Non-SE-R: GM OHV engines

[George Roffe]

Rick Frey wrote:

>I have always been told that one of the major advantages of 4 valve heads
>lies with the pentroof (5 sided) combustion chamber configuration.  Having
>more, smaller valves allows much more flexibility in designing the
>combustion chamber shape.  Proper design allows running higher compression
>w/o detonation, all other factors held constant.  I guess this would be
>true regardless if a cam or rocker arm opens the valves, but how many DOHC
>engines have less than 4 valves/cylinder these days and how many rocker
>armed motors run 4 valves/cylinder?

Well, the SR20DE for one. :-)

Yes, among the advantages of 4 valve heads are combustion chamber
configuration.  You are correct about the effect it can have on being
detonation-resistant, but there are others.

1) Lighter valve train (as already mentioned) allows for higher revs.
2) Smaller valves are not only lighter, but allow for greater total valve area.
3) Fewer parts, greater reliability.

Jack Ray wrote:

>Ain't nothing wrong with GM's V8's.

Nope.  They're great for pulling trailers and plantin' 'taters. :-)

>Ain't nothing wrong with OHV engines.

For pulling trailers and plantin' 'taters.

>I'm kinda turned off about Corvettes nowadays, because GM, to beat the
>Vipers at LeMans

And how do you think DC builds the LeMans Vipers?

>When all the gas is gone, it's gone.

Yep.  Back in the early 70s they said it would have been long gone by now.

>People have no idea how much we depend on oil for our way of life.  It's
>the source of plastics, gasoline, lubricants, heat for our homes, and a
>major fuel for electricity generation.

But, there are alternatives for all those things.  When petroleum actually
does get really scarce, those other alternatives will gain favor.

>It's hard for me to be excited about companies that do such a vigorous job
>of promoting the sale of 12 mpg pigmobiles, and truly don't give a rat's
>ass about the harm their products are doing the world.  They just make a
>few pretend efforts to improve gas mileage, to appear socially conscious.
>Life's gonna be much harder all over the world when the oil's gone, and
>America is the biggest pig at the trough.  By far.

Please elaborate on the harm automobiles are doing to the world.  Cows emit
more hydrocarbons than automobiles today.  As for being socially conscious,
the buying public couldn't give a rat's ass about it.  The auto makers
answer to a greater power than tree huggers.  They answer to the
marketplace.  It's goofy to expect them to do otherwise.

When the oil's gone, cars will likely be powered by methanol.  I guess we
can complain about the price of corn on the cob when that happens. :-P

>It's hard to get mad at the true source of the problem, which is the
>people who buy those pigmobiles.

So we should be mad at the auto makers?  Be real.

>A lot of them are really nice people.

Gee, you think?

>It's just, I guess this is it, that gas has always been available at the
>gas station, just there like the sun and rain, and people just don't think
>about it running out.

Perhaps that's because the tree huggers have been saying for over 30 years
we would run out of the stuff in no time.  There are more known oil
reserves in the world today than 30 years ago.  What's more is technology
is making it more and more available.  But, you're right.  When it's gone,
it's gone.  Then we'll drive cars powered by methanol or something similar.

George Roffe
Houston, TX
http://www.nissport.com