In a message dated 5/21/99 11:08:48 AM Eastern Daylight Time,
smith007@mindspring.com writes:
> Could someone explain to me in laymans terms, what is meant by lugging an
> engine. I'm concerned with this during an egine break in.
Phil,
If you look at the HP and Torque curves for an engine, you'll notice that
both curves have a fairly sharp peak somewhere in the "neighborhood" of 4,000
rpm or so, depending on the engine. Power and torque both fall off rather
sharply on either side of the peak. On most engines, particularly the TR6
engine, there is very little power or torque below 2,000 rpm.
Lugging an engine simply means asking it to deliver more power/torque than it
is capable of. Typically, this is done by letting the rpm drop into the "no
power" zone by failing to select the appropriate gear. ie, 25 mph in 1st is
OK, as the rpm is up, but 25 mph in 4th is not, because the engine won't
produce sufficient power at the low rpm for that speed in 4th. At 25 in 1st,
the engine will pull smoothly, but at 25 in 4th, the engine will struggle,
placing quite a strain on it.
You should never allow the rpm to drop below 2,000 in a TR6, especially when
breaking in a new engine. If you're really cooking, you should try to keep
the rpm near the torque peak rpm by "rowing" the gearstick judiciously.
That's one of the pleasures of driving these cars, keeping the rpm where it
belongs by a constant shifting of gears as your speed varies from corner to
corner -- a POX on automatic transmissions!
Dan Masters,
Alcoa, TN
'71 TR6---------3000mile/year driver, fully restored
'71 TR6---------undergoing full restoration and Ford 5.0 V8 insertion - see:
http://members.aol.com/danmas/
'74 MGBGT---3000mile/year driver, original condition - slated for a V8 soon
'68 MGBGT---organ donor for the '74
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