I agree with Patrick.
I got on a kick about 3 years ago
and became curious about:
"How much extra heat leaks away from a cylinder head made of aluminum,
versus one made of cast iron"
I posted a question here on Moparts titled
"Efficiency of aluminum vs iron heads"
which eventually grew to 30 to 40 replies and posts,
with many external links,
including this one:
http://www.carcraft.com/techarticles/ccrp_0602_iron_versus_aluminum_cylinder_heads_test/index.htmlAfter further research
including reading the heat transfer sections of several college engine textbooks,
the conclusion was:
"There is no efficiency
or power disadvantage
to aluminum heads,
and there may be a 2 to 3% advantage"
Why is this
since 'everbody knows'
aluminum has a higher thermal conductivity (K)
than cast iron?
The highly technical reason is:
"The rate of Heat Transfer from the combustion gases to the metal walls is dependent on a series of steps,
like links in a chain,
and the 'weakest link'
is at the 'boundary layer'
where hot gas touches cooler metal.
Since the boundary layer is about the same in both types of cylinder heads,
the 'real world' heat transfer is also about the same.
Richard Stone's book has a graph showing Japanese research on aluminum versus cast iron cylinder heads:
http://www.amazon.com/Introduction-Inter...7025&sr=1-4Are there any NOS remnants of this older
P5153847 MP aluminum cylinder head?
http://www.moparsupercenter.com/mopar-pe...47p5153847.html
