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Treadmill Dyno
taylorp035:
Here is a video of my personal rotary valve 3.0 design running. Probably my best engine video yet. Completed the whole thing over Christmas break. This version of the engine already has more run time on it than all of the previous versions combined. I can't wait to make a dyno for it.
https://www.youtube.com/watch?v=iW7MRZB7Ris&feature=youtu.be
Version 3 has a floating bronze seal in the center that gets pushed up by the combustion pressure. The springs are there to lightly pull up so it doesn't fall down during the intake stroke and cause a vacuum leak. The engine was designed to be a 10.2:1 compression ratio, but currently is about 8:1 since the seal is up in the air a bit. A compression test revealed a healthy 135 psi.
In other news, we also found the reason(s) why our mini 53 cc engine wasn't very efficient at competition. Basically, it was severely worn out, with the valves, valve guides, and valve seats pretty much past their usable lifespans. A new set of valves, seats and some sleeves for the guides will get it back to new again. This explains the halfway decent efficiency at high rpm's and very low efficiency at lower rpms.
SparWeb:
Hey thanks for the update Taylor.
Gotta love the brass for journal bearings and the like.
But is it exposed to the combustion side of the chamber?
taylorp035:
The brass piece is a cylinder that goes all the way to the combustion chamber. It has the sparkplug, half-pipe journal surface, the port and the combustion chamber milled into it. On the outside, there is an o-ring and some teflon backers for sealing.
The brass piece floats and is pushed up by the combustion pressure. The springs prevent it from dropping back down.
SparWeb:
The pipe is more complicated than I thought. How hard is it to make?
Is it machined as one piece? Can the machining of each path be completed from the port side, or do you have to do some tricky things at the bottom of the hole bored into the bar? Now that I see the way the passages are separated, I wonder if maybe an insert that pushes in from one end would be easier to make.
SparWeb:
You have too many files open Taylor.
If I did that on my computer, Inventor would crash!
:)
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