UHV 5
In some respects I wasn’t completely excited with the engine performance, so wanted to do 2 things before I progressed any further.
The first thing was the cylinder. It was something left over that was junked for one reason being a hole through the bore to the outside world. I did fill this with Devcon, but as you can see that this wasn’t lasting and was externally seeping. So, created a new liner (we fortunately had some spare blanks kicking around) with exh and inlet ports only.
The other thing was the nature of the flow coming from the 3 petals. Are we getting a nice pancake mixture descending slug or is it some high velocity swirl motion around the outside of the bore, perhaps not displacing the centre exhaust gases?
So, with a bit of 3D printing made up the rig in the vid so one could see the valve movement and also maybe get an idea of the gas motion.
https://www.youtube.com/watch?v=iceFOIRa6Fw&t=8s
The problem with bloody 2 strokes is that, when “off the pipe”, there is always exhaust gas remaining in the cylinder. The scavenging streams are intended to both displace this as much as possible out the exhaust, and not itself escape out the exhaust and also, remain stratified enough to ensure there is a combustible mixture at the plug. Each and every cycle = a 2 stroke that 2 strokes.
So, the plan is to observe the 3 petal flow plus try some other alternatives that I have ready to go.
In some respect it could be treated like a Jante rig, but I don’t think that this is a great system. Interestingly the Jante rigs I have seen used a fixed piston and air being blown thru the crankcase, whereas in this case, the flow will be derived from a motored engine.
More to come.
Bookmarks