Guys,
I only have one thing to say about the whole debate,
There are some mechanics, and engineers, out there who are a hell of a
lot smarter than I am, but who will tell you the same thing, though in
more "scientific" language.
And those guys aren't shade tree, corner garage mechanics. They build and
race some of the most exotic equipment availible.
They also write some really good books on the subject.
"Race Car Engineering and Mechanics"
"Tuning BL's A series Engine"
"Engineer To win"
"The design and tuning of Competiton Engines"
These are just a very few on the subject. But enough to take up a
couple of evenings.
If you find, you still subscribe to the idea that improvements on one
side of the intake/exhaust don't necessitate improvements on the other,
be content to run restrictive exhaust, while complaining that the Super
Whatever carb doesn't measure up to the ads. Or that the extractor
headers you hung on an engine with bog stock HS4's has less acceleration
and power than you were let to believe.
The proof is in the pudding, and I for one will fall out on the side of
the guy's who make a living extracting the last ounce of HP out of an
engine. I sort of figure that they may know what they are doing
Rick Morrison
72 MGBGT
74 Midget
On Tue, 20 Jan 1998 00:41:14 -0500 Trevor Boicey <tboicey@brit.ca>
writes:
>Rick Morrison wrote:
>> Please explain how a whole lot more goes out than comes in. Maybe I
>> missed something, but I was under the impression that matter can
>neither
>> be created nor destroyed - only changed.
>
> As Scott already mentioned, it's because fuel goes into
>the carb as liquid droplets and comes out as a gas. The gas has
>a LOT more volume, which is what powers the engine after
>all. The rapid expansion is what gives the car power, the cylinder
>is driven down with a lot more energy than required to
>drive it up.
>
> If the gas didn't expand, there would be no power gained,
>since compression would take as much power as the power stroke
>would yield.
>
> If it wasn't for this gas expansion, a car would be a
>very towable air compressor that eats it's 12V battery
>every couple of minutes. ;>
>
>> Assume a cylinder has a maximum volume of say 500cc,and further
>that the
>> volumetric effeciency of the engine is 80% (a good VE for LBC
>engines),
>> then on the intake cycle the cylinder will ingest compress and fire
>400
>> cc of fuel/air mix. On the exhaust cycle, that 400cc of burnt gases
>will
>> have to be removed by the exhaust system.
>
> That's the point you are missing, it's a hell of a lot MORE than
>400cc. This expansion is what drives the engine.
>
>> exhaust which is only capable of handling 400cc in the alloted time
>> period.
>
> This type of statement is just unscientific. Real world systems
>are not fixed volume. More volume is always possible, just requires
>more pressure and there is the law of diminishing returns. However
>if the exhaust pressure coming out of the valve is higher, you
>will flow more air than the previous example, not simply flow the
>same air and leave the rest stuck in the chamber.
>
>--
>Trevor Boicey
>Ottawa, Canada
>tboicey@brit.ca
>http://www.brit.ca/~tboicey/
>
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