Exhaust performance

[krj]

I've got an exhaust performance question, here's a little background.

I'm currently rebuilding an '83 22r (it's been bored 30 over) and trying to balance the three qualifiers of any job; price, time, and quality.

While tearing apart and cleaning I found a crack in the exhaust manifold.

Should I take the cheap and fast route of welding the crack and re-using the manifold and existing exhaust and 27 year old cat?

I've got a friend offering up a Hedman header which would need some fabrication and would, most likely, preclude the cat.

Third option would be an after market header which would work with existing exhaust system and cat (most expensive option).

While I'm not an 'environmentalist' (I own 10 combustion engines for f#$&s sake!) I do really like clean air and fresh water so I'd rather keep the cat, if its still doing any good.

So I guess the real question is; I've got an '83 22r bored 30 over, is it any different if I put the Original Exhaust Manifold on, with a welded crack and original exhaust from manifold back through tailpipe OR

New performance header to existing exhaust with orig. cat. OR

New performance header with new exhaust system.

[Maineah]

I'm all for stock in the long run they are less trouble. Headers will give you a little boost in power, cats are restrictive as are small pipes with bends but I doubt that you had drag racing in mind. Cats do clean up the act and it may not pass emission test if it's required where you live a lot of states even if they do not test emissions require the cat even if it is only visable. The older exhaust manifolds the ones wrapped up inside of a tin shell cracked all the time I have welded dozens of them with a mig.

[krj]

Thanks for the info, Maineah, I like the sounds of it. I've got an old arc welder, any certain kind of rod I should use? I just started welding a year ago and don't yet know a ton about it. A guy at the local Napa told me that without a high Nickel content that cast iron manifolds would just crack again. Does that sound plausable or is he just giving me the old 'fetzer valave' line.

[Gulfstream Greg]

New Header, new cat and new exhaust is what I would do. Sounds like you are tweeking the engine for some more horsepower why not the exhaust too.

[krj]

The engine was bored in the course of a rebuild, its the only mod thats been done. I would love to increase the horsepower but money is tight right now, maybe in the future.

Does a header and exhaust upgrade make a noticeable difference? I could put on the header from my buddy now and upgrade the rest later. Any recomendations?

[Maineah]

Thanks for the info, Maineah, I like the sounds of it. I've got an old arc welder, any certain kind of rod I should use? I just started welding a year ago and don't yet know a ton about it. A guy at the local Napa told me that without a high Nickel content that cast iron manifolds would just crack again. Does that sound plausable or is he just giving me the old 'fetzer valave' line.

If you stick weld it you'll need nickle rods. Drill a small hole at both ends of the crack (this will stop the crack from extending while you weld it)and grind a grove in the crack.

[krj]

Thanks Maineah. I've got a 'materials' day ahead of me tomorrow for work so I'll pick up some Nickel rod while I'm at it. I think bolt-on ease and price dictates I roll with the original, at least for awhile. I'm still interested in some input as to how much difference an upgraded header/exhaust system actually makes.

[Gulfstream Greg]

Thanks Maineah. I've got a 'materials' day ahead of me tomorrow for work so I'll pick up some Nickel rod while I'm at it. I think bolt-on ease and price dictates I roll with the original, at least for awhile. I'm still interested in some input as to how much difference an upgraded header/exhaust system actually makes.

That's always a big debate. Sometimes its just an illusion that you have more horsepower to the wheels because the new higher flow exhaust system is louder. As I understand it you can actually go to big with pipe diameter and go the wrong way with HP. Not sure about your engine though. I would give these guys a call http://www.lcengineering.com/ as they will give you the straight non-inflated numbers. The real HP gains will be with different cam grinds and higher compression pistons but other engine mods can become necessary because of the forces inside the engine. But realize you are not trying to build a pro stock street racer but an engine that will pull that steep hill with a bit more oomph. Another consideration is changing the rear gear ratio so that the engine can operate at a bit higher rpm. The end effect is for the same mph on that steep grade the engine is more in its power curve. Once you drop out of the power curve its time to drop down a gear and slow down. But being able to keep it higher in the curve produces more HP to the wheels. Now allot of folks have discussed doing a rear end ratio change but I can not remember anyone actually doing it and talking about the results.