The simple fact about MVA is:
- has been around for decades.
- modern engines use it in electronic form. [ After engine is started, timing at idle is increased electronically ]
- people such as Tim [ Newbomb Turk ] do not understand combustion & requirements for such
- if they did, they wouldn't be rubbishing MVA
- all the people who are using MVA all around the world, & have better running engines because of it.....cannot all be wrong.
Really? How many books tell people how to time power valve opening WRONG?
Damn near every one,
I understand combustion well enough.
If you would shut your mouth and pay attention, I never said MVA doesn’t have a place.
I’m saying if everything you build needs it your philosophy is *** backwards.
I’d remind you of your misreading of combustion pressure on piston area. You did what you always do and refer to books and articles you read incorrectly.
And you defending that to the very end.
Same thing here Geoff.
I’m not saying the OP may need MVA. If it does it won’t be because it’s the optimal way to get to the end result.
For the exact same reason you need more timing at a cruise than you do at the same throttle opening and load.
The more timing you need to add at a cruise, the less efficient the engine is, for whatever reason. It’s the exact same thing at idle.
The more efficient the engine is, the less initial timing it will need.
And what are the two biggest factors in low speed (I’m saying from the start of peak torque and down) efficiency?
Compression ratio.
Valve timing.
Too little of the former or too much of the latter (or both) makes the engine less efficient.
And that takes more timing to make the same power. Until you calculate in pumping losses.
We could talk about how compression ratio affects different parts of all the cycles but this is a long post already.
