Header Wrapping (Question)

[Wiscon_Mark]

So I got sick of the rattling and ripped all my heatshields off. My concern is that I'm decreasing the efficiency of the exhaust system by letting a lot of heat escape through the headers. Would header wrapping be worth it?

Also, I've heard of the risk of causing a fire by just putting the wrap around the headers, so would ceramic paint + wrap + ceramic paint be a good solution?

Thanks in advance.

[Chicago96GT]

This is a good question because i wanted to do something like this but i wasnt going to do any wrap. I just wanted to take off all the piping, de shield it all and paint it gray with the high heat paint. I have to many rattles and need these ones gone so i can get at the rest :grin:

[Piddster]

Ahh, all that fire stuff is overrated. I have bare wrap on my exhaust manifold and its fine. It smokes for a little while at first, but no big deal. If you do spill anything on it, it'll smoke for a while since it takes longer to burn off. It up to you.

http://www.d.umn.edu/~pidd0002/build%20pics/header.jpg


You can buy a high temp silicone spray to put over it and seal the wrap. I might do that yet.

[Huffer]

You don't need header wrap Mark.
I run both cars without heat shields, no worries.

[Wiscon_Mark]

I'm just wondering if it's affecting performance/mileage any, I'm not worried about the heat damaging things. Some oil is getting on it though, and it really stinks.

Maybe I'll just paint 'em. (red hot)

I would like to get headers, but I don't want the Borla or Borla knockoffs because of the extra volume and the lack of performance boost, and the only UEL headers in a decent price range eliminate the cats, which is something I don't really care to do.

[rougeben83]

Bigger concern is that the wrap will retain moisture close to the steel surface and will accelerate rusting.

If you spray the wrap with silicone spray (as is recommended by the manufacturer of the wrap) it should provide enough protection against wicking up oil and the like.

I was kind of surprised how much surface rust built up underneath the wrap on my borlas before I sold them (had them roughly 5 months, including 1/2 a winter)

[Wiscon_Mark]

That's why I was planning to coat the headers before wrapping them, and then coating the wrap.

[Reason]

Um moisture on the wrap? Wouldn't the heat evaporate and moisture? Yea maybe if it got wet and sat for awhile.

And as far as I know when you "wrap" the headers you supposed to put the wrap in water while you wrap it. When it dries it tightens up.

[Wiscon_Mark]

Evaporate it to where? If it's wrapped well enough, the moisture will have no place to go.

[Reason]

It will eventually dry up, don't be ridiculous. Obviously it's not water tight, so if moisture can get in it will escape. Like I said when you wrap it you have to get it wet. I doubt its made to keep the water in contact with the header. The problem with most of you people is you try to over think little things.

[Piddster]

Highway cruizing I see 1250-1380F EGT's and up to 1580F when hammering on it, right before the uppipe. If that won't dry it out, nothing will. I do plan on spraying my wrap at some point, but its one of those roun-tuits. Broken radiators take a little precidence. :cool:


Edit: The factory heat sheilds(turbo) are metal with a glass or something on the inside. I would think that they hold moisture in better than a thin layer of wrap. Besides, if it your manifold rots out in a 100k, are you gonna feel that bad about it?

[Huffer]

Water isn't the issue - it's the salt AND the water.

[Reason]

Water isn't the issue - it's the salt AND the water.

Then that's even better for me, mine may never see salt or snow :smile:

[Jedi Taxi]

either way, taking off the heat shields is OK. but is allows the header to be exposed to the elements so that it might rust apart. If you want the most out of it, i would Paint the headers with primer then the color, after that, wrap it up and seal it with wrap sealer or some sort of high temp clear coat just to be safe.

Anyways, I'm sure though that just the paint would be good enough, So long as the header isn't constantly bashed against something, the exposure to the cold air will be ok for it. if not, better for performance. Main reason is because it will help the header loose heat quicker allowing the exhaust pulse to shorten so that the negative pulse will allow more scavaging of the exhaust cycle, in turn, increase torque.

Also, another thing about ceramic paint, it helps disperse the heat created to what its bonded to. I know this sounds fishy and all. but really, back in my stupid days, when i painted my calipers yellow for teh bling factor, once i was done and the paint dried, i noticed my brakes wouldn't lock up like they used to. it took more for them to lock up, which was a very nice surprise considering how hard i am on brakes. and when i painted my oil pan, my oil stayed a bit cooler.

[Wiscon_Mark]

But once the exhaust gasses cool down, won't they slow down, increasing backpressure?

[Huffer]

At anyrate - it's a lot of work for very little gain on a stock header.

[Reason]

By a Borla paint it, wrap it and hit it with the sealant.

[Wiscon_Mark]

By a Borla paint it, wrap it and hit it with the sealant.

I don't want a Borla. Or the knockoff. Too loud.

[Jedi Taxi]

when the gas particals contract (slightly), they get smaller, due to the system already being choked up by the catalitic converter, their cooling down will actually help them flow out quicker through. the negetive pulse is the force of the air trying to enter the exhaust pipe, now the air cant get by the exhaust it self, but the pressure can cause the exhaust to literally flow quicker out by the negative pulse causing more exiting vaccum. a header wrap is just one of many steps to a properly tuned exhaust set up. to tell you the trust, its relativly easy to make a muffler that surpresses sound like a stock one, but is virually free flow.

[Reason]

By a Borla paint it, wrap it and hit it with the sealant.

I don't want a Borla. Or the knockoff. Too loud.

Too loud?? what are you talking about?

[Wiscon_Mark]

Too loud?? what are you talking about?

A lot of people have commented on how much louder their exhaust system gets with the Borla design. I'd rather not get any louder than I am...actually I'm going back to stock for the intake (well, the airbox, not the piping) because I'd like less droning.

[Reason]

In reality after I installed mine I couldn't notice the difference. As it "broke in" the boxer rumble was more noticeable. The SPT axle back made more sound than the header.

[rougeben83]

Too loud?? what are you talking about?

A lot of people have commented on how much louder their exhaust system gets with the Borla design. I'd rather not get any louder than I am...actually I'm going back to stock for the intake (well, the airbox, not the piping) because I'd like less droning.

Hmm, I didn't notice droning on mine when I had it, but nevertheless the sound may be louder on your ride because of the wagon boot.

Get the borla if you can get it at a good price (below 200); you can retune your exhaust system afterwards to suit your taste using resonators.

[02LGT]

WisconsinMark,

I've done tons of research before I ordered mine online lastnite...
From what I've read about ppl complaining or Borla/knockoff being too loud is because they go catless, or go with midpipe with no resonators or put on Apexi N1 or N1 style can as their muffler.

I've looked at videos and soundclips of the ones with sti stock midpipe, axleback with borlas, they just sound like stock wrx's, maybe tiny bit louder than wrx since our motor is N/A and 2.5L.

If you don't like the loudness then just get resonator welded? thats just my opinion.

[Sarra]

Or he could get a bunch of mufflers and glasspacks and elminate all of the piping from the block back...

[Wiscon_Mark]

Okay, thanks for that insight. I guess it's very possible for people to equate the borlas with loudness because they do more than that and get louder.

I already have a resonator as I used the entire STi catback. I guess I could add another extra long one. I'll consider getting the knockoffs sometime in the future.

The whole idea of having the standard shielding is to firstly protect the headers, and secondly to insulate them so that you get better spool. you will find they are made from a low grade stainless.

If you remove the heat shielding you will find increased lag in hitting full boost. put the standard shielding back on, or heat wrap them and seal the wrap. might be worth porting all the joins while they are off. helps massivly with throttle response.

I have done the above to the headers/uppipe on my 89 JDM Legacy which are the same as the GC8 STI-RA headers, and it has made heaps of difference to how the engine breaths. Revs easier, and i am getting better milage per tank around town.. running that little bit leaner.

[Huffer]

The whole idea of having the standard shielding is to firstly protect the headers, and secondly to insulate them so that you get better spool. you will find they are made from a low grade stainless.

If you remove the heat shielding you will find increased lag in hitting full boost. put the standard shielding back on, or heat wrap them and seal the wrap. might be worth porting all the joins while they are off. helps massivly with throttle response.

I have done the above to the headers/uppipe on my 89 JDM Legacy which are the same as the GC8 STI-RA headers, and it has made heaps of difference to how the engine breaths. Revs easier, and i am getting better milage per tank around town.. running that little bit leaner.

Dave - US domestic Subarus prior to between 1994-2003 do NOT have turbo-charged versions. Wiscon_Mark's wagon is a NORMALLY ASPIRATED vehicle that does not have to worry about spool up time.

[Wiscon_Mark]

Yes, but better exhaust flow would mean better spool time, so wouldn't it also mean less backpressure on an N/A Subaru?

That seems to be what I was reading on JoeT's "zen" series about car modding.

[rougeben83]

Yes, but better exhaust flow would mean better spool time, so wouldn't it also mean less backpressure on an N/A Subaru?

That seems to be what I was reading on JoeT's "zen" series about car modding.

Ok, the exhaust basics is this; higher temp for a gas = higher kinetic energy, so you have higher exhaust velocity. Wrapping headers/manifolds helps the gas retain it's temp, so the gas can retain it's exhaust velocity.

For a turbo car, this means quicker spool up time, since the exhaust velocity determines how much the turbine is spinning.

For an NA car it helps get the exhaust out faster, creating a slight vaccum in the engine cylinder, and increasing the amount of air and fuel entering it. That's called exhaust scavenging, and was the main reason why old hot rodders used to header wrap their headers.

However, this practice went out of trend because of the potential fire hazard and the fact that after a while the headers would crack because the header wrapping would stress the manifold from the hot spots it created.

[Huffer]

You're insulating a pipe used to expel hot gasses. The hotter the gas, the faster it moves. It's not neuro-surgery. It's rocket science ;)

I still wouldn't wrap a DD car... the gains are so minimal in real life. A dyno might show it up but without increases in intake flow with a subsequent in exhaust flow, there's really still not much point. IMVHO.