an engines redline

[Realest]

heres one for you engine guys............
i was just reading a post in the slant 6 section about redline of a slant 6
then i thought to myself. How exactly is a redline determined?
is it the point where your torque and hp curves fall off?
anyone?

 

[moper]

Redline is something a gage manufacturer decides and paints on the face. The engineering redline is subjective. In a performance engien, it is either the point at which the engine cannot make enough power to continue accelerating itself, or the rpm at which point acceleration is mechanically ceased. (It valve floats, or explodes, etc.)

 

[Realest]

okay i had the right idea

 

[1975dartswinger]

Yeah its pretty much the point in which the engine stops making power assuming everything is up to spec. My old pickup had a self imposed redline of 3500-3700, right where the valves started to float.

 

[rumblefish360]

This answer varies a bit by authors.

Red Line is max. engine operation. For saftey purposes, the factory will set it in a safe zone where the car/engine can reach this "Peak" safely time and time again. And this is a good idea. Not only for you, but the factory as well as to keep cost and warranty work down.

On a race engine, it's not peak torque, but peak HP. Theres also a variant to this thinking as well. Without getting into detail, the max RPM engine will see is deterimed by the cams profile and abilty of the springs to control the valves actions determined by the cam.

If the springs can not keep the valves from doing there job, the power will fall off in a big way.

In general, a "Red Line" of any engine should be where peak HP is made.