two stroke motors in automobiles again
two stroke motors in automobiles again
(OP)
I came across this article today, it appears to be happening in Greg's neck of the woods.
http ://www.the engineer.c o.uk/10008 36.article ?cmpid=TE0 1&cmpt ype=newsle tter#video
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RE: two stroke motors in automobiles again
RE: two stroke motors in automobiles again
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I haven't played with it, I don't like Flash.
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?
RE: two stroke motors in automobiles again
RE: two stroke motors in automobiles again
Rod
RE: two stroke motors in automobiles again
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?
RE: two stroke motors in automobiles again
With the recent pace of emissions regulations, it's a use-it-or-lose-it world. Once you give up on a particular system (e.g. automotive diesel in passenger cars) it's very difficult to re-enter, although clearly not impossible since that particular one has been accomplished (although it's still uncommon).
RE: two stroke motors in automobiles again
The engine presumably needs a blower for intake/scavenge etc. - so this is a bit awkward and complicates things a little. Also presumably - they probably need the variable CR to make the engine comparable to a 4-stroke in fuel efficiency - but again this takes away from the 2-stroke engine's advantage of simplicity. It would probably not be cheaper, lighter or simpler than a 4-stroke. This is interesting but probably not the future of the IC engine.
RE: two stroke motors in automobiles again
From that experience I can see a possible future for this two stroke design...Much the same in 2040 as the rotary engine is today.
Rod
RE: two stroke motors in automobiles again
Unburned Hydrocarbons
5.5g/kwh
CO
30g/kwh
CO2
0.27g/kwh
NOx I didn't note down from the paper as it was something ridiculous like 95% under what a comparable 4-stroke was running. Off the top of the head I think it was in the range of 2-3g/kwh
Any input on how close this is to automotive regs?
The variable CR could play hell with NOx emissions.
RE: two stroke motors in automobiles again
HCCI is supposed to be good for NOx because it allows operation with a dilute charge and a lot of EGR, which reduces peak combustion temperature. The variable compression ratio is the trick they're using to get self-ignition to happen at the right crank timing.
RE: two stroke motors in automobiles again
RE: two stroke motors in automobiles again
What an odd mishmash of units they use, grams/hp hour.
RE: two stroke motors in automobiles again
RE: two stroke motors in automobiles again
I saw the engine presented at a conference recently, and the discussion about full load emissions was not really concluded.
If not for the emissions laws though, it is quite a little powerhouse.
RE: two stroke motors in automobiles again
And on that point ... 4-stroke spark-ignition engines usually intentionally run somewhat rich at full load to protect pistons and exhaust valves. The standard automotive EPA drive cycle does not include any full load operation at all, and it's possible to arrange for the more aggressive US06 to not include full load operation, either. Some underpowered vehicles may need intermittent full throttle for that one, but you can game that by operating stoichiometric for a certain time delay then going rich to protect engine components. This isn't really much of an issue since existing 4-stroke engines have a problem with full load operation anyway. If anything, the 2-stroke operation will allow a bit of air out the exhaust ports to allow overall lambda=1 even though in-cylinder lambda can be slightly rich if it's necessary to protect the piston.
One other thing that two-strokes have trouble with, is that the ports in the cylinder wall inherently let some lubricating oil out the exhaust, even on engines without crankcase scavenging. Don't know how they're handling that - this is a trickier problem than full load.
RE: two stroke motors in automobiles again
I think they had pretty much solved oil loss past the rings at the port, saying that it was no greater than a modern 4-stroke. The setup is a bit exotic though and I wonder how they would still seal at 100,000 miles.
"Two pegged half-keystone compression rings in upper section, unpegged Napier and U-Flex oil control rings in lower section for oil control and containment"
RE: two stroke motors in automobiles again
RE: two stroke motors in automobiles again