Removing catt's and putting in stright pipe questions

[AllanD]

The cats do have to work, so gutting them is just as bad as removing them. If someone lives in a state that does emissions testing theres no sense trying to get around running a functioning cat. Maine doesnt test for emissions, so its more lenient up here. My firewood buggy BII has no cats, but is only run in the woods for 10 miles a year.

You are aware catalytic converters became government-mandated equipment in 1972 during the Nixon administration, right? Hell, the EPA was Nixons idea, so I dont see why Obama is mentioned in this.

Cats were not universally applied to ALL vehicles until the 1980 model year.

It was catalytic converters that forced the switch to unleaded gas.

 

[cody93]

ok, your engine needs some back pressure, or else you can suck air in your exhaust and burn out your valves.. second a gutted cat is worse than a working cat, might as well go to strait pipe, less turbulance, but a good flowing cat would be the best way. 3rd, you have a danm 4 cyl, not only that, but a late one with dual o2 sensors, you'll sound stupid. just put a new good flowing cat on and call it good

 

[Bondo]

Cats were not universally applied to ALL vehicles until the 1980 model year.

It was catalytic converters that forced the switch to unleaded gas.

I know they werent applied to all vehicles then, but thats when the focus started.

Im pretty sure the hazards of lead poisoning had alot to do with the introduction of unleaded gas. Many people died from absorbing/breathing exhausted lead through the years. Leaded gas had to be phased out by government order for public health reasons, starting in 1975.

The leaded gas would render the cats useless in keeping pollutants from being released in the exhaust, yes. The poisonous leaded gas was on its way out at that time anyway, so there was the perfect opportunity for killing two birds with one stone.

 

[85_Ranger4x4]

ok, your engine needs some back pressure, or else you can suck air in your exhaust and burn out your valves.

Without O2 sensers it will be running pig rich which makes it hard to burn valves. I have heard a whole lot more "you can't do that or you will burn your valves" than I have actually heard of people burning their valves... I don't think there is much fact behind that when it comes to changing exhaust parts.

 

[kryptonitecb]

Without O2 sensers it will be running pig rich which makes it hard to burn valves. I have heard a whole lot more "you can't do that or you will burn your valves" than I have actually heard of people burning their valves... I don't think there is much fact behind that when it comes to changing exhaust parts.

The only fact I can present is my extra 2mpg after having a cat reinstalled. That's good enough for me to keep it.

Sent from the road while ignoring traffic

 

[adsm08]

I am thinking about removing the catts and replacing them with stright pipe. what will that sound like with the stock muffler? Iv been heavily involved with truck pulls and im looking for some more power. Iv got this F-150 I havent been able to pull hahhahhaha

It will sound a lot like "Federal Crime".

 

[adsm08]

Without O2 sensers it will be running pig rich which makes it hard to burn valves. I have heard a whole lot more "you can't do that or you will burn your valves" than I have actually heard of people burning their valves... I don't think there is much fact behind that when it comes to changing exhaust parts.

Removing the cats won't burn a valve. Running open headers or having a massive leak right by the head will burn a valve.

Burnt valves are not just a product of lack of pressure, you have to have a source of fresh air right by the valve to oxidize the metal. A sealed system that provides very little pressure but still keeps the exhaust train in a positive pressure environment will not allow a burnt valve assuming the engine is not running super lean.

 

[shane96ranger]

I have no experience with going catless on an RBV. From all I've read, it's not as good as the expectations or hopes are for.

I'm guilty of running an off-road H-pipe on my Mustang. I'm here to tell you that an off road H-pipe does produce more power over the factory 4 cat pipe on my car. However..... I have since put a high-flow cat H-pipe, and feel it is quite comparable in power to the off road. I did it when I was young and wouldn't do it again unless it was a temporary fix.

In other words, consider a high flow cat and get the best of both worlds.

 

[85_Ranger4x4]

I have no experience with going catless on an RBV. From all I've read, it's not as good as the expectations or hopes are for.

I'm guilty of running an off-road H-pipe on my Mustang. I'm here to tell you that an off road H-pipe does produce more power over the factory 4 cat pipe on my car. However..... I have since put a high-flow cat H-pipe, and feel it is quite comparable in power to the off road. I did it when I was young and wouldn't do it again unless it was a temporary fix.

In other words, consider a high flow cat and get the best of both worlds.

As a general rule of thumb IMO, the newer the vehicle the less restrictive the cats are. I know there isn't much difference between say your '97 F-150 cats and high flows except one sounds neater (verbally, "stock" sounds boring compared to "high flow") than the other.

 

[shane96ranger]

As a general rule of thumb IMO, the newer the vehicle the less restrictive the cats are. I know there isn't much difference between say your '97 F-150 cats and high flows except one sounds neater (verbally, "stock" sounds boring compared to "high flow") than the other.

Yeah, I think they've come a long way. The cats on my car were very restrictive (you could see it visually). At some point the cats on the Stang actually broke inside, which is why I changed it.

 

[Lucifer sam]

I know there isn't much difference between say your '97 F-150 cats and high flows except one sounds neater (verbally, "stock" sounds boring compared to "high flow") than the other.

FUNNY you should say that, I recently put on a cat off of a 99-04 Lightning, with a few modifications it works great, I still need to have it welded up its clamped together at the moment.

But between the lightning cat and the roush mustang cat back, I have a full 2.5" exhaust.

The funnier part is that it was louder and ricey sounding WITH THE STOCK CAT, and the roush catback.

The way around the check engine lightning is quite simple, you just need to move the after cat o2 sensor further from the exhaust stream

 

[AllanD]

I know they werent applied to all vehicles then, but thats when the focus started.

Im pretty sure the hazards of lead poisoning had alot to do with the introduction of unleaded gas. Many people died from absorbing/breathing exhausted lead through the years. Leaded gas had to be phased out by government order for public health reasons, starting in 1975.

The leaded gas would render the cats useless in keeping pollutants from being released in the exhaust, yes. The poisonous leaded gas was on its way out at that time anyway, so there was the perfect opportunity for killing two birds with one stone.

My point was that catalytic converters were CHOSEN by vehicle manufacturers to meet emissions standards and were not "mandated" by the government until 1980.

Leaded gas was eliminated not because of the issue of poisoning people but because the lead leaving the engine in vapor form "poisons" the catalytic converter.

Lead also "poisons" Oxygen sensors.

It is practical to "clean" an oxygen sensor, simply heat until it glows with
a propane torch and keep it glowing at that temp for 5minutes or so.

Cleaning a catalytic converter the same way is a bit more difficult, and generally impractical

 

[--weezl--]

I know they werent applied to all vehicles then, but thats when the focus started.

Im pretty sure the hazards of lead poisoning had alot to do with the introduction of unleaded gas. Many people died from absorbing/breathing exhausted lead through the years. Leaded gas had to be phased out by government order for public health reasons, starting in 1975.

The leaded gas would render the cats useless in keeping pollutants from being released in the exhaust, yes. The poisonous leaded gas was on its way out at that time anyway, so there was the perfect opportunity for killing two birds with one stone.

except that leaded gas is still available and used on a regular basis for aviation purposes

I have no experience with going catless on an RBV. From all I've read, it's not as good as the expectations or hopes are for.

I'm guilty of running an off-road H-pipe on my Mustang. I'm here to tell you that an off road H-pipe does produce more power over the factory 4 cat pipe on my car. However..... I have since put a high-flow cat H-pipe, and feel it is quite comparable in power to the off road. I did it when I was young and wouldn't do it again unless it was a temporary fix.

In other words, consider a high flow cat and get the best of both worlds.

that's a different story, remember we were saying quality cats that are matched with the output of the engine? yeah, the mustang's wasn't... they were also junk cats, hence why they needed 4 of them...

mine on my mustang were gutted too

 

[Bondo]

My point was that catalytic converters were CHOSEN by vehicle manufacturers to meet emissions standards and were not "mandated" by the government until 1980.

Leaded gas was eliminated not because of the issue of poisoning people but because the lead leaving the engine in vapor form "poisons" the catalytic converter.

Lead also "poisons" Oxygen sensors.

It is practical to "clean" an oxygen sensor, simply heat until it glows with
a propane torch and keep it glowing at that temp for 5minutes or so.

Cleaning a catalytic converter the same way is a bit more difficult, and generally impractical

And my point was that in 1975, cats were to be used in new vehicles produced. No, not all of them got them, but thats when they started getting used in American built vehicles.

The tweaking of the Clean Air Act in 1970 helped usher in both unleaded gas and the use of catalytic converters. Leaded gas was being phased out for the 2 reasons mentioned already, as early as 1973. YES the cats couldnt function correctly, but the health data was piling up as well. 2 birds, 1 stone.

Had GM not dragged its feet both couldve happened 15 years prior....

 

[Bondo]

except that leaded gas is still available and used on a regular basis for aviation purposes

I know.

Actually the US (auto) gas wasnt totally lead free till 1996. Sad.