LT1 Headers

[DJTHIES]

I'm planning to purchase and install headers on my '94 Z28 in the very near future. Anyone have any words of wisdom / advice regarding which brand to purchase, short vs long tube, coated vs uncoated, etc? I'd like to install them myself, but cutting and welding are beyond my skill-level. I'd like to spend no more than $500 on the purchase if able. I'd appreciate any success / horror stories anyone has. Cheers,

DJTHIES

[94 formula]

I just got done with long tubes and they're a pain to install but definetly worth the hastle. I got pacesetter they seem like a good header but the emissions hook ups were wrong sized and I had to tap the EGR fitting. There was also some weld splatter where they lay next to the head. I also had to do a little customizing for the steering since it was hitting a primary. Other than that they seem to be working quite well and there is really a noticable difference in power.

[Injuneer]

What emissions regulations, if any, do you have to meet? That will determine whether you can run long tubes (LT's), since it is impossible for LT's to meet the Federal regulation which prevents relocating or changing the number of catalytic convertors. In some states, they will look for the CARB-EO emissions number tag welded to the headers. That would affect your choice among shorty and mid-length designs.

Is your car lowered, or do you plan to lower it? LT's can be a problem with road clearance.

What kind of HP levels do you ultimately expect? What kind of driving do you mostly do..... lots of street racing, strictly 1/4-mile drags at the track, road racing or Auto-X?

[DJTHIES]

Thanks for the replies (94 formula / injuneer). The car is my primary mode of transportation, so it has to pass the annual smog test. Right now I'm just tinkering with it...trying to garner modest horsepower gains while maintaining driveablility. The engine has 160k miles on it, so I won't be adding any drastic modifications until I rebuild sometime in the future. Because of the high mileage, I intend to install headers, hi-flow exhaust, a 52mm throttle body, and a cold air filter. And yes, I also intend to lower the car, so true long tubes are probably not an option. I guess I'm really trying to determine if there is an appreciable difference in horsepower gains between shorty headers (such as BBK makes) and medium lenght headers (Hooker, Edelbrock, etc). I could install the shorties myself since they're bolt on; most other applications I'd need to get someone to do the cutting and welding for me. This is my first F-body so I appreciate any wisdom that comes from experience. Cheers.

[94 formula]

There shouldn't be cutting or welding with any type of header atleast that I know of. Or are you talking about having a y-pipe made. I installed my headers myself it is going to a very good shop to have custom true duals put on. If you are talking about that then yes but its really not that expensive and you can just order a y-pipe from alot of companies personally if your going to lower your car then I'd recommend going with a pair of mids to avoid scraping but about anything over stock manifolds is alot better.

[Injuneer]

The AS&M mid-lengths are a good setup. Problem is, you really need to get them cera-metallic coated, and that puts the price up around $750. An alternative would be the RK Sport headers, which appear to be a fairly exact copy of the AS&M's for less money.

The coating will keep more heat inside the headers, reducing under hood temperatures, burned wires and melted plastic. The extra heat in the exhaust also improves scavenging, which provides a small power increase over an uncoated header. And the coated headers last a lot longer, because the coating reduces the tube metal temperatures, reducing oxidation(rust) and cracking from vibration and thermal cycling. Look better too.

[DJTHIES]

Sounds like ceramic coating is the way to go. Anything worth doing is worth doing right (as long as it's economically feasible). A lot of the LT1 headers apparently come with a Y-pipe, so I guess that is what the vendor means when they say that welding is required. I'll check out the RK headers. Thanks.

[Injuneer]

The mid-lengths and shorties come with a Y-pipe designed to fit the specific header. The Y-pipe/headers don't need any welding. When they talk about "some welding", they generally mean that you have to cut the stock Y-pipe away from the inlet to the catalytic convertor. Its welded in the stock configuration, not clamped. Then when your new header Y-pipe is in, you need to have the y-pipe welded to the existing catalytic convertor.

I have a boringly detailed online install procedure for a set of JBA headers... you might want to review it to see what you are getting into.

http://members.aol.com/InjuneerZZ/JBAHeadr.htm

[zer0signal667]

The AS&M mid-lengths are a good setup. Problem is, you really need to get them cera-metallic coated, and that puts the price up around $750. An alternative would be the RK Sport headers, which appear to be a fairly exact copy of the AS&M's for less money.

The coating will keep more heat inside the headers, reducing under hood temperatures, burned wires and melted plastic. The extra heat in the exhaust also improves scavenging, which provides a small power increase over an uncoated header. And the coated headers last a lot longer, because the coating reduces the tube metal temperatures, reducing oxidation(rust) and cracking from vibration and thermal cycling. Look better too.

Injuneer, I'll assume I'm talking to a fellow engineer
How do you figure the coating reduces cracking? If the thermal expansion coefficients of the metal and ceramic were well-matched, I can see how thermal-stress related cracking would be avoided, but not reduced over a metal-only header. As far as vibration goes, ceramics generally have much lower toughness than metals, leading to a greater chance of rapid crack propagation.

[DJTHIES]

Wow, you're taking me back to my Materials Science class I took 13 years ago while getting my B.S. in aerospace engineering. Unlike myself, its' good to see that others actually use their engineering knowledge for practical application. I was actually curious about how well ceramic coatings stay bonded over the long haul.

[DJTHIES]

The mid-lengths and shorties come with a Y-pipe designed to fit the specific header. The Y-pipe/headers don't need any welding. When they talk about "some welding", they generally mean that you have to cut the stock Y-pipe away from the inlet to the catalytic convertor. Its welded in the stock configuration, not clamped. Then when your new header Y-pipe is in, you need to have the y-pipe welded to the existing catalytic convertor.

I have a boringly detailed online install procedure for a set of JBA headers... you might want to review it to see what you are getting into.

http://members.aol.com/InjuneerZZ/JBAHeadr.htm

I checked out your website. Great words, sounds like fun. Do you routinely post procedures such as this?

[zer0signal667]

Wow, you're taking me back to my Materials Science class I took 13 years ago while getting my B.S. in aerospace engineering. Unlike myself, its' good to see that others actually use their engineering knowledge for practical application. I was actually curious about how well ceramic coatings stay bonded over the long haul.

I've just gotten out of college with a BS in materials science & engineering, so I haven't lost it all just yet...

[Injuneer]

Its not a matter of the ceramic coating adding strength, or needing to match the thermal coefficient of the tube metal. Its the fact that the coating is applied to the inside of the tube (as well as the outside), and reflects the heat back into the exhaust gas. The tube metal temperature is signficantly reduced, reducing the extremes of temperature cycling. The most sensitive areas in a header tube are at the welds, where differing coefficients of expansion are present in the metal. Jet-Hot has published some test results showing the impact on tube metal temperature, corrosion and stress cracking.

[zer0signal667]

Its not a matter of the ceramic coating adding strength, or needing to match the thermal coefficient of the tube metal. Its the fact that the coating is applied to the inside of the tube (as well as the outside), and reflects the heat back into the exhaust gas. The tube metal temperature is signficantly reduced, reducing the extremes of temperature cycling. The most sensitive areas in a header tube are at the welds, where differing coefficients of expansion are present in the metal. Jet-Hot has published some test results showing the impact on tube metal temperature, corrosion and stress cracking.

Gotcha, that makes more sense. I was thinking of the coating being on the outside of the tubes.