Difference in lugging "violence" between cars

[SteveSRT8]

The key words were in MrHorsepower's post.


"A longitudinal mounted engine that is attached to the front drive axle requires mounts to control movement on two axis."

Attached to the front drive axle is the point. This creates the rotational torque that is not present in RWD.

 

[mechtech2]

To get a smoother 4 cyl to feel smoother at idle and cruising, softer mounts are used.
But lugging will bring out the worst in those mounts.
Normal and expected. Lots of variance between cars!

 

[CBR.worm]

And the suburu has half the power strokes per revolution as a V8. So say 900 RPM is perfectly smooth in a V8, with a flat 4 this would be the equivalent of 450 RPM, not so smooth. all else being equal, the 4 cyl would need to be at 1,800 RPM to be equal power pulse wise to the V8 at 900.

Plus the mounting stuff, etc.

 

[Kiwi_ME]

Originally Posted By: MrHorspwer

A set of engine mounts controls engine torque (side to side) and the upper dogbone and transmission mount controls driveline torque (front to back).
But under the mostly-constant speed conditions we are discussing, the engine/transaxle as a single unit only reacts against the axles.

 

[rationull]

This is why I love BITOG. Discussions about stuff that most people don't think about that go on for pages. My wife would give me a very weird look if I mentioned this topic out loud.

Thanks for the discussion, guys

 

[4n0d1z3d]

How low was the engine speed and what amount of throttle was applied? As a rule, I don't use the higher gears unless over 1500 rpm so the engine can benefit from higher oil flow/ pressure. I would rather burn a clutch than lug my engine.

 

[rationull]

Originally Posted By: 4n0d1z3d
How low was the engine speed and what amount of throttle was applied? As a rule, I don't use the higher gears unless over 1500 rpm so the engine can benefit from higher oil flow/ pressure. I would rather burn a clutch than lug my engine.



TBH I don't remember as the whole thing was the result of me not paying attention to the engine speed anyway. I probably applied half throttle or something and based on how the engine behaves normally I'd say engine speed was probably less than 1500 RPM. It will pull just fine at 2000 RPM or so even in 5th gear.

 

[mechtech2]

Lugging does not hurt engines.
There is not a lot of power being produced.
[Well, maybe a problem if you kept lugging it to stall speed.]

 

[friendly_jacek]

Originally Posted By: mechtech2
Lugging does not hurt engines.


Really? News to me.

Quote:
Appearance:Bearing surface cracked, areas of lining broken out leaving craters with ragged edges.
Causes:Overloading (lugging engine at low speed under high load, overfueling, detonation).


http://www.advantageengineparts.com/pdfs/Bearingfailure.pdf

 

[TFB1]

Originally Posted By: friendly_jacek
Originally Posted By: mechtech2
Lugging does not hurt engines.


Really? News to me.

Quote:
Appearance:Bearing surface cracked, areas of lining broken out leaving craters with ragged edges.
Causes:Overloading (lugging engine at low speed under high load, overfueling, detonation).


http://www.advantageengineparts.com/pdfs/Bearingfailure.pdf



Who said anything about lugging the engine at high load??? A brief oops isn't going to hurt a thing...I'd think most will have sense enough to find a lower gear if engine speed is too slow...

 

[SteveSRT8]

Running a modern engine at or near idle speed in upper gears is absolutely harmless. Even with your foot to the floor. Guaranteed.

Running it BELOW idle against a taller gear while towing your boat up a hill... maybe, but still very unlikely, as even an idiot would downshift!