Wankel Engine

After our recent LS3 Engine Block video, we mentioned we may be working on a functional Wankel engine – and the response was incredible!

NOTE: This project has been postponed due to increased work on our Speeds & Feeds related company, sign up for the Beta here! We hope to get working on this as soon as possible!

I’ve been working on the model for our own Wankel engine for the past few months, and it’s just about ready! We just need one more thing: YOU

Have any of our viewers made a rotary engine of their own? Does anyone have any input, tips, concerns, or thoughts? There are a few things unfinished, so be sure to read the project description first.

Project Synopsis

Fuel

The fuel for this project will be RC Nitro fuel. This means I don’t need to worry about timing spark plugs, and can rely solely on the glow plugs. It’s worth noting that the holes for glow plugs are not properly sized on the current model, and will not be until a final glow plug is decided on and purchased. We are not decided on a concentration of fuel either, and are open to suggestions on which percent concentration would be best.

Size & Construction

The engine block will be made from three individual plates, roughly 8″ x 6″ x 1″ thick. The rotor overall is 2″ thick. The eccentric shaft has a diameter of 3/4″ on the output side of the engine, and 1/2″ on the back side. Each of the three plates will be aligned by six dowel pins around the housing of the rotor, and held together by four 1/2″-13 bolts running through the engine. There are also two 3/8″ holes on the bottom of the engine for mounting purposes.

Materials

Most of the engine should be able to be machined aluminum. The exceptions to this will be the Eccentric Shaft and Gear Insert, which will be machined from steel.

Cooling

Cooling is a little trickier – I don’t think air cooling will work with a larger engine like this that will remain mostly stationary. So, to cool the engine I have modeled eight cooling passages. Four larger cavities at the top and bottom of the block, and four smaller pipes through the outer parts of the engine. To pass coolant through these, I think the best way is to use PC watercooling components. They are readily available, reasonably priced, and easy to use. However PETG or acrylic tubing will not work in this situation like a PC, so copper piping will be cut to size. Two (?) 240mm radiators will be fed by two individial loops, one running coolant through the larger four passages and one through the smaller four in order to cool the engine.

Fuel & Oil Delivery

A small fuel port and oil port will need to be added to the chamber with the air intake on the engine model. A model engine carburetor will more than likely be the solution to fuel delivery, but we are open to suggestions.

Seals

Apex seals on the rotor will be made from M2 tool steel, the same material used for production Wankel engines. Each will have 2 holes both in the seal and in the corresponding apex slot on the rotor, containing a spring to maintain constant pressure against the epitrochoid housing. Face seals don’t seem to be crucial on non-production, model engines so those are being overlooked for the moment. Each coolant passage will need sealed by an O-Ring.

Questions, Comments, Concerns?

I’m not quite an expert, so I have a few questions I need answered too!

  • What concentration fuel should we be using?
  • Is the planned cooling setup overkill? Is it not enough? Some can be aircooled, but I don’t see that being effective for our project.
  • Is aluminum an appropriate material for the majority of the engine?
  • What is the best way to seal the coolant passages?

Be sure to reach out! There is a dedicated forum for this project (Pro Members, link below) as well as Instagram, YouTube, and Facebook.  You can also reach me directly by email:  my email is my first name (alex) at saundersmachineworks.com.

Thanks!

-Alex Pinson

Downloads:

Wankel Engine

Forum Link, Related Videos & Resources:

SMW Wankel Engine
5-Axis CNC Machined V8 Engine Block!