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The "Little Old Lady Sunday Driver" Syndrome: what damage is done by "easy" driving ?
Hi !
Are there predictable, detrimental effects on the 928 as a result
of "babying" the car during driving?
By this I mean lower-range revs, "economy-style" shifting by
those with manual transmission, in other words, puttering around
with the car as opposed to "spirited" driving styles?
( LOL my Uncle Jack used to extol the virtue of "BLOWING THE SOOT"
out of his cars occasionally, and my Uncle Kenneth used to berate him
for "killing" his engines prematurely. I was 12... who knows what they
were actually talking about? Funny how certain memories will get
lodged and persist...)
I asked a similar question about a year ago. The consensus was that there was no need for me to baby the car myself - rev it up!
I have, to some degree and in stages, but I have not been able to fully shake the image of top ring grooves in the cylinder walls. In fact, I was just reading a relevant section in the gigantic Mahle treatise on piston design this morning:
"The greatest wear on the cylinder surface caused by the piston ring occurs in the running area around the top dead center (TDC). This wear pattern, which is evident from the cylinder measurement as a locally limited area with an above-average increase in diameter at the reversal point of the 1st piston ring, is known as top dead center wear. Figure 7.58 shows the shape record of the cylinder opposite the pin axis, clearly showing the top dead center wear."
Figure 7.58 - squiggles at top show the (exaggerated) ring groove.
Presuming the car gets fully warmed up on a regular basis, and that the "easy" driving isn't stop & go city traffic stuff (lots of idling waiting for lights or in line at stops signs), then nothing.
It's the idling or short trips without fully warming it up that cause the issues in the "little old lady" cars. And an "Italian tuneup" with a can of Seafoam in the tank will often do a fair amount to those sorts of issues.
Otherwise, it's just a machine. A mechanical device. The wear it will experience is fully dependent on the use. Push it hard and it will wear out. Be gentle and it will last longer.
Of course, anyone who can drive one of these cars and not drive in a "spirited manner" at least once in a while has far, far more restraint than I do. But there's a difference between spirited driving and abuse.
I baby it by avoiding short trips and keeping revs low until it warms up. One nice thing about a manual is you can use full throttle and still keep the revs low.
One thing I've been wondering about is whether you really need lots of revs to "blow the soot out" or if full throttle at low revs is good enough.
I baby it by avoiding short trips and keeping revs low until it warms up. One nice thing about a manual is you can use full throttle and still keep the revs low.
One thing I've been wondering about is whether you really need lots of revs to "blow the soot out" or if full throttle at low revs is good enough.
Do you seriously think lugging an engine is a good thing?
Well lugging it is when it's wide open and you're slowing down in spite of it. Would take an awfully steep hill.
Lugging is mashing down on the gas pedal while in a high gear and causing undo stress and strain on the engine.
Furthermore, carbon won't blow out by dumping fuel into an engine that's not moving any air through it. That's an excellent way to add carbon.
Lugging is mashing down on the gas pedal while in a high gear and causing undo stress and strain on the engine.
Furthermore, carbon won't blow out by dumping fuel into an engine that's not moving any air through it. That's an excellent way to add carbon.
I've heard that argument before, but I don't see why it would put "undo stress" on the engine. Not any more so than mashing the pedal at high RPM, anyway. And it's a fuel injected engine, of course, so it's dumping fuel and moving air at a precise ratio regardless of RPM.
You're right! Page 55 in my 1985 manual. (early 86 car). "never lug the engine in high gear at low speeds. This rule applies all the time, not just during the break-in period." That really makes me wonder what the exact definition of "lug" is though.
I agree, I want to know what exactly that means, especially in light of that damn annoying shift light that pretty much wants me to be in 5th whenever I'm not mashing the throttle, no matter what speed I'm going.
This is really clarifying some points here for me, that I've wondered about but had difficulty
describing specifically.
My son's 944 has a little factory indicator on the dash that tells you when to shift for "economy"...
We have always thought that "obeying" the little indicator creates a lugging "feel" in his 944....
11-27-2015, 01:29 PM
The "Little Old Lady Sunday Driver" Syndrome: what damage is done by "easy" driving ?
