5 stroke motor

gettinggrey, Nov 30, 3:35am
Well, they call it a 5 stroke.
Looks interesting though.

intrade, Nov 30, 3:41am
i had a quick look as soon as i seen a piston engine it was over i dont even want to read the crap they write
you know a 4 stroke engine has a empty stroke to push out the exhaust gas and fill the cilinder with fresh air. so how in the hell will a 5th stroke help lol. just like these frigen morons with no clue whom think they can run there car on hydrogen made from a coke bottle under the bonnet.
A piston engine is serious stone age technology bashing more stones in a cave wont magically make things work better.

intrade, Nov 30, 3:43am
i would have Read it if it was a 1 stroke engine haha that would be interesting how they would pull that off.

skin1235, Nov 30, 3:52am
the prototype engine certainly delivers the goods, and impressively delivers them from some very basic kit
the next gen engine will be extremely interesting, whoever said the combustion engine could never be developed past the 35% efficiency barrier would be a bit worried now

sr2, Nov 30, 3:55am
One of the most thermally efficient motors ever made was and still is the triple expansion steam engine. It looks like these guys are using a similar design to achieve the same result in an internal combustion engine.
Remember that in a conventional 4 stroke there is still hot pressurised gas (i.e.kinetic energy) in the cylinder at the end of the power stroke. If they can use this energy (as they have in steam engines) surely there is no reason why it wouldn't be a winner?

tony9, Nov 30, 3:57am
A turbo charger uses the same principle - using waste energy from the exhaust to produce more useful energy.

The Atkinson cycle engine also does much the same.

tamarillo, Nov 30, 5:23am
So it isn't really five stroke in the way I thought. Has two cylinders doing normal 4 stroke stuff and a 3rd in between taking the exhaust outlet of them to drive piston down under low pressure. No spark in middle cylinder I think?
Prof will be in pudding, some very clever people have already done this proof of concept so it should work.
Let's see if anyone explores further. VW might want to look.

tamarillo, Nov 30, 5:25am
Take time to watch video Intrade, I think 5 stroke name is steering us in wrong direction. I think.

gettinggrey, Nov 30, 6:04am
Yes, tamarillo has it right.
They have just called it a 5 stroke (and I've seen reference to a 6 stroke too).
I guess they had to call it 'something' to differentiate it from a 4 stroke.

tweake, Nov 30, 6:21am
interesting you mention steam. there is another "5 stroke" that injects water into the exhaust gas to create a steam engine effect.

strobo, Nov 30, 7:13am
5 stroke would be true but not to be confused with a 5 cycle engine , in which ignition would be regarded as part of the cycle . ie. intake ,compression,ignition,power stroke & exhaust , so technically it is a 6 cycle engine! ;-)

daz59, Nov 30, 8:31am
Steam trains have one stroke engines. it could be done with petrol.

daz59, Nov 30, 8:44am
Are you sure about that? Normal double acting (non triple expasion) dont even get 10% efficiency.

sr2, Nov 30, 8:54am
Yes i'm very sure of it, my father was an engineer and lecturer (one of the ATI originals) who originally trained as a steam fitter at the end of the 2nd world war. Triple expansion was phenomenally efficient but anything but cost effective (i.e.overly complicated).

mm12345, Nov 30, 9:26am
That's not really how a turbo works. As you mention atkinson cycle (so not true atkinson engine but modified atkinson cycle) like the engine in a prius, then yes - that uses valve timing to effectively create a longer power stroke than compression stroke, so maximises energy conversion from combustion gas expansion, and IIRC can reduce losses to 60% from 65-70% from a normal otto cycle. But as I understand it, perhaps not attractive in terms of power/weight ratio.
But turbo in action is generally in effect doing the reverse, increasing charge volume under boost so the the amount of air/fuel is greater than would be achieved with normal aspiration, effectively the same as a long compression stroke and short power stroke. But there you can get extremely good power/weight ratio.
Toyota/Lexus (new IS200t) claims that the engine uses atkinson cycle under normal load, then under higher load changes valve timing (I assume) to close the intake ports earlier so it's running in otto cycle, then also adds boost from a turbo. I've not seen a full description of how it's implemented.
It'd be interesting to see how fuel economy stacks up in real life. performance is okay, apparently. Conventional performance orientated turbo petrol cars I've owned/driven had okay economy when you have a very light right foot, but driven in anger sucked gas like no tomorrow - to the point that you may as well just have a V8.

sr2, Nov 30, 10:03am
Good post.

attitudedesignz, Dec 1, 12:52am
Wouldn't mind finding more on the Coggins V4 2 stroke / 4 stroke

elect70, Dec 1, 4:11am
YEp its all Henry Fords fault for mass producing ICE engines .Imagine where we would be today is team had been the choice . polution & sic "climate change " would be the big issue it is . Some steam engines small enough for cars can produce steam in under a minute today & no huge boilers . But no ones prepared to be the first to mass produce .

sr2, Dec 1, 4:12am
LOL, bring back the Stanley Steamer!

elect70, Dec 1, 4:14am
parasitic losses from driving the extra piston ? Whats the point better to turbo charge a small 4 pot

321mat, Dec 1, 11:17pm
I was thinking that myself.
I feel that ultimately, the frictional losses associated with an extra, non-power-making cylinder, will doom this project to the scrapheap.

If, as an earlier poster remarked, piston engines are effectively "stone age" technology, then perhaps w should be revisiting the turbine style engines first proposed in the late '50's. Power and efficiency are only limited by the lubrication of the ball bearings holding the turbine - all of which technologies have advanced enormously in the past 50 or 60 years.

elect70, Dec 2, 1:26am
^^problem in cars is getting the turbine up to speed quickly , perhaps a turbine /electric hybrid the electric motor brings it up to speed then when turbine is up to speed cuts out . Worth a try nigel

sr2, Aug 11, 6:34pm
I don't think you've quite got your head around how it works, the extra cylinder is making the extra power.
As I said in my earlier post at the bottom of the power (3rd) stroke there is still hot gas in the cylinder that is at many times atmospheric pressure; the extra cylinder uses this pressure to generate the additional power.

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