Exhaust cut-out/cat delete project

[K15 Blazer]

yeah, you only see "smog pumps" on these engines if theyre in impala police cars... because cars have higher emission standers than trucks... another reason why "engine options" have gone the way of the dinosaurs....

it seems to me that the only thing that would cause burned up & cracked exhaust valves is bad timing and tuning.
not zero back pressure, that would shoot the exhaust up and out of the head so quickly that it would burn the valve seats... unless it was still burning fuel. timing and tuning.

but the idea that back pressure slows and therefore cools the exhaust of the engine is kind of counter intuitive.... I think

 

[98_k1500]

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These are headers with the air injection tubes on them.

 

[Mississippi]

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[Mississippi]

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[Mississippi]

But in a previous post I did say that these were carbed engines that they used this method on.

 

[98_k1500]

This subject has been debated SOOOOO many times, I don't think anyone on this earth has a definitive answer. If there was any way to prove one way or the other, someone would have some proof. Its all speculation. Yes, valves burn. Is it from having short exhaust, I doubt it, but there is really no way to prove what did it. I think i'm gonna opt out on this one and keep my opinions to my self on this subject from now on.

 

[great white]

But in a previous post I did say that these were carbed engines that they used this method on.

I AM one of those guys that has been doing this before you were born. I started on carbs when they were the only option (other than Rochester mechanical injection) and moved on to FI when it came out.

Got a list of qualifications in both automotive and aerospace as long as my arm after my name also.

Drag racing, circle track, motorcycles, autocross, cars, trucks, mud bog. You name it, I've probably built it and or driven it.

you can toos some aircraft recip work and jet engines in there also.

I'm not exactly talking out of my butt.

Valves are compromised by excessive heat. Excessive heat is caused by a compromised combustion process (usually a lean condition).

What people confuse backpressure with is scavenging. Scavenging works to assist in the removal of exhaust gasses and the filling of the cylinder during charge. A 4 cycle engine works best with the lowest pressure differential possible after the exhaust valve. This is not practical on a street driven vehicle that sees transient throttle conditions so you end up with a "tuned" exhaust. IOW: one that is designed to scavenge.

Race cars that run "zoomies" straight up do so for safety reasons. They have to get exhaust and heat out of the way but they also have to direct thrown parts/fluids in a safe direction.

The only other way to compromise a valve with heat is if it has insufficient sealing. This is caused by a poor valve seat/valve surface or perhaps a piece of carbon or FOD caught between the valve and it's seat. This allows the combustion event to escape past the valve and further erodes the sealing surface. This is caused by the high gas velocity and the heat in a localized are (IE: the pointy valve sealing edge).

But, believe what you want. I couldn't possibly know what I am talking about....

 

[Mississippi]

Yea I've also had John Deere qualified / certified mechanics come do a service call and ask me where are the batteries. Before it was said and done I ended up doin the vast majority of the work. I believe in that certified bs as much as I believe in the tooth fairy. There's no where in a book that will tell you to do certain things to a vehicle to fix a specific broken part. Sometimes you have to get creative and think outside the box. Just out of curiosity are you over 60??

 

[great white]

Yea I've also had John Deere qualified / certified mechanics come do a service call and ask me where are the batteries. Before it was said and done I ended up doin the vast majority of the work. I believe in that certified bs as much as I believe in the tooth fairy. There's no where in a book that will tell you to do certain things to a vehicle to fix a specific broken part. Sometimes you have to get creative and think outside the box. Just out of curiosity are you over 60??

I'm done with this.

Go find someone else to argue with.

 

[Mississippi]

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