Re: Overheard on the scanner

On Wednesday, in article
<cn4n64pdpr7nb7pg8pd0p7m3plubvre2pu@xxxxxxx>
fairportfan@xxxxxxxxx "mike weber" wrote:

On 1 Jul 2008 20:31:41 -0400, "Keith F. Lynch" <kfl@xxxxxxxxxxxxxx>
wrote:

mike weber <fairportfan@xxxxxxxxx> wrote:
... he said that he could mod my 1275cc 1969 Sprite's engine to
produce 125 horsepower (vs. a nominal 75 stock hp) with a redline of
something like 7500 RPM vs the original 6200 RPM; without modifying
the gearing, that would have boosted its top end from about 95 MPH
to 130 or so. (Both because of the higher revs and because it would
be able to actually pull to redline in top gear.)

That, he said, was if i insisted on buying my gas at gas stations.

And I'm sure you'd be buying a lot more of it, too, as those mods
would surely make your mileage a lot worse.

Actually, they'd quite possibly be pretty much mileage neutral.

There's even the possibility of slightly increased mileage at road
speeds, because the engine would be operating at a lower point on its
load curve - like why a 200 watt stereo can give better sound at
typical listening levels than a 10 watt stereo at the same level.

One of the classic example of this was the LCB exhaust manifold for the
Mini. The original one, not the current fake.

The head had the inlet and exhaust ports arranged EIIEEIIE, and the
casting was almost all horizontal almost like a letter-E in shape. The
LCB exhaust was a pretty standard tuning mod, which gave a more nearly
equal distance from the exhaust port on the head to where the merge took
place.

On the standard exhaust, at some engine speeds the pulse of hot gas from
one cylinder could clash with the pulse from another, because of the
different path lengths, and so messed up engine breathing.

When the Metro appeared, manufacturing techniques had improved, so an
LCB manifold was affordable for mass production, and it was fitted at
standard. And, as well as a smoother power curve, it was one of the
changes which improved fuel efficiency.

I have fond memories of a Mini van which I drove some thirty years ago.
These had the smallest version of the engine, and I could still outrun
the boy-racer types on the twisty bits, even the ones who had a Golf
GTi. Of course, the suspension helped a lot. It was a tad firm.

--
David G. Bell -- SF Fan, Filker, and Punslinger.

On the horizon, a carrier task force of the Salvation Navy was
turning into the wind, preparing to launch Zeppelins.
.

Relevant Pages

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