Bob....a decade or so ago, I tried one....the red one....very well made...
I wasn't fond of the fast that the crankcase was significantly wider than OS's....
I fooled with it quite a bit, and could not "Tame" the critter....tried a 11 X 3 prop, wanted an 11 X 2...
Had two local (and good) engine gurus modify it to no avail...
Something else that bothered me is the fact the to OD if the venturi was/is HUGE....
A friend had one about the same time with similar results...
I think they would make terrific carrier or speed or combat (except they are porky as well) engines.....
Hope this helps...

Hi,

I purchased my Irvine 36 through Barry Robinson from the UK in 1994 after seeing Barry flying it in his Northwind plane series. This plane (usual size Stunter) was so incredibly flown by Barry during the World Champs that I needed to have one. Barry used the following setup. The venturi I think was standard. He used the small Les Neering 32 pipe but had probably 18" pipe length. The engine was mounted in 45° angle nosing sidedown. Barry had a short OS-header and an aluminium tube from this side to rear header to the pipe. The prop was an 12.25x3.75 APC. Fuel consumption 150 ccm.
You might think now that the pipe is too short and the prop too large but in my impression the plane was as powerful as Paul Walkers Impact powered by an PA 40. Especially in the windy and turbolent conditions in Shanghai I was more than amazed by its power.

I thought of improving the system and used a 3-blade Bolly (11x4) and a 40 Smith Werwage pipe. No success. The engine wasn't powerful enough. I then gave up using piped engines and never used the motor again. I still have the Les Neering pipe if you want (unflown) 

Give this engine a try. It is probably an undiscovered jewel.

Christoph Holtermann, Germany