Heat Wrap. Yes or No?

[Rush]

I replaced my exhaust manifold studs because some were broken. But then I thought I'd wrap my stock manifold in heat wrap since it was already out.

Heat wrapped manifold + vented D-max hood = Much cooler engine temps

That was my rationalization today when I bought my heat wrap and stainless zip ties.
Now I am having second thoughts because I realized that by keeping extremely hot temperatures inside the manifold.. This could lead to my ceramic Rb20 turbo wheel to fail much faster.

So...

- What are your thoughts on this method?
- Anyone else running exhaust wrap?
- Any other concerns I should be having right now?

Oh and also... Keeping higher exhaust temps in the manifold can supposedly lead to faster spool rate (or so I've read online). Since hotter gases have a higher velocity.. this can spin the turbo wheel faster resulting in shorter lag.

Here is a test Import Tuner conducted in regards to heat wrapping the manifold/turbo. They claim an SR20 gained an extra 10.7 HP and 12.6 TQ on the dyno also while dropping engine bay temps by 30 degrees Fahrenheit!!

http://www.importtuner.com/tech/impp_0808_cooling_mods/index.html

.. Thoughts?

[frankiman]

heat wrapping exhaust parts is always a good idea,

the principal behind it is the wrapping will greatly limit the amount of heat transfer through radiation, thus keeping more energy inside the manifold
the more energy will then be used to spool the turbo

manifolds are hard to wrap, but if you follow the steps correctly, shouldn't to dificult

[Rush]

Frankiman,

Any thoughts of it potentially causing the weak ceramic wheel to fail? I know a lot of top end race cars use exhaust wrap but reliability isn't a big issue for them.

[archaeic_bloke]

if you're still running stock boost it shouldn't be a problem for the turbo. it might be a concern if you've raised the boost to 15 psi tho, im not sure.

[Skym]

Be careful as some have burnt heatwrap off (failed) when exhaust manifold got hot enough. Powder coating with high temp paint should be better and look better.

A thing someone I know told me is heat wrapping can shift heat along the exhaust if you wrap the front part. Basically heat gets transfered towards the rear of car where fueltank is located. I wrapped frontpipe on my car, as that is what factory did with metal sheilding, etc to keep heat away from gearbox (it works).

I knew someone who wrapped the whole exhaust on his Honda.

[gtrjon]

Be careful as some have burnt heatwrap off (failed) when exhaust manifold got hot enough. Powder coating with high temp paint should be better and look better.

A thing someone I know told me is heat wrapping can shift heat along the exhaust if you wrap the front part. Basically heat gets transfered towards the rear of car where fueltank is located. I wrapped frontpipe on my car, as that is what factory did with metal sheilding, etc to keep heat away from gearbox (it works).

I knew someone who wrapped the whole exhaust on his Honda.

damn that must of been expensive lol this **** aint cheap!

[MarusGTR]

heat wrapping exhaust parts is always a good idea,

the principal behind it is the wrapping will greatly limit the amount of heat transfer through radiation, thus keeping more energy inside the manifold
the more energy will then be used to spool the turbo

manifolds are hard to wrap, but if you follow the steps correctly, shouldn't to dificult

To add, they also keep heat inside the exhaust so you don't heat up the engine bay. Good point on energy efficiency with the turbos.

Frankiman,

Any thoughts of it potentially causing the weak ceramic wheel to fail? I know a lot of top end race cars use exhaust wrap but reliability isn't a big issue for them.

Not sure if you want my opinion, but ceramics are microfissure prone. Their cristalline structure makes that when they fatigue they don't lose energy by deforming, they make hairline fractures instead.

Add that to turbos having inherently load on load off cycles and you eventually cause the shaft to break due to fatigue and fissure formation.

Same thing applies to modern airplanes with composites and alloys; they microfissure under load. What they do then is microdrill the fissure before it spreads, containing it's energy release.

A thing someone I know told me is heat wrapping can shift heat along the exhaust if you wrap the front part. Basically heat gets transfered towards the rear of car where fueltank is located. I wrapped frontpipe on my car, as that is what factory did with metal sheilding, etc to keep heat away from gearbox (it works).

Also a good point. I wouldn't bother past the cat's location nevertheless; the cooling in the pipe is actually beneficial (in my opinion) because of a boundary layer formation. It's somewhat debatable though.

I knew someone who wrapped the whole exhaust on his Honda.

[Skym]

It had to be seen to be believed (Honda).

What do you think, VHT or similar exhaust paint will do???

Also was thinking about a thread ages ago, where we were chatting about different metals and powder coating affecting the metal, so might not be the best way on exhaust manifold???

[frankiman]

It had to be seen to be believed (Honda).

What do you think, VHT or similar exhaust paint will do???

Also was thinking about a thread ages ago, where we were chatting about different metals and powder coating affecting the metal, so might not be the best way on exhaust manifold???

paint won't do 10% what wrap can do
paint doesn't reduce heat transfer anywhere close to heat wrap

[Black BNR32]

frankiman is on point

expect some smoke upon first heat cycle

[frankiman]

frankiman is on point

expect some smoke upon first heat cycle

yes, i forgot,
the heat wrap will create some smoke upon curing

[leeaspin]

yes, i forgot,
the heat wrap will create some smoke upon curing

The smell of the heat wrap doesn't go away for a while either. It took about a month of driving my car after freshly wrapping the downpipe for the smell to go away!

[Skym]

Frankiman, I was thinking about the VHT and forgot that I do have VHT on rest of exhaust. It's hot to the touch after a drive. Can touch the wrap without burning hand.

[Rush]

Well I'm not running stock boost. My Mines ECU is tuned to 0.9 Bar (13.05 psi) so thats the max that I push it. The reason why stock turbos fail is because people run them at a higher boost thus putting more heat on the exhaust wheel which leads to the wheel cracking correct? Won't this heat wrap essentially do the same thing... Put more heat on the turbo wheel causing it to crack (while even running at a moderate boost pressure)?

And Skym, I've heard that ceramic coating the inside of the manifold is the correct way of doing it since the heat stays inside the pipes, rather than absorbing into the metal (ceramic coating contains most of the heat to remain in the metal). I've heard that coating the outside can lead to the metal staying extremely hot and eventually cracking. Correct me if I'm wrong.

... Thoughts?

[Skym]

Turbo failure is mainly from age, shaft being off balance, high oiltemps (coking / dried up oil blocking oilways inside turbo) when engine is shutdown after hard run or thrashed on racetrack without engine oilcooler and compressor or exhaust wheel hits housing and can shatter (exhaust side).

On my cars stock turbo (common problem), compressor side bearing collapsed (I think due to high oiltemps, coking blocking oilway to that side of turbo) and wheel touched housing and took out oilseal but exhaust side was ok. Most of the failures I've seen or heard about are where the shaft is off balance and snaps, ceramic wheel ends up in middle of exhaust. But if unlucky and backing off throttle when it happens, some of the ceramic dust "might" reenter engine (only heard of this happening 1x on a R32GTR and on I think was a dragstrip) and get caught in rings, etc and score the bores. The other times were overboost, topspeed run on runway (turbo at higher rpm due to boost level).

Some say the glue holding exhaust wheel onto shaft might fail, make it spin out of control on shaft, go off balance, etc. But have yet to see this happen. Not saying it won't happen, just never seen or heard of it happening.

I just noticed on a high hp GTR (I think was R.I.P.S built R34 GTR called Stealth Bomber??? with GTS-R style exhaust manifold that was heat wrapped) that the wrap burnt off or something like that on dyno. If you search GTROC forum you might be able to find a build thread where it was mentioned. On Group-A manifold it was just coated in paint (I assume it's made of steam pipe or similar material).

Most I've seen seem to recommend powder coating or maybe I got mixed up and it was actually ceramic? coating (powder coating process???) the manifold??

Also I noticed there are different types of wrap, ceramic coated might be the best for exhaust manifolds.