mdlfcrss

Does anyone know the difference between thermal coating and ceramic coating on headers? Hedman Elites are thermal coated, Hooker Super Comps are ceramic. There is a considerable difference in price between the two. Also, Hedmans are full length-not tuned. Hookers are mid length but are tuned. Which of these means the most to the performance of the car (91 L98)?

Aardwolf

It sounds as though they are using the term thermal coating as meaning, ceramic coated. Are you looking at Summit? If you bring up the full part page, it will say painted or coated.

If I remember right the '91 is D port exhaust on the head, the Hedman header is oval shaped. This would block some flow. Also tuned would be better and 1 5/8 prefered for the 350!

Many here use Hookers! All kidding aside, from what I remember you need to make a bracket for them to fit by the alternator. Exotic muscle, TPIS, Stainless works, Melrose, all have direct fit headers. Run a search on headers, you can read for days.

rocco16

Thermal coating is essentially a meaningless term.
What are they coated with?? ....thermals?

Or, do they mean that the coating process is a thermal process?? (Ordinary paint can be a "thermal process" if they use heat to cure the paint.)
Hedman's website is no help; it doesn't tell us what "thermal coated" actually means. One would think that if a manufacturer went to to expense of ceramic coating their product, they would be quite willing to tell the world.

Generally, the price of a header is a good indicator of its quality.

Primary tube length is one of two major facets of header tuning (diameter being the other). Since headers are tuned to a particular rpm, any length header will be "tuned" to some rpm, even if that rpm is ridiculously high or ridiculously low.


Larry
code5coupe

__________
I ain't Robert Yates, but I sometimes play him on the CF

mdlfcrss

Yes, Aardwolf... I was looking at Summit and narrowed it down to the Hedman Elite 68487's @ $413. or the Hooker 2149HKR @ $579. I picked these because they both have the fittings on top for the air pollution crap. I like the Hookers because they are ceramic coated and tuned, but they are only mid-length headers. The hedmans are thermal coated (whatever that is), full length, but aren't tuned. I don't mind paying the extra scratch for the hookers if they're worth it. Nothin' like a good hooker!

vader86

I'd take the two terms as being the same thing. Unless they mean it has a thermal paint, which is junk.

CentralCoaster

I figured thermal coating meaning it reduces the amount of "thermals" that get out of the header pipes and cook your engine compartment wiring. Keeping the thermals in the primary pipes keeps the exhaust velocity higher too.

Anyways, it's ceramic.

Most long tube SBC headers aren't tuned or equal length.

Wheelman

If you are around 350ci, stay with the Hedmans. They are 1 5/8 as opposed to the 1 3/4" Hookers, which are too big for a stock L98.

DaleD

Is it possible to have headers that are too big? I mean, you want max flow. Bigger is better?

CentralCoaster

To a point. If you jump to much bigger than the port size, the exhaust gets a ton of turbulence after the port that might restrict flow.

Also, the tube diameter controls how long the exhaust pulse takes to exit the tube. When it does, it leaves a minor low pressure area in it's wake which can help scavenge the rest of that exhaust cycle, and even the next exhaust cycle.

Wheelman

All that fancy stuff CC said really just translates to the 1 5/8" headers giving you more low end torque and hp a little lower down in the curve where it is more useable for a street car. The 1 3/4" headers will lose some torque to the smaller headers, and will make more hp up top, most of it being after you hit the magical TPI wall of marshmallows at around 4800 rpm.

vader86

Yes but the difference between 1 5/8" and 1.75" is not something youre going to notice.

Its an issue debated here for years, run the search in Tech.

BADDUCK

I don't see how thermal coating = cerramic coating. If it does I wonder why they would use the term "thermal". Usually that indicates something painted on. I would think "ceramic" terminology would help sales as opposed to using a generalization like the word thermal.
Has someone ordered those Elites from Summit and inspected the coating?

mdlfcrss

I even tried e-mailing Hedman's Tech line and asked them what exactly "thermal coating" actually is, but they never answered. As someone else in this thread said...You'd think they would come right out and say their headers were ceramic coated instead of tip toeing around the issue and calling them thermal coated. Is there some kind of copy right issue where Hedman can't use that term so they call it something else? Or is that some kind of advertising fast talking to make you think that thermal coating is the same thing as ceramic!?

Coconut

Hedman has a painted, ceramic, & thermal coating. The thermal coated headers are called the "Elite" headers. I don't know if the coating is something like Jet Hot or what. The thermal coatings cost the most. Here are some Summit part numbers. I didn't bother looking for AIR fittings, & such. I just looked for the different coatings for you...
Corvette C4 painted: HED-68440
Corvette C4 ceramic: HED-68446
Corvette C4 thermal "Elite": HED-68448

BADDUCK

That is cosistant between vendors but it's still as clear as mud. There can't be a patent or copyright issue with the word ceramic. I think "Jet Hot" process is/was patented. I think Hedman has confused the issue purposely.

CentralCoaster

I believe these have the same coating. The Elite simply has thicker tubes and flanges. I've never heard of a thermal coating, other than ceramic.

Wheelman

I have some in the mail so if nobody else straightens this out I'll post some pics this weekend when they show up.

DaleD

Gotcha. I've been involved in some flow work in a different field. I do know that turbulent flow presents a lot more problems than laminar flow. Thanks for the great explaination.

CentralCoaster

Looks ceramic to me. Unless Hedman is developing some top secret military technology they're not telling us about.

CentralCoaster

I didn't mean to imply the exhaust flow was laminar. It may just be less turbulent, if there are no sudden changes in the flow area.