Last Friday, we clamped the engine to a table and let it run for 73 minutes straight! The previous record was 6 & 1/2 minutes. It was idling at 1100 rpm with a few minutes of goosing the throttle (up to 4k) and low as ~800 rpm. For the last 10 minutes, we upped it to ~2k rpm... it finally got a bit hot on the exhaust end and I think burned the oil off the edge of the seal, which then greatly increased the friction and lead the end of the valve to turn blue (measured at 400F). You could hear the #25 chain start to groan under load, so I shut it off. The head/ block were about 260F, which isn't too bad considering the complete lack of cooling. There were some bubbles in increasing intensity coming around the seal near the end, which leads me to question how well the o-ring held up. I can't wait to tear it apart. Next step is to put it on my friend's go-kart.
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.
We've made two valves at this point. Both started with precision ground steel, which takes care of the OD. It is machined as once piece, drilled from both ends and then each of the openings in the center get milled on a mill or 4-axis lathe. Generally, you can't mill the transition between the drill operation and the mill operation to be very smooth, so some dremmel work is required. You can make the path better for air flow, but it increases the machining complexity. A nice multi-axis lathe could do a better job... kind of like how custom intake runners are machined in normal engine heads for race cars.
Here is a video of my mini 4-axis mill cutting the valve. The rest was done with a 3/4" drill bit.https://www.youtube.com/watch?v=qBgn5FxVOYs
You have too many files open Taylor.
If I did that on my computer, Inventor would crash!
That's nothing. Running CFD, I pushed my laptop to 59 Gb of RAM used (16 Gb actual ram). A solid state disk drive helps in that endeavor. At work, at times I have had 40+ applications open at once (I do a lot of data mining across different programs) and it only has 4 Gb of ram and the motherboard tends to only allow me to use 2.2 Gb of it... the rest of it gets swapped to an encrypted disk drive, which is really slow.