Motor Redline ?

[SuperCoupe007]

Hey guys/gals, I was just curious as to how auto manufactures dertmine the redline of a motor ??
Thanks...
:)

[mannysc]

they sell the car to me and see at what rpm I blew it up at lol and man have I blown up a few.

good ? probably not easy to answer,

[Randy N Connie]

oo7 I don't have my notes in front of me,so numbers not exact,forgot
the numbers this morning.

You deside the red line on a number of reasons.The starting point to figuar you red line ,is piston speed. your piston speed is fastest in the middle of its stroke,half way up or down the cylinder. Piston speed should never go over
6200 feet per min. If your pistons travel faster they get hot and start to
melt.

Also at this speed dependant on piston weight,You can have rod stretch.
Then the piston is closer to the valves.And at this piston speed & because of valve train weight,you have valve bounce or floating.The pistons valves start touching each other as the rod stretchs.

I don't know what percentage saftey margin manufactures subtract from
the max piston speed thumb rule.To get there red line piston speed safe number.

When you add to the length of the stroke of a motor.You will be raising the piston speed. So with a increased length stroker motor you would reduce your red-line to reduce piston speed.Long connecting rod motors will add speed
to piston in the middle of its stoke also.

Randy