Motorsportdesign & Malbeare,
By the way, for sake of simplicity, please allow me to abbreviate Fairbanks-Morse as F-M. Thanks.
I have now explored Malbaere’s website. And yes, my assumptions are suspect.
In regards to Motorsportdesign initial specs and comments:
Simple design for racing application
-no valves in head
-pressurized intake manifold
-2stk, v8 configuration
-machining a spherical sealing surface is too complex
-component life is relatively short (no million mile overhauls)
Are you planning on individual heads for each cylinder? Large 2stks use this time saver. Even ones with fuel valves/injectors in the head.
This is a simple supercharged two stroke engine. My thought on your plan Motorsportdesign, is that your 2stk idea/design is sound. People have done the same thing many times over, in many different applications. I would expect that your 4stk design would work also.
Is your proposed market able to support either your 4stk or 2stk engine? Most of the people in the racing circles like to tinker themselves, and making their own engine, allows them to do that. How many people buy factory stock engines and race them? Do the people who have the factory engines prefer the tested designs that Chevy, Ford, et. al. have? Would they be willing to risk running a startup company’s engine. Those are the questions I have, when I hear your proposal. {shrug}
My observation is that most people don't make or lose money on the quality of the design, as much as a lack of marketing and buisness ability. As I am an engineer and not a buisness major, I won't give you advice in this area.
In regards to Malbeare’s engine:
I assumed the bore for the upper cylinder was the same as the bore for the lower cylinder. This is my main mistake. With the upper cylinder roughly half the area of the lower cylinder you have half the force on the upper piston and driving components. Thus you don’t have the weight of the F-M upper drive train.
The F-M upper piston was used to make a small amount of power; which the Beare engine probably doesn’t do. My guess is the peak firing pressure on the upper piston creates more friction on the scotch yoke at that point and the possible power gain is negated. This would be hard to measure, but is probably moot anyway.
How has the loss of work due to the upper piston expanding during the power cycle worked out?
How well has the scotch yoke survived sliding during the peak firing pressure event?
Did you weigh the Ducati Desmo heads, intake runners, and throttle bodies?
How about the Beare head parts, reed valves and throttle bodies that went on the Ducati engine?
How do you maintain an oil film on a scotch yoke bearing?
How do deal with the oil pooling on the top of the upper piston?
From your pictures of the exhaust disk, is that the exhaust port that is shown right below the upper crankshaft?
Why is it so much smaller than your air intake system?
Or is this just perception from the pictures?
Why do you have two intake manifolds, when most ported cylinders only use one?
Can you/have you taken a pressure trace of the engine during operation? How does it compare to your predicted values?
What do you think of the fact that you have 3 seperatly unique sealing surfaces in your process, while the poppet valve has one type of sealing surface? (maybe two if you count the different temperatures of the intake and exhaust valves)
I suppose these questions are considered hijacking this thread.
I don’t know gentlemen, maybe Beare's head is a good alternative to poppet valves. I lean towards the not side, but we’ll see what happens in about 40 years. I read somewhere that Lord Kelvin said that people could never travel faster than 60 miles per hour. If I miss my prediction here, at least others have made inaccurate predictions as well. I certainly don’t place my intellect on the same level as Kelvin’s, so I will probably guess wrong more than he did. Maybe I can do as well as a meteorologist.
Good Luck
