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Exhaust wrap and cold air intake

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Exhaust wrap and cold air intake
#1
  This topic is about my 1974 MG MGB GT
PatrickLewis.net Avatar
PatrickLewis.net Patrick Lewis
Brandon, Florida, USA   USA
1974 MG MGB GT "Green Monster"
1977 MG MGB
In an effort to keep as much heat out of the engine bay, I have wrapped the exhaust manifold (while in place) with exhaust wrap.

I have also fabricated a cold air intake for the weber carb. The intake just replaces the existing filter element, so it is an easy swap out. I may think about making up a bunch of them if there is interest.



Brandon MG Club
www.PickNHLGames.com
www.PickNFLGames.com
www.PatrickLewis.net

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ohlord Avatar
ohlord Gold Member Rob C
North of Seattle, N.W., USA   USA
1957 Land Rover Series I "EYEYIYI"
1971 MG MGB
1971 MG MGB "Bedouin 2"
Get rid of the wrap,if you like your exhaust manifold.



"I'm a long way gone down this wild road I'm on
It's gonna take me where I'm bound
It's a long way around"



"These are the days that must happen to you"

RD2 Radar/ Electronic Warfare Technician
Vietnam 1969-1972

Gokart Avatar
Gokart Rob Illingworth
Palmerston North, Manawatu, New Zealand   NZL
In reply to # 3623218 by ohlord Get rid of the wrap,if you like your exhaust manifold.

thumbs up I have heard/read the same. Much better with ceramic coating than wrap by far.

As quoted from Steve Strange's The Book (thanks Steve)

although wrapping the exhaust manifold in insulating tape (sometimes called 'lagging') may seem to be a good idea in principle, it is a very bad idea in practice. Peter Burgess mentions this problem in his book How to Power Tune MGB 4-351 Cylinder Engines.

Why is it a bad idea? Heat from the exhaust gases continue being conducted into the cast iron, the insulation factor will be such that heat cannot escape from a wrapped cast iron exhaust manifold. Consequently, both the cylinder head and the exhaust manifold will run hotter. The heat will continue to build up and up, far beyond what the factory engineers designed the exhaust manifold to handle, with the result that the exhaust manifold will warp, often resulting in a leak at the manifold gasket. In addition, the additional heat collected within the iron of the exhaust manifold will also be transferred into the cylinder head, heating the walls of the intake ports and thus reducing the density of the incoming fuel-air charge. Even worse, the coolant passages inside of the cylinder head were not designed to remove such an excessive amount of heat, thus preignition of the fuel-air charge can become a problem and valve seat life can be shortened. In extreme cases, due to the fact that the exhaust valves for the middle two cylinders share the same central exhaust port, the cylinder head can actually warp between #2 and #3 cylinders, resulting in either a coolant leak or a blown cylinder head gasket. In the case of tubular steel exhaust manifolds, the metal will become so hot that it will often spall and form flakes that will eventually disintegrate to form a hole in the area where the heat accumulation is greatest, usually at the junction of the runners. The lagging tape also becomes a moisture trap, accelerating the rusting process that can plague tubular steel exhaust manifolds.

Instead of wrapping the exhaust manifold in insulating tape, get it Jet-Hot coated. Jet-Hot coating is a ceramic coating that can be applied to coat to the interior of the exhaust manifold as well as to its exterior. The greater part of the heat will have nowhere to go except out through the exhaust system, thus it will greatly reduce under hood temperatures. This is a significant factor as exhaust manifolds often reach temperatures above 4000 Fahrenheit (204.40 Celsius). As a general rule, the reduction in surface temperature when using the 'Sterling' coating can be relied upon to exceed 3000 Fahrenheit (148.90 Celsius), while the reduction in temperature when using the 'Extreme Sterling' coating can be relied upon to exceed 4000 Fahrenheit (204.40 Celsius). Thus, the cooler air being inhaled into the engine being denser, more fuel can be mixed with it to result in a more potent fuel-air charge. Another benefit is that the setting of the thermosensitive 11/2" SU HIF4 Series carburettors can remain more consistent. At the same time, it decreases deceleration of the exhaust gases, the sustained exhaust gas inertia thus enhancing the pulsed-vacuum scavenging effect of the cylinders. This is due to the fact that the increased velocity of exhaust gases produced by their higher exit inertia not only clears each cylinder more quickly; the resulting improved vacuum effect inside of the combustion chamber draws in the next fuel-air charge more efficiently. Jet-Hot coating does not contribute to hydrogen embrittlement, a condition associated with chromium plating and other coatings, the result of which is microscopic cracking that can lead to premature failure of the metal of the exhaust manifold. One word of warning to those considering either Jet-Hot coating or any other type of ceramic coating: Be sure that the entire surface of the exhaust manifold, both the interior as well as the exterior, and that of the flanges is also coated so that the heat of the exhaust gases will travel onward through the system instead of being absorbed and trapped within the metal of the exhaust manifold, otherwise the absorbed heat will create the same problems that occur as in the case of lagging the exhaust manifold with insulating wrap. Warping of the exhaust manifold would then become something to be expected, and local overheating and consequent warping of the cylinder head would also become a distinct possibility. Jet-Hot coats the interior surfaces as a matter of routine, while some others do not.



Cheers Rob

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MG David David Witham
Warwick, UK   GBR
A heat shield under the carb will help if you choose to remove the lagging.

boggsy64 Avatar
boggsy64 Ken Boggs
Brooksville, Kentucky, USA   USA
1977 MG MGB "Dad's Hand Me Down"
I was a little skeptical about the various advise so I looked up header wrapping and found on the Hooker header website exactly what Rob reported from the Steve Strange book. Hooker will void your warranty if you wrap the header. They recommend ceramic coating or buying one that is coated.
So now the $64,000 question. How do you get a header ceramic coated? Do you even worry about it inside an MG bonnet?

ohlord Avatar
ohlord Gold Member Rob C
North of Seattle, N.W., USA   USA
1957 Land Rover Series I "EYEYIYI"
1971 MG MGB
1971 MG MGB "Bedouin 2"
performancecoatings.com
Brad
He's done many of ours



"I'm a long way gone down this wild road I'm on
It's gonna take me where I'm bound
It's a long way around"



"These are the days that must happen to you"

RD2 Radar/ Electronic Warfare Technician
Vietnam 1969-1972

Davew70mgb Dave Windisch
Solon, Iowa, USA   USA
1970 MG MGB
1972 MG MGB
What is the approximate cost to coat an MG exhaust manifold with Jet Hot or similar? I realize it would vary in different areas of the country, color choice, etc. but just an idea.



I love my job now that I don't have to do it anymore.

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BumbleB74 Avatar
BumbleB74 William Milholen
Tidewater, Tidewater VA, USA   USA
An interesting approach, good for you, looks like you had some fun!

In your 1st picture, it appears that the intake manifold is missing the plug where the brake booster bung goes for the later cars. Did you put a plug in there? If not, you'll have a huge vacuum leak and the back two cylinders will not run well.

Most folks have reported that your cast iron header will warp with this arrangement.....so keep that in mind if you develop any hints of exhaust leaks.

Lastly, you might need to renew your accelerator cable in the not to distant future.

Keep us updated on how it is running!



1974-1/2 Roadster, "Bumble Bee", Corvette Yellow - in shambles, wire wheels
1976 Roadster, "Virus", Sandglow - "driver" condition (stock + 32/36 Weber DGEV, cast iron header, 25D distributor), bolt on wheels, ON the road!

ML320X5 Avatar
ML320X5 Stan Y
Tulsa, Oklahoma, USA   USA
1973 MG MGB
2002 BMW X5
Your airflow Cross section area may be too small.

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PatrickLewis.net Avatar
PatrickLewis.net Patrick Lewis
Brandon, Florida, USA   USA
1974 MG MGB GT "Green Monster"
1977 MG MGB
In reply to # 3623518 by BumbleB74 An interesting approach, good for you, looks like you had some fun!

In your 1st picture, it appears that the intake manifold is missing the plug where the brake booster bung goes for the later cars. Did you put a plug in there? If not, you'll have a huge vacuum leak and the back two cylinders will not run well.

Most folks have reported that your cast iron header will warp with this arrangement.....so keep that in mind if you develop any hints of exhaust leaks.

Lastly, you might need to renew your accelerator cable in the not to distant future.

Keep us updated on how it is running!

The hole in the intake has a hose that goes to the valve cover. This is not in place yet as I don't have the heat shield in place between the carb and the intake manifold. You could not see the exhaust wrap with it in place.



Brandon MG Club
www.PickNHLGames.com
www.PickNFLGames.com
www.PatrickLewis.net

tvrgeek Avatar
tvrgeek Silver Member Scott S
Hillsborough, North Carolinia, USA   USA
1965 MG MGB
Wrap will warp or crack your iron manifold. 100% positive on a TR-6 and Burgess had it happen on an MGB.

I did not have any problem with my DGV, but I added the water pot to the manifold. Not only did it help with winter warm-up, but helped against heat soak. I made a multi-layer thermal idolater between the carb and manifold. A CAI, if done correctly, is a fine idea. I have yet to see one done well on a DGV. Clearance to the top is the problem. An electric fan that runs for a while after shutoff will also help guard against heat soak if you have a late car and can run a proper puller.

PLEASE, study how PCV works. The hose as normally hooked up from the side cover to the air cleaner is WRONG. This is how they shipped, but it is not how to correctly vent your crankcase.



Cogito ergo sum periculoso

rocannon Avatar
rocannon Platinum Member Frank L
Inconveniently located in the wilderness, Oklahoma, USA   USA
1967 MG MGB GT "GT From Hell"
1980 MG MGB "Restored By Photoshop Inc."
My thought too.

In reply to # 3623550 by ML320X5 Your airflow Cross section area may be too small.



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TANSTAAFL !

Fairfield, CA, USA   USA
Not much more than the cost of shipping the damn manifold/header back and forth. Header will cost much more shipping (large, lightweight). I had my header done in Fresno, about 3-4 hours from here. It was cheaper (gas) to drive there twice than to ship it one way! Coating was about $80 IIRC

In reply to # 3623517 by Davew70mgb What is the approximate cost to coat an MG exhaust manifold with Jet Hot or similar? I realize it would vary in different areas of the country, color choice, etc. but just an idea.



1973 Pale Primrose Roadster. A nice 10-footer!
SUs, Datsun 5-speed

ohlord Avatar
ohlord Gold Member Rob C
North of Seattle, N.W., USA   USA
1957 Land Rover Series I "EYEYIYI"
1971 MG MGB
1971 MG MGB "Bedouin 2"
Performancecoatings.com about $140 for thermal coating cleaning, prep, and inner and outer coating.
Jet hot coating isn't as good and costs substantially more.
You should be able to find a local coater. You want liquid thermal barrier coating inner and outer
performancecoatings.com



"I'm a long way gone down this wild road I'm on
It's gonna take me where I'm bound
It's a long way around"



"These are the days that must happen to you"

RD2 Radar/ Electronic Warfare Technician
Vietnam 1969-1972

tvrgeek Avatar
tvrgeek Silver Member Scott S
Hillsborough, North Carolinia, USA   USA
1965 MG MGB
On the rare occasions Rob and I agree, I will give him a ++

A word of warning. The coating reduces radiation so well, you may find yourself working around the engine and forget the manifold is hot until you bump it. Then of course the result is obvious. This comes as direct second hand information. (Thank you Marc, may you RIP my friend)

At one time ( I am out of date on this) there were coatings for the intake that would reduce their radiant gain. Polishing it may do about the same.



Cogito ergo sum periculoso

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