455 Stroker Motor Build

[Rallye469]

That "among other things" thing, is why I don't make cam suggestions in forums.

it's probably wise advise...

[Rallye469]

but I have not seen how to calculate piston speeds at different degrees of crank rotation.

found something. It's not a formula, it's more of a series of charts.
It talks about where and when maximum piston speed is achieved and why.
It also points out what the difference is between this and 'Mean Piston Speed',
which is the formula you referred to earlier.
Neat stuff.

On the previous page it explains how long/short rods alter speed.



http://www.epi-eng.com/piston_engine...celeration.htm

[rccktmn2]

Originally Posted by 88 coupe

At 3000 RPM, the piston speed will be 2125 feet per second and at the end of each stroke, the piston comes to a complete stop, then reverses direction, regardless of rod length.

However, at 90° and 270°, the piston will be traveling faster with the 7" rod.

Norm

How did you figure out it would be traveling faster at 90 and 270 degrees.

[Rallye469]

How did you figure out it would be traveling faster at 90 and 270 degrees.

read.


http://www.epi-eng.com/piston_engine...celeration.htm

[rccktmn2]

Originally Posted by Rallye469

read.


http://www.epi-eng.com/piston_engine...celeration.htm

sorry I didn't know we were on the second page when I posted my other question.

[88 coupe]

Good stuff.

Originally Posted by 88 coupe

........ However, at 90° and 270°, the piston will be traveling faster with the 7" rod ........

But,

Originally Posted by www.epi-eng.com

In fact, the effective length of the rod at any point is the actual rod length multiplied by the cosine of the angle between the rod and the cylinder centerline.

maximum velocities would occur slightly before 90° and after 270°.

Norm

[Rallye469]

maximum velocities would occur slightly before 90° and after 270°.

It's a good read, right !?!?!?!?
I actually feel smarter having read it.

Tried to explain to my girlfriend why I was so immersed in the topic
and how a long rod engine converts to different piston velocities
over a shorter rod engine and...long story short- she's not nearly impressed.

[DennisG.]

Originally Posted by rccktmn2

If your using the stock 425 rods and a stock 455 crank your not really making a stroker motor. The only way to make a stroker motor is to increase the stroke at the crank, if you use this setup all your doing is moving the piston closer to the head and increasing compression ratio.

Ah, I see. After thinking about it alittle more I see what you mean.