Exhaust gas w/o cats?
12-22-2005, 12:47 AM
#1
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Exhaust gas w/o cats? Do you smell exhaust gas inside the car with an ORY and catback setup? I'm re-thinking my true dual setup because of the smell, and I can't get an inspection. I want to know if I can kill 2 with 1. Thanks!
I really gotta do something about it. Then again I've got a 408 with a 244/248 cam so I may be in a different boat than you. Just giving my input. 
12-22-2005, 02:34 AM
#4
how about without a cam just with stock everything but LTs ORY and cat back ?
i was behind a cammed ls1 vette the other day with LTs, no cats, I could smeel it from my car !
i was behind a cammed ls1 vette the other day with LTs, no cats, I could smeel it from my car !
12-22-2005, 04:23 AM
#5
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Originally Posted by 93octane
Do you smell exhaust gas inside the car with an ORY and catback setup? I'm re-thinking my true dual setup because of the smell, and I can't get an inspection. I want to know if I can kill 2 with 1. Thanks!
Seriously, if you have the exhaust venting under the car (dumps) then yes you will likely get fumes inside aswell.
If you have a strong smell of petrol (like someone has already mentioned) this has nothing to do with the CATS. They either have a fuel leak, or are running far too rich.
In the UK CATS where not mandatory until 1993. There was NEVER an issue with petrol fumes on any car built before that period. I currently have 4 cars all with out CATS (which is legal!!!) none smell anymore than my z28 with CATS, or any of the other cars in the family that have CATS on them.
Last edited by 300bhp/ton; 12-22-2005 at 04:31 AM.
12-22-2005, 10:06 AM
#6
Originally Posted by 300bhp/ton
No!
Seriously, if you have the exhaust venting under the car (dumps) then yes you will likely get fumes inside aswell.
If you have a strong smell of petrol (like someone has already mentioned) this has nothing to do with the CATS. They either have a fuel leak, or are running far too rich.
In the UK CATS where not mandatory until 1993. There was NEVER an issue with petrol fumes on any car built before that period. I currently have 4 cars all with out CATS (which is legal!!!) none smell anymore than my z28 with CATS, or any of the other cars in the family that have CATS on them.
Seriously, if you have the exhaust venting under the car (dumps) then yes you will likely get fumes inside aswell.
If you have a strong smell of petrol (like someone has already mentioned) this has nothing to do with the CATS. They either have a fuel leak, or are running far too rich.
In the UK CATS where not mandatory until 1993. There was NEVER an issue with petrol fumes on any car built before that period. I currently have 4 cars all with out CATS (which is legal!!!) none smell anymore than my z28 with CATS, or any of the other cars in the family that have CATS on them.
12-22-2005, 10:27 AM
#7
There is a noticeable difference from when I had cats to now with no cats.
If I have the windows down and I come to a stop I can smell fumes. Nothing bad, but you can tell there's no cats. The car gets 400 or better miles per tank so I think I'm running pretty good A/F wise. Check the sig for mods.
If I have the windows down and I come to a stop I can smell fumes. Nothing bad, but you can tell there's no cats. The car gets 400 or better miles per tank so I think I'm running pretty good A/F wise. Check the sig for mods.
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12-22-2005, 10:32 AM
#8
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As far as I know cats don't filter, they promote a chemical reaction to reduce certain chemicals. Now unburnt petrol may be one of them, but I think it's a little more complex than that. All I can say is I drive 110 miles a day in a car which doesn't have a cat due to it's age (pre 1993). This journey takes a total of 3 hours, if petrol fuems where bad I would either be hi or in hospistal at the end of each journey.
Also I have owned probably 10+ cars all without cats. The smell of PETROL was not a factor.
Of course the acutal smell may change, becuase the chemical composition should be different with CATS, but that doesn't mean it will smell strongly of petrol.
My TR7 V8, runs a pretty wild cam, large 4brl carb, long tube headers and a single silencer exhaust, uprated fuel pump and so on. It does not have a CAT, yet it does not smell any stronger of petrol than my STOCK Z28, or my brothers catted MGF.
Also I have owned probably 10+ cars all without cats. The smell of PETROL was not a factor.
Of course the acutal smell may change, becuase the chemical composition should be different with CATS, but that doesn't mean it will smell strongly of petrol.
My TR7 V8, runs a pretty wild cam, large 4brl carb, long tube headers and a single silencer exhaust, uprated fuel pump and so on. It does not have a CAT, yet it does not smell any stronger of petrol than my STOCK Z28, or my brothers catted MGF.
12-22-2005, 05:52 PM
#9
What I'm saying is, the difference between cats and no cats is extremely noticeable. When you take out the only part of the exhaust system that tones down the CO and fumes, you're obviously going to smell them more, on some cars more than others (for example, big cam engines). Taking true duals off and putting on a muffler will have no effect on the smell. It might reroute it more toward the back, allowing you to smell less, but it doesn't change the fact that there is nothing in there reducing the exhaust fumes.
12-23-2005, 07:40 AM
#11
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You absolutely can tell the difference. With just a lil tr224, i could tell the difference big time between when i bought it with an ORY and when i put cats on it to get it inspected and back again afterwards. I like the smell so i dont care but its certainly noticeable.
