cat removal from 10 headpipe audio file
Road Warrior
Joined: Mar 2009
Posts: 1,518
Likes: 59
From: Port Neches Texas
I have to politely dis-agree..The mufflers and or removing the catalytic converter will allow more exhaust gasses to pass by the O2 sensors, resulting in a higher 02 reading, resulting in the ECM adjusting more fuel in it's limited range. Unless you increase the air in, it won't get leaner.I ran slip-ons for a 1000 miles with no issues.
Mark
Mark
what would be great is if someone had the ability to measure the backpressure of their system prior to removing the cat and meassure after.
Road Captain
Joined: Apr 2010
Posts: 709
Likes: 1
From: Maine
Cat removal
I have been kicking the cat removal around for a while, my question is if the cat is the greatest restricting factor in the current stock system, then how could a stage one effect the performance? the greatest restriction (cat) is still in place so the back pressure on the system remains the same prior to the cat. the photo of the cut headpipe shows how much larger the oval shape section that holds the cat in the pipe is compared to the pipe leading into it, even packed with all that crap the area may be equal.
what would be great is if someone had the ability to measure the backpressure of their system prior to removing the cat and meassure after.
what would be great is if someone had the ability to measure the backpressure of their system prior to removing the cat and meassure after.
Outstanding HDF Member
Joined: Oct 2007
Posts: 3,437
Likes: 15
With the cat gone and a high flow SE air filter i needed fuel management ran like **** for the 1/4 i drove it. Plugged in the PCV from Fuel Moto and it ran great all i had to do was add a little fuel to the 0 column to stop a decel snapping. Face it the cat has to raise the exhaust temp to burn the bad gases for emissions,it has to be some sort of restriction to do this. The thing turns orange at night just look at your headpipe it's blue and gold which is orange in the night. My bike was way cooler and peppier with it gone and an air filter/fuel management system. The stock 96 is still a weak engine in a bagger got sick of that engine fast.
Last edited by mtclassic; Dec 12, 2010 at 11:41 AM.
Banned
Joined: Apr 2008
Posts: 2,492
Likes: 10
More exhaust gases would certainly pass by the sensors without hitting that plug they call the "cat". More O2 would be picked up in the slightly increased volume simply because it exists in the exhaust gases that are now "rushing" past the sensors. Agreed without an air cleaner upgrade it wouldn't be much, but some none the less. I am taking the OP at face value in his post, and you are assuming an air cleaner addition.I completely agree if pipes and A/C are changed a tuner is definitely needed.
Mark
Mark
Banned
Joined: Apr 2008
Posts: 2,492
Likes: 10
I have been kicking the cat removal around for a while, my question is if the cat is the greatest restricting factor in the current stock system, then how could a stage one effect the performance? the greatest restriction (cat) is still in place so the back pressure on the system remains the same prior to the cat. the photo of the cut headpipe shows how much larger the oval shape section that holds the cat in the pipe is compared to the pipe leading into it, even packed with all that crap the area may be equal.
what would be great is if someone had the ability to measure the backpressure of their system prior to removing the cat and meassure after.
what would be great is if someone had the ability to measure the backpressure of their system prior to removing the cat and meassure after.
Mark
Road Warrior
Joined: Mar 2009
Posts: 1,518
Likes: 59
From: Port Neches Texas
Part of this discussion is flawed in assuming back pressure is bad..I actually helps performance to a point. It was related to me as when the performance upgrades make more power than you are losing by not having some back pressure it becomes a non-issue. (ie: a blower uses some HP to operate but makes more than it uses.)
Mark
Mark
I agree that the engine requires a specific amount of back pressure, i was just questioning that it must be that the breather, the cat, and the muffler from a viewpoint of stock is probably balanced with the cat having a larger throughput than the breather and the muffler or a stage one would not produce better performance when the cat is in place. because if the cat was the bottleneck the other two would not be relevant.
Road Captain
Joined: Apr 2010
Posts: 709
Likes: 1
From: Maine
Cat removal
are you saying it ran like **** for a 1/4 mile after removing your cat and adding the air cleaner? Not quite sure why the cat getting hot would cause a restriction. The metals in the cat get hot from the exhuast being expunged from the motor and once they reach a certain temp a catalyst occurs between the harmful gases and the metals.
Banned
Joined: Apr 2008
Posts: 2,492
Likes: 10
Mark,
I agree that the engine requires a specific amount of back pressure, i was just questioning that it must be that the breather, the cat, and the muffler from a viewpoint of stock is probably balanced with the cat having a larger throughput than the breather and the muffler or a stage one would not produce better performance when the cat is in place. because if the cat was the bottleneck the other two would not be relevant.
I agree that the engine requires a specific amount of back pressure, i was just questioning that it must be that the breather, the cat, and the muffler from a viewpoint of stock is probably balanced with the cat having a larger throughput than the breather and the muffler or a stage one would not produce better performance when the cat is in place. because if the cat was the bottleneck the other two would not be relevant.
Mark
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Road Warrior
Joined: Jan 2010
Posts: 1,290
Likes: 20
From: Salem, Or
You are right, the cat looks like more of an obstacle than it probably is ,and that chamber is considerably larger than just the two pipes..The folks that design these things are a lot smarter than I am, but for some reason I can't leave stuff alone. You know, "if it ain't broke I'll fix it until it is".
Mark
Mark
You sound like me.....
Road Warrior
Joined: Mar 2009
Posts: 1,518
Likes: 59
From: Port Neches Texas
You are right, the cat looks like more of an obstacle than it probably is ,and that chamber is considerably larger than just the two pipes..The folks that design these things are a lot smarter than I am, but for some reason I can't leave stuff alone. You know, "if it ain't broke I'll fix it until it is".
Mark
Mark