Re: fuel air
 

Could you go into more detail about why using all the oxygen provides the most power.

Thanks a lot

For generating power, we need both fuel & air.
On one given engine, the bottle neck is usually at the "air", not the fuel.
So we'd better use up every bit of it.

Just in case, you have a diesel, the role is reversed. You need more fuel - the bottle neck is fuel.

Tuning up the boost or using bigger interccooler may not give any more power (mechanical diesel).

I have dug out a few old pictures on combustion (spark ignition engine) that may be interesting:

Various spark configurations and flame developing and propagation speed:

http://www.aquamist.co.uk/forum/gall...on/final3s.JPG

Burnt fraction after spark:

http://www.aquamist.co.uk/forum/gall...ion/mbt-bk.gif http://www.aquamist.co.uk/forum/gall...tion/mbt1s.JPG

One more factor that will help you consume all your oxygen inside the cylinder - the burnt rate at various a/f ratios
(ref: Internal Combustion Engine Fundamentals - John B.Heywood. ISBN 0-07-028637-X )

http://www.aquamist.co.uk/forum/gall.../burn-rate.gif

Ignition timing had to be close to MBT (maximum brake Torque) timing to achieve maximum cylinder pressure (torque or power per RPM)

http://www.aquamist.co.uk/forum/gall...tion/MBT-c.gif

Figure left shown Cylinder pressure versus crank angle for overadvanced spark timing (50deg), MBT timing (30deg), and retarded timing. Your a/f ratio will greatly affect the MBT timing due to slowing down of burnt rate. Figure right shown the effect of spark advance on brake torque at constant speed and (A/F), at wide-open throttle. MBT is maximum brake torque timing.