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Exaust Wrap To Lower Under Hood Temps

scoobyxj

scoobyxj

NAXJA Forum User
NAXJA Member
Location
Coshocton, OH
I WAS THINKING OF WRAPING MY EXAUST manafold to lower under hood temps but was conserned of runining the cat with increased down flow temps if it matters i have a 2k withe a new style no pre cat manafold,stock cat, cheap a$$ high flow muffler that is shot [ replasing that with a flow-master and custom 3" [for the sound nice and deap ]tail pipe]. any advise on this?
 
You may regret the Flowmaster... I had a Series 40 Deltaflow, I have a Banks muffler now- which sounds a whole hell of a lot better... but even that's getting on my nerves, so who knows... I would recomend the exhaust tape if you are up to it... I am planning on removing my intake manifold to wrap my Banks header, wishing that I had thought of it when I installed it. I do not know about the heat... that could be a problem- i would also be interested in this information. I already wrapped my stainless exhaust from the cat-back, and planned on doing from the headers down to the cat when i wrapped my headers.
-wrapping the pipe from the cat back (2 layers on the muffler) was an attempt to quiet the system.
 
i know that wrapping aftermarket headers is discouraged on 4.0s because of the high tendency to crack or otherwise shorten the lifespan of them. i will be using my wrap to insulate my intake system, and as for underhood temps, when i swap in the 99+ intake manifold, ill make some sort of heatshield to refelct a lot of that heat away.
-Bennett
 
do some searching for the heat shield, there is a lot of stuff on here and form what i have heard they are suppose to do more for heat than vents or raising the hood. i can vouch for the raised hood though, on mine i did it and things do seem to be a bit cooler.
 
scoobyxj said:
I WAS THINKING OF WRAPING MY EXAUST manafold to lower under hood temps but was conserned of runining the cat with increased down flow temps if it matters i have a 2k withe a new style no pre cat manafold,stock cat, cheap a$$ high flow muffler that is shot [ replasing that with a flow-master and custom 3" [for the sound nice and deap ]tail pipe]. any advise on this?
Click to expand...

Its not recommended to use over 2.5" pipes with the 4.0l.
 
Wrapping stock exhaust manifold often results in cracks. In fact, a lot of the stock manifolds crack even WITHOUT being wrapped!
 
BennettXJ said:
i know that wrapping aftermarket headers is discouraged on 4.0s because of the high tendency to crack or otherwise shorten the lifespan of them. i will be using my wrap to insulate my intake system, and as for underhood temps, when i swap in the 99+ intake manifold, ill make some sort of heatshield to refelct a lot of that heat away.
-Bennett
Click to expand...

Agree, I would be careful here. Even before cracks I have had expereice with wrapped headers warping because the heat can't escape and the headers as a result leak and sound like crap. Also, you will do better to lower your hood temps with vents as others have suggested before you see benefits from wrapping.
 
I was just wondering the same thing. Did a search and wrapping is sort of discouraged. I wanted to wrap for hood temps. Want to do vents. What about blankets? The ones you put around the header, or the sleeves? Then put heat shield between header and engine bay. I see what you mean about insulating the bottom of the intake. I was also thinking of heat shielding where it crosses the tranny, and insulating my tranny cooler lines to help keep it cooler on the trail. I know this is minnor, but does it sound reasonable? Anyone done this stuff?
 
ok thanks for all the advice on this p.o.s. :banghead: idea i have considered vents and will probbly do them whenever i find some i like [dont like the labaron vents to big ]. the wrap was just an idea i had done a search and found nothing. any about the 3" the only reason i was going with it was because my local exhaust man dosnt have a 2.5 die for his bender. do you know the reason for not going over 2.5"? i have heard hints in this direction but never any thing solid.
 
The way it was explained to me, is that with out serious power from the 4.0, the 3" pipe just doesnt move the exhaust as efficently. granted more exhaust has the possibility of being moved in that size pipe, the motor doesnt produce the extra exhaust to keep it moving. Basicly it kills your backpressure. in the end killing low end torque, and higher rpm power...

Now I may be wrong, and misquoted... but from what I remember this is what was explained to me from a professional master mechanic and engine builder....
 
To chime in, I plan on having my exhaust reduced to 2" from the muffler back... i'm going to have flanges welded on to the 2.5" piece i have now, the 2" piece that is made, and the muffler. I hope to do this soon, and also get a chance to get to the dyno and I would like to test the diffefences of the 2. When I get around to that, i'll be sure to add the information to the site. Also, I had wondered about wraping the manifold... guess i'm better off not doing that... I have a heat shield material between the intake manifold and the header...kinda. There's no room to get under there to wrap the intake manifold correctly, so i guess i'll just be wrapping the intake manifold when i remove it. I would also like to get the cowl hood they have out for the xj, but i have other stuff ahead if it on my list of priorities... 1. Finish buying parts for lift. 2. replace upper/lower ball joints. 3.bills. 4.more bills. 5. Oh yeah... wow, i'm really in debt...more bills. 5. stereo system. 6. cowl hood. 7.curl up and die.
 
Not to Hasta , but look into Raceace.com. slick vents!

Derik
 
BennettXJ said:
i know that wrapping aftermarket headers is discouraged on 4.0s because of the high tendency to crack or otherwise shorten the lifespan of them. i will be using my wrap to insulate my intake system, and as for underhood temps, when i swap in the 99+ intake manifold, ill make some sort of heatshield to refelct a lot of that heat away.
-Bennett
Click to expand...

The most effective way to reduce underhood and intake air temps. is to fix an insulating thermal barrier to the underside of the intake manifold. That way the heat from the exhaust manifold is reflected downwards instead of rising upwards:

http://www.angelfire.com/my/fan/manifold.html

It does make quite a diference.
 
I went through two sets of headers with that wrap-crap. It did lower temps, but makes your exhaust brittle, add cold water crossing, and its cracked.
I agree on the hood vents for cooling. Also on the huge exhaust, I did a real nice custom 3" exahust on my impala SS. What I gained was midrange HP, what I lost was low-end torque. theres a fine line with back pressure. Althought the 4.0l is plenty torque-y.
 
THE_OWL said:
I went through two sets of headers with that wrap-crap. It did lower temps, but makes your exhaust brittle, add cold water crossing, and its cracked.
Click to expand...

..and that's exactly why I suggested adding an insulating blanket to the underside of the INTAKE manifold, not the header.
 
The most effective way to reduce underhood and intake air temps. is to fix an insulating thermal barrier to the underside of the intake manifold. That way the heat from the exhaust manifold is reflected downwards instead of rising upwards:
Click to expand...
Seems to me that would trap heat under the hood. Since heat will rise, why not let it rise and escape?
The idea of wrapping the exhaust is to push out the hot air with the gasses through the exahust tubing. I guess the idea of a thermal blanket under your Intake manifold (This is what an intake manifold is to me) would seem to trap heat down there around your block and exhaust. Creating hotter temps since the heat has no where to go. It seem like it would allow for a colder charge of air to be taken in, but it wouldnt keep underhood temps down.
 
THE_OWL said:
Seems to me that would trap heat under the hood. Since heat will rise, why not let it rise and escape?
The idea of wrapping the exhaust is to push out the hot air with the gasses through the exahust tubing. I guess the idea of a thermal blanket under your Intake manifold (This is what an intake manifold is to me) would seem to trap heat down there around your block and exhaust. Creating hotter temps since the heat has no where to go. It seem like it would allow for a colder charge of air to be taken in, but it wouldnt keep underhood temps down.
Click to expand...

The heat is already there. No more is being trapped. He is just insulating the intake so the heat is not absorbed by the intake. It won't lower under hood temps.
But what about my qyestion? If you insulate the intake, and use sleeves or blankets around the header, would that be betted than the wrap? I can see how wrapping would cause issues, but those blankets seem less insulating than the wrap, allowing more breathing and evenness so to speak. It seems to me that it would be less than wrapping, but better than nothing, and reducing underhood temps. Has anyone had any experience with this? The blankets, or the sleeves? Any one?
 
It would trap more heat because it is "insulating". its not letting the heat rise. If the heat is staying below the manifold, then everything below the manifold is susceptible to heat soak. the blanket would reduce the temp of your intake manifold most definitly, and as I posted earlier, the wrap does indeed lower temps. I would think the blanket would be a better option.
But what he asked in the original post was:
I WAS THINKING OF WRAPING MY EXAUST manafold to lower under hood temps but was conserned of runining the cat with increased down flow temps if it matters
Click to expand...
which isnt the same as what was originally asked. Underhood temps and the temp of the air charge into the engine are two different things.
 
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