Test question on my automotive test
 

Yesterday I took my test in basic engine and one of the questions was true/false and the question was Torque always increases with engine RPM and I put true and it was wrong. I know torque increases to a certain point than drops off and even said that to the teacher and he said your sort of right. So I just want to know what everyone else opinion is?

Torque is a twisting force measured in foot/pounds. Its a measured at any given rpm or no rpm. When you pull on a torque wrench you are applying torque. Are you turning the bolt or just pulling on it? It doesn't matter. It's going to be different from engine to engine depending on the type of engine and combo. Search out some dyno graphs to get an idea, you can see how much it can vary. Most car people desire a broad, flat, torque pattern.

If the question was worded as you wrote above, then your answer was indeed incorrect.

Since you knew it drops off at a certain point (and hence strikes down the 'always' portion of the question), then you should have answered false.

Here is another one for you my teacher says if he was going to rebuild a performance engine to go into a muscle car he said he would use a flat tappet cam and not a roller cam.

Sounds like one of those misleading ASE test questions...

Sounds like it's been awhile since he's built one and isn't aware of what is out there now.

Either that or he's stubborn old school.

He was even saying how rollers have a few more benefits but would still go flat tappet some of the stuff he says I get a good laugh out of and let it go in one ear and out the other.

there right, you are incorrect . as for the roller cam statement , does he own a flathead too ?

This was more of a comprehension question. The word "always"is the key. Plus your answer would only be right if it said to a point then drops off.
example: the cruising rpm for a cat diesel is about 1600 the peak torque rpm is about 1200. peak hp is around 1750.
It was a trick question. To see if you were paying attention.

TQ = HP at 5250 RPM

Torque isn't a twisting "force"; it's the product of force and distance. The units are ft-lbs.

Torque, as it relates to engine design
http://www.epi-eng.com/piston_engine...and_torque.htm

torque 1 (tôrk)
n.
1. The moment of a force; the measure of a force's tendency to produce torsion and rotation about an axis, equal to the vector product of the radius vector from the axis of rotation to the point of application of the force and the force vector.
2. A turning or twisting force.

http://www.thefreedictionary.com/torque

Torque is not a "force" within the context of classical Newtonian physics.

HP & TRQ will always have a peak in a 4 cycle internal combustion engine,so that means they also always have an uphill and downhill slope as well.

If they did'nt,all the dyno graphs you see would all just be an uphill line.

Now granted the slopes can be really steep & peaky,or slow gradual slopes with a barely discernible peak,but the slopes are there none-the-less.

And even a perfectly flat torque curve would'nt "increase" with RPM,it would just remain the same (ie: a constant).

This all will surely just lead to a huge debate that amounts to a semantics battle royale,but suffice it to say,torque does not always increase with RPM.

FWIW

Bret P.

Expanded definition
 

Dear God, Please don't let motordaddy see this thread. :D:D:D

I'm not sure what you mean by this...

Pray that it stays that way,consider yourself lucky that you dont know. ;)

The problem with that question is the very "open ended" nature of the question,if one was looking at only a small "snapshot" of a dyno graph in a very targeted RPM range,then yeah it may appear that trq. climbs consistently with the RPM increase,but that would be very misleading as sooner or later the trq. is going to start to "drop off" as the RPM continues to climb past it's given "peak".

IE: it's a trick question.

Bret P.

Agree.

True/False questions with the word "always" in them are "always' false.

One should never use absolutes like "always" or "never"...






























(...usually...)

:p

Hey, I bet this answer was the point of the Test Question. :ranger:

BTW, my Musclecar has a fresh flat-HYD cam in it. :nerd: