93 7.3 idi exhaust question
#11
exhaust myth
hey to everyone out there, i'm new to the diesel world and was wondering about an exhaust upgrade for my 1993 f-350 7.3. i have read many threads and articles saying not to go bigger than a 3 inch exhaust on a non turbo because the muffler and smaller pipe causes back pressure that is needed. but on a turbo it is ok to go big because the turbo causes the appropriate back pressure needed. so i would like to know is this true or is this all just a folk lure. i would really like to stack my truck. thanks for any and all help.
#12
#13
I have a 7.3 IDI with no turbo. I was wondering if I can "straight pipe" my exhaust by simply removing the muffler and replacing it with a piece of pipe but i have seen the posts about the backpressure. If i do this will i retain enough backpressure so that i dont burn valves or anything?
#14
#15
The backpressure myth is false. The valves are cooled by contact with the cylinder head.
People that burn valves after going straight pipes are also the same people that run their engines harder than normal, which is even worse on non-turbo engines because there is no boost to cool combustion. That extra heat is what burns the valves. A pyrometer is just as important to non-turbo diesels as it is to turbo ones!
People that burn valves after going straight pipes are also the same people that run their engines harder than normal, which is even worse on non-turbo engines because there is no boost to cool combustion. That extra heat is what burns the valves. A pyrometer is just as important to non-turbo diesels as it is to turbo ones!
#16
What I've heard, and what makes sense to me, is that on a NA engine you need to size your exhaust propperly to maintain exhaust gas velocity. Too small, you get flow restriction, too large and the gasses cool off and slow down, and then they don't help scavenge the rest of the exhaust out of the cylinders. Once you get a few feet past the manifolds, the scavenger effect has done its job and you can go larger without harming anything. That seems to work in my experience, hope it helps
#17
What I've heard, and what makes sense to me, is that on a NA engine you need to size your exhaust propperly to maintain exhaust gas velocity. Too small, you get flow restriction, too large and the gasses cool off and slow down, and then they don't help scavenge the rest of the exhaust out of the cylinders. Once you get a few feet past the manifolds, the scavenger effect has done its job and you can go larger without harming anything. That seems to work in my experience, hope it helps
#18
I have 2.5 right at the manifolds about four inches from the manifold it goes to 3" ... to the Y, then to 4" ... the big restriction is the intakes on these engines .. i run a 14X6" K&N filter ... picked up 2 mpg doing exhaist and air cleaner alone ... Royal purple 15/40 and Zmax ... another 2 mpg alone .... regurally was getting 17.5-18 city and 20 freeway .. they need to breathe .... if you ever pull the manifolds ... check out the size difference between the gasket and the head port ...LOL i ported mine .... wil have it done here soon
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