Engine Oils and Needed Ignition Timing

[jaguar]

OMG I'm blown away by my test results showing timing needs for best power can vary as much as 6 degrees depending on what type engine oil is being used. I first got a hint of this when I lighted different oils on fire and found the synthetic was the least combustible. Yes they are all derived from petroleum (as is gasoline) but the average number of carbon chains in the molecules increases on a scale from group 1 oil to group 5 oil. The higher # makes them lubricate better but less readily flamable (which is why synthetic oil makes more spooge).

So the logical conclusions are:

1) when you switch oil types (mineral, synthetic/mineral, synthetic, castor, castor blend) you need to recheck your timing. (FYI Yamalube is now fully mineral oil)

2) it's very possible that engines needing a quick burn would give more power with an engine oil that lowers the burn speed.

Factors in need of a quick burn fuel/oil mixture: high RPM, low squish velocity (typical on most stock bikes), excessive squish volume (typical on most stock bikes), high exhaust ports (large duration)

I guess I should tell some details of my tests. I have an air cooled 48cc engine and there's a long uphill road in my town and with my present gearing the bike slows down at the top section of the road to about 68% of top RPM. It has an adjustable CDI (my own design) and so each run I noted the RPM at one point on the uphill and the head temp after shutting the engine off. Gasoline is ethanol free.

Look at these two test results to see one engine oil is almost indifferent to timing changes whereas the other is very dependent on the timing.

The zero on the horizontal scale is just a selected point of timing as a reference point. It does not signify 0 degrees (TDC).

 

[jaguar]

This graphic shows how a fuel mix that burns too slow for the ignition timing causes the peak pressure to be delayed. It's known that best power is had when the peak pressure is between 10 and 15 degrees ATDC. That "too slow" mix needs the timing to be more advanced (happen earlier).

 

[jaguar]

Skeptic: "6 degrees! You're going to burn a piston!"
Me: "No. I am advocating setting timing for best power or best powerband, like always. I'm just saying that the timing you chose may be more advanced with slow burn oils, or more retarded with fast burn oils, but the method of selecting the timing doesn't change. Also you may want to prefer fast burn oils for high RPM engines, and slow burn oils for low RPM engines."

Skeptic: "You can't test without a dyno!"
Me: "Yes you can. If your uphill angle matches your engine power so that you never top out the RPM then higher power will always result in higher speed & RPM. No motorcycle engineer will disagree with that. Different ignition timing results in different power. I'm not trying to know the exact horsepower, just the timing that matches the oil for the best power. And I can most definitely do uphill testing for this purpose."

 

[jaguar]

the 3 main types of engine oil:

 

[jaguar]

full info at www.dragonfly75.com/moto/oilpower4.html

 

[jaguar]

My video on the subject: