2 stroke thread (with occasional F1 relevance!)

[gruntguru]

Not "impossible", it has been claimed that current F1 engines ( non-emissions constrained, like aero-engines), consume ~5 litres of oil per race, so a g/hp/hr calculation on that basis will allow comparison..

If we assume the engine produces 800 hp.hr of energy over race distance* while consuming 4 kg of oil, you get average oil consumption of 5 g/hp.hr.

(* Based on 800 hp @ 100 kg/hr and 100 kg total fuel consumption per race)

[manolis]

Hello all



Mudflap wrote:
“On a certain forum you even boasted you will make millionaires out of potential investors!”


This is a lie and, “Madflat”, you know it.


For the rest, it is easy to check the truth:

Go at http://www.ultimatecarpage.com/forum/sh ... 958&page=9 and read the post #125.

It is the reply to a guy (Brand Howell Smith, the founder of Revetec) who not only bankrupted thousands of investors with his “genius” engine design but, he was also accusing others for what he was doing.

Here is what he wrote:

“The problem with amatures like these people is that they don't understand engines and even though some theory may look good and the design looks simple, doesn't mean there are no inherant problems with what they are trying to do. Companies like this just burn investors money without having any prospect of getting an engine to perform or get to production. (who never took a dollar from any investor) that they spend investors money.”

In my #125 reply I explain to the forum members that pattakon never took investors money, not a single dollar.


Then go tohttp://www.ultimatecarpage.com/forum/showthrea ... 58&page=98
and read the last sentence of the last post of that discussion.



“Mudflap”, to accuse / to slander anonymously is not decent.

So, sign with your real name and address and explain your “On a certain forum you even boasted you will make millionaires out of potential investors!”



“Madflap”,

I will give you the US1,000$ Muniix (Mrac Jackson) refused to reveal the “certain forum” you are talking about.


Thanks
Manolis Pattakos

[gruntguru]

Then go to http://www.ultimatecarpage.com/forum/sh ... 58&page=98 and read the last sentence of the last post of that discussion.

Very wise words.

[gruntguru]

The design is old (more than 80 year old).

The 37.5% BTE is maintained in a wide range of revs (from 1,500 to 2,500).

The 37.5% is not the peak BTE of the engine.

The fuel efficient, lightweight and reliable Junkers Jumo Diesels enabled, for the first time, airplanes to travel at distances not possible before.

So,
either Heywood is not right, or the rest characteristics of the Opposed Piston Jumo 205 are by far superior than those of the state-of-the-art modern Diesels (wherein the flame initiates centrally, wherein the fuel is injected at way higher pressures (fine droplets) and with the perfect timing, wherein everything is optimized by computers, etc, etc) to justify the 37.5% “working” BTE .

Deceptive again, modern diesels are nealy 10% higher in efficiency, automotive diesels would also be at least 10% better at the same bore and stroke giving the same surface volume ratio where heat is lost.

10% better than 37.5% - is that 47.5% or 41.25%?

For a 1.6 litre per piston engine, 37.5%+ TE over a wide operating range is remarkable. For an engine built 80 years ago it is absolutely astonishing!

I have spent some time on the dynamometer with a modern (12 y.o.) 6 litre, 6 cylinder, common-rail, turbo diesel. That engine has a peak TE of 38%. Convert the Jumo 205 to turbo-charging and the peak TE would push 40%.

[Muniix]

Oil consumption is not restricted to the internal combustion engine, the turbo or Supercharger and various other auxiliary units consume the oil.

So yes you can have high oil usage and reasonable efficiency.

[J.A.W.]

The design is old (more than 80 year old).

The 37.5% BTE is maintained in a wide range of revs (from 1,500 to 2,500).

The 37.5% is not the peak BTE of the engine.

The fuel efficient, lightweight and reliable Junkers Jumo Diesels enabled, for the first time, airplanes to travel at distances not possible before.

So,
either Heywood is not right, or the rest characteristics of the Opposed Piston Jumo 205 are by far superior than those of the state-of-the-art modern Diesels (wherein the flame initiates centrally, wherein the fuel is injected at way higher pressures (fine droplets) and with the perfect timing, wherein everything is optimized by computers, etc, etc) to justify the 37.5% “working” BTE .

Deceptive again, modern diesels are nealy 10% higher in efficiency, automotive diesels would also be at least 10% better at the same bore and stroke giving the same surface volume ratio where heat is lost.

10% better than 37.5% - is that 47.5% or 41.25%?

For a 1.6 litre per piston engine, 37.5%+ TE over a wide operating range is remarkable. For an engine built 80 years ago it is absolutely astonishing!

I have spent some time on the dynamometer with a modern (12 y.o.) 6 litre, 6 cylinder, common-rail, turbo diesel. That engine has a peak TE of 38%. Convert the Jumo 205 to turbo-charging and the peak TE would push 40%.

The 2T Jumo was robust, too - Ju 86 P/R high-altitude recon-bombers - used a brace of 'em,
turbo'd & NOx boosted, which proved problematic to catch - with regular service interceptors..

[Tommy Cookers]

as the aviation distance records show the Junkers 205 did not enable aircraft to fly further
SI engines could lift more fuel into the air
the 205 was Guernica-era technology dropped before 1940 and used up as convenient to heavily supercharge for very high altitude reconnaisance
similarly presteigeous & momentous Junkers airframe programmes were founded on what we now know to have been faulty aerodynamic techniques

the Wright TC was of course designed for the same niche market (low altitude endurance for patrol at sea)
Wright freely admitted that at normal altitudes and speeds exhaust recovery was pointless
without recovery propulsion from SI free exhaust is much greater (10% power equivalent at 300 mph, 20% at 400 mph and 30% at 500 mph)
CI exhaust is of course deficient in this respect

the only aviation job the 'diesel' can do better is propelling airships (because fuel weight is not lifted by engine power)
eg 57 litre 18 cyl 1928 SI Isotta-Fraschini Asso developed for 75 years into the CI CRM 18D/SS 1850 hp was selected for USN Sentinel 5000 surveillance

the undisputed ability of the CI engine is to burn such fuel as is genuinely cheap or otherwise genuinely desirable
it was invented to burn fuel that was artificially cheap and has so lived most of its life
remember the SI engine was invented to burn its fuel because that at the time that was artificially cheap
IC engines then ran on gas made from coal, kerosene was in demand as lamp fuel, and gasoline was a waste product

[J.A.W.]

NASA disagrees with you T-C, they sponsored a 2T CI turbo-compound helo-mill proposal from Garrett*,
which clearly showed the potential for such a 'diesel' engine to outperform geared gas turbines in the role..

A Jumo 2T CI equipped Dornier flying boat did get the record for non-stop distance flying in 1938, from
Blighty-to-Brazil..

& the Jumo 2T CI also got the Ju 86 up to 49,000ft, one dropped a bomb on unwarned Bristol to nasty effect..
See here: https://www.flightglobal.com/pdfarchive ... 01865.html

& noted here, Bristol Hercules sleeve valve radial, oil consumption figures..
https://www.flightglobal.com/pdfarchive ... 02242.html

* See 2nd to last post, on page 5 of this thread - for the link..

[Tommy Cookers]

the Hercules did a worse job than the Merlin at twice the cost
the Sabre cost more than twice the Hercules
$ resources and manpower resources are the same thing - as Stalin saw

why do we think that our car engines cost can be doubled again because doing this looks good under testbed conditions ?
when the diesel air pollution scandal that Europe has inflicted on itself shows that testbed results so falsely represent real world behaviour

whether F1-esque hybrid magic beans or CI magic beans the testbench has little to do with real world conditions
the testbench is all about disguising the fact that we use our 200 hp cars at 20 hp but we keep on buying 200 hp

[J.A.W.]

the Hercules did a worse job than the Merlin at twice the cost
the Sabre cost more than twice the Hercules

why do we think that our car engines cost can be doubled again because doing this looks good under testbed conditions ?
when the diesel air pollution scandal that Europe has inflicted on itself shows that testbed results are lies

& how much has the current Honda F1 engine program cost - per race win T-C?
In war, as in G.P. racing, its results that count, & certainly the Halifax was a dead-duck when Merlin powered..
..yet the Hercules got it performing to an acceptable level..

Economies of scale in Merlin production slant the figures somewhat too, not to mention that every Sabre
went in to an actually useful airframe, unlike so many Merlins which went into obsolescent make-works..

Here below are the post-war 'civil' Merlin figures to compare with the Hercules already linked..
..was the Hercules doing a "worse job"? & note the Sabre too, no military Merlin ever mustered 3000+hp..
https://www.flightglobal.com/pdfarchive ... 01455.html

[Tommy Cookers]

as I said the CI aero engine was blown out of the water by SI fuel etc improvements ie 80/87 to 100/130 overnight

similarly developments based on 80/87 thinking quickly looked stupid
you are trying to blame the Merlin's availability that made it a victim eg of this ie the 20 series rut vs the 40 series and 60 series

the subject to hand is engine technology eg whether the sleeve valve justified its extra cost (and weight eg in radials)
our engines eg outside F1 should be judged on factors including cost - Joe Public has a right for this to be the bottom line

[J.A.W.]

Apples & oranges T-C, what was the TBO for the hard run civil Merlin? & the overhaul cost, at that..
I note that the Hercules was not only more powerful than the Merlin, but was more efficient BSFC-wise, too..

[63l8qrrfy6]

I am sure this is not a deliberate attempt to mislead and you simply overlooked the fact that the extra piston contributes its own displacement, so oil consumption as a function of engine displacement remains the same were you to substitute the opposing piston with a cylinder head.

A cylinder head that leaks oil, yes.

No - a cylinder head that leaks no oil. Think about it and see your mistake before critiquing the engineering abilities of others.

Suppose you have a cylinder with bore b and stroke s and a single piston.
You have another engine with 2 cylinders, same bore b and half the stroke.

The 2 cylinder engine has 2 times more rings and implicitly 2 times more ring gap area and 2 times more groove vertical clearance area.

Which engine has a higher oil consumption and higher ring pack friction ?

[J.A.W.]

A cylinder head that leaks oil, yes.

No - a cylinder head that leaks no oil. Think about it and see your mistake before critiquing the engineering abilities of others.

Suppose you have a cylinder with bore b and stroke s and a single piston.
You have another engine with 2 cylinders, same bore b and half the stroke.

The 2 cylinder engine has 2 times more rings and implicitly 2 times more ring gap area and 2 times more groove vertical clearance area.

Which engine has a higher oil consumption and higher ring pack friction ?

"I will stop here..."

Well, perhaps you should've, - since there are other considerations you have apparently missed..
..such as an engine which operates every single cylinder, with 2 pistons..

[gruntguru]

Deleted post.