The bottom end of a DI 2-stroke still needs to be lubricated and that means oil mist mixed into the intake air and getting burned, thus high hydrocarbon emissions: dirty.
I think not!
In reality, any largish 2-stroker has engine oil in a sump, and does NOT route the incoming (oilless) air through the crankcase. OTOH, many new handheld power tools are FOUR stroke, and utilize premix instead of oil in a crankcase (because they are designed to run in any orientation–can’t have a “wet sump” upside down!
Oil mixed into fuel, and 2-stroke combustion are two entirely different (though oftentimes co-incidental) issues.
Never minded 2 cycle, but in the name of gas conservation there is no longer a throttle control on my mower
There is a (governor-controlled) throttle on every mower I've encountered. Typically, you have a throttle spring fighting against a vane driven by the cooling fins on the flywheel. The spring wants to open the throttle; the vane wants to close it. They "deadlock" around 3200 RPM or so.
What you’ve lost, is the ability to adjust the ‘preload’ on the spring. AFAIK it’s because mower carbs are optimized in a narrow range; running too slow would muddle the mixture in ways likely bad for emissions.
More horsepower with a 2 stroke- yes, but lousy torque when the rpms are dropping. That is the reason why 4 stroke diesels are much more popular for Class 8 trucks.
Needed the “High Torque Rise” engine like the “Maxidyne” charge air cooled engine(intercooler) largely did away with a ridiculous number of speeds in the gearbox and endless gear shifting around town
There is no oil in the fuel of direct injection two strokes…Yes of course. But I still must remember they lubricate and burn in the combustion chamber. It isn’t in the fuel initially, but contaminates the process becasue the whole idea is that, enough of it doesn’t burn off in order to supply lubrication. The oil has for a long time had direct injected while the fuel has not been until recently. If it worked, the car industry would have something on the market in a heart beat.
The areas of use where two strokes have an advantage are limited to weight savings and limited power bands. They make great outboard motors, great dirt bikes, great model airplane motors etc. I have whined enough I hope to convince most what terrible car motors they would make. The exception would be when used with a CVT transmission as with the old Arctic Cat snowmobiles, in a country with low polution standards.
But, the bottom line, is economy. I never met a two stroke that didn’t like gas. Not a problem in chainsaw or trimmer with a small tank and low use time…but imagine a full size car with four aboard when my old tiny SAAB 96 barely broke 20 mpg at times with one person aboard. The newest 4 stokes have so technologically advanced, that power to displacement advantages of two strokes just don’t exist any more. See, 2.7 L Ford truck engine with 325 hp over a much wider band then a two stroke might never have. Two strokes have seen better days in cars they will never see again, I hope.
Ford Motor Company was developing on a 2 stroke/direct injection engine for economy cars in the early 1990’s;
A pilot run of 25 two-stroke engined Fiestas has been built at Ford’s Dagenham plant in the UK. They will be used by key component suppliers and selected fleet operators. A further run of 35 prototype cars will be produced during 1992.
All 60 test vehicles are being built to gain early service experience of this advanced engine concept as part of the run-up to low- volume production of two-stroke cars, planned by Ford for the second half of the decade. About half the test cars have been built with left- hand drive for operation in Germany while the other half have right-hand drive for use in the UK.
It looks like we are getting stuck (as I was briefly on the “Premix issue” and even the piston porting issues… These are now non existent. Today with DI there is no need for oil in the fuel. So we can forget burning oil and blue smoke completely. The lubrication systems of a modern 2 Cycle will negate the oil/fuel mix entirely. So there goes a lot of preconception on what these new engines actually are. They are WAY ahead of my initial thoughts apparently. Watching the animation on these new 2 cycles basically crumbled EVERYTHING I was even pondering about a “New and improved, Modern 2 Cycle Engine” These new engines are far far ahead of my early thoughts, I can tell you that…
Did anyone actually click on those links I included a ways back? These new 2 cycles don’t resemble anything you were thinking…of that I’m sure.
I really do wonder what will happen with these newer engines…its certainly intriguing…to me anyway.
I looked at the links. Personally though, I’m pretty happy with the engines we have available and would just like to see them hardened for dependability rather than continuous redesign.
You mean there really were/are two stroke semi tractors out there. I argued with a Volvo truck mechanic about 15-20 years ago that there were and he said I was nuts. I likewise thought he was ill informed. I’m not familiar with DI and the other terminologies though. I’m more Clinton go cart engine, or Lawn Boy two stroke familiar.
One of the major problems of most 2 stroke designs is the crankcase scavenging. If oil is mixed with the fuel some of the oil vapor will be entrained into the combustion chamber. Any oil that adheres to surfaces in the crankcase will eventually exit through the combustion chamber, Oil and catalytic converters don’t work well together. If oil is injected directly to the bearings, some still needs to splash on the cylinders, pistons, and rings (sealing). Another advantage of crankcase scavenging is that piston valving can be used. In some 2 stroke motor cycle engines the piston times crankcase inlet, exhaust venting, and loop scavenging blow. In most outboard marine motors the inlet is through reed valves with piston valving for the loop scavenging of the cylinder.
The Diesel 2 stroke of the Detroit Diesel uses the roots blower to pressurize the air box. When the piston uncovers the scavenging ports the exhaust valves have already opened in the head allowing linear flow scavenging from the face of the piston to the top of the head. This could be done with 2 cycle gasoline engines. However, again the excess air out the exhaust would upset the optimal operation of the catalytic converter which requires close to stociometric gases , especially if a three way cat is being used to reduce NOx.
The potential for a direct injection 2 stroke gasoline engine has seemed overlooked to me for many years, as is the use of catalytic converter heat to power a boiler that powers a turbine which turns an alternator.
Researcher…I read your comment and there’s no need to mention crankcase scavenging, Piston Porting, Fuel Oil Mix etc when referring to the newest 2 cycle engines… ALL of that stuff is HISTORY and I mean all of it…Totally out the window man…
Might want to click those links I posted prior. I was thinking along the lines you were previously until those articles blew everything I was thinking out of the water. Todays 2 Strokes or rather the one the latest mfg’s are pondering barely resembles anything you’ve even imagined…let alone the 2 strokes we are familiar with.
Honestly when I posted this…I was thinking of the 2 stroke engines we all are familiar with…and then imagining Direct Injection and maybe some kind of pressurized lubrication system, computer controls, etc…then I saw those articles…and Boom! Forget ALL OF IT… these new engines dont even look like a normal 2 stroke…in fact I don’t think they share one single characteristic…Except the fact that it is a 2 Cycle…after that…theres no crossover
…and YES absolutely…there were 2 Stroke Diesels… Many were Turbo AND Supercharged at the same time no less. LOL
Now, “the use of the heat from a converter to power a boiler that powers a turbine which turns an alternator”
. I I thought maybe too, we could put a small wind turbine on back of the car to generate electricity to run an actuator to raise and lower the rear spoiler. It could be heavy weighted to drop down on it’s own when the electric power was reduced from the turbine when traveling at lower speeds.
Every once in a while,you hear of a turbo compounded engine,RKs idea isnt that far fetched as car makers search for ways to recover energy lost as waste heat,theoretically a 2 stroke could be on the order of half the size of a conventional engine and deliver comparable power(old GMC diesels did) because they had twice as many power strokes an example of a crankcase scavenged 2 cycle diesel engine would be a 4-53 T Detroit engine,with a turbo(only displaced 212CID but had comparable power to a engine twice the size(wasnt much in the hole-but once you got er in the power band,it did fine)
Other systems are being touted,such as thermo electric generators etc,but I still maintain that 4 cycle is probaly the way to go.
Hang onto your confederate money and your non-deteegent oil to mix with the gasoline. Both the South and the two stroke engine will rise again!
I thought that the 2 stoke LawnBoy mower my dad bought back in 1955 was great. It was light with its magnesium deck. I preferred using this mower to a self propelled that I had to use on a yard I contracted to now. The LawnBoy 2_stroke was easy to rebuild. However with its 16:1 ratio of a,half pint of non deteegent 30_weight oil to a gallon of gasoline, it did pollute the atmosphere. Most 2 strokes on lawn equipment today are 40:1 or 50:1 and still smoke.
My guess is that as battery technology improves the electric motor will replace the gasoline engine in lawn equipment. I have a battery powered string trimmer and it works great for me. I bought a Black and Decker battery mower from a friend. It has enough power to do the job and is quiet. Unfortunately, it is beavy as compared to the push gasoline mowers, so I don’t use it very often
Funny you mention the old Lawn Boy 2 Stroke Mowers… I have an old 2 stroker in the basement with a 2 stroke Clinton engine on it. It even has a recoil CABLE to start the mower… I will never understand how my dumb friend actually BROKE the cable and spring return mechanism when he took it upon himself to mow my back yard… He must have had the on off switch OFF while he frantically pulled the cable until it self destructed from repeated Full Pulls on the cable…all the way out to the stop he must have been yanking on that cable. When the switch is in the “Run” position the mower would start before you even got that pull cable Halfway out of its home. The mower was from the 50’s and was something I enjoyed using in the rugged backyard of my home. I never forsaw an idiot like my buddy…descending upon the mower and ruining the entire cable pull and spring load return because he had the Run switch in the off position. I never screamed profanities at another human being than I did on that day when I found my old mower completely messed up… This was even AFTER I told him that the mower starts right up on the first pull…I said if it doesnt start on the first or the second pull then SOMETHING IS WRONG AND YOU SHOULD STOP… Despite me telling him this…he pulled the cable until oblivion. I will NEVER understand that…NEVER.
OK…I just got very very sidetracked… Can you tell Im still mad about it? Those 2 stroke mowers were small, light, compact and very powerful…you could barely find grass high enough to even slow them down sometimes. This has inspired me to fix the mower today…its not fair that I left it in that condition because of someone elses absolute retardation. Im going to tell that special friend of mine that I am repairing that mower…He will remember which one I am talking about. I mean HOW does one actually pull a metal cable long and hard enough to break that spring return? Especially when I told him that it never EVER takes more than two pulls to start the thing.
Im sorry to go so far off topic here…at least the core of the story is a 2 Cycle Engine…LOL
...the use of catalytic converter heat to power a boiler that powers a turbine which turns an alternator.
I think that once the catalyst “lights off” and goes to closed loop, there is little net heat energy produced.
Years ago an article described adding heat recovery from the exhaust of big trucks. It used a freon cycle to convert the heat to power which was geared to the crankshaft. The conclusion was that it just cost too much for the energy recovered (<10% I think).
I skimmed thru this thread & did’nt see any mention of the problem of carbon build up on the GDI/gas direct injection engines intake valves. I’ve read of cases where decarboning these intake valves costs as much as 800 bucks.
Problem 1 even though my wifes 09 Kia Rondo only has 140 k on it and has been reliable as a stone, shes getting the itch for a new car.
Problem 2 she really likes the VW tiguan
Problem 3. she knows that C.R. sez they are reliable.
My problem is I don’t see any way of curing the intake valve carbon deposit problem on the GDI engines.
On conventional engines gas/freah air/crankcase fumes are pulled in thru the intake valves. The gas keeps the valves free of carbon.
On the GDI engines only gas and PCV vapors are pulled thru the intake valves. The PCV vapors are causing the carbon build up. Have any of the auto makers come up with a cure for this?
Synthetic oil creates less vapor, is that part of the answer?
