correct distance for visual inspection.

 

[K5dreamer]

may not apply to your fresh install, but a clogged cat can literally glow cherry red from heat build up. keep in mind the catalytic reaction taking place is in effect combusting unburned fuel, so a catalytic converter is like a little blast furnace. see the comment above about the heat shield between the cat and the steel floor of the car on production models.

the cats should be as close to the header pipe as possible. on a factory setup the manifold would connect to the cat via a flex pipe. then the exhaust pipe would route the gasses to the rear of the vehicle where the muffler(s) are. giving the gasses time to cool.

most fuel pumps are near the tank, so this keeps them well away from the heat of those cats.

in your case, I would likely move the fuel pump to another location to accomodate the cats.

 

[wheeler]

I failed emmissions 6 times... So i just want to pass..... They r making it harder and harder for a carb vehicle to pass.....

Are you doing this in NJ? I've never had any issues passing my truck even when it didn't run...for 50 bucks that is. I would talk to a smaller shop and see what they can do for you. Would probably be cheaper in the long run, and easier to pay 50 every couple years than redoing that much of your exhaust.

 

[diesel4me]

I'd move the pump,and closer to the tank--electric pumps PUSH fuel,and wont last very long if they are located far from the tank,they'll run constantly,instead of only coming on when fuel is needed and it'll shorten its life quite a bit...(assuming we're talking about a carbed engine with an aftermarket electric fuel pump)..

 

[4X4HIGH]

The cat on drivers side is closer to the header... Passenger side is cosmetic.. Was going to mount it right behind the muffler so inspection doesnt gripe that i was only running one.. Then was going to remove them both if i pass.... But now trying to make it permanent....


Oh yeah my only concern is blowing up.... Hah

I failed emmissions 6 times... So i just want to pass..... They r making it harder and harder for a carb vehicle to pass.....

Sent from my Epic 4G Touch using Tapatalk

What part of the emissions test did you fail? If HC's then CATS will help reduce that number if it isn't too much higher than Max allowed. If they test for NOx then you need to be looking elsewhere for your problem. How about posting up the test results from your emissions test.

 

[chulisohombre]

Stick position was a foot after the y pipe just about under the passenger seat. So I say if you are around that position you should be good.

 

[RootBreaker]

What part of the emissions test did you fail? If HC's then CATS will help reduce that number if it isn't too much higher than Max allowed. If they test for NOx then you need to be looking elsewhere for your problem. How about posting up the test results from your emissions test.

ppm allowed is 300... im 1550 without cats and 1780 with