Turbojet Riding Mower Build

[noshell]

How fast was the "high speed run"
Do you think youre anywhere near your target power output?

Looked like you were pretty much on idle most of that video?

[barnyard]

Jan 31, 2023 7:16:55 GMT -5 noshell said:

How fast was the "high speed run"
Do you think youre anywhere near your target power output?

Looked like you were pretty much on idle most of that video?

Hard to judge the speed, I would say almost twice as fast as the factory riding mower max speed, maybe 15-20km/h. I would like it to reach speeds of 40km/h, any more than that and the steering/stability would become to sketchy for me. As for power I haven’t sensed a torque limit yet. It’s also hard to determine as the hydrostatic transmission doesn’t really have a brake that I can build boost against. I’m thinking of ways to incorporate a brake disk, possibly to a second pedal so that I have more control that way, and am able to stall the turbine if needed.

The video clip does show mostly idle, with a small bit of throttle just before I have to turn around and idle back down.

[barnyard]

Here’s a quick update guys. I’ve done a lot of work trying to contain the heat to within the engine area of the hood. There is now a double layer of stain heat shield between the engine and the “firewall”, separating the battery and electrical department. I’ve made a stainless shield to wrap the turbine scroll, which is then covered with a heat blanket, it’s well insulated now. Lastly I’ve wrapped the ducting between the two turbines with exhaust wrap.





Starting this engine has always been… exciting. I think if it doesn’t light right away the fuel spray hits the spark plug and drowns out the spark. I build a propane nozzle right next to the spark plug, but even that lights with a violent explosion. Not sure what’s next, maybe a better coil. 


Saturday I was able to get a good 20min test run in. I had replaced the drive chain, and installed a larger sprocket on the power turbine, to keep rpm’s down. It worked, the chain did not over speed like last time, though it did stretch considerably. For high temp testing I tied the mower to the shed and let it dig a hole with the tires. With the diverted valve only 25% open, and almost full throttle, EGT was at 550’C, boost was 0.8bar. I think if I closed the diverted fully and ran full throttle the temps would eventually climb to 650’C. I’ll be keeping the diverted partly open going forward. 

test video
youtu.be/Sm5ohkryzwg


next steps are to get some driving time in, maybe convince the kids to go for a wagon ride! Then I’ll be looking at the mowers rear transaxle, it’s slipping and loosing some power, can’t have that. 

James