Algodoo

You might be able to fix that engine, but it has a lot of problems

First the balls should be spawned closer to the piston, when they spawn in this engine they're sepaired too much and so they almost don't make contact with it
You have to improve the timing there, if you make the simulation speed slower you'll see that the ball spawns when the piston is at half the height
For that you have to go to the stretched axle that links the circle with the spawner to the crankshaft, and do this:
Untick the brake, and go to the script menu. now on the bend part:

bend=true
bendConstant = +inf
bendTarget=2

This will make the timing always perfect

And one more thing: stretch the piston so that it is a square (1m x 1m).

With all those changes I could make this engine run at 70 rad/S stable

Thanks for help

Is this better?

Not bad at all... But there is what do do to improve engine up to 1600Nm just by moving two parts of the engine.

Move killer box lover, about one cube line (you can see it when you turn on your grid)higher then pistons down death point.

Move spawning parts (timing ball and the box) that they would spawn balls just where piston reaches a top. That way you get more collision and more power.

Transition is good, but you might would want to use all 7 Gears, and make them shorter. Because trucks use short gears. And you should make vehicle in his real weight. That kind of truck would weight about 5 - 6 tons. So 1600Nm engine is not going to move it. I'll be making new engine tutorial on new tricks how to get over 900HP out of inline 5 spawn engine. Like my truck that I have made 15 000 Torque @ 45rad/s, 917HP. So that would be useful for you. You at least need 300HP engine.
But that was well done.

Killer higher, spawner lower? Got it!
I work on transmission, a just deleted 5-th gear, because engine turn everything so fast that it starts vibrating (transmission gears, axle drive, wheels)
Now i´m calculating new transmission on paper, because max gear ratio need to be 2:1 (that is 4-th gear now)
I want to made this to be like dakar truck
BTW: How you calculate HP? I just run engine on full gas and brake it until it go as slow as possible without stopping (=1400Nm)

"I just run engine on full gas and brake it until it go as slow as possible without stopping (=1400Nm)"

What you need to do is brake your engine as you did here but brake it until engine runs in between 40-50 rad/s. When you do that write down two thinks,
1. How many rad/s that was when brake was on. (For example lets take 45 rad/s)
2. Nm that was on that engine at that rad/s. (1300 for example)

Now when you have these two count like this (these numbers are from example numbers i made)
(RAD/S * NM) / 736 = HP
So,
(45 * 1300) / 736 = 58,500 / 736 = 79.4 Horse Powers.

Also if you want that that gear would not start shaking at high revolutions just open axle script menu and change legacyMode from 1 to 0.

How you made sopowerfull engines? they do NOT rotate so fast as mine, but they have WAY more power
When i was inspecting your engine i find that your pistons are made from few boxes at same size and position
Help this create more torque, because more collisions?
I looking forward to:
"new engine tutorial on new tricks how to get over 900HP out of inline 5 spawn engine."