Hi Flow Catalytic converters

[doctorpimp]

Blah blah blah - environment issues etc...

Since I'm going to fuel injection anyways, would there be any real negative issues to installing cats ? 
Besides a few HP lost...
I know I don't have to.

Just askin...

[Silver R/T]

Depends if you want to quiet down your exhaust.

[doctorpimp]

Yeah, that's kind of the idea - I was thinking of adding resonators so I figured WTF might as well help out the environment at the same time...

[A383Wing]

If you get the fuel injection set up correctly, the emissions should be better than a carburetor motor and catalytic converter should not be needed.

[doctorpimp]

You still have Oxides of Nitrogen from the combustion process that gets converted to O2 and Nitrogen in the cat... I'm pretty sure Fuel Inj still produces those Oxides...

Anyway, for less $$ than stainless resonators I can get stainless cats...  I wonder what the real HP loss would be?

[mauve66]

dump the mufflers and just run straight through the cats, i did that on a 81 Rustmaro i had after i ripped off the mufflers cutting across a corn field.................. long story

still decent rumble but no extra money

[doctorpimp]

LOL nice!!  I did the same on my '83 Rustang GT - rolled in Neutral past all the cops... LOL

Well, in my Charger I have 3" stainless, custom X pipe with Magnaflow straight through mufflers... sounds awesome, but LOUD for long cruises... no cats at all '73s don't require them here.  I was going to install Magnaflow's 4" round resonator mufflers in the 3rd gen Hemi style, by the tips.  I wonder which will give the best sound results etc...

[Rolling_Thunder]

I was thinking of adding cats for emissions reasons here in CA - with the 6.1 and cats is should pass a sniffer test no problem...    not that is it needed - would just be pretty cool to say it can pass a smog test 

I  decided against it simply because I already have my TTI exhaust - don't want to cut it up.

[doctorpimp]

Yeah, I know what you mean about cutting nice tubing...
But I'm going to cut it to add resonators anyway - that idea of passing a smog test is cool too!  That and less drone inside the car...

Anyone have any experience in this area?
On new cars with a V8, when you add a "test-pipe" approx how much HP and Torque do you gain?
These new era of cats don't seem to be all that restrictive anymore - compared to cats and a rich running carb...

[firefighter3931]

Paul, if you want to tone the exhaust down just install some race bullet mufflers in the tailpipes. These are cheap and won't restrict your exhaust system. The bullets will act as resonaters. 


Ron

[doctorpimp]

Yeah Ron, that's pretty much what I was going to do.  But for the same price, I can get hi flow bullet cats from magnaflow.
I was just figuring, why not kill two birds with one stone - a green(er - LOL) 470 cu/in electronically controlled engine and slightly quieter exhaust.
Not sure if I'll miss a few ponies (unless we're talking 100 or so...) - she is designed as a street cruising machine anyway.
Why not also do the environmental thing...?  Just to see...

Has anyone installed cats on their projects?

I mean how much HP potentially could be lost? 

I know we're all about the highest HP we can make, but even for my project I sacrificed a few HP for driveability, comfort and longevity of the drivetrain.  470 as opposed to 500 stroker, milder cam for FI, Fuel Inj, etc... 

[flyinlow]

I used bullet mufflers on my 3 inch exhuast as resonators behind my magnaflows. Mellowed  out alot while cruising. Also have an H pipe which helps.

I wondered about converters too. To work well they should be close to the engine. They would need heat shields . The factory frequently used an air pump or asperator to get extra oxygen to the converter. I wondered if a aftermarket carb and cam would overload them.

[doctorpimp]

Well, I will have O2 sensors on both headers and it is S-MPFI based on EEC-IV.  New cars now don't have air pumps etc. 
Anyone have experience with a fuel inj 5.0 mustang, camaro etc running a bigger cam, headers and cats?
I think those hi-flows might work...

Yeah with a carb I wouldn't even consider it!

[mauve66]

being a carb shouldn't matter, my 81 Rusmaro had a carb and cats, no problems

[doctorpimp]

Yeah I guess... any air pump or tubes for the GM cats? 
In my 83 GT - the cats got plugged from running too rich with the Holley 4bbl...

[firefighter3931]

If quieting down the exhaust is the primary goal....the bullets as resonators would probably do a better job. 

I can't think of anyone who would "voluntarily" install cats on a hotrod. 



Ron

[doctorpimp]

LOL yeah I know - sometimes I think really abstract...

I think I may be digging myself a hole too deep anyway - after investigating cats, I'd need to have 4 in total - due to the Litre displacement of a 470.  There goes the same $$ argument...

Bullets it is.

Thanks all!