Many times when people say they lose backpressure, they actually gained it.
Exhaust backpressure is bad when considering it as a restriction. To much can push hot spent gases up into the intake charge during overlap (exhaust valve closing/intake valve opening at the same moment).
To little backpressure, could possibly have some of the incoming fresh air go right into the exhaust runner and cut VE.
Tune the exhaust to a certain length. You don't want a positive wave front from the exhaust pushing back into the cylinder (intake side) of things due to the wrong tuned length of an exhaust.
I would suggest buying Larry Meaux's PipeMax. It is fun to play around with and some big-timers have found it is a very accurate software for the price.
Here is what I got using a 01 PI 4.6L SOHC engine as an example, just for the needed exhaust specs:
Best: 21.1 - 42.1 - 84.3 - 168.5
Worst: 31.6 - 63.2 - 126.4 - 252.8
Length is important and it can depend on combination and need:
- Full emissions
- Full race car
95Vert - No need to get your underwear in a twist, he was just giving his thoughts.
Exhaust backpressure is bad when considering it as a restriction. To much can push hot spent gases up into the intake charge during overlap (exhaust valve closing/intake valve opening at the same moment).
To little backpressure, could possibly have some of the incoming fresh air go right into the exhaust runner and cut VE.
Tune the exhaust to a certain length. You don't want a positive wave front from the exhaust pushing back into the cylinder (intake side) of things due to the wrong tuned length of an exhaust.
I would suggest buying Larry Meaux's PipeMax. It is fun to play around with and some big-timers have found it is a very accurate software for the price.
Here is what I got using a 01 PI 4.6L SOHC engine as an example, just for the needed exhaust specs:
Best: 21.1 - 42.1 - 84.3 - 168.5
Worst: 31.6 - 63.2 - 126.4 - 252.8
Length is important and it can depend on combination and need:
- Full emissions
- Full race car
95Vert - No need to get your underwear in a twist, he was just giving his thoughts.