will this chip really do anything??
#21
02-17-2010, 06:58 PM
This is why I have straight through mufflers (no baffles like flowmasters tend to have) to reduce back pressure as much as I could, but I'm still using an H pipe because I need to keep the torque envelope in the lower range of RPMs. where did you find mufflers like that??
#22
02-17-2010, 06:59 PM
how could I make a 3.5" "turndown-pipe" connect with a 2.5" muffler outlet?
#23
02-17-2010, 08:24 PM
Options that I can think of off the top of my head.
1. get a 2.5" pipe and flare one end until it's 3.5" and then weld.
2. Find a 2.5" to 3.5" adapter/flange and then weld.
C. get a 3.5" pipe and mark one line straight along the side. Mark one end with 2 marks that are 7.85" (Diameter * pi) around the pipe from each other and equally distant from the line. Draw a line from the two marks to the end of the line at the other end of the pipe. Cut the wedge out. Weld the edges together to form your adapter. Weld to the pipes.
1. get a 2.5" pipe and flare one end until it's 3.5" and then weld.
2. Find a 2.5" to 3.5" adapter/flange and then weld.
C. get a 3.5" pipe and mark one line straight along the side. Mark one end with 2 marks that are 7.85" (Diameter * pi) around the pipe from each other and equally distant from the line. Draw a line from the two marks to the end of the line at the other end of the pipe. Cut the wedge out. Weld the edges together to form your adapter. Weld to the pipes.
Last edited by slymer; 02-17-2010 at 08:29 PM.
#24
02-17-2010, 10:34 PM
Options that I can think of off the top of my head.
1. get a 2.5" pipe and flare one end until it's 3.5" and then weld.
2. Find a 2.5" to 3.5" adapter/flange and then weld.
C. get a 3.5" pipe and mark one line straight along the side. Mark one end with 2 marks that are 7.85" (Diameter * pi) around the pipe from each other and equally distant from the line. Draw a line from the two marks to the end of the line at the other end of the pipe. Cut the wedge out. Weld the edges together to form your adapter. Weld to the pipes.
1. get a 2.5" pipe and flare one end until it's 3.5" and then weld.
2. Find a 2.5" to 3.5" adapter/flange and then weld.
C. get a 3.5" pipe and mark one line straight along the side. Mark one end with 2 marks that are 7.85" (Diameter * pi) around the pipe from each other and equally distant from the line. Draw a line from the two marks to the end of the line at the other end of the pipe. Cut the wedge out. Weld the edges together to form your adapter. Weld to the pipes.
Where can I find option #2 online?
#26
02-19-2010, 09:55 PM
i was told that putting welding a piece from the 2.5" outlet and that piece turning into 3.5" wouldn't change the sound. This dude at work is telling me to just have the last 2 cats taken off, and I should be satisfied.. So far everything this dude has told me was pretty on-point as far as meeting my expectations. I'm seriously thinking this is my only "cheap option" left. BTW, I thought "quality" mufflers would reduce back pressure more than straight pipes.. How did it affect your performance?, and how is the sound diff. than if you had mufflers on it instead?
#27
02-20-2010, 08:52 AM
I have free-flow mufflers (no baffles), not straight pipes. worked wonders on the mid-range RPMs. Still bogs at the top end due to the weenie heads on the old 302 that's in my car. The 3.5" wouldn't change the sound, but may amplify it a bit (more volume). Quality mufflers usually do reduce backpressure, but free flow mufflers help the most with that. Baffled mufflers (no matter how open they are) will still provide some back pressure due to the odd path the exhaust has to take. As for the sound on my car, it's pretty smooth. No thump to it at all (Flowmasters tend to create a little thump because of the baffle setup they use). It's definitely noisier than the stock setup with the extremely baffled stock muffler. You couldn't hear the exhaust on that until it was at least about 2500-3000 rpm. Now you can hear it purr faintly at idle, but it will do a mild roar when I put my foot in it. Can't really expect much noise with the cats still on it and 2 inch pipes.
#28
02-20-2010, 07:08 PM
so this Bootleg tire shop wanted to charge me $80 to remove the last 2 cats on my car. If I go Monday, he said $70 (wtf?) He's saying it will be much louder. What do you think about this price Sly?
#29
02-22-2010, 02:20 AM
Not much of a volume difference tho, but deff-nutly a change in tone.
I have Fail Master 44'z and no rear cats on my car, check out my youtube vids...
http://www.youtube.com/user/DerWahns.../7/qqzUpS4ExS4
#30
02-22-2010, 04:45 PM
Sorry,new guy here
Reading this,there is alot of misinformation and misunderstood concepts.
First,for the original OP-the entire ebay ad is a joke. I wouldn't buy from the guy just for GP. The ad pic says +100hp +25mpg.
He's preying on stupidity.
The "CHIP" is a resistor in a box,slymer's sig says he is an electrical engineer so I imagine he can explain how there is no way that little box holds a "CHIP"(EEPROM it looks in pics),associated circuits and wiring,yet only has two wires coming out of it.
It is a resistor that is placed across a sensor,usually a thermistor ( intake or coolant/cylinder head temp) that will alter the return signal to the PCM making it think the air/engine is cooler than it actually is.
Cooler means denser ,denser means more-more is generally fuel. Or in some cases this is reversed to get leaner.
It's a gimmick,a gag etc...
Never trick the computer,just throw a carb on it if you can't do it right.
As for the Cat argument,it's really a moot point.
A shop can charge you $500 to remove it and it's still not an unfair price.
It is against federal law to remove,with a minimum 10k fine and possible 5yrs jailtime IIRC. Our local shops won't just cut off anyone's cats,they have to be referred by a trusted local.
It's not a legal service,so they just throw out a number whenever they are asked. The person will pay it or not,they don't really care.
As for cutting them off,there is no freaking point.
Unless your cammed,turbo/supercharged or have otherwise significantly changed the CFM/RPM limits of your engine than they aren't limiting you.
Taking it off MIGHT gain you LESS than a single hp at some obscure point in the rpm graph.
You are more than likely losing hp due to a negative change in velocity,maybe.
Backpressure isn't good,but necessary in a small amount for the existence of velocity at lower rpm's for torque.
Big as you can get it on the intake and exhaust side is the most ignorant statement i've ever heard for an N/A equipped engine.
The air is a pump,but the idea is more air in,more air out,more efficiently.
It's not more air in,more air out makes it more efficient.
Fluid dynamics tell us alot about pressure drops,velocity,scavenging etc..
On an FI engine,the dynamics are different-but when the engine has to work for it's air,it matters in determining how much the engine is getting for that work.
And of course all decisions made in any of these area's will affect the powerband. Who cares if you gain the ability to flow 50 more cfm and gain 20hp if it's at the edge of your redline or out of where you normally drive.
I'm not an expert in anything but my opinion,but there are alot of good reads on the internet explaining combustion,intake,exhaust and air density theory.
(oh yeah,and cutting off the cats will generally trigger p0430/p0420 codes. The computer will go constantly go through routines trying test and/or save the cat from damage. This usually involves adding a metered amount of extra fuel to the mix. So cutting your cat without properly removing it from the pcm will be simply killing your gas mileage and running rich anyway*generally.
Sorry for the long post,hope I didn't come off as a dik-I suck at the written word.
Reading this,there is alot of misinformation and misunderstood concepts.
First,for the original OP-the entire ebay ad is a joke. I wouldn't buy from the guy just for GP. The ad pic says +100hp +25mpg.
He's preying on stupidity.
The "CHIP" is a resistor in a box,slymer's sig says he is an electrical engineer so I imagine he can explain how there is no way that little box holds a "CHIP"(EEPROM it looks in pics),associated circuits and wiring,yet only has two wires coming out of it.
It is a resistor that is placed across a sensor,usually a thermistor ( intake or coolant/cylinder head temp) that will alter the return signal to the PCM making it think the air/engine is cooler than it actually is.
Cooler means denser ,denser means more-more is generally fuel. Or in some cases this is reversed to get leaner.
It's a gimmick,a gag etc...
Never trick the computer,just throw a carb on it if you can't do it right.
As for the Cat argument,it's really a moot point.
A shop can charge you $500 to remove it and it's still not an unfair price.
It is against federal law to remove,with a minimum 10k fine and possible 5yrs jailtime IIRC. Our local shops won't just cut off anyone's cats,they have to be referred by a trusted local.
It's not a legal service,so they just throw out a number whenever they are asked. The person will pay it or not,they don't really care.
As for cutting them off,there is no freaking point.
Unless your cammed,turbo/supercharged or have otherwise significantly changed the CFM/RPM limits of your engine than they aren't limiting you.
Taking it off MIGHT gain you LESS than a single hp at some obscure point in the rpm graph.
You are more than likely losing hp due to a negative change in velocity,maybe.
Backpressure isn't good,but necessary in a small amount for the existence of velocity at lower rpm's for torque.
Big as you can get it on the intake and exhaust side is the most ignorant statement i've ever heard for an N/A equipped engine.
The air is a pump,but the idea is more air in,more air out,more efficiently.
It's not more air in,more air out makes it more efficient.
Fluid dynamics tell us alot about pressure drops,velocity,scavenging etc..
On an FI engine,the dynamics are different-but when the engine has to work for it's air,it matters in determining how much the engine is getting for that work.
And of course all decisions made in any of these area's will affect the powerband. Who cares if you gain the ability to flow 50 more cfm and gain 20hp if it's at the edge of your redline or out of where you normally drive.
I'm not an expert in anything but my opinion,but there are alot of good reads on the internet explaining combustion,intake,exhaust and air density theory.
(oh yeah,and cutting off the cats will generally trigger p0430/p0420 codes. The computer will go constantly go through routines trying test and/or save the cat from damage. This usually involves adding a metered amount of extra fuel to the mix. So cutting your cat without properly removing it from the pcm will be simply killing your gas mileage and running rich anyway*generally.
Sorry for the long post,hope I didn't come off as a dik-I suck at the written word.