More power and better MPG

[1.5Ldave]

Originally Posted by dwtaylorpdx

It also depends on which gas you believe is worse, C02, CO, SulfurDioxide....

They all have bad effects... Pick your poison.

Matrix Full metal cats actually help exhaust flow at street speeds.
They make the exhaust laminar in the pipe, flows better.

Cats don't last on race cars, the sustained exhaust flow at race RPM melts them.

Dave

Lets agree to disagree on global warming and the usefulness of emissions regulations. Id rather talk about our cars. My main goal is to prove that a high efficiency car doesnt have to be way under powered or a hybrid.

I hadnt heard of those matrix full metal cats before, thanks for the info. Far too expensive for my testing purposes though. Changing the exhaust out for a few tanks of A-B-A testing will suit my needs. To be honest, at the speeds I drive normally I doubt even a regular ceramic core cat hinders flow much. But Im going to test it and find out for sure.

Regardless of the cat findings, I will be keeping the mandrel exhaust and straight through 22" muffler in the stock location, so its a win-win. I like things done right, and crush bent is junk.

For now my main focus is getting the header on and retuning it. With the cam 5 degrees advanced its got a whole lot more torque down low. It feels like a vw engine almost. With the header and retune Im expecting another 1-2 mpg, hoping for a bit more than that since its running a bit rich right now.

I was looking at these bumper spoilers from a prius and it got me to thinking of picking them up for some experiments. Check em out:

04-08 TOYOTA PRIUS OEM LEFT RIGHT REAR BUMPER SPOILERS:eBay Motors (item 400077954374 end time Nov-07-09 20:30:34 PST)

[ncs]

Sport Compact Car magazine(rip) published some aftermarket cat test results a few years ago. Power losses were something like 1 hp per 100hp produced. The aftermarket cats didn't clean as well as the factory ones, but they did well enough to pass the tailpipe part of California's emission test. There is no excuse anymore not to run a cat.

[mhmitszach]

The earth naturally absorbs volcanic out-gasses (CO2 etc) That carbon is turned into sedimentary rocks like limestone. However, it absorbs it slowly. When we increase the man made CO2 , it throws off that equilibrium. The earth cannot absorb it fast enough, thus causing the greenhouse effect. So the earth heats up because of the extra greenhouse gases, thus causing global warming. It's simple science.


Anyways, why remove the cat? I don't think people will appreciate breathing the fumes behind your car.

[99LeCouch]

I like the plans, except removing the cat. The restriction it provides is negligible. It also quiets the exhaust nicely.

On some cars, such as mine, people cannot outflow the stock exhaust until they build their motors to insane power levels.

[elhigh]

I live in a place with no emissions testing at all. None. Zip. I even see cars that are running open headers on the street, and cops still don't do a thing.

And yet, I keep the cat on there.

[jamesqf]

You might also consider the fact that a catalytic converter does next to nothing to affect the amount of CO2 that goes out the tailpipe. There's just a very small effect from converting CO-->CO2 and oxidizing those unburned hydrocarbons (which are measured in parts per million).

[drew1d]

Exhaust work is cool. You can change the torque curve of a motor, and that can net some horsepower.

As for the emissions, If you take off a cat, and it gives you that much mpg's I'd suspect that the cat was bad.

I'm also fairly sure your Honda motor produces far less emissions than a Ford Truck, even without a cat. But it's what keeps your ride legal, so... good luck.

[j.reed]

Originally Posted by jamesqf

You might also consider the fact that a catalytic converter does next to nothing to affect the amount of CO2 that goes out the tailpipe. There's just a very small effect from converting CO-->CO2 and oxidizing those unburned hydrocarbons (which are measured in parts per million).

I was about to say that...cats are designed to recduce CO, NOx, and unburnt fuel. Not co2... And yes a good quality performance cat will flow more than your engine, so there really is no gain to be had. I do not believe in the whole global warming(as a way of life, not the theory) but i DO believe in cleaning up the air. If youve ever driven a car without a cat, youll want one back. It stinks and gives you a headache even with the windows up

[Christ]

Originally Posted by j.reed

I was about to say that...cats are designed to recduce CO, NOx, and unburnt fuel. Not co2... And yes a good quality performance cat will flow more than your engine, so there really is no gain to be had. I do not believe in the whole global warming(as a way of life, not the theory) but i DO believe in cleaning up the air. If youve ever driven a car without a cat, youll want one back. It stinks and gives you a headache even with the windows up

I haven't had that experience personally, but I do also keep my vehicles tuned to run within emissions limits regardless of their purpose (race cars don't get cats, but I do drive them to the track, as I keep them in street legal classes.)

I can get the cars smogged by a friend of a friend for $20 after hours, but there are no emissions testing procedures around here that I need to pass, including (in some cases) visual inspections.