Exhaust idea...

[gmagnan]

I am a Protege newbie, but I've been a car enthusiast for a long time...

Anyways, from what I gather the 3rd gen Proteges have 2 cats, one resonator and one muffler, all 2 1/4 inch...

How much would one gain from replacing both cats with one high flow cat? I've run a cat-back in my current car (1990 8V Jetta, 2.5 inch with no resonator) and it didn't seem to provide any gain at all, I even felt like I lost some low & mid range torque... I guess there wasn't enough back-pressure. Now this may seem irrelevant, but the north american engine in theses things made 100-105 hp, while the cat less european ones made a solid 120hp. While the difference may not be as big in every car surely the same principle applies.

I think this setup could make a good difference in flow while maintaining enough back-pressure (stock diameter) and keeping the noise down (muffler and resonator still there, cat absorbs some noise too)... And the car would probably stay emmissions legal since the cat would still be there... Anyone know if this is feasible?

If not why?

 

[RZFD]

I don't see any problem but it may throw a cel I'm doing a little reaserch on the same thing right now b/c I want to use a long tube header (Mazdaspeed). I'll let you know what I find out I'mcalling a well known Mazda shop to see what the deal is.

 

[70]

I am a Protege newbie, but I've been a car enthusiast for a long time...

Anyways, from what I gather the 3rd gen Proteges have 2 cats, one resonator and one muffler, all 2 1/4 inch...

How much would one gain from replacing both cats with one high flow cat? I've run a cat-back in my current car (1990 8V Jetta, 2.5 inch with no resonator) and it didn't seem to provide any gain at all, I even felt like I lost some low & mid range torque... I guess there wasn't enough back-pressure. Now this may seem irrelevant, but the north american engine in theses things made 100-105 hp, while the cat less european ones made a solid 120hp. While the difference may not be as big in every car surely the same principle applies.

I think this setup could make a good difference in flow while maintaining enough back-pressure (stock diameter) and keeping the noise down (muffler and resonator still there, cat absorbs some noise too)... And the car would probably stay emmissions legal since the cat would still be there... Anyone know if this is feasible?

If not why?

The stock 3rd gen Protege does not have 2 1/4" piping all the way.

From the first cat to the second, the pipe is 1.75" inside diameter. After that, the stock pipe is 2" all the way back.

You do not want back-presure in an exhaust system.

As far as taking off one cat, you would still propbably be able to pass a sniffer test, however if you have to have an actual visible inspection you will not.

If you don't have to worry about smog inspections, then the above doesn't matter.

Simply getting a decent cat-back (which on this car would replace everything from the second cat back) would be a nice change. Racing Beat has a nice pipe (sedan and wagon), as does FM Protege (Protege 5 only at this time). There is also Bosal and Borla (both have for sedan and wagon).

I'm not quite sure why you want to remove one cat, as both cats actually flow pretty well. Just keep in mind that removing the catalytic converter is technically a federal offense. You would lose the ULEV status of the vehicle as well.

 

[PGT95]

2" is entirely too small for the air this motor is pumping but risking emmissions aint worth it IMO :shrug: so get cat back ~ 3 inches and be happy!

Ben

 

[Sir Nuke]

2" is entirely too small for the air this motor is pumping but risking emmissions aint worth it IMO :shrug: so get cat back ~ 3 inches and be happy!

Ben

3 inch is entirely TOO BIG unless you are running a turbo.....about 2 1/4 to 2 1/2 is ideal

 

[Sir Nuke]

oh yeah....PGT95, Welcome to our happy little corner of the net, and to our Club. There are TWO BIG fridge'S in the corner with anything you can think of in them...help yourself...of course only take what you can LEGALLY have.

make yourself at home on one of the big fluffy couches, kick your shoes off, put your feet up on one of the tables, yes we are allowed to do that, mom don't care....and take it easy.

oh...btw....every once in a while a food fight breaks out...so you may not want to wear nice clothes here.

Welcome!!

 

[Mackdaddy]

Unless your going FI anytime soon, don't bother with crazy fabricated exhaust ideas... not worth it.

The RB cat back is a very nice unit. I've had mine on for less than a week, but it does make a slight difference in performance. They state it's 2.375", but I measured it right at 2.125" ID (maybe the former is OD, not ID.) Who knows, but it works. Not loud by any means, but still enough to satisfy you audibly in the cabin.

This combined with the newly installed Sparko plug wires does make a difference. I'm really interested in seeing an improvement in fuel economy, too. This would make both purchases very worthwhile IMHO, as I've yet to see the EPA sticker rating of 25mpg city. Granted with only a little over 2k miles on her thusfar, but an avg of ~22mpg back and forth to work everyday is not as good as I'd hoped.

HTH - Jim

 

[chdesign]

As for backpressure with a turbo you dont' want backpressure but with a NA car you do want some degree of backpressure.

 

[PGT95]

As for backpressure with a turbo you dont' want backpressure but with a NA car you do want some degree of backpressure.

Let me rephrase that for you just a touch:

You never want backpressure in ANY car regardless of use (turbo, NOS, SC, Nigh Compression, Deisl) however for some natural aspirated motors peak performance occures with some back pressure still in the system.

READ: this backpressure is a coincidence and in no way adds to the power of the motor! It just so happens that in some car maximum Exhaust flow occures with some degree of backpressure present

Ben

 

[KYREDP5]

As for backpressure with a turbo you dont' want backpressure but with a NA car you do want some degree of backpressure.

Exactly, that's why his car felt slower. Backpressure = torque.

 

[PGT95]

Exactly, that's why his car felt slower. Backpressure = torque.

Incorrect but a common misconception, read my above post

ben