a direct drive EV has deficiencies as a direct drive ICV would haveMuniix wrote:.........all the superbikes are gobbling air and fuel at a rate and levels that produce well over 1,000 hp of heat energy .......No wonder electric vehicle racing is taking off. We need to come up with ways to put liquid/gaseous fuels into contention again. .... When electric vehicles have a near perfect torsional torque and don't have to be designed for economy or performance they can be both at the same time. They are througing down a challenge for ICE to respond to.J.A.W. wrote: ........this thread has strayed off the 2T topic basis lately ..
With the new Tesla racing class vehicle achieving 0-100 kph in 2.1 seconds, now that is insane, not even F1 can do that and in a body that can seat 5 adults and two children and still have two boots, that is damn impressive.
........My ideas were along the lines of finding a more efficient crank train, with all the recent research interest in offset cranks and gudgens pins. If we can find ways of putting more energy into a single engine cycle and make it as efficient as possible .....
This is what interests me at the moment, clearly research shows that larger cylinders have better volume surface ratio's that assist thermodynamic efficiency.
......Maybe by using a torque filling and damping using mild hybridisation ....... Any Ideas ?
Maybe one should look at the Zoche Aero Diesels, they exist now two stroke diesels for aircraft, decades of development went into these. You can buy one today.manolis wrote:Hello J.A.W.
“I'd also note that this thread has strayed off the 2T topic basis lately.”
Here is an intriguing 2-stroke, the PatTwo:
(more at http://www.pattakon.com/pattakonPatTwo.htm )
It combines several unconventional characteristics.
For instance, it minimizes the pumping loss at light loads (as in an Atkinson / Miller 4-stroke).
For instance, it eliminates the thrust load between the piston skirt and the cylinder liner.
For instance, it has a 4-stroke lubrication inside the crankcase.
For instance, the double acting piston performs a pure sinusoidal (harmonic) reciprocation: the position X of the piston can be described as : X = (S/2)*sin(f), wherein S is the piston stroke and f is the rotation angle of the crankshaft.
For instance it is perfectly balanced (as perfectly as the Wankel rotary engine, as perfectly as the best V12 engines).
Unconventional is also the control over the load:
When the throttle valve at the middle of the cylinder (the dark, with the yellow lever) is fully open, the engine idles.
When it is fully closed, the engine runs at full load.
In case of tuned-exhaust things get even more interesting: the peak power can be obtained with the throttle valve fully open. Idle with fully open throttle, peak power with fully open throttle. . .
Isn’t it interesting?
Comparing apples to oranges doesn't work, the na F1 engines were very fuel efficient, they had far superior BSFC figures than the current generation marine engines, Marine engines use mhp, marine hp. Remember one F1 that was rained out, their were concerns that the Safetycar a Mercedes AMG with 100+ litres would run out of fuel before restart. The twin spark bishp rv F1 engine used 6% less fuel again. One has to think of equivelence when doing comparisons, clearly a mistake someone with an engineering or physics degree would not make.manolis wrote:Hello all.
The Evinrude E-TEC G2:
http://www.pattakon.com/tempman/Evinrud ... d_Spec.jpg
has not 86mm (as, by mistake, I wrote in a previous post) but 98mm bore and 76mm stroke (1.3 bore to stroke ratio).
Despite its big bore (98mm, i.e. as much as the bore in the F1 engines before the turbo-era), it uses one only spark plug in the center of an open cavity wherein almost all the compressed mixture is concentrated at TDC.
As an extra-over-square engine, it has a substantially bigger over-all surface-to-volume ratio.
However, and despite it is an over-square big-bore single-spark 2-stroke, it achieves better fuel efficiency and emissions than its 4-strokes competitors.
The LiquidPiston rotary has even higher surface-to-volume ratio. As the Evinrude E-TEC G2, it concentrates all the mixture in a compact cavity wherein it is burnt (they claim constant-volume-combustion).
During the combustion (i.e. when the rate of thermal loss maximizes), the actual surface-to-volume ratio is one of the best.
After the combustion the rate of thermal loss drops substantially; the increased surface-to-volume ratio is a problem, but not a significant one.
The stereotype “the smaller the surface-to-volume ratio the better the Brake Thermal Efficiency” is wrong.
One should consider not the overall surface-to-volume ratio but the actual surface-to-volume ratio.
The OPRE-Tilting, for instance, has a big overall surface to volume ratio:
The overall stroke of the first OPRE Tilting prototype:
http://www.pattakon.com/tilting/OPRE_Ti ... _video.gif
is 30+30=60mm with a bore of 84mm, which means a bore-to-stroke ratio of 1.4, i.e. just a little bigger than that of the Evinrude E-TEC G2.
However, during the combustion the mixture is concentrated in a quite compact (it can easily be true “spherical”: a part of the sphere on the two piston crown, the rest sphere on the "separator disk") chamber / cavity and is burnt there, minimizing the thermal loss during the period wherein the rate of thermal loss maximizes.
The pulling-rod architecture (during the high pressure period the connecting rods are loaded in tension) offers an additional 30 to 35% piston dwell around the combustion dead center, which calls for more “constant volume combustion” than the LiquidPiston can achieve.
The two spark plugs is a requirement for aviation applications (Portable Flyers etc) for safety.
Ibchecked their website and I see no indication that they've achieved type certification yet, or any indication that they're available yet.Tommy Cookers wrote:is the Zoche really available ?
afaik it has a reputation for continuous decades of unavailability - the reason I mentioned it to those scheming similar items
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