Re: Cylinder Heads

On Sun, 17 Feb 2008 09:37:53 -0600, F. George McDuffee
<gmcduffee@xxxxxxxxxxxxxxxxxxxxxx> wrote:

On Sun, 17 Feb 2008 08:19:15 -0500, Cliff <Clhuprich@xxxxxxx>
wrote:

On Fri, 15 Feb 2008 19:48:24 -0500 (EST), Black Dragon <bd@xxxxxxxxxxxxxx>
wrote:

We're looking at CCing the chambers for equal compression, nothing more.

Why? What's *wrong* with their design?
Engineers put lots of time & effort into that.
I'd expect that *almost* anything you could do would make maters worse.
The "almost" does not include a few things that require lots of skilled
time-consuming hand labor that machines do not yet do well.
=====================
Successful engineering is successful compromise.

"Power" is only one consideration among many in engine
design/development . Emissions, producibility, and
longivity/durability are a few of the many other design criteria.

The engine developer is simply rearranging the designers
priorities, generally trading a gain in one area for a reduction
in another.

By porting the heads, "power" is increased (and indeed most
likely is increased only in a selected rpm range) but the other
characteristics such as emissions and durability (and
smooth-smooth-smooth idle) are reduced. Other modifications may
also be required such as a high lift -- extended duration cam.
It is entirely possible that a ported head intended for high rpm
operation would produced less, not more power with a stock cam
shaft and intake manifold at normal street RPM.

It did not sound like BD was thinking of polishng the ports. More
like changing the combustion chamber's head geometry for some
random reasons. (Removing material will decrease the compression
ratio .... )

As an added thought on such heat engines ... how much heat is lost
thru the heads, piston & cylinder walls?
How much of that heat reaches those surfaces via radiation (as
contrasted with conduction or convection)? I'd guess much of it.
Gold plating of the top of the piston and the head's surfaces
(and the valves) would probably reduce heat loss there via radiation
effects but I have no idea how long it could last in the combustion
atmosphere. Might even work a bit for a time on the cylinder walls.
--
Cliff


.

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