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Discussion Starter · #1 ·
I read about this engine technology about 5 or 6 years ago in one of the motorcycle rags. It certainly looks interesting but like the Rad Fork of years past it never seems to have made it into mainstream manufacturing. The info on the link appears to be at the same level of development as when I first read about it. VWW
 

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Looks like packaging it in a bike would be a beare (sorry) because of the length of the barrel/head assembly.
 

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Discussion Starter · #4 ·
Take a look a the site pushrod. The Beare top end doesn't appear to be much taller that the standard desmo over head cam setup on the ducati in the pictures. VWW
 

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The head height is 150mm the same as the original.

(1) The 6-stroke engine is fundamentally superior to the 4- stroke because the head is a net contributor to, and an integral part of the power generation within the engine, unlike a cam only absorbing power.

(2) The 6stroke is thermodynamically more efficient because the change in volume of the power stroke is greater than the intake, compression, & exhaust strokes.

(3) The compression ratio can be increased because of the absence of hot spots in the combustion chamber.

(4) The rate of change in volume during the critical combustion period is less than in a 4stroke.

(5) The absence of valves within the combustion chamber allows design freedom.

(6) A one-piece engine from crankshaft to upper shaft becomes feasible. No head gasket.

(7) Fewer components, 15 per cylinder compared to 40 for a 4-stroke. Therefore the cost of manufacture is much less.

(8)Can be fitted to standard engine blocks so the market is much larger than the OEM sector, also includes the retrofit aftermarket sector.

The engine has proven to be robust on the racetrack, & have significant advantages over 4-strokes

(1) The valving is desmodromic

(2) There are no valves to drop or bounce.

(3) The rev limit is only what the bottom end can stand.

(4) Gas flow on intake increase of 20%.

(5) No possibility of engine damage if the timing belt slips or snaps

(6) the reed valves are so close to the intake ports that their tips become the virtual port opening. This achieves variable port area & variable engine demand valve timing. The tips open late & small amounts with low throttle settings & open early & fully at full throttle

(7) air assisted fuel injection has unsurpassed (5 micron with 20% air premix) fuel mixture preparation directly into the cylinder without the inhibiting poppett valve in the way, just a lovely big port. And the injector is protected from combustion.

The valving is really piston porting augmented by disks and or reed valves. First the upper piston opens the exhaust ports. No other ports are exposed for 20 to 30 degrees to allow for a blowdown period. When the intake ports are exposed the reed valves prevent backflow and the intake disk is blocking its port. The exhaust stroke continues and towards TDC the exhaust disk begins to close its port and the intake disk begins to open its port. The intake reeds open whenever pressure differentials between intake manifold and cylinder allow. The disks are set in timing for the desired overlap. The exhaust system design plays a large part in evacuating the cylinder and starting the intake, as the ports are fully open at this stage.

The exhaust disk closes and intake continues.

The upper piston closes all the ports at aprox 60ATDC and compression begins. I have found it to be most advantageous to retard the upper piston in its relationship with the main piston by between 10 and 20 degrees to have peak cylinder pressure at the upper pistons TDC or aprox 15degs ATDC ignition timing advance seems to be best at aprox 25 degs advance.

The cycle has some similarities to the Miller and Atkins cycle in that the intake volume is less than the expansion volume.http://www.jack-brabham-engines.com/

Malbeare
 

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I don't agree. It's a very clever variation on the theme of engine breathing and could prove to be very robust. A good question would be whether or not it improves the ratio of cost to efficiency and longevity compared to conventional designs.
 

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Hey PoppySTS, I really think it's time for you to go. It's obvious that your little pea brain couldn't comprehend what the man had to say. So of course, you insult him, which is what I'd expect from a fekkin moron such as yourself.
 

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Discussion Starter · #9 ·
Thank you for a very thurough explaination. Are there any plans for this technology to reach the public thruogh the mainstream manufacturors, of the after market? VWW
 

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BMW4VWW,

It seems that the most likely commercially available bikes will be in India & China

125cc to 250cc singles.

I would like to personally tackle the aftermarket with yamaha or Honda 500cc single dirt bikes or classic single roadys like the SR500 Yam. possibly in about 3 yrs.

Malbeare

http://www.jack-brabham-engines.com/
 
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