JetCat P160 + freepower bike

[racket]

Hi Andrew

There wasn't a lot of bleed air used , just enough to prevent hot gases getting into the bearings and to prevent heat soakback , sorta like the RC turbines used , but a decent lube supply will be better :-)

Cheers
John

[enginewhisperer]

I'll play with some ideas once I see what parts are available

[noshell]

May i suggest a scooter cvt, clutch and generator/stator for the final drive.

[enginewhisperer]

I had thought about that, but I'm hoping to keep the gearbox side of things pretty compact so I can make it bolt in using the original engine mounts in the bike, and possibly use the whole setup for other purposes later.

[enginewhisperer]

I'm still searching for suitable ball bearings, but finally found some half decent looking ones with 16mm ID.
I have a couple of those on the way, as well as a pair of 17mm ID hybrid ceramic bearings.

A ball bearing shaft tunnel will make a few things easier, including needing smaller material stock which is nice.

Designing a nice turbine scroll housing in CAD is a bit of a pain so I'll do some of it roughly in CAD and make most of it by hand.
The turbine exducer shroud section will probably be CNC machined, so I 3D printed a section of it to check the profile against the turbine wheel.
I probably shouldn't have done it in clear plastic since it's hard to see how well it fits, but it looks pretty good

[enginewhisperer]

Bearings arrived.
The 16mm ones are pretty loose on the shaft so I'll have to make sleeves and use the 17mm bearings I think - which are at least more common.
The shaft measured at 15.99mm with a micrometer but I haven't measured the bearings yet.

There bearings are pretty small, so I was thinking of stacking two of them side by side at the gearbox end to help with the loads.
Any opinions on that?
Also is it worth setting up a small oil jet into the bearings, or is it ok to just let oil build up in the middle of the shaft tunnel and exit through the bearings?

[racket]

Hi Andrew

If you try running flooded bearings at high speed , they skid and don't last long :-(

And if they don't skid , the oil can't get through them and they run "dry", its a fine line between success and failure.

Either oil jet lube at pressure high enough for the jet to penetrate the air barrier created by the high speed balls and some means of draining that oil away , or use oil spot lube with bleed air so that theres minimal drag on the balls and the air does the job of cooling the bearings whilst the drips of oil do the lube .

Cheers
John

[enginewhisperer]

hmmm, that's what I thought...
A high pressure jet is probably the simplest way to be reasonably sure it'll work.

I'd like to avoid pulling the Jetcat engine apart to get bleed air from it. There's an unused propane start port, but I figure that will probably end up venting extremely hot air and / or flames if I try to use it as an air bleed!

[racket]

Yep , the propane port best left alone ;-)