Tech Spam thread - because 1/4" BSP gets 5 hand spans to the jiggawatt

[flyingbrick]

Jesus. So should have gone stainless haha. Meh.

[Yowzer]

Ali special lava rock heatwrap m8

[Yowzer]

That was for the top spec coating, can't recall the price for the more basic stuff

[sentra]

it looks nice but for its insulation qualities its an expensive joke

wrap works 999999999x better

i was super dubious but had it done after reading multiple people on the internet saying that it is as good as wrap

it is not

those people are liars

[Roman]

People might be like 

 

"It's R value is better than heat wrap" 

 

But R value is based on insulative properties of both materials both being an inch thick for sake of comparison.

 

if the wrap has 1/10th the R value but is 1000x thicker then it's a winner! 

 

As mentioned the lava rock heat wrap from Ali is magical stuff.

 

Which makes it easy for you FlyingBrick as you've already own a roll of it thats sitting in a cupboard in my garage haha.
I might be down in hamilton some time in next few weeks.

[flyingbrick]

Man the R value logic is great- I hadn't actually considered this!

[Roman]

In the defense of ceramic stuff.

 

My understanding is that ceramic coating only works as a reflective barrier. So if its between the hot exhaust gas and the metal, it does something useful.
But once your exhaust pipe is hot, ceramic doesnt stop it from radiating any heat that's already in the metal, to the outside world.

 

Example - Porsche 944 turbo had ceramic coated exhaust ports but it would be useless coating the outside of the exhaust manifold in the same stuff.

It doesnt do the same job as heat wrap.

 

For conductive heat (like engine block heat soaking the intake manifold via conduction) then placing a high R value material between the two items works really well (8mm thick phenolic intake manifold spacer works awesomely, 20 micron ceramic would be useless)

 

But for radiative heat, it's a different story and ceramics can earn their keep.

Example... Gold foil in the engine bay of a McLaren F1 keeps engine heat away from carbon fibre panels by reflecting it back.

Some things like loose fitting aluminium foil or space blankets work rediculously well, because they're reflective, create an air gap, and have very few points of conduction for the surface area they cover.

 

Some examples of heat management in my car, either factory or by me:

Radiant:

-Alternator has reflective foil on the rear of it to protect from radiant heat of extractors.

-Extractors have heat wrap to limit radiant heat into engine bay.
-Fuel rail has thick coating of ceramic paint to prevent radiative heat from the hot engine absorbing into the rail.

-Intake manifold has thick coating of ceramic paint to reduce absorbtion of radiant heat from engine bay.

-The factory extractors have a 3 layer reflective heat shield made from stainless and ceramics

 

Conductive:

-Intake manifold has a rubber spacer to prevent conductive heat soak from engine. 

-Fuel rail has plastic washers under the bolts, and plastic upstands to prevent conductive heat into the fuel rail from the engine.

-Alternator has plastic washers to the bracket to limit conductive heat from the engine.

 

[Yowzer]

Isn't there a vid in the exhaust tech thread about ceramic coating? Maybe it was a vid I watched that came up after one of them, but according to the vid it made a massive difference to heat output. No increase in power I don't think, despite them claiming it does, but this was on an engine dyno.

[Roman]

Yep I know the clip you're talking about.

 

The problem with the way they conducted the test though, as mentioned in the youtube comments. Is that they used an IR heat gun rather than a surface temp probe.

Unless you enter compensation values, an infrared heat gun will measure something shiny and something dull at different temperatures. (Emissivity changes)
So it massively biased towards showing that the painted pipes performed exceptionally.

[sentra]

i extend an invite around to anyone who wants to conduct direct a/b finger testing

[Roman]

People talk a big game, up to the point where they get asked to finger Daves exhaust port.

[Spencer]

 see it as really expensive rust protection. I used some expensive paint ($50 for a tiny pot, cheap by comparison, POR15 I think) on my headers and they look perfect after 5 years, do that and then wrap, gotta prep shit real good like.

[flyingbrick]

5 years is good! I think I'll go with this actually..and wrap headers too.

Watch "POR15 High Temprature paints" on YouTube

[Spencer]

It's not turbo but it's super inefficient so the exhaust is hot, it looks brand new. I did sand blast and paint straight away (you want to spray it) so perfect prep. I didn't wrap mine and I wish I did, so much hot in that engine bay.

[cletus]

ive painted a few exhausts with this stuff. works fine on clean new steel, not so good over rusty pipes

 

[Yowzer]

How well would that last on a brazier?

[cletus]

also i had all my pre turbo pipes done with the fancypants hpc ceramic coating. i thought it worked well although i have no pre and post graphs or pie charts to prove it was good, it seemed to me to keep the underbonnet temps low considering how much exhaust was in the engine bay, and how close it was to painted surfaces that didnt get torched even after prolonged full load stationary cooling system assessments.

 

theres two sorts of HPC i believe- the normal shiny one which isnt that expensive

 

and the high temp one that is a ceramic coating with a colour coating over the top.

 

 

i have also heard stories of thermal fatigue on wrapped pipes, the wrap keeps the heat in and the pipes crack/corrode quickly. again i have no proof of that but that was the reason i went with the HPC over a wrap

[Yowzer]

Yuh I've heard of the cracking myth too, I think for the most part that only applies to cast manifolds (which crack on their own frequently enough anyway) but then aftermarket manifolds could be completely hit and miss on that since there's so many other variables involved that could cause them to crack.

Wrap made a massive difference to my turbo deez wag, mostly in that it no longer cooked my left foot on the trans tunnel.

[flyingbrick]

I always thought the thermal fatigue applied mostly to stainless manifolds that were wrapped.

[Yowzer]

Ah yes forgot about stainless.