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 Where did it all go?

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Trevor Amos



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PostSubject: Where did it all go?   Fri Oct 10, 2014 7:59 pm




I was ploughing through a pile of Bantam related papers the other evening and came across a record of the volume measurements I took for the transfer ducts of the w/c cylinder. Upon re-acquaintance with them I was startled to discover what a large, collective figure they amounted to!
Bearing in mind that the ducts connect directly to the combustion chamber and that has a minimum volume of,lets say 10cc, many times smaller than the duct figure, where has all of that mixture gone,
or was it ever there in the first place, and what of the rest of the stuff in the crankcase?
If all of that mixture ended up in the chamber then the dynamic compression ratio would be so stratospherically high it would render the engine just about impossible to turn over!
Any ideas anyone?

Trevor


Last edited by Trevor Amos on Sun Nov 30, 2014 10:34 am; edited 1 time in total
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nigel breeze

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PostSubject: Re: Where did it all go?   Fri Oct 10, 2014 9:17 pm

Alright Trevor, well.if it ever got in there, probably right out the exhaust port! affraid
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john bass

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PostSubject: Definitely a condundrum...   Sat Oct 11, 2014 4:18 am

A conundrum of a constant flow system pausing in the combustion chamber for -- say -- 1/100 to 1/200 of a second. It is like me looking at a Jumbo Jet as I board, wondering, "... however can this wacking great, heavy lump ever beat gravity and fly?"

Between mid 1968 and early 1974 I didn´t bother much about the detail, leaving the engine to Derek, my mentor-cum-engine tuner and wanting only to race. Derek reckoned my racing style was awful, sort of like I was still racing on grass track....

Now it is all too late I´ve got intersted in the WHY -- as put here -- and it is definitely a conundrum.

Great fun to have done it, though my shouldere just clicked to remind of that dreadful circuit Snetterton... Ah! but rushing smoothly through the curves like a constant flow system:- Brands, Cadwell and Thruxton etc...etc... Aaaaahhhh!

Cheers!
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dansofield550

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PostSubject: Re: Where did it all go?   Sat Oct 11, 2014 6:59 am

Eer dunno is my best guess, or some sort of voodoo !?
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john bass

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PostSubject: Voodoo?   Sun Oct 12, 2014 5:18 am

Voodoo? --
-- must admit, at times it does seem like magic and other times like somebody was putting `The Mokkers´ on yer ...

...particularly when after so much careful preparation the Bantam goes poppp-doodle--doodle--poppopp -pop and doddle-poddle, then Andy´s 250 ABS won´t even do that and just goes woofle-woofle -- bblll -- wuffle-plop!!.... Just that once when I didn´t even have a spotty-faced teenager raring to help ....

That actually happened at Lydden on a damp, drizzling morning when I arrived late and had no helper. All alone and miserable not even a cat to kick. Practice was over with racing started when Chris Newport brought his 6cylinder Italian 150 (or was it more ccs?) and lent it to me for the 250 race. What a beautiful sound. Despite its having gear changing facility on the wrong side it provided me with a wonderful new ride around Lydden. The start was a wheelie with about 14000rpm on the clock -- well! I wasn´t used to high revs. When I got used to braking with the gear change lever and passing riders in odd places in the wrong gear -- and having them pass me back -- the chequered flag came out too soon.

It is the theme of Time -- where did it all go -- we never realized then HOW it would go with where and when of the BRC....

Oh! for heavens sake, cheer me up!

Cheers!
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Trevor Amos



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PostSubject: Re: Where did it all go?   Mon Oct 13, 2014 4:24 am

Dan echoed my initial reaction, Nigel offered a plausible explanation with John puzzling over the conundrum, so lots of head scratching all round.
The first question that sprang to my mind was simply, during each cycle does the engine actually empty then re-fill itself. Following this, was the engine, just prior to the transfer event ever full with fresh mixture?
Are we able to accept that that the missing mixture diverted straight out of the exhaust port and so play no part in the combustion process? Were this the case then at the rpm that the engine is at its most efficient, so drawing in the most fresh mixture, a whole load of petrol and oil will flood into the pipe. Far more than the normal short circuiting charge loss, but this isn't seen to occur. But in any event there should be no significant loss when the engine is at peak torque/revs efficiency if the pipe is doing its job properly and the ign. is optimally timed.
To enable mixture to be drawn into the crankcase there has to be a sufficient pressure difference between the atmosphere and the case, for the positive to move to the negative! In piston port and disc valve inlets there is a period where a significant quantity of mixture is subject to expulsion by flow reversal, thus incurring an overall loss.
Mixture transfer from atmosphere to the cylinder is overwhelmingly performed by the exhaust pipe action. along with a small amount of case pressure assisting. We are talking about race engines here and not lawn mowers. There is no way that the required amount of air/fuel mix can be shifted in the time scale available by case pressure alone!
So, when the engine is flat out at peak torque and revs it is the pipe that controls what is sucked in. Then engine becomes a series of through-flow chambers of varying volumes and pressure ratios, the case is never full, there isn't time.
The mixture was never there in the first place!

Trevor






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john bass

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PostSubject: Right!   Mon Oct 13, 2014 5:14 am

Right, Trevor...

Dan was right -- it is Voodoo!--

But Trevor! I do like your way of `compartmentizing´ the bits -- I am sure it makes it easier to understand.....

In fact I am in error saying the cycle of operation is `Steady-Flow´ when it is a combination -- or rather a succession -- of several steady-flow processes which might be said to be non-flow at TDC when things stand still for a bit depending on the action of the con-rod length and the crank-throw ...


Keep on -- keeping on...

-- `cos my brain ain´t yet slipped off its gymbals, on its way to the sump...

Cheers!

JohnBoy.
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Trevor Amos



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PostSubject: Re: Where did it all go?   Wed Oct 15, 2014 7:05 pm

Secondary compression is now defined as:

Static+dynamic= Effective

It is the Effective compression I should have quoted and not just the dynamic. Apologies for that confusion.
It makes little difference to the thrust of the article but it`s better to be as accurate and factual as is possible to avoid any confusion. This stuff is tricky enough to get a handle on without people like me adding another layer of duff info on top!

Trevor
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john bass

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PostSubject: Stuff & Duff...   Sat Oct 18, 2014 6:03 am

Nah nah Trevor! you don´t get off the hook by quoting Stuff & Duff...

Firstly, is there anyone out there reading this that knows what happened to the Mayflower e3 engine which Dr Joe Ehrlich was endeavouring to get into production before he died???

And --
It matters not that there are only 3 of us interested in this subject -- on HERE -- there´s a lot more gas to it than we´ve so far gassed....

Part of the voodoo vanishes when numbers are put onto the image of the cycle of operations. I am sure Trevor, you can do that....

I jogged my memory when absently flipping thro´a number of my ancient files and came across "Technical Briefs" which spoke of Dr Joe Ehrlich´s e-3 (later called the `Mayflower´...) engine. This report came out in the mid to late 1990´s and the Montreal enthusiasts & I were playing with a similar notion way back in 1981....

Dr Joe´s arrangement uses a pivoted lever arm between the connecting rod and the crankshaft which has the effect of varying the compression-ratio and capacity. We were trying to shift the max-combustion pressure to occur later than TDC (at a more advantageous angle of the conn-rod) in the cycle with some-sort-of-mechanical arrangement and since I had used the AE (Associated Engineering) conn-rod link to measure piston temperature at Ford Dunton in 1968 it was one of the ideas we played with....

What was significant in this recent bit of my muddled-headed `research´ was that I had calculated (way back in 1981) the piston displacement using dimensions that were strikinglingly similar to Bantam...
... Just to cut this short (before it gets boring) I had it that at 2°-3° Before TDC thro´to 2°-3° After TDC the piston would be at 4/5ths of a thou away from its absolutely stopped position, which means that for ALL practical purposes the piston stopped still for a period of 7-ten-thousands of a second at 12,000rpm.*** Whilst that happens the combustion pressure is virtually `locking´ the piston is place and transferring useful energy into the conn-rod isntead of rotating the crank....

There was a lot more to the calcs, so-called designing and experimentation than the above which has me -- NOW -- thinking if it could have been done it would surely have been done by now??

There is the other factor of advantage for small capacity piston/conn-rod engines over turbines that the combusting medium´s max temperature of the former is more than twice that of the latter where the temperature is well above the melting point of aluminium alloy.

It is obvious that some voodoo is still attached -- even after doing the calculations!

Cheers!

*** At 12.000 rpm one cycle of operations (1 crank rotation) takes 1/200th of a second which suggest gas-flow is at some high velocity during the cycle....?
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Trevor Amos



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PostSubject: Re: Where did it all go?   Sat Oct 18, 2014 6:48 am

John,
If you do a Google search by typing in.....Mayflower E3 variable motion engine.... you will discover lots of references and articles about his alternative concept. It appears to be an on-going project, fascinating stuff, glad you brought it to our attention!

Trevor
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nigel breeze

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PostSubject: Re: Where did it all go?   Sat Oct 18, 2014 7:56 am

evening, could you believe that if an engine(may flower) could produce such a saving on fuel usage, would be allowed to be developed ? bit like the ever lasting light bulb...... study
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john bass

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PostSubject: I thought it had died....   Sun Oct 19, 2014 5:30 am

I thought it had died like its inventor. Last I´d heard was that GM were taking up the prototyping of e-3 ... Must do as Trevor says and look it up on the internet....

Hi Nigel! Welcome to the, "Wonder what happened to ...." club.

Don´t tell me some B...B... clobbered Dr Joe´s concept? I saw a P-V diagram which showed a lower peak combustion pressure that extended into the expansion stroke such that the Work-Done envelope was like the belly of a long, fat bee or hornet. Which must surely have meant a flatter torque curve over the operating speed range as well as improved fuel consumption.

I am old enough to remember when ITV became rival to BBC TV --even before Raymond Baxter & James Burke´s "Tomorrow´s Wortld" -- that a new science programme showed a demo of what its inventor called a "Perpetual Motion" machine. The operating cycle was not shown and a lot of reviewers reckoned the inventor to be a crank and the concept a joke. Then someone revealed it was akin to the Stirling engine with a difference that overcame the Stirling´s sealing problem. Then it vanished. A couple of decades later the toothed belt appeared and people were saying the metal chain is finished but somehow only a few motorcycles -- like Harley -- have a toothed belt final drive today. I was doing a job in Zambia, Africa and a Zambian army colonel asked me if I could persuade the Germans to adopt the "Salad Oil" engine. The idea in Zambia was to harvest rape seed and run military vehicles on rape-oil. This engine had a 2-part, composite piston, two fuel injection pumps and a controlled injection-rate system (very expensive?) -- before computer `engine management´ came into being, which returned phenomenol fuel use. Rumour had it that a top German manufacturer bought the patent to kill it off and then the microprocessor came into its own to top it completely. About 5 years ago I was told that that a form of double-laser spark plug was going to oust the spark plug as we know it.
The notion of that came, was discussed and vanished also.

Maybe the large, specialist company sees the threat to their long-term plans, buys up the patent to kill it off dead and thus ensure their long term profit continues unhindered. It might be that they are working on a similar concept in a different way and buy up the patent to ensure zero competition in the meantime.

Whichever it is -- it is doubtful that such lousy behaviour will ever kill off the motivation to try something new, or even old with a new twist.

I´ll shut up and go look at the web-site as Trevor suggested.

Cheers!.

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john bass

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PostSubject: Time to leave the Mayflower setting sail for Americas...   Mon Oct 20, 2014 5:08 am

Time to leave the Mayflower sailing toward America -- I feel quite sure it is there that big-business-lobbying would have it PUT DOWN like a mangy dog....

I did look at the site as Trevor suggested and there was nothing really new except for some big companys´ like Peugot and their VCR engine which our Montreal enthusiasts had considered yonks ago. Not to decry Peugot´s R&D it is probably that "`Engineering Mínds`frequently think alike...." Thing to Knock the e-3 and other similar connections between conn-rod and crank is that engine, max operating speed becomes limited by the increasing forces of the rotating/oscilating masses: I know that from use of the AE piston temperature measuring device: it destroyed itself several times before adequate information was obtained.

There was, of course, the BICERA*** VCR engine way back in the dark days of engine development which was adopted by Continental Aircraft. This was a two-part piston. The auxilliary piston sat on the main piston which lifted according to the oil-pressure applied. The objective of this Variable Compression Ratio sytem was to automatically lower the maximum cylinder pressure when it exceeded the upper limit. This was acheived by having the auxilliary piston lowered by lowering the oil pressure which reduced the CR and increased the Clearance Volume which would not have been acceptable a few years later in view of exhaust pollution, inreased fuel consumption ...etc...etc... The concept was quite different from the "Montreal Apprentices" version in that we wanted to move the piston --or the head -- on every cycle, not over a period of engine-run-time...

Sorry about that digression away from the racing 123cc Bantam...

To kill off some of the voodoo what say we look at numbers attached to the cycle of operations.
First, there´s the induction of the Fuel-Air charge. If things worked perfectly the piston rushing from BDC to TDC would suck in 123ccs of charge volume -- or even more....? More likely less. The former is only possible if some sort of pressure wave -- similar the resonant exhaust system -- happens in the air flow thro´the carb and reed valve.
The crankcase itself would be warm from the previous crankcase compression so how much change in temperature would the intake-charge experience as it rushes in?

These sort of numbers require sophisticated intrumentation -- but the large companies must have done such...?

So. what is the response to that? Are there systems and calcs showing how simple `supercharging´ could be achievede? And what about the Air-Box, ducted, cold air to the bell-mouth or ejector cooling of intake air and other wild ideas?

Cheers!


*** BICERA -- British Internal Combustion Engine Association at Slough.... On behalf of Ford Dunton
I visited them several times between 1970 and 74 to obtain specialist test rigs and instrumentation.

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