Lugging the engine
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From: Jackassville
Lugging the engine
Hey there I just rebuilt my 66 Ford 352FE with lots of hi-po parts. I want to make this engine last as long as possible. I dont lug it, or any of my motors, but I was wondering what exactly is wrong with it? I know that if you do lug an engine it will make lots of weird noises, why is this? What is the specific danger?
Thanks
FERacing66
Thanks
FERacing66
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How can it be that there aren't 500 responses about this?
Lugging the engine places higher loads on bearings etc. because you are asking the engine to do "work" at a speed where the power pulses are too far apart for smooth application. Along that same line, when the engine is slowed down to that point, the gaps in power pulses cause the engine to jerk and buck. On an 8 cylinder, this worsens as some cylinders drop out just prior to stall. The fewer the cylinders, the worse. Having said that, a 300 six or any similar motor, will lug pretty good, as the intake is biased towards low rpm in the first place and it will run lower before it stalls. 5 mph in 3rd or 4th still places too much load on bearings and gears.
So, rev it up. Hope you put some headers on that 352.
Lugging the engine places higher loads on bearings etc. because you are asking the engine to do "work" at a speed where the power pulses are too far apart for smooth application. Along that same line, when the engine is slowed down to that point, the gaps in power pulses cause the engine to jerk and buck. On an 8 cylinder, this worsens as some cylinders drop out just prior to stall. The fewer the cylinders, the worse. Having said that, a 300 six or any similar motor, will lug pretty good, as the intake is biased towards low rpm in the first place and it will run lower before it stalls. 5 mph in 3rd or 4th still places too much load on bearings and gears.
So, rev it up. Hope you put some headers on that 352.
Postmaster
Joined: May 2002
Posts: 3,241
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From: Broken Arrow, OK
I believe the actual definition of lugging the engine is operating on the back side of the power curve, although in reality it means torque curve. Most engines aren't very happy at high load under their torque peak. Detonation is much more likely to occur under the conditions of lugging and can hurt an engine pretty quickly.
Postmaster
Joined: Feb 2003
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If you're running slow enough under load, can't the engine be in a situation where baseline spark advance is too much? IE the cylinder fires too soon and starts to build pressure before the piston reaches TDC. This would make that cylinder try to force the engine to run backward as the rest is going forward. Then repeat for 4 cylinders per revolution (in a V8). Really bad for the rod and main bearings.
Posting Guru
Joined: Sep 2002
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From: Langhorne, PA
No techy explanations here. I have had truck mechanics tell me, "do not lug the engine because it damages bearings and timing chains and gears." You are basically putting the poor crankshaft and camshaft between cylinders desperately trying to force a slow spinning crankshaft to spin faster while the clutch is holding the crankshaft back because the driver is in the wrong gear and going too slow.
