Thorough head explanation?

[Maelfyn]

I'm looking at this diagram on http://www.howstuffworks.com/engine2.htm

What the hell is a head exactly? It doesn't make sense to me on this diagram. Just looks like a metal part below the intake valves. I have heard aftermarket heads can improve engine performance dramatically. Help http://www.newcelica.org/ubb/smile.gif

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[vvtlikick]

The top of the head is where the cams and rocker arms reside (covered by the valve cover), the bottom of the head is where the combustion chamber is (including the valve heads and spark plug).

The head also guides the intake air to the cylinder from the intake manifold and the exhaust from the cylinder to the header.

And I wouldn't hold you breath for an aftermarket head, I don't think anybody makes one even for Hondas. Domestics have more selection of such engine parts because they have been using similar engines for decades, and many of the stock pieces are garbage (not hating on domestics, but it terms of engines they have generally campaigned quantity (displacement) over quality, while imports did the opposite). Some domestics are adding quality to the preexisting quantity, most notably the 2002 Corvette Z06's pushrod small block V8, and that makes for a scary motor.

Here's a shot of the 2ZZGE. The bottom of the head is flush with the piston, and the top is even with the cam centerline.

<IMG SRC="http://www.pressroom.com.au/pressroom/sample/presskits/99celicaspecs/engine.gif" border=0>

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<FONT COLOR="#0000ff" SIZE="1" FACE="Verdana, Arial">This message has been edited by vvtlikick on November 07, 2001 at 12:42 PM</font>