Removing Catalytic Converter = Better Gas Mileage

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Here is a neat one, if we looked at a total package emissions solution, all through the chain, would reducing emissions equipment on vehicles to improve mileage overall reduce emissions in less fuel being burned?
 
Originally Posted By: Chuck1986

And lastly, the feds ain't getting their dirty hands on someone's car without a warrant - it's not government-owned property. We don't live in a communist country.


If you live in a country that enforces private property rights, polluting someone else's air without their permission is against the law.
 
The Miata may have been tuned (engine and exhaust) to get the most out of the engine which is great. The late model GM trucks we sell usually run worse with exhaust mods (even just a Flowmaster muffler) and lose some mpg.

The Spec V exhaust was so restrictive it was unbelieveable. Acceleration was improved throughout the power band. And it didn't have the ricer sound.
 
The Acura TL has around 220~230 RWHP and you claim 30 WHP gain by a cat delete? I'd like to see the dyno graph of the before/after please.

Originally Posted By: BuickGN
Different cars are different. My TL uses 1200 cell precats I believe and a 300 cell single cat. The exhaust leaves the head (only one exhaust port) and makes a 90 degree turn in the course of about 1.5" straight into the precats. Deleting all three shows close to 30hp at the wheels and about 4mpg. My third cat is gutted and I just ordered the precat deletes.

On the GN, there was no single cat that flowed enough. I tried a Random technologies cat and lost 8psi boost and 10mph through the 1/4.
 
My stock auto version dyno'd 210hp and an anemic 183lbs of torque. The auto should see just under 20hp. The manual transmission TL is what I was referring to. This is the precat, post cat delete, and better J-pipe. I'm not really interested in the hp gain because it might see WOT once a month if that. It's the mileage I'm after.

If you look at the factory TL exhaust, 30hp is completely believable. The cats are bolted to the heads. Exhaust comes out of the single exhaust port, makes a very sharp 90 degree bend, right into a 1200 cell cat. Exhaust literally has less than two inches to make the 90 degree turn.

Do a search on acurazine. There's a guy putting down nearly 250whp in a 3.0L Accord with nothing but exhaust mods.
 
Originally Posted By: chuckerants
The Acura TL has around 220~230 RWHP and you claim 30 WHP gain by a cat delete? I'd like to see the dyno graph of the before/after please.


The last TL I saw on the dyno made exactly 0 RWHP.
 
I was the 3rd owner of the Spec V. I wish them good luck proving which owner/car dealer removed the cats.
 
Forty-five of the fifty states have statutes or regulations which prohibit the tampering of or driving without pollution control equipment on motor vehicles or selling such vehicles. They don't have to prove who removed the catalytic converter. It's your responsibility to make sure the car has working emission control devices when you bought the car, while you're using it, and while you sell it. A receipt that mentions "as-is" in the selling documents does not preclude this law.

I don't know who those five states are though.
 
Visual inspection shows the cats are there. There is no emission test in Louisiana. The car does not have a CEL.
 
Believable? Maybe. Credible? Doubtful. Again, show me the dyno graph.

As for the Accord, my Odyssey has the same engine and it make (according to Honda) 255HP (at the flywheel). So considering drivetrain losses, maybe 220~230 HP STOCK.

I say again, show me the before and after dyno graphs.

I can say all day long my car makes 1000HP. Would you believe it without proof?

Originally Posted By: BuickGN
My stock auto version dyno'd 210hp and an anemic 183lbs of torque. The auto should see just under 20hp. The manual transmission TL is what I was referring to. This is the precat, post cat delete, and better J-pipe. I'm not really interested in the hp gain because it might see WOT once a month if that. It's the mileage I'm after.

If you look at the factory TL exhaust, 30hp is completely believable. The cats are bolted to the heads. Exhaust comes out of the single exhaust port, makes a very sharp 90 degree bend, right into a 1200 cell cat. Exhaust literally has less than two inches to make the 90 degree turn.

Do a search on acurazine. There's a guy putting down nearly 250whp in a 3.0L Accord with nothing but exhaust mods.
 
Originally Posted By: chuckerants
Believable? Maybe. Credible? Doubtful. Again, show me the dyno graph.

As for the Accord, my Odyssey has the same engine and it make (according to Honda) 255HP (at the flywheel). So considering drivetrain losses, maybe 220~230 HP STOCK.

I say again, show me the before and after dyno graphs.

I can say all day long my car makes 1000HP. Would you believe it without proof?

Originally Posted By: BuickGN
My stock auto version dyno'd 210hp and an anemic 183lbs of torque. The auto should see just under 20hp. The manual transmission TL is what I was referring to. This is the precat, post cat delete, and better J-pipe. I'm not really interested in the hp gain because it might see WOT once a month if that. It's the mileage I'm after.

If you look at the factory TL exhaust, 30hp is completely believable. The cats are bolted to the heads. Exhaust comes out of the single exhaust port, makes a very sharp 90 degree bend, right into a 1200 cell cat. Exhaust literally has less than two inches to make the 90 degree turn.

Do a search on acurazine. There's a guy putting down nearly 250whp in a 3.0L Accord with nothing but exhaust mods.


I could care less what you believe. My purpose in life is not to dig up dyno graphs for you. Go over there and do a search and you will find it.

Mine is rated at 258hp and it put down 209.8 at the wheels. I have numbers to back up my claims, not estimates of what it "should" put down at the wheels.
 
If removing/modiying the cats would cause such a big improvement in HP and gas milage, why wouldn't the mfgs. incorporate changes to the emmission systems to improve HP/milage as a selling point?

Seems with the cut-throat competition, no modern car engineer, esp. sporty cars, would leave that much HP and milage on the table.

Kinda like the old "car companies are holding back the 100 mpg carburator", where any rational business would pounce on the money making potential of such a break-through.

Drew
 
I'm sorry, I did not intend for this thread to become a political thread about whether removing cats is right or wrong. All I will say though is when you consider air quality, I can assure everyone that more people develop lung cancer and emphysema from 'perfectly legal' second hand smoke than cars without catalytic converters.

BuickGN - did that guy with 250whp on a 3.0L Accord have any ECU tuning done? Those are incredible numbers. Those are some sweet numbers with your GN too..and you have a nice daily driver to complement it!
 
Originally Posted By: Chuck1986
I'm sorry, I did not intend for this thread to become a political thread about whether removing cats is right or wrong. All I will say though is when you consider air quality, I can assure everyone that more people develop lung cancer and emphysema from 'perfectly legal' second hand smoke than cars without catalytic converters.

BuickGN - did that guy with 250whp on a 3.0L Accord have any ECU tuning done? Those are incredible numbers. Those are some sweet numbers with your GN too..and you have a nice daily driver to complement it!


Thanks! I'm still not used to having a daily driver and a toy. Until I bought the TL at 29 years old, I never had a car with working AC so I'm very appreciative for what I've got.

The Accord had no tuning but I think the primary reason for the big gains is the factory system is so restrictive.
 
Originally Posted By: Drew2000
If removing/modiying the cats would cause such a big improvement in HP and gas milage, why wouldn't the mfgs. incorporate changes to the emmission systems to improve HP/milage as a selling point?

Seems with the cut-throat competition, no modern car engineer, esp. sporty cars, would leave that much HP and milage on the table.

Kinda like the old "car companies are holding back the 100 mpg carburator", where any rational business would pounce on the money making potential of such a break-through.

Drew


Emissions compliance overrides power and mileage. With convertors my car has ULEV status. Without, it's a gross polluter.

Do you really think a 1200 cell convertor haning off each head is not restrictive?
 
Originally Posted By: Chuck1986
I'm sorry, I did not intend for this thread to become a political thread about whether removing cats is right or wrong. All I will say though is when you consider air quality, I can assure everyone that more people develop lung cancer and emphysema from 'perfectly legal' second hand smoke than cars without catalytic converters.


The way I see it is, if you've got smog in your area, it's irresponsible to contribute to that more than necessary by removing your cat. But if not, you're just conserving energy. Thanks for bringing the topic up. I'm very interested in how much a catalytic converter affects power and mileage.

Originally Posted By: Drew2000
If removing/modiying the cats would cause such a big improvement in HP and gas milage, why wouldn't the mfgs. incorporate changes to the emmission systems to improve HP/milage as a selling point?


They just can't do it without a cat. Look into the 1995 Honda Civic VX. I believe it's the only car made since emission laws came into place that could pass them without a cat. It beats the Prius for highway mileage, and even beats the smaller and much less powerful 1.0L Geo Metros in both city and highway mileage. Back then, nobody wanted to pay an extra grand for less power and more mileage so it only lasted one model year.
 
Originally Posted By: BuickGN
Originally Posted By: Drew2000
If removing/modiying the cats would cause such a big improvement in HP and gas milage, why wouldn't the mfgs. incorporate changes to the emmission systems to improve HP/milage as a selling point?

Seems with the cut-throat competition, no modern car engineer, esp. sporty cars, would leave that much HP and milage on the table.

Kinda like the old "car companies are holding back the 100 mpg carburator", where any rational business would pounce on the money making potential of such a break-through.

Drew


Emissions compliance overrides power and mileage. With convertors my car has ULEV status. Without, it's a gross polluter.

Do you really think a 1200 cell convertor haning off each head is not restrictive?


I second that - when you remove the cats, you'll notice these things are very heavy pieces of metal that are welded right to the exhaust manifolds, which are the most crucial passages for airflow in the exhaust system. Then when you look inside of the cat and see how much metal is in there, you'll know you've just taken the cork off a champagne bottle.

If that guy's 3.0L Accord can make that much power, I can't imagine how much you could get with your TL...then again, you already have yourself a pretty nice toy to satisfy the need for speed with that Buick :)
 
Experiment on Civic and Integra on Honda-tech shows no improvement between hi-flow cat and test pipe on a highly modded car on dyno. In a typcal car running below peak RPM, it won't make much difference.
 
Who runs their Integra or Civic below peak rpm?


"I live my life one Quarter Pounder at a time"-Vin Kenworth
 
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