The Wankel engine took a new twist (no pun intended) and went to a continuous rotating mass to help effiency. What gains could be achieved if, and it's a big if, a new engine design would allow for added compression at the top of a four cycle (or 2 cycle) engine with the crank past center by approximately 10 degrees before ignition. It sounds physically impossible, but what gains would there be? I'm thinking that fuel effiency gains would be substantial. Any thoughts?
What are you trying to say?Bob
engine design would allow for added compression at the top of a four cycle (or 2 cycle) engine with the crank past center by approximately 10 degrees before ignitiononly issue is .. 10 ATDC is 10 to 50 degrees after the spark has already started the flame front...let me start back a ways...flame fronts happen at the same speed... starting small at the spark. then expanding to build pressure as the air and fuel are consumed... at idle, the spark is usually set off 8 to 12 degrees before TDC so the expanding pressure wave/flame front is still building pressure as the crank reaches TDC... with electronic spark timing. this can be set up between 20 and 36 degrees before TDC at idle...the faster the engine rpms.. the earlier the ignition spark needs to be set off... to a point.. combustion chamber design.. piston shape.. compression ratio... manifold vacuum ... air fuel ratio... all control the speeds of the flame front in the combustion chamber.. you also have to throw in rod angle ratio.. some performance engines need only 34 degrees to reach maximum advance needs.. others need over 50 degrees...want to have some fun... find a mid 80s to early 90s gm car or truck.. throw a timing light on it in park... get the engine up to operating temps.. look at the timing... it will be around 15 to 20 degrees at idle... don't touch the throttle.. have somebody step on the brake and drop the transmission in drive.. look at what the computer does with the timing.. its going to be well up over 45 degrees... this is most visible on buick V6 motors.. others are similar..i don't personally know how you could inject more air and fuel into the chamber when the flame front is still expanding.. i just don't think thats possible.. but the impossible is only what i think.. you might have a totally different mouse trap in mind... few people can visualize my inventions until i show them to them .. there would be a tremendous amount of pressure during the EXPLOSION of air fuel mixture in the chamber. so the faster the piston is moving up and down.. requires the ignition spark to light the air fuel mixture earlier to reach maximum pressure at TDC so it pushes the hardest downward...
want to have some fun... look up triple expansion steam engines.. where the high pressure steam is released into the smallest cylinder first.. that releases it into the middle sized cylinder and the it gets released into the largest diameter cylinder.. so as much of the steam pressure is used to turn the crank... these were used in ships and big power plants during the late 1800s and early 1900s only thing is the amount of heat input needed to boil the water to super heated steam temps.. usually around 350F.. i had thought about why not using high test peroxide.. using a ceramic or stainless diesel fuel injector pump to spray variable amounts into chamber thru a platinum grid.. or honeycomb block to break the H2O2 down into H2 and O2 that would instantly burn, as the liquid breaks down into base elements then recombine in a fire to become super heated steam with an extra oxygen .. that could be an instant boiler to drive the steam engine.. and be Throttlable. so you could change the speed of the steam engine by changing the amount of peroxide injected through the platinum catalyst.. and this is not taking some new tech and working with it.. this is tried and true tech juggled and reconfigured into a power plant... only problem.. hydrogen peroxide at high percentages is UNSTABLE.. can blow itself up.. violently.. if one could find a magic powder to mix into small amounts of water to make it easily onboard.. it might be usable. or see if one could run oxygen through a carbonation pump to make it.. bill lear of lear jet fame spent 20 years working on steam.. but i came up with this idea after he had passed away...perhaps i should stop by jay lenos shop.. he still likes steam power... careful design might make this a mostly a closed system that could have very little water loss... all one needs is the magic to make peroxide..
I'm still pondering if there is a loss of energy at spark due to the need to overcome added compression and detonation BTDC. What I think you are indicating is that the time for maximum burn is delayed so that the loss in minimal - maybe less than 2%. If that is true, wouldn't the maximum force from the explosion be at the most advantage when the stroke is at 30 to 45 degrees ATDC so that the rod is not near TDC where the geometry has the most opposing force? I'll play with your suggestions. Does fuel burn that slowly that it burns continually thru the downward stroke? With regard to your instant burn peroxide, where would likely timing for detonation be set; the same as fuel or ATDC.
Does fuel burn that slowly that it burns continually thru the downward stroke? that i don't have an answer to.... its beyond my knowledge...if one could figure that out... they could design the bore and stroke with a rod angle to reach the highest power possible and use the fuel to its max...If that is true, wouldn't the maximum force from the explosion be at the most advantage when the stroke is at 30 to 45 degrees ATDC so that the rod is not near TDC where the geometry has the most opposing force?nope... to get the most PUSH from the expanding gasses.. you want it pushing as hard as possible close to TDC as possible.. if you lit the fire after TDC... the flame front would be chasing the piston down the bore.. the more compression of the air fuel mixture.. the bigger the push you get out of it..
OK; going back to the drawing board. The only advantage my mousetrap has is added compression at TDC, which isn't a bad thing. Thanks for input!!
actually... that adding to the charge is used.... IN STEAM ENGINES.. to increase horsepower and torque... i completely forgot about that... but it uses the pressure of the steam to push the piston down...at high speeds an additional valve is opened to allow more volume of steam into the chamber as the piston picks up speed after top dead center.. . i have forgotten what this modification was called.. i will call a friend who is into rail road stuff and see if he knows...if you were able to use a CFD program... one might be able to fine tune intake port design... right around the back of the valve.. so the opening and closing of the intake valve which causes the airflow to stop and start.. did not create a reflection backwards up the intake passage.. stalling the intake charge.. one could create a tapered bowl area... so there was less volume of air/fuel charge there to start flowing again as the intake valve opened... perhaps the ram air effect could focus the pressure to increase the amount of airflow into the chamber as the intake opens...i came up with a tuning pipe inside the collector adaptor that allowed a friend with a hot honda to pick up 10HP on a chassis dyno.. it also got rid of that horrible raspy sound that was the shock waves of the exhaust stopping and stretching then slamming back into the next pulse of exhaust gas coming out the exhaust port.. i hope that you get this message...
this tuning tube lives inside your exhaust system.. acts like an anti reversion device.. but it changes your exhaust system into something more like a 2 stroke extractor system..as the exhaust can flow out of the primary tube and expand into the collector... causing low pressure as the ends of the other primary tubes helping them scavenge those primary pipes...because of the reduced area of flow of the tuning tube.. the exhaust speed is increased again... this time that inertia as the 4 cylinders pulse into the collector... ONE AT A TIME the exhaust flow through the reduced area creates more scavenging and lowers the pressure in the collector ... the end of the tube is open and centered in the exhaust pipe.. so any reflections come back off the muffler or just reflections when the flow slows down between the highest speed of the pulses comes back up to the open end. only a small percentage might try to go up the center pipe.. the rest is cut like an apple core and goes up to the tapered area right at the collector flange.. since there is no flat surface to reflect off of.. less reflection... but any reflection becomes a second siphon.. lowering the pressure in the end of the tuning tube.. helping extraction.. this design really needs to be worked out with somebody with 2 stroke exhaust knowledge... who is not a member of NIH... (not invented Here)
Interesting .... That's brings to mind a thought I had some while back about expediting exhaust gases. If hotter gases expand (see expanding gases in cylinder example above), it follows that gases, if cooled, contract or get more dense. That said, would exhaust gases escape faster if they were cooled? The answer is probably. What if a coil of 3/8" copper tubing were wrapped around the exhaust pipes with coolant pumped through an intercooler or radiator? Would that remove enough BTU's to sufficiently contract the gases? If so, the next question is - would it be better to cool from the back forward or from the most forward area toward the back? Mans ability to link random thoughts in an orderly fashion exceeds the best computer today - still better than fuzzy logic. "The impossible should provoke thought outside normal boundries, not become the limits to stay within!"
thats a TON of heat to dissipate someplace else..but i did something like that a LONG time ago... a friend had a mustang 72 i think.. he had a STEAM injection system... were distilled water was in a reserve tank... some of it flowed into the semicircular copper semicircular tank that was hose clamped to the exhaust pipe... this caused the water to boil and become steam.. he had the air cleaner assembly off so i could not study how he injected the steam into the intake or carb inlet.. he said it worked great.. but the tank corroded away laying against the exhaust manifold.. i was not able at that instant to fabricate a new tank.. as i was without shop.. so i took some UNCOATED 5/16 steel brake line.. wrapped the end around the exhaust pipe.. then continued pushing it around and around until i had wrapped several inches of the exhaust pipe.. i used inverted flair unions to extend more coated tubing up to his secret small pump and solenoids.. i was not privy to what was hidden ..i used a NO HUB coupling to cover the loops of tubing around the exhaust pipe... but without the rubber inner liner.. he said it worked fine after he finished hooking it up... i would probably have a few ceramic ball check valves to prevent blow back into the reservoir or pump.. might even have a TINY opening at the inlet of the loops.. so only a small amount of water could be dispensed into the tubing.. it would flash to steam a lot faster.. but again..i don't know what was in the box or under the air cleaner..
mintstick:The Wankel engine took a new twist (no pun intended) and went to a continuous rotating mass to help effiency. What gains could be achieved if, and it's a big if, a new engine design would allow for added compression at the top of a four cycle (or 2 cycle) engine with the crank past center by approximately 10 degrees before ignition. It sounds physically impossible, but what gains would there be? I'm thinking that fuel effiency gains would be substantial. Any thoughts?not impossible. there are a few variable compression engine designs due to be released in the next few years. the power gains and fuel economy gains are significant. imagine being able to go from 7:1 to 16:1 compression on the fly! heres a link to one design, but a search on the net will show many designs. http://www.nissan-global.com/EN/TECHNOLOGY/OVERVIEW/vcr.html
thats creative....i just forgot that about a decade ago.... some manufacturer created a engine block that the cylinders and head were in a separate casting.. with a pivot on one side...they could rock the cylinder bank and head to change the compression ratio... the used a bellows to control the leakage of crankcase vapors...i don't recall how it worked on a dyno... its so much easier to vary the actual amount of compression by changing the amount of intake manifold pressure... ie.. Turbo charging..i like engines that create HIGH manifold vacuum... these seem to get the best mileage... as there is less volume of air passing through the motor... less air.. less fuel... open the throttle and the vacuum decreases and makes more power... with turbo charging or super charging.. you can increase the intake manifold pressure to force more air and fuel into the cylinder..
heres a kinda low-tech video showing variable compression. http://www.youtube.com/watch?v=TZ0QO_NgNow and a better video of whats next.http://www.youtube.com/watch?feature=endscreen&v=DdM2VbbdtB4&NR=1