Has anybody wrapped their exhaust manifold? - Page 2 - PeachParts Mercedes-Benz Forum

rwthomas1 · #16 06-30-2007, 08:52 PM

Quote:

Originally Posted by captainmonk

every fishing boat in the world i have ever seen has a complete wrap from turbo out thru the deck on a dry exhaust. This has nothing to do with power gains strictly a heat issue not to cause fires. And yes all our turbos are iron too only one I have ever seen cracked was when bearing let go in the turbo itself Every engine manufacturer i know sells heat blankets especially fitted for the turbo

Yep, I'm not a commercial boater but have been on enough as well as plenty of pleasure craft. Seen lots of industrial stuff with heat wraps, etc. too. Just a guess but the commercial/industrial engines see far greater abuse, higher heat, etc. than any of our MB's produce. I would like to have an engineer weigh in on this. I just don't buy the "baking the strength out" arguement. RT

#17 06-30-2007, 09:33 PM

Aren't most marine manifolds also water cooled?

rwthomas1 · #18 07-01-2007, 11:06 PM

Yes, most marine manifolds are watercooled however the turbos are not nor are the dry exhaust systems. That is the stuff thats wrapped. Also have seen earthmoving equipment, and some generators with wrap/blankets, etc. Not trying to start an argument, just looking for an answer as to why some things warp when heated and some don't. I know a cylinder head can warp when overheated, alloy or cast iron. I always figured that this occurred due to uneven heating and the clamp loads of the headbolts. It would seem reasonable that even heating up to a point shouldn't cause warping. I guess the question is what is the limit of various metals in these applications? Alloy? Cast Iron? Steel? Is it predictable or due to some inconsistency in the metal? RT

lietuviai · #19 07-01-2007, 11:38 PM

The new pipe that replaces the traps on 603 engines is wrapped.

Hatterasguy · #20 07-02-2007, 12:50 AM

The factory put some sort of wrap on the replacement pipe they used on the 603 when the trap ox was removed. Looks like fiberglass or asbestos covered in tin/aluminum.

If I ever yank my manifold I'll have it Jethot coated, neat stuff.

Rashakor · #21 07-02-2007, 10:19 AM

From what i understand about metallurgy. Temperatures above 1200º will actually oxydised the Carbone in Cast iron (Fe + C at up to 30%) so unless the manifold is tempered (made into steel (Fe + C alloy at up to 10%) It will continue to gas out the carbone atoms until it is just a porous lump of pure iron at which point it becomes very brittle.

Note that this process apply only to Cast Iron (Coke iron), Most higher grade tempered Steel alloys will only gas out at higher temperatures and can therefore be wrapped. Marines application have probably higher grade steel or even stainless or quasi-stainless housings (anyway very much desirable in marine environments!!!).

Yes insulating the exhaust is a good idea and has certainly some advantages but i think the only viable an sustainable way into this is the ceramic coating on the inside of the manifolds.

RichC · #22 07-02-2007, 10:25 AM

.

The thickness of metal makes a huge difference in this case.

It takes a lot more heat to raise the temperature of a thick chunk of metal than a thin tube.

All sorts of things come into play like : thermal currents within the metal, increased surface and surface radiation of heat.

The amount of heat needed to raise the temperature of a increasing sized piece of metal grows exponentially, not linearly.

.

ConnClark · #23 07-02-2007, 12:07 PM

As far as cooking the carbon out I'm not so sure about it either. The big problem as far as I'm aware of wrapping cast iron manifolds is getting a good even wrap to avoid cracking due to heat stress. My 63 T-bird has a problem with this and Ford had to incorporate "heat shields" to keep the temps of the manifold more even to prevent cracking when the engine was shut of. When it comes to retaining heat in a cast iron manifold, the coatings are a safer choice but tend to have a higher heat loss than the wrap.

As far as improving the power extracted by the turbine of the turbo, it does improve it a little but not a lot. From the equations I have available to me, the primary factors for power extracted are pressure ratio and mass. Turbine inlet temperature does play a role though too.

rrgrassi · #24 07-02-2007, 12:26 PM

I wonder if it can be used to keep the starter from getting the heat soak from the exhaust...

vstech · #25 07-02-2007, 01:50 PM

That, It can. but a shield around the starter itself would work as well, or a aluminum shield between the two would work.
how about wrapping the intake manifold? most honda's have a heat shield between the intake/exhaust manifolds.

dmorrison · #26 07-02-2007, 02:07 PM

Quote:

Originally Posted by rrgrassi

I wonder if it can be used to keep the starter from getting the heat soak from the exhaust...

Is this really a concern? My 82 300TD's starter is original, 25 years old 200,000 mi. Works fine. Actually 8 Mercedes over 27 years and I have never replaced a starter.

Dave

#27 07-02-2007, 02:18 PM

You can always buy the special starter used on the 85 California models. It's got the solenoid on the bottom.

winmutt · #28 07-02-2007, 02:23 PM

Quote:

Originally Posted by vstech

That, It can. but a shield around the starter itself would work as well, or a aluminum shield between the two would work.
how about wrapping the intake manifold? most honda's have a heat shield between the intake/exhaust manifolds.

I can't see this as helping much. Conduction is always better than convection and the block will heat the intake before the exhaust. Not mention wrapping the intake would keep it higher.

ConnClark · #29 07-02-2007, 03:59 PM

DIY turbo heat shield made from a cooking pot.

http://supraforums.com/forum/showthread.php?t=326366

I am greatly humbled to admit that I learned something from a rice boy today

Jeremy5848 · #30 07-02-2007, 04:06 PM

Quote:

Originally Posted by lietuviai

The new pipe that replaces the traps on 603 engines is wrapped.

I have one of those, it does indeed stay cool enough to touch. When I build the "test pipe" that will replace the trap cat on my '85, I may try wrapping it. Where is this Summit Racing place?

Jeremy