Will I pick up any power?
TECH Fanatic
Joined: Jun 2006
Posts: 1,285
Likes: 1
From: Elgin, Il
Engines are air pumps. They don't want any back pressure - what you need to do is keep your exhaust moving at a quick velocity (which is why a stock car can lose power removing cats). Going to an ORY may pick up a little but I don't think you'll notice a difference if you have high flows on now. I've seen street cars make over 800 horses through cats, I don't think your catted Y is a problem.
Engines are air pumps. They don't want any back pressure - what you need to do is keep your exhaust moving at a quick velocity (which is why a stock car can lose power removing cats). Going to an ORY may pick up a little but I don't think you'll notice a difference if you have high flows on now. I've seen street cars make over 800 horses through cats, I don't think your catted Y is a problem.
TECH Fanatic
Joined: Jun 2006
Posts: 1,285
Likes: 1
From: Elgin, Il
the piston will push the exhaust out unless you have like 80% leakage on a CLT lol. But ok, if we're talking about open heads - yes of course you need SOME "backpressure" to prevent your exhaust valves from cooling too rapidly. You don't really lose torque - you just shove it higher into the power band (engine spinning faster = increased exhaust velocity regardless). Back pressure isn't something you should be concerned with when modifying an exhaust. Velocity and scavenging are the important things.
Search on here if you like about backpressure. I've searched on here, other forums, talked to my instructors, and a lotta guys into racing/tuning. The consensus is unanimous that the whole "lack of backpressure kills torque" thing is a myth.
Search on here if you like about backpressure. I've searched on here, other forums, talked to my instructors, and a lotta guys into racing/tuning. The consensus is unanimous that the whole "lack of backpressure kills torque" thing is a myth.
Last edited by FiredUpZ28; Jan 29, 2009 at 03:59 PM.
Back pressure is needed at some point, it assists with the savaging effect of headers and the exhaust in order to assist with pulling and keeping the exhaust velocity at its peak. Lower RPM will benefit from some, granted at the higher RPM Range, you wouldn’t need any if at all.
A tuned header is that the each tube are designed to keep the exhaust flowing and assisting each of the other pulses of the exhaust.
If you have ever measure back pressure of a know good Cat or Muffler, there should be very little (from drilled holes before and after the cat/muffler to messure the pressure) pressure difference. If you do have a measureable amount, then replacing it would be the recommendation.
But this is one of those debates that will go on forever..Back pressure or none!? IMO, you need to evaluate your requirements and build the system that will benifit you driving style and habits (WOT, crusising, Auto-x, etc).
A tuned header is that the each tube are designed to keep the exhaust flowing and assisting each of the other pulses of the exhaust.
If you have ever measure back pressure of a know good Cat or Muffler, there should be very little (from drilled holes before and after the cat/muffler to messure the pressure) pressure difference. If you do have a measureable amount, then replacing it would be the recommendation.
But this is one of those debates that will go on forever..Back pressure or none!? IMO, you need to evaluate your requirements and build the system that will benifit you driving style and habits (WOT, crusising, Auto-x, etc).
