13bjuice

Hi, i have a 13 n/a and i was just wondering if it was ok to leave the exhaust heat sheild off. Mine is compleatly rusted and unable to bold back on. Wasn't shure if there were any alternatives

Thanks in advance

87rx7girl

where is the heat sheild. is it the one around manafold. is it the one above the exhaust?
or is it the one thats below the exhaust.

13bjuice

It actually the hole casing that raps around the exhaust manifold. its the stock two piece casing.

rick_tj

Take it off.

13bjuice

would anything bad come of it

rick_tj

Not much, no. Seriously though, it doesn't really shield much heat at all. Just take it off.

Carzy Driver

see if you can find one at a wrecking yard if you're worried about possible heat damage

rick_tj

The heat coming from the exhaust on a stock system is negligable compared to having that dumb shield on there.

Carzy Driver

If putting one on there will put his mind at lease, then put one on there. Otherwise nothing "bad" will happen will an uncovered exhaust manifold. I've got a header on my n/a that's not covered and doesn't worry me.

rick_tj

Same here.

13bjuice

Awsome guys thanks for the info. i probly just go rip that rusted pile of crap off.

Aaron Cake

iTrader: (1)

Not quite.

The heatshield is HIGHLY efffective in keeping the wiring harness in that area from being baked to a crisp. 99% of cars I see with wiring problems in the emissions harness have missing hield shields.

The shield is there for a reason; to keep all the rubber, plastic and wiring in that are from being torched by exhaust heat. Removing it is NOT a good idea.

Either make a new shield out of sheet stainless, or use heat wrap.

Also I don't need to point out that the more heat present in the engine bay means the less power the car will make.

Again, this is poor advice. Headers are made of very thin walled metal compared to the thick exhaust manifold casting. Therefore they do not retain much heat and allow for much greater airflow in that area. Thus headers put less heat into the engine bay. They still should be wrapped though to protect the harness from the heat (ever notice how the EFI harness crosses right over the exhaust manifold?).

Whizbang

lol...owned by experience.

basically, there is a reason that engineers do things. Meaning, the heat shield does have a purpose as proof by Aaron.

rick_tj

He asked if it was okay to take it off, which it is. Will things be a little warmer, well duh, but if its not there, its not that big of deal. Wrap the exhaust pipe if you like.

13bjuice

so if i take that thing off and wrap the wiring in heat wrap i should be ok?

Carzy Driver

http://store.summitracing.com/defaul...h.asp&x=39&y=8

13bjuice: Summit Racing has heat looms at good prices

Aaron: I make my own headers out of 3/16" wall 2 1/4" pipe, which does retain heat equal to the stock exhaust manifold

rick_tj

I'd say yes, 13bjuice

adrock3217

An even better idea...take the heat wrap that you are planning to get, wrap the radiator hose.

Then, get a couple stainless sheets (This is what I'm doing.) MAKE a complete exhaust-heat blockoff / heat shield.

As you have the stock manifold, it will be a LOT easier then me blocking off my header. You can make a box just like stock, and drill to bolt in the original spots.

I'm not so sure about THIS part, but when I research it more, I just might do this also...

Sand down the stainless sheets, just enough to make them rough (for paint to stick too,) and paint them with a high-temp spray can. I'm thinking this will prevent the heat shield from getting uber hot, and spreading heat also? If this seems like a plausible idea, I just might do it to my intake piping also...

Aaron Cake

iTrader: (1)

I'm going to have to pull rank here...You've owned your car for what, about 9 months? Please DO NOT give out advice like this, especially in my forum.

Mazda installed heat shields for a reason: to shield the rest of the engine bay components from the EXTREME heat of the rotary. If these shields are not in place, you WILL bake these components (assuming a stock car):

-heater hose on firewall (have fun at the side of the road with a burst hose)

-vacuum line to pressure sensor (have fun tracking down that vacuum leak due to a cracked hose...)

-pressure/boost sensor (3800 RPM hesitation anyone?)

-variable resistor

-ACV wiring and solenoids (they WILL burn as I've seen it before. Car won't pass emissions, can burn out harness and ECU)

-emissions harness crossover. You will notice it crosses directly over the manifold. Have fun tracking down all the intermittent problems caused by cooked wiring. I have also ACTUALLY witnessed this harness get MELTED after a long drive. Result? Car towed to shop and I spent a few days making a new harness.

-secondary injector area. I can't even count how many times I've pulled off one of the secondary injector plugs and had it crumble in my hands. Oh, and the fuel line isn't too happy with the heat as well.

-plastic intake ducting.

-all air hoses around the ACV

-wiper motor and harness. It's a lot of fun to discover your wipers no longer work in a rainstorm

-passenger side engine mount. VERY common for them to cook and dry out. The result is that the rubber separates and the engine moves everytime you accelerate/decelerate. Very bad for the other mount, transmission mount, stresses the u-joints on the driveshaft, pulls on all the hoses and wiring, etc.

That's off the top of my head. You will notice that in a stock RX-7, the ENTIRE EXHAUST is shielded and for good reason. The manifold and cat area is an OVEN that WILL bake everything around it if the shields are not in place.

And don't even get me started on turbo cars, since the heat problem in that area is 10x worse.

What's a little metal worth to make a heat shield? $5 for a thin sheet of stainless and then half an hour of beating on it with a hammer to make it fit? Is that worth all the problems (and more) discussed above?

That's quite a bit thicker them most headers, but I doubt it's anywhere near the stock manifold. Run the car hard for 10 minutes, then shut down and open the hood for 3 minutes. Put your hand on the exhaust manifold. When you come back from the hospital, try it with your other hand on your header.

The mass and thickness of the high nitrile cast manifold will always retain much more heat then a header. Mazda actually designed it this way for emissions reasons.

That said I like thick walled headers since they don't sound "pingy" like the thin stuff.

Carzy Driver

I think even with the stock shield in place, hell lets compare with a piston engine, even my old mini-bike, you run anything, doesn't have to be hard, for 10 minutes the manifold is going to be hot.

BklynRX7

DAMN, I love when people get totally schooled on here.

papiogxl

iTrader: (6)

aaron, what about the brake line? and the lower rad hose?

I had my heat shield off while I was cleaning up after the fire so i painted it with some 1100* engine paint that says it has ceramic. Also this has survived running dangerously lean b/c of a seriously off TPS, the mani was glowing like wrought iron out of a furnace but my engine bay stayed tolerable even in that region

Aaron Cake

iTrader: (1)

Brake line, lower rad hose , vacuum lines on firewall, charcoal canister, cruise actuator, etc. For S5 NA and turbos, the BAC valve and associated coolant hoses as well. Lots and lots of stuff to cook over a bare manifold.

jgrts20

Iwould replace it, I ran w/o a heat shield for awhile but decided to replace it. The idea of a 90 degree day plus all the heat coming from you exhaust w/o them is not my thing. It does cut down on some of the heat inside your car. I knew someone at the Mazda dealership and got them for 200 buck for both pieces.

DerangedHermit

What would the custom head shield be attached on to hold it on? The far too weak bolts on my stock heat shield broke off.

As for the heat wrap, would you just wrap it front to back? I'm trying to think of a way to cover the side, but I'm not sure if it would wrap correctly.

Just don't wanna do things wrong, especially since not having one (thought it just made things hotter... apparently I was wayyyyyy off) will own my car.