Here is some info that might help one understand what Volumetric Efficiency (VE%) is.

Trapped Ve% is the Measured CFM minus the Ring Blow-By CFM, minus the CFM

lost during the OverLap Period, then divided by the theoretical CFM

Theoretical CFM @ 100 % Ve = CID * RPM * .000289352.

For those that prefer to divide instead of multiplying using the

above decimal value, the reciprocal of .000289352 is 2.4.

TrappedVe = ( MeasuredCFM - ( BlowbyCFM + OverLapCFM )) / TheoreticalCFM

Increasing VE% also means more fuel can be added helping to make more power.

However, fuel takes up space within the combustion chamber.

This then leads to an increase in your 'Dynamic Compression Ratio'.

which is also more accurately described / called 'Trapped Compression.

These engines, the stock LSA, have very low static compression ratios.

So as we spin the little 1.9L blower harder, it moves more air, we add

more fuel, and the Trapped Cr increases.

__One more however..lol__

The 'Burn Angle' increases considerably relative to an NA Engine

having a higher geometric or static Cr.

This is because the higher the static compression,

the more efficient the engine will be.

The above can be referenced either as the 'Otto Cycle' or the

'Percentage of Air Standard Efficiency' (%ASE).

So, if we take a low compression engine, and apply 2-BAR of boost,

we will (unassumingly) also be filling the cylinder with a larger amount of fuel,

which will take much longer to burn, hence . . . . 'The Burn Angle' will be

longer as referenced to time, in order too burn all of the fuel.

The above issue leads to a very different Exhaust Lobe requirement than

would be the case for an NA Engine, making the same fwHP, but having an

higher Static / Geometric Cr.

Using an oxygenated fuel also helps, as many on this forum do when using E-85,

as an oxygenated fuel burns quicker, hence a lower numerical value, given in degrees,

will be seen for the burn angle.

The above referenced (lower value) burn angle, associated with the oxygenated fuel

will also be of an lower / similar value for an engine using a higher static Cr.

Finally. . . . .

Please do not pay attention to articles ill written on the Internet regarding 'Dynamic Compression Ratios'.

A dynamic compression ratio of, lets say. . .8.0:1, is a simple scalar value,

which does not change. The term 'Dynamic Means. . . It is a Changing Value.

If your 'Static Compression Ratio' is 8.0:1 and your able to achieve 125% VE

as the intake valve closes moving from the intake cycle to the compression

cycle, then your 'Trapped Compression / Dynamic Compression' will be. . . .

=> (8.0 * 1.25)= 10.0:1.

Cheers,

RD