What is the difference whether cylinder pressure is made from compression or boost? In the end, isn't it all the same?

Basically to control cylinder pressure, wouldn't it be easier and cheaper to control the amount of boost with some sort of a wastegate, than cut away an all ready weak piston?

Cylinder pressure is what pushes the piston down to turn the crankshaft, that's what makes the power. So by reducing cylinder pressure you reduce power output. The reason we lower the compression ratio is to allow more room for the fuel and air mixture to keep from hydrolocking the motor. Boost by itself will not make more power unless there is unburned fuel already in the cylinder. So when we lower compression and add more fuel and air it makes more cylinder pressure and more power. Hope that gives you an idea of what's going on inside.

So basically:

More fuel and air with less compression= more cylinder pressure

Less fuel and air with more compression= more cylinder pressure

My question is, why is more fuel and air with lower compression a better route than just the opposite, if the end result is the exact same cylinder pressure?

I can easily control how much fuel and air go into my motor, but compression is fixed unless major work is done.

With improper tuning Cylinder pressure can spike and be bad for motors health . You have to have high pressure to make power. The less compression just lets more fuel and air in to make more power as Steve explained.

Multiplication. The thought that it adds air is a misconception. You have not increase the displacement of the engine when you decompress.

Let take a couple extreme, yet simplified, examples:

10:1 with 45 psi of boost is 485 PSI just from compression. 20:1 would be 985.

Add fuel. That is the same as adding heat. Which also multiplies the pressure. So for a given amount of fuel that doubles the absolute temp of the charge, 10:1 gets you to 985 PSI and the 20:1 would be 1985 PSI. You can see the spread in the cylinder pressure.

In reality, the higher compression gives you more power for a given slug of fuel, but the engine can't take the pressures. You make up for it by being able to run higher boosts (cram more air in the cylinder) and burn much more fuel with similar CP as the high compression engine.

Can't you bleed off cylinder pressure with a custom grind camshaft with these motors or by doing this you would cause street manners to go away?

A custom camshaft will change where and how the air gets into and out of the cylinder. This will help in moving the location of peak power and torque and increase them as well. So you may get lower cylinder pressure at one engine speed while increasing it at another. Our custom grind camshafts work very well and do not cause the street manners to be hurt much at all. Our smaller grinds increase the performance across the board with no loss in street mannors.

A custom camshaft will change where and how the air gets into and out of the cylinder. This will help in moving the location of peak power and torque and increase them as well. So you may get lower cylinder pressure at one engine speed while increasing it at another. Our custom grind camshafts work very well and do not cause the street manners to be hurt much at all. Our smaller grinds increase the performance across the board with no loss in street mannors.
Was reading a post you made about testing cylinder pressure along with others. I guess this is why tts programming with a lb7 is so strong. You guys have the cylinder pressure under control but the right amount for the best power curve from your testing:) .

I'm certainly not an expert on this subject, and feel free to correct me if I'm missing the boat here.

Lower compression ratio(S) increases the volume or squash area where the fuel starts to burn. A higher compression motor is more likley to build heat near or at TDC. This smaller squash area also creates a higher potential for early combustion which may start the ignition cycle before the piston reaches TDC. This is when cylinder pressures go crazy (bent rods). By lowering the CR the likelyhood of this happening is reduced. The increased squash volume with lower CR acts to provide more of cushion, when fuel timing get's ahead of TDC. This helps reduce pre-ignition. I don't think cylinder pressure in it's self breaks parts, it's where it ocurrs in the cycle that does the damage. Reducing these high pressures before TDC may be the key to making our motors live.

Sounds good anyhow..................

There is an always will be a peak pressure the componets can take but that does not mean one pressure all the time. If the pressure occurs before the piston has reached TDC the pressure is trying to force the piston/Rod down while the crankshaft is trying to push it up thus the failures will occur at a much lower cylinder pressure than if the piston was already heading down the bore when peak pressure occurs.