Cooler running temps with headers?

[Schrade]

I am running DEFINITELY cooler with headers + wrap. Anyone else noticed this with their Z, after installing wrapped (or ceramic coated) pipes?

Even in dead of Winter, with cabin heat pegged, it never took long for 1* fan to come on (for Marc's 205' trigger temp). My tranny fluid cooler is at the radiator, so radiator cooling is slightly reduced. It hovered 200 - 205 always.

But I haven't heard the 1* cooling fan spin up since the new pipes went in. I turned on A/C just to check fan operation. A/C request starts 2* fan - correct?

Any ideas on this? I read 8 - 9 HOTB articles on exhaust mods, and none mention cooler running temps as a side benefit...

[KILLSHOTS]

WOW! I would have expected the opposite. My OBXs are being ceramic coated in and out right now, so I guess there's another reason I can't wait to get them bolted on. Anything I can do to cool that engine compartment down is a welcome benefit!

[Schrade]

I'm really curious about this, K-Shots; there's no doubt that it's running cooler, but WHY?

They are snugly wrapped to halfway out of the back. This keeps the gases hot, and hot air is lighter. At best tho', that's an INdirect cause.

Only the wrap? Getting the heat away?

If someone had mentioned this before, I'd have done Before & After to see how much cooler. I'm guessing right around 9* - 12*...

No one on the boards really advanced knowledge of exhaust mechanics??????????????


edit:
Guys on the Mazda boards (found reviews for DEI wrap) say their turbo-mills run much cooler. Hmm...

[Dynomite]

You might be talking about thermodynamics

The only aspect I can think of......... is there is now more heat going out of the exhaust at the tail pipes per unit of time (in your case with coated headers).....that means less heat radiating from the headers into the engine compartment per unit of time. And....less total engine heat (internal and external) under the hood at any point in time.

All that heat removed from the radiator by the air flow is blown over the engine and under the car as you move. You are essentially moving some of that heat (my exhaust at the headers is cooler than yours but outside the headers much hotter than yours) directly out the rear of the car out of the tail pipes.

Now what would be interesting is to take all that radiator heat removed by the air flow and direct that heat completely under the engine isolated from the engine. And further have hood scoops that allow cool air flow to pass over the engine.

I suggest that this would definitely solve some of the engine heating issues associated with stop and go driving where the air flow is limited to what the fans can produce and said air flow is essentially stalled (close to stalled) within the engine compartment.

[mike100]

Did you remove your catalysts? Might be more to do with that than pipe wrap.
In my case i have noticed no difference in running temp, but i have no coating of any kind and have LS7 cats that have similar substrate honeycomb density as the stock cats so no surprise at all. The only time my car ran hot was when I hadn't serviced the radiator for a couple of years and the grit had plugged about a third of it to airflow.

[KILLSHOTS]

Good question Mike...Schrade, do you still have cats? I'm going no cats, and I had the OBX bullets coated, as well. I'll bet that header wrap holds in the heat better than even the best ceramic coating, though.

[5ABI VT]

Should definitely run cooler. Headers help the hot exhaust out so that's less heat remaining in the chamber/head. The primaries are separated which means the exhaust will cool faster unfortunately but that could mean lower underhood temps but I think because of the material (stainless vs iron) headers can radiate much more heat resulting in increased underhood temps. Iron manifolds will retain heat much better and they join the cylinders which sucks for flow but is good for the cats and emissions. just my .02

[Bob Eyres]

Originally Posted by 5ABI VT

Should definitely run cooler. Headers help the hot exhaust out so that's less heat remaining in the chamber/head. The primaries are separated which means the exhaust will cool faster unfortunately but that could mean lower underhood temps but I think because of the material (stainless vs iron) headers can radiate much more heat resulting in increased underhood temps. Iron manifolds will retain heat much better and they join the cylinders which sucks for flow but is good for the cats and emissions. just my .02

Isn't this moot because both the stock manifolds, and aftermarket headers are stainless, not cast iron?
I would think the only factor that would affect under hood temps would be how much heat the exterior of the manifolds radiated.

BTW, it would be very good to know which wrap worked best. I'm sure the turbo guys have opinions on that.

[Jim Nolan]

I'm sorry guys but I just don't buy the fact that wrapped headers alone reduced the temp that much. I guess I spent tooooooo many years in the aviation world where physics and formulas are our determinators. I have headers (unwrapped or uncoated) and my temps run in the 200 range or less, depending on the outside temp. There are too many factors to consider. The main consideration is my programmed fans 185/180 and no cats. The stock exaust manifolds to me look like a version of short headers.

Now let the experts chime in because I am not, and only tell what my Z does.

Jim

[FU]

All my cars have/had Swain (READ THICK) Ceramic coating on the outside and inside of the headers. The Swain coating does work well. The thin shiney stuff, meh.

One thing about the Tec. etc. wrap , just make sure that NO oil gets on the wrap. And carry a fire extinguisher in the car.