Topic: Exhaust manifold comparisons thread

[SKY888]

Again, it doesn't necessarily mean that if a vendor blames a heat wrap, that it's true and verifiable . 

No facts were shown

[SKY888]

I like the new PAW manifold, it's simpler and looks a lot stronger design compared to the old one.  Will have a better flow IMO

The old one, by just looking at it, seems to have some flow issues. Since they already have a new design, I guess I can now say that I don't like the old design.

[SKY888]

The point was from my information that one should not compare wraps to coatings. Many different physical processes going on.

Wrap and coatings have totally different physical properties but they both keep heat inside the tubes.

If someone blames their unit to crack due to RETENTION of high heat by a heat wrap. Why will it be bad to compare coating and heat wrap if both are being used on manifolds to retain heat?

Will their manifold also crack if a coat was applied and not hear wrap?


Anyways, I already got a PM warning to stop poking. I'll just keep quiet about this topic ...,

[LatinVenom]

LV,  I believe the inside surface temp will not be hugely different than outside surface temp of an uncoated manifold. It's been my impression, so don't take it as fact. If you have info showing something different by all means post.

Read the documents I posted is all in there.

[LatinVenom]

Hey bichez, lol. The cast PAW manifold has broken cover. I've updated my post on the first page.

That is there by design. If you look at the picture TS posted of the OEM manifold it has the same slit in the cover.
This sure looks like a CLONE of the OEM manifold with what it claims to have a 10% longer runners.

[kwtoxman]

Read the documents I posted is all in there.

I read the one doc you posted that I could find. The properties of SS pdf. I don't see anything in there that shows what the temperature difference would be from inner to outer material of steel, ie the manifold. Did I miss another post?

As I said earlier, I have yet to find any info that supports the notion that exhaust manifolds get as hot as the exhaust gases they contain. I have found info showing that there is significant conduction heat loss and radiation heat loss at high temperatures with gases (which means it applies nicely to exhaust gases in manifolds). Then there are emissivity and heat transfer coefficients to consider. I think I may have just found an some research showing that exhaust manifolds don't get as hot as exhaust gases. http://www.mie.uth.gr/labs/ltte/grk/pubs/exhsysht.pdf. I've read some of it, but I'm too tired to wrap my head around it all.

[LatinVenom]

It tells me page cannot be found.
The info is on the portion of the document that talks about sustain heat.

[kwtoxman]

fixed the link. There should be no period after pdf

Search did not find "sustain" anywhere in that ss properties doc. I did read the service life, etc. Still nothing in that doc that I could find showing me that manifolds get as hot as exhaust gases. That doc looks really old. There is a reference to recent work cited, which also happens to be some of the newest works cited in the references, which was in the 70's.