input on mod exhaust wanted
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input on mod exhaust wanted
While crawling around under my truck, I'm noticing that from the Y pipe bolt up point to the muffler, the exhaust seems like it would be fine for flow. The only benefit I can see after the muffler would be to use mandrel bent tubing instead of the standard benders.
What I'm getting at, is thinking that the biggest benefits per dollar would come from a redone Y pipe and a high flow muffler...without replacing the rest of the system. We have a shop here that does race exhausts, and I'm thinking that just replacing the muffler and having a custom Y pipe installed would cost about the same as a cat-back system, but yield larger gains, as the Y pipe seems to be the worst culprit in the entire exhaust. COMMENTS???
What I'm getting at, is thinking that the biggest benefits per dollar would come from a redone Y pipe and a high flow muffler...without replacing the rest of the system. We have a shop here that does race exhausts, and I'm thinking that just replacing the muffler and having a custom Y pipe installed would cost about the same as a cat-back system, but yield larger gains, as the Y pipe seems to be the worst culprit in the entire exhaust. COMMENTS???
Last edited by motochris; Sep 5, 2004 at 04:02 PM. Reason: spelling
Fleet Mechanic
Joined: Sep 2002
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From: Gretna ,LA.
The y and the wimpy exhaust log manifolds are the restriction.A new y will definitly help along with some headers.The stock muffler is big and restrictive also.You can check my two galleries and see my redone y-pipe [heh heh].
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motochris
You observation is good and Z71 killer is correct.
I reccommend when getting a "one off" headder to cat set of tubes designed, strive to keep both sides close to equal length. Try to resist dumping the small exhaust manifold outlet into a pipe that is more than 25% larger in ID. for the first three feet. And insist that the "collector" (two into one) before the cat is well designed.
Exhaust flow dynamics is one of my interests and hobbies that relates to my racing of drag cars and bikes. Opening up your system can indeed increase HP and Torque. Unfortunatly, tuning by experimentation can be time consuming and expensive. The frustration being the shift of the powerband up the RPM range.
You observation is good and Z71 killer is correct.
I reccommend when getting a "one off" headder to cat set of tubes designed, strive to keep both sides close to equal length. Try to resist dumping the small exhaust manifold outlet into a pipe that is more than 25% larger in ID. for the first three feet. And insist that the "collector" (two into one) before the cat is well designed.
Exhaust flow dynamics is one of my interests and hobbies that relates to my racing of drag cars and bikes. Opening up your system can indeed increase HP and Torque. Unfortunatly, tuning by experimentation can be time consuming and expensive. The frustration being the shift of the powerband up the RPM range.
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So far, I plan on staying with the stock tubing size from the manifolds to the cat. Just making a high flow style Y-pipe instaed of the nasty one thats there. It looks as though it is 2.25-2.5 into a single 3in.
Logistics Pro
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That is the most logical plan.
I played around years ago with stepping up in size every 4 to 6 inches until about three feet past the headder flange. I was collecting into 3 inch. The trick in this method is to know the expansion volume of each exhausted cylinder and try to size each pipe section to hold a little less than that volume. Velocity is your friend, and thermal expansion helps pull tthe spent gases towards the increasing sizes.
We used to do our own "180" exhaust headders and other scavagening methods on the modified circle track and darg motors. We knew one guy experimenting with a small turbine engine to blow high speed exhaust down 5 inch pipe creating a ton of back vacume and a mechanical scavenger effect on the small block exhaust system. It was wicked loud but he never could get a cam that had the right intake timing to help this system achieve its theoretical effeciency.
I played around years ago with stepping up in size every 4 to 6 inches until about three feet past the headder flange. I was collecting into 3 inch. The trick in this method is to know the expansion volume of each exhausted cylinder and try to size each pipe section to hold a little less than that volume. Velocity is your friend, and thermal expansion helps pull tthe spent gases towards the increasing sizes.
We used to do our own "180" exhaust headders and other scavagening methods on the modified circle track and darg motors. We knew one guy experimenting with a small turbine engine to blow high speed exhaust down 5 inch pipe creating a ton of back vacume and a mechanical scavenger effect on the small block exhaust system. It was wicked loud but he never could get a cam that had the right intake timing to help this system achieve its theoretical effeciency.
