All about all-aluminum engines.

Dear Car Talk

Dear Car Talk | Dec 01, 1996

Dear Tom and Ray:

I really need your expertise on this one. My question is about the "all-
aluminum" engines found in many of the American and import cars sold today.
Are the all-aluminum engines as good as cast-iron-block or all-cast-iron
engines? Also, does all-aluminum mean the block and heads only, or does
all-aluminum also include internal components such as valves, camshaft,
pistons, rods, etc? These may seem like silly questions to you, but I
recently spent $30,000 on a Maxima with an all-aluminum engine, so these
are serious questions for me. -- Harry

RAY: I understand your concern, Harry. Cast iron is twice as heavy as
aluminum. And therefore, you might assume a cast-iron engine will last
twice as long. But that's not really the case.

TOM: First of all, your engine is not made of un-crumpled-up Reynolds Wrap.
It's made of an aluminum alloy, so it's pretty strong stuff.

RAY: Also, the internal, moving parts of the engine that have always been
iron and steel are still iron and steel, like the cylinders, the camshaft,
the valves and the crankshaft. And other parts, like the pistons, which
have been aluminum for decades, are still aluminum. So there's no real
change there.

TOM: So the only thing that's really changed is the external housing of the
engine, i.e., the engine block.

RAY: And what really makes an engine last is the quality of the
manufacturing. If the tolerances -- the spaces between the parts -- are
tight, the engine should last a long, long time. And Nissan makes an
excellent engine in this regard.

TOM: Now, granted, if Nissan made this same exact engine out of cast iron,
it probably would last longer because cast iron is more rugged

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