removal of exhaust pre-silencer??
#21
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Originally posted by Apexi350z
westpak: it would be funny that all it needs is to remove this little pre-silencer and you will gain the 6-8hp that most exhaust gives you
I think I might go shop around various muffler shops this weekend and have it removed, and weld a straight pipe. If it sounds that good, I will leave it on...
westpak: it would be funny that all it needs is to remove this little pre-silencer and you will gain the 6-8hp that most exhaust gives you
I think I might go shop around various muffler shops this weekend and have it removed, and weld a straight pipe. If it sounds that good, I will leave it on...
If you do it, would you mind doing dyno after, I will chip in just to find out, although I wuould prefer to go the bolt on route.
#22
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I replaced it with a straight pipe and it sounds like A$$! It is very raspy and definitely louder. May just be me, but it was faster with the pre silencer on.
NittoZ
NittoZ
#23
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Originally posted by NittoZ
I replaced it with a straight pipe and it sounds like A$$! It is very raspy and definitely louder. May just be me, but it was faster with the pre silencer on.
NittoZ
I replaced it with a straight pipe and it sounds like A$$! It is very raspy and definitely louder. May just be me, but it was faster with the pre silencer on.
NittoZ
It costed me $45.. Oh well, good experiment..
#24
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Originally posted by PistolPete
Plus all catalytic converters do is store polution, only to release it into the ground after they are junked. People think they magically make pollution go away.
Pollution in ground water is becoming a very disturbing problem. Here in Missouri, there is enough mercury in fish the conservation department recommends children don't eat them. The mercury seeps into the water and is absorbed by the fishes food.
Plus all catalytic converters do is store polution, only to release it into the ground after they are junked. People think they magically make pollution go away.
Pollution in ground water is becoming a very disturbing problem. Here in Missouri, there is enough mercury in fish the conservation department recommends children don't eat them. The mercury seeps into the water and is absorbed by the fishes food.
AFAIK, mercury is not involved at all in the process of burning gasoline. Lead was a major concern before the switch to unleaded gas.
Moral of the story - Leave the cats alone. They are not robbing you of anything, except pollution.
-TB
#25
Originally posted by Them Bones
Dude, are you on crack? Cats do not store polution. What do you think is in there, a big sponge that absorbs smog? Cats attempt to fully burn the unburnt fuel that is exiting your engine. The byproducts of completely burned gasoline are carbon dioxide and water, both relatively harmless.
AFAIK, mercury is not involved at all in the process of burning gasoline. Lead was a major concern before the switch to unleaded gas.
Moral of the story - Leave the cats alone. They are not robbing you of anything, except pollution.
-TB
Dude, are you on crack? Cats do not store polution. What do you think is in there, a big sponge that absorbs smog? Cats attempt to fully burn the unburnt fuel that is exiting your engine. The byproducts of completely burned gasoline are carbon dioxide and water, both relatively harmless.
AFAIK, mercury is not involved at all in the process of burning gasoline. Lead was a major concern before the switch to unleaded gas.
Moral of the story - Leave the cats alone. They are not robbing you of anything, except pollution.
-TB
Boomer
#26
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um in indiana we have no smog / emissions tests period.. so removing the cats is not illegal in anyway as long as your exhuast doesnt go above X dB.
what i'd try instead is removing the cats and replacing w/ straightpipes and leave the silencer in ... the silencer is how they "tune" yoru exhaust pitch and get rid of the annoying irregularities such as teh raspiness and high pitch sound you heard.. leave it in there... the cats however do impede the flow of gas slightly because they promote a temperature change which changes the speed at which gasses move causing turbulence..
also for those of you who welded the pipe in.. heres your problem.. now that you cut and welded, thers not going to be a smooth surface on the internals of the pipe anymore, those slight disturbances actually create a lot of turbulence and will also impeded exhaust flow... i know a mufflershop that'll mandrel bend and weld on flanges and such.. replacements for cats w/ flanges usually run about 45-60 bucks depending on type of flange etc. also pick up the correct gaskets :P
what i'd try instead is removing the cats and replacing w/ straightpipes and leave the silencer in ... the silencer is how they "tune" yoru exhaust pitch and get rid of the annoying irregularities such as teh raspiness and high pitch sound you heard.. leave it in there... the cats however do impede the flow of gas slightly because they promote a temperature change which changes the speed at which gasses move causing turbulence..
also for those of you who welded the pipe in.. heres your problem.. now that you cut and welded, thers not going to be a smooth surface on the internals of the pipe anymore, those slight disturbances actually create a lot of turbulence and will also impeded exhaust flow... i know a mufflershop that'll mandrel bend and weld on flanges and such.. replacements for cats w/ flanges usually run about 45-60 bucks depending on type of flange etc. also pick up the correct gaskets :P
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Originally posted by ^Tyr
um in indiana we have no smog / emissions tests period.. so removing the cats is not illegal in anyway as long as your exhuast doesnt go above X dB.
um in indiana we have no smog / emissions tests period.. so removing the cats is not illegal in anyway as long as your exhuast doesnt go above X dB.
Buy high-flow cats if you want, but spare the rest of us the smog by not removing them altogether.
-TB
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well,, there are so many cars on the road around here that just leave clouds let it be oil burning whatever,, i really doubt the already fairly clean emmissions from the z will hurt much,, but ok.. 5 hp doesnt meant hat much to me anyways.. i was just trying to state that in some states it is not illegal. or at least i guess from what you say there is not active monitoring or ticketing of people who do not follow the rules.
but in indiana there are no checkups of any kind and i've never heard of nor seen anyone ever pulled over or ticketed for bad emissions, granted im 1 person, but i have plenty of friends w/ cars that would be ticketed 5 miles into the border of the states you guys live in
plus since they would be bolted up w/ flanges and all, anyone w/ a lift could change them out in 15 min tops,, why wouldnt that be a good idea ofr track days and such?
but in indiana there are no checkups of any kind and i've never heard of nor seen anyone ever pulled over or ticketed for bad emissions, granted im 1 person, but i have plenty of friends w/ cars that would be ticketed 5 miles into the border of the states you guys live in
plus since they would be bolted up w/ flanges and all, anyone w/ a lift could change them out in 15 min tops,, why wouldnt that be a good idea ofr track days and such?
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Did any of you guys dyno your cars before/after you pulled the pre-silencer? I'm not only interested in peak HP gains, but the pre-silencer should also work as a resonator. If that is the case, you would see a HP dip in the 900-1400 RPM range.
#30
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Man some of you guys get really **** about this "Cat" removal subject. You guys act like your murdering someone. RELAX! And for those of you that said it doesn't rob horsepower, I have dyno plots from my prior car that prove it does. I gained 13HP from removing my cat on my Turbocharged Civic SI. I felt the difference too! And you know what, I also got pulled over by the police once and they looked under there and caught me. I had to go to a referee station and my car was tagged as a gross polluter. It was only a $250.00 fine I had to pay that's it... And I live in the worst state of them all, CALIFORNIA! I have all paperwork for proof in case some of you don't believe me. Anyway, I would remove all cats from this car but leave the pre-silencer and muffler alone. That's just my .02 cents, cat's are more deadlier than you think!
#32
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I did that on my turbo Z (gutted cats). It did improve HP!!
But thats a turbo car!
I thought naturally aspirated cars NEED a certain ammount of back pressure, which the cats, pre silencer and muffler provide?
Any experts know if this is true?
But thats a turbo car!
I thought naturally aspirated cars NEED a certain ammount of back pressure, which the cats, pre silencer and muffler provide?
Any experts know if this is true?
#33
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Originally posted by TRACK350z
I did that on my turbo Z (gutted cats). It did improve HP!!
But thats a turbo car!
I thought naturally aspirated cars NEED a certain ammount of back pressure, which the cats, pre silencer and muffler provide?
Any experts know if this is true?
I did that on my turbo Z (gutted cats). It did improve HP!!
But thats a turbo car!
I thought naturally aspirated cars NEED a certain ammount of back pressure, which the cats, pre silencer and muffler provide?
Any experts know if this is true?
#34
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You guys have to look at the system as a whole. Throwing a $1500 exhaust system is going to just make your wallet lighter.
Step back and look at the whole picture. The presilencer is the least of this guys worries.
hint .................look at the T pipe................
Step back and look at the whole picture. The presilencer is the least of this guys worries.
hint .................look at the T pipe................
#35
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um.. thembones,,, you do NOT want backpressure in an exhaust system.. what you are talking about is the scavanging effect the headers create from the exhaust pulses from different cylinders.. granted in the headers you will have slight backpressure.. but if you are talking about after headers,, you dont want backpressure,,
#36
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Dude, are you on crack? Cats do not store polution. What do you think is in there, a big sponge that absorbs smog? Cats attempt to fully burn the unburnt fuel that is exiting your engine. The byproducts of completely burned gasoline are carbon dioxide and water, both relatively harmless.
Seriously, though, don't throw around accusations. It's not nice.
Do a bit of research. Howstuffworks.com has a simplified write up on cats and how they work. Catalytic converters do not burn fuel. They use a catalyst (hence the name) to chemically change some pollutants created by gasoline combustion. This catalyst (there are actually more than 1) is a chemical which is applied to screens inside the cat itself. The chemical reaction has byproducts which adhere to screens and the inside of the converter. When the converter is disposed, this contaminants can leach into the soil, and then groundwater.
Cats are a decent pollution control. My point was they are far from perfect, and needed less in computer controlled engines than they were in the past. They are definately restrictors to exhaust flow. Not every state currently requires them.
The best possible solution is for everybody to ride motorcycles. Smaller displacement means less pollution.
#37
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motocycles w/ fuel injection maybe.. but i can guaruntee that my cbr600f2 makes more pollution than a 350z does even missing a cat or 2... cbr runs fine (well its drained for winter) but maybe i'm wrong ... but i think more control over the combustion etc. is what really lowers emissions
#38
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Originally posted by PistolPete
I might be on crack, but that has nothing to do with my argument.
Seriously, though, don't throw around accusations. It's not nice.
Do a bit of research. Howstuffworks.com has a simplified write up on cats and how they work. Catalytic converters do not burn fuel. They use a catalyst (hence the name) to chemically change some pollutants created by gasoline combustion. This catalyst (there are actually more than 1) is a chemical which is applied to screens inside the cat itself. The chemical reaction has byproducts which adhere to screens and the inside of the converter. When the converter is disposed, this contaminants can leach into the soil, and then groundwater.
Cats are a decent pollution control. My point was they are far from perfect, and needed less in computer controlled engines than they were in the past. They are definately restrictors to exhaust flow. Not every state currently requires them.
The best possible solution is for everybody to ride motorcycles. Smaller displacement means less pollution.
I might be on crack, but that has nothing to do with my argument.
Seriously, though, don't throw around accusations. It's not nice.
Do a bit of research. Howstuffworks.com has a simplified write up on cats and how they work. Catalytic converters do not burn fuel. They use a catalyst (hence the name) to chemically change some pollutants created by gasoline combustion. This catalyst (there are actually more than 1) is a chemical which is applied to screens inside the cat itself. The chemical reaction has byproducts which adhere to screens and the inside of the converter. When the converter is disposed, this contaminants can leach into the soil, and then groundwater.
Cats are a decent pollution control. My point was they are far from perfect, and needed less in computer controlled engines than they were in the past. They are definately restrictors to exhaust flow. Not every state currently requires them.
The best possible solution is for everybody to ride motorcycles. Smaller displacement means less pollution.
Yellowstone has worse pollution than L.A. in winter because of the snowmobiles. A senator, who is an avid snowmobiler, blocked legislation to require snowmobiles have smog controls like every other motorized vehicle and the legislation is dead for another year. The snowmobile manufacturerers screamed, they would lose money if they had to comply with smog regulations. I don't give a damn about them losing money, they are the worst polluters around our Nat'l Parks and they need to comply with smog regulations just like any other vehicle that transports human beings. And no, I do not approve of removing the cats on cars to gain 2-3 more HP. Wait until a good cat back system comes on the market, but please don't remove or gut the cats on your Z, you are polluting my air and everyone else's and we don't need any more **** in our air.
Boomer
#40
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[B]You guys have to look at the system as a whole. Throwing a $1500 exhaust system is going to just make your wallet lighter.
Step back and look at the whole picture. The presilencer is the least of this guys worries.
hint .................look at the T pipe................
Step back and look at the whole picture. The presilencer is the least of this guys worries.
hint .................look at the T pipe................