Getting the right turbulence.

[Simonas]

I've already searched on this topic and didn't run across anything of significance.

If you want the main question and none of the background, look below.

Background

Since I am in the process of a total engine rebuild, I think I'll try to make the engine as efficient as I can.

First off, my goal for this engine is that be reliable. An efficient engine that won't run is useless because it won't run. Better a guzzler that runs.

This is a total rebuild. New rings, pistons, wrist pins, bearings, camshaft, rockers, valves, valve guides, valve seats, oil pump, freeze plugs, gaskets, etc. The carburetor is rebuilt by me...

So... I wanted to raise compression, but because of my new pistons being off a Lada, they don't have the dome on the piston. I also don't want to remove a lot off the head, as that will not allow me room for the engine overheating in the future. Not that I plan to overheat, but I want to leave room for error. I already have had the block milled 0,6 mm, but that only covers the Lada pistons having a lower deck height. So, I am stuck with a 7.5:1 compression ratio, or milling the head...

So, my idea of raising compression has failed... I suppose I'll look for efficiency elsewhere. Perhaps I should try to get every last bit of fuel burned?

The Main Idea

So...I want the fuel to be as well atomized before the intake as I can get it to be. I'd even prefer for it to be already getting vaporized. I'm one of those strange characters that even succeeded somewhat in getting a 7.6:1 compression ratio Briggs and Stratton OHV, 17 hp engine to run on vegetable oil. Yes, it ran quite nicely if the throttle was high. I didn't give it a load, though I'm sure it would have started detonating if I had. And it had a plastic intake runner.

So, the main question is this: How do I get the fuel to mix completely and evenly with the air before the spark that ignites the fuel?

I have the heads off, and am in the process of replacing the valve guides. Should I clean up the ports a little? They have a fine sort of roughness (which is good, right?), but they also have a lot of casting leftovers that are like.

But then I got thinking... I can hear you all sighing in the background

Why not make some turbulence in the intake track do the work? I know this is a before mentioned subject. I thought of spirals, but the centrifugal force could cause the fuel droplets to fall against the walls of the port. This would be unproductive, because not all of the fuel would be able to arrive at the intake valve in that stroke because of being caught in some corner of a port. But, it would allow heat transfer, and that would help with vaporization. Or, I could try a series of "waves" this would cause the mixture touch the wall for a short time, then jump over the gap and touch the next tip of the "wave". Or I could use a combination of these, swirling the mixture to heat it up, then making it stop swirling and "float" over the wavy part of the intake.

I know that turbulence should be engineered, not just a haphazard occurrence that just "happens" because of excessive casting flaws or port shape as the manufacturer make them.

Also, I'd have no way of doing ABA testing as I only have on head... I do have two intake manifolds in good condition, as well as another exhaust manifold.

I am asking for theoretical and practical ideas on how to get the fuel/air mixture to do what I want it to do.

If you have experience in this field, or just tried something and it worked, or just want to theorize with me, feel free to do so. If something worked that you "just tried and it seemed to work" then mention it even if it is not scientific. Just please include what else you did, so we don't have a bunch of ideas that "work" but don't include the complete picture. Like saying, "I tried Singh grooves, and it increased efficiency" when you also had the head milled to increase the compression ratio. The CR gain in efficiency is guessable to some extent, so we could "calculate" the gain of the Singh grooves. We can't guess the gain of the Singh grooves without first subtracting out the gain of the raised CR.

Thanks a lot