Exhaust cut-out/cat delete project

[Mississippi]

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[98_k1500]

How do smog pumps not burn valves then? They push air into the exhaust literally 1/2" from the exhaust valves.

 

[Mississippi]

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[98_k1500]

No, they push air into the exhaust manifolds where there is oxygen available to help the catalytic converters burn any unused fuel. They can't burn anything with no oxygen present.

 

[Mississippi]

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[thz71]

I fail to see how that could "burn up" valves makes no sense to me

 

[Mississippi]

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[98_k1500]

Newer vehicles don't use air injection (smog) pumps because the egr and the computer tuning keeps the air/fuel ratio VERY close to perfect. They don't have the large amounts of unburned fuel in the exhaust like older vehicles do. Thats why the converters last on newer vehicles too. There is very little that they are actually having to burn. I'm not trying to argue with anyone, i just think that its a very debatable subject. Just so everyone knows, a burned valve starts with a leaking valve. When the spark plug fires, the extremely hot gases from the fuel burning escape thru the leaking valve. This has a torching effect on the head of the valve, and cuts away some of the metal, which makes the valve leak worse. This does not happen to a valve that is not leaking because the thin seat area on the valve is against the much cooler head in a properly operating engine.

Btw, i was referring to an air injection pump, not an egr valve. Totally different system. The tubes on the top are for the smog pump. The lower tube is for egr.

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[bow61509]

Has any body in here talking about burning valves ever seen a rat rod, or mud truck running zoomies? Guess not....

Have fun "burning up your valves" with too short of a pipe :lmao:

Sent from the....... Ferd

 

[great white]

Elaborate

Already have. Nothing post combustion is "hot" enough to cause valve sealing failure. Everything after the combustion even int he cylinder is post combustion.

People can believe whatever they want. Suffice to say, lots of bad info is being passed out here.

I've said my piece and I'm done with it.



Re: cat converters. They do not need O2 to function. At least not in the strictest sense. The first word is "catalytic". It strips NOx into nitrogen and oxygen. Does so by running the exhaust over a (usually) platinum substrate.

RE: air pumps, They introduce air into the exhaust stream to further complete combustion of unburned hydro carbons in the exhaust stream. Adds a little extra O2 to the stream for the oxidizing section of the converter (Where CO is processed into CO2). There is sufficient O2 in an exhaust stream after combustion for this anyways. Has nowhere near enough volume or pressure to do anything but join the exhaust in a downstream path.

Re: DPF. Diesel particulate FILTER. They burn nothing by intended design, they trap particulate matter (IE: soot). They only time they "burn" anything is in the new trucks when they hit a temperature such as to complete combustion with the soot or the PCM goes into regen mode (because the filter media becomes loaded) which runs the engine hot in order to get the DPF hot enough to combust the soot into less harmful particulate/emissions.

Re: backpressure. Learn how a 4 cycle engine works.....