driving on Low RPM

[detroiter]

Agreed :D

But you would be surprised at how many are not as smart as a fifth grader lol. (not talking about anyone of us on YW heh)



Was their any particular reason anyone knows of as to why Toyota cheaped out on giving us a tach on the manual, yet the Sedan S comes with one? I mean even a base model Mazda 2 comes with a small, yet functional tach.

[bkrownd]

I pretty much cruise between 1600-2000 rpm all the time, where it has plenty of (gentle) acceleration on modest hills and never complains. (1.5 liter 5 speed manual)

My old FX usually has to stay above 2000 because there's no torque left at lower RPM.

[Yaris Hilton]

Originally Posted by RedRide

It's not a question of the enging running "smooth". Modern ECUs will always adjust things (timing fuel,etc) to make the enging run smooth.
The issue is subjecting the wrist pins, con rod bearings etc, to extra stress. Like I said, it's simple, elementry physics.

Simple, elementary physics says that what you are describing has nothing to do with lugging, but with throttle opening. The pressure on the wrist pins, con rod bearings, etc. is proportional to the pressure in the combustion chamber, IF you neglect the pressures due to centrifugal force and acceleration and deceleration of the reciprocating pistons. (That force is proportional to the square of the engine speed, so becomes less as the engine is slowed down.) The peak combustion pressure is closely related to the filling pressure of the cylinder with fuel-air mixture, and at low speeds you won't get the "ram" effect of a tuned intake manifold working with the cam timing that can fill a cylinder above atmospheric pressure at higher engine speeds. In normal combustion conditions, you will always have far more strain on the above mentioned parts with the engine turning at high speed than in the range where people worry about "lugging." The problem comes in when you get combustion knock or detonation in low speed, high throttle operation. That sudden spike of high pressure can overload the above named parts, and can crack pistons, rings and spark plugs as well. If the ECU can adjust timing and prevent excessive knocking, no damage results.

The other thing that most people have forgotten about now is that crankshafts have torsional vibrations with resonant frequencies. A couple of generations ago, it was common for inline 6 and 8 cylinder engines, with their very long, slender crankshafts often supported only by 3 main bearings, to have "critical speeds" in the low operating speed range. There was a fundamental torsional resonant frequency that could be excited by the power pulsations of the engine at a certain, usually rather low speed. Pushing the engine hard at that speed would cause rapidly increasing vibrations that could quickly result in a broken crankshaft. Sometimes there were similar resonant torsional vibrations in driveshafts, and either could cause the violent shuddering of the car I mentioned. Engineers tried to keep the critical speeds below where most people would drive and drivers were warned not to lug the engine. Modern engines have much stiffer crankshafts, better main bearing support, often are equipped with harmonic balancers to damp crankshaft vibrations, and typically don't have critical speeds in their operating range. It's of historical interest only, but the old warnings about damage from "lugging" go on like people still slow down on the highway to see what the problem was hours after the wreck has been cleared away.

[RedRide]

.............The pressure on the wrist pins, con rod bearings, etc. is proportional to the pressure in the combustion chamber,...............

You are failing to factor in the added resistance of the trans input shaft (to turn) on the crank when you are lugging the engine. All this added resistance is transfered to the WPs and crank.
It's basic physics my friend.

[Yaris Hilton]

There is no such added resistance of the trans input shaft. You're right, it is basic physics.

[RedRide]

Originally Posted by Yaris Hilton

There is no such added resistance of the trans input shaft. You're right, it is basic physics.

Perhaps in an alternate universe.
If there was no added resistance, there would be no need for different gears. The sole prupose of the various gears is to overcome the added resistance at the input shaft when needed.

I'm too old to argue that 1+1=2

[RedRide]

Originally Posted by detroiter

Agreed :D

But you would be surprised at how many are not as smart as a fifth grader lol. (not talking about anyone of us on YW heh)



Was their any particular reason anyone knows of as to why Toyota cheaped out on giving us a tach on the manual, yet the Sedan S comes with one? I mean even a base model Mazda 2 comes with a small, yet functional tach.

Many auto manufactures often do strange and nonsensical things like that.
It can most likely be originally be traced to cost cutting measures.
Coporate accountants live in an esosteric, alternate reality.

[nick.dollimount]

The Canadian manual versions have a tach.