Oddball engines and prototypes

[Pursang]

Interesting, I did consider making the bottom half of a cylinder from silicon, with cavities in behind the transfers, so oil could be pumped in so as to squeeze off the transfers area. For low speed and high speed. Never happened though.

That's a really good idea, I was going to have a hard time loosening off the cable ties when I got up to speed.

Jan said, as do I, that the internal radii in the transfer ducts should be as large as possible. In the RSA cylinders the available duct length was used to the max. Lengthening the transfer ducts any further which would have nullified the effect of the larger radii.

Yes, the transfer flow would also be reluctant to stop, but the piston would not give a damn and slam the transfer ports shut regardlessly. That would create a pressure rise in the transfer ducts, but that pressure rise would not wait around till the next transfer opening; it would spread over the crankcase volume. So no compensation for the reluctant initial mass flow into the cylinder and on top of this a higher crankcase pressure after transfer closing, which would hurt the next induction phase.

Fair enough...How about a couple of chambers, mounted off each side of the cylinder at transfer height, short direct ducts to the A, C & D ports. Each chamber has a reed valve fed by a large (enough) passage from the case through holes cut into the bottom of the main B transfer duct. Piston ported to the case and the B transfer, reed valved to the rest

Re the silicon oven mitts: they don't come in engine sizes, but you might use this thermal insulation paint, developed for the Russian space program and liberated by my friend Martijn Stehouwer of Emot Racing (www.emot.nl). Martijn became twice European classic 50 cc champion using the stuff.
Attachment 331570

Martijn's Site looks great, some really nice gear. Looks like he's not selling the Russian Rocket paint. Pity 'cos it would be perfect for my Ram Jet cooling & propulsion system.
The only flaw with that system is we don't get the thrust until we're already travelling pretty quickly. Needs some fans and stuff to complicate it.
Here's a link to a interesting analysis of an 'oddballish' engine. A Two stroke, compound, uniflow helicopter engine that's as light and powerful and 31% more fuel efficient than the standard turbo jet. http://dtic.mil/dtic/tr/fulltext/u2/a180007.pdf Another great idea that didn't get of the ground. A cynic might think that Rolls Royce & Honeywell could afford more Generals & Senators than the Garrett Turbo Co.

Remember the hinged 'comma' roofs in the transfer ducts that we discussed two years ago? That didn't happen either as you came up with your sliding cylinder solution whilst I got stuck with the problem of how to operate those commas. Now I think that rubber bladders could have been a solution. Keep thinking outside the box Neil .

Daryl, in one of my early posts to KB (but it seems to be missing) there was some discussion on cooling, I mentioned and experience when I was at Orbital baselining an aircooled PE400 engine. Basically it got hot under steady state power testing causing the power to fall, irrespective of lots of practical forced air cooling. So then we set up a small micro irrigation spray to wet the cylinder and the power just rose. So, that gave rise to a couple of thoughts:

1. Dribble water over the engine
2. Arrange a small leak of fuel from the carb so it ran all over the cylinder (if you are carb forward)
3. Arrange a hose between your good self and allow this to discharge in front of the cylinder. Drink lots of water and have lots of diuretics before you go out.

I think we should keep the Piss & Dribble for discussion on how to fuel inject this thing.

re: #2 I rather like Amal carbs, so this one is a given.

Version PE400 3.1 - A mist spray into the airsteam. I proposed this early on, when Frits first raised the Temperature Dragons ugly head.

I did some basic googly research on this and the results were mixed. Most of it is HVAC related & not relatively high velocity airstreams
Enthalpy differences between dry & humid air - the humid air already has more heat energy than dry, for example.
It takes more energy to raise the temperature of moist air than dry, blah blah.
Actually I think that is the solution. Heating the moist air takes more energy. (From the engine and then the airflow carries it away).

If I really had to, I could carry say, 20 litres of water to spray at the engine. (does one litre of ambient temp water mist cooling = 3 or 4 of hot recirculated water??)
and then perhaps I could spray some on the pipe, on gear changes, to lower the frequency and fill in the acceleration gaps caused by the extra weight

cheers, Daryl.

[Grumph]

Know anyone in the aussie V8 supercar teams - or the GT endurance series ? Both routinely use water spray on brakes.
I believe there's quite a bit of hardware for it available over the counter.
You don't have to re-invent the wheel.

[WilDun]

Shit! - This is mind blowing stuff ........... and I thought I was going to be able to walk in and show you all how a two stroke should be designed - how wrong I was! rubber cylinders, body fluid cooling, - what next?...... the possibilities are limitless!

[Pursang]

Know anyone in the aussie V8 supercar teams - or the GT endurance series ? Both routinely use water spray on brakes.
I believe there's quite a bit of hardware for it available over the counter.
You don't have to re-invent the wheel.

Actually...I do. I was in the Walkinshaw pit for the Bathurst 12hr.

Shit! - This is mind blowing stuff ........... and I thought I was going to be able to walk in and show you all how a two stroke should be designed - how wrong I was! rubber cylinders, body fluid cooling, - what next?...... the possibilities are limitless!

Limited only by Imagination, Time, Money...and Newtonian physics.

Next? Quantum engines, they Will be mind blowing.

[Mental Trousers]

Next? Quantum engines, they Will be mind blowing.

Is the piston going up or down?? Both!!

[Grumph]

Is the piston going up or down?? Both!!

Schrodinger had something to say about that - but he couldn't tune his way out of a cardboard box.....

[Pursang]

Is the piston going up or down?? Both!!

Two strokes, but they're doing exactly the same thing, in different places, at the same time. (Most commonly occurs on (any) Sunday).

Cheers, Daryl

[Frits Overmars]

Schrödinger had something to say about that - but he couldn't tune his way out of a cardboard box.....

He had help

[WilDun]

Think maybe all this stuff is becoming way too highbrow for me!
I was hoping to dumb it all down when I asked the perfectly simple, logical (and innocent) question a while back but got no reply,.... which was, whether the good old (compact) SV engine might still be compatible with hydrogen or HCCI?? well, it makes as much sense as an all Iron two stroke .... eh Daryl
I asked this because the SV combustion chamber shape when you look at it is probably nowhere near as ugly and misshapen as your average high compression OHC four valve arrangement, or the Wankel - and the engine would be nowhere near as tall!

[Grumph]

He had help

From when we bred Burmans....

Will - I suspect that a sidevalve combustion chamber is the worst possible shape to encourage combustion.
While the current 4V chambers consist of basically the valve cutaways in the piston crown - and a dimple for the plug - at least the flame path is short.

[pete376403]

Know anyone in the aussie V8 supercar teams - or the GT endurance series ? Both routinely use water spray on brakes.
I believe there's quite a bit of hardware for it available over the counter.
You don't have to re-invent the wheel.

Tyrrell did watercooled brakes in F1 years ago, not because the brakes needed cooling, but because they could dump a whole lot of weight as soon as the race started. Cars had to be weighed after the race, but regs allowed that they could be topped up with consumed fluids before weighing.

[husaberg]

Is the piston going up or down?? Both!!

LOL
Heisenberg's Uncertainty Principle states that there is inherent uncertainty in the act of measuring a variable of a particle. Commonly applied to the position and momentum of a particle, the principle states that the more precisely the position is known the more uncertain the momentum is and vice versa.

[WilDun]

From when we bred Burmans....

Will - I suspect that a sidevalve combustion chamber is the worst possible shape to encourage combustion.
While the current 4V chambers consist of basically the valve cutaways in the piston crown - and a dimple for the plug - at least the flame path is short.

Aaaaaaaww, isn't that cat so innocent and .....well......just lovely! - Yeah well, "ahem" anyway, (deep gruff voice), HCCI doesn't have a flame path unless I'm mistaken.!

[Pursang]

Think maybe all this stuff is becoming way too highbrow for me!
I was hoping to dumb it all down when I asked the perfectly simple, logical (and innocent) question a while back but got no reply,.... which was, whether the good old (compact) SV engine might still be compatible with hydrogen or HCCI?? well, it makes as much sense as an all Iron two stroke .... eh Daryl
I asked this because the SV combustion chamber shape when you look at it is probably nowhere near as ugly and misshapen as your average high compression OHC four valve arrangement, or the Wankel - and the engine would be nowhere near as tall!

I know little of hydrogen, and less of HCCI, but have delved into flat-heads.

They can be made to work rather well.
You can put whatever cam you like in them and your valves will never interfere with each other, or hit the piston.
The valves can be considerably larger than any 2V OHV can fit in the cylinder, except perhaps a pure Hemi head.
You can have 100% squish if you want to.

Probably controversial but, I think this an application where a Singh groove could be useful. In a side valve engine with a lot of squish, combustion starts and burns in the chamber but then it must travel, pretty slowly, all the way across the top of the piston. My thought is that the groove provides a warmer & denser volume (less quenched) path that allows the ignition to travel quicker than the normal flame front to ignite gasses at the far end of the piston, before it is too late for them to add any value.

I guess hydrogen could also speed that up, it goes Pop! not Whoomph!


Cheers, Daryl

[WilDun]

Probably controversial but, I think this an application where a Singh groove could be useful. In a side valve engine with a lot of squish, combustion starts and burns in the chamber but then it must travel, pretty slowly, all the way across the top of the piston................ the groove provides a warmer & denser volume (less quenched) path that allows the ignition to travel quicker than the normal flame front to ignite gasses at the far end of the piston, before it is too late for them to add any value.

Daryl, I realise that I probably don't know a helluva lot really (doesn't stop me thinking or talking though).... but it appears that with HCCI, there is no spark plug needed to initiate combustion,(at least in the running mode, as opposed to starting mode which may require a spark). So there is not actually any flame front, combustion is instantaneous. When it has reached the correct temperature and pressure, it ignites (all through the chamber) and does not have to spread, as it would do in a normal engine, so possibly there doesn't need to be a "trench" to conduct it across to the other side. That's my thinking but maybe someone else can veryify that for me.