NM2K

My Feedback: (14)

Being retired and mostly housebound, I have a lot of time to think about things. Fortunately, I enjoy thinking, although the results are somewhat dubious at times. <G>

Being a model diesel fan since my first exposure at the age of 13-15 (can't nail it down better than that), and, being a glow engine freak since I can first remember anything coherently, the two fields intermingle in my mind from time to time.

I was really impressed by an OS.61SF side exhaust engine in the early nineties. It was my first exposure to a model two-stroke engine that was intentionally designed to turn larger props at lower rpms. A friend had one on a Kaos 60 (Ben Campanella). When I heard it run, I thought he had the sleeve in backwards. It just wouldn't turn up like my old OS.61FSR and .61VF of some years previous. Then I noticed the huge prop (12x8).

What really impressed me was how this engine hauled this rather heavy Kaos straight up without noticably slowing down or sagging in the least. OS was really on to something good with this engine.

Someone mentioned an OS.46SF in another post. I responded by saying that if it was designed like the .61, they had a real serious torque producing engine. Then, a while ago, it occurred to me that this might make an ideal engine for converting to model diesel operation. Has anyone tried this with this particular engine? Either size is okay.

After thinking a bit more, I remembered that Irvine also had a few engines that were designed to turn large props powerfully at lower rpm. These too would make outstanding diesel conversions, I would think.

Anyone care to comment?

Hobbsy

My Feedback: (102)

Irvine made two that were designed to turn larger props, the Q .40 and the Q .72. The Q .40 has the same bore and stroke as the .40 Diesel, I never measured the Q .72. I just remember I treated the Q .72 as if it were a .91. The Irvine 1.50 is also capable of turning some larger than 1.50 sized props. In fact I'm seriously considering getting another 1.50 to put an AJ conversion head on.

donkey doctor

Hello; I have a Laser 100, which is that companys long stroke high torque engine. They recommend a 15 x 8 prop to keep the revs below 8800. I have this engine on a BUSA Taube which will fly just two clicks above idle. I don't like flying at full throttle and really like the way the Laser swings that big stick in an unhurried way. In fact, I wish all four strokes could make power like that. I know that there's more to an engine then long stroke, and valve sizes and timing may have more to do with producing torque then bore/stroke ratio. That high torque kind of engine performance is what interested me in diesels in the first place. I have searched high and low for an engine that will give me lots of torque at low (ish) revs. The four strokes seem to do it better then the two strokes, but I still haven't found anything that works as good as that Laser. I have a few old OS 90FS' that like running slow, but it seems the trend is to get more power by turning higher revs, which is something that the long stroke motors don't like to do.

I was hoping to get a more torquey performance out of my Irvine 40 diesel, but though it runs good, it doesn't have the bottom end I was hoping for. Maybe I haven't found the "right" prop for it yet.

Ldalmas

for the irvine 40 diesel the best ive found is a 12x6 apc or zinger and it gives me 9.4k which is good

Laurence

[email protected]

I have an MVVS .61 long stroke with a diesel head and it turns a Zinger 16/5 at 7,000 rpm. I have been told that is too much prop. It turns a 15/6 at 8,500 maybe a better prop selection.

NM2K

My Feedback: (14)

The beauty of the adjustable compression is that it is difficult to get "too large" of a prop and still generate enough thrust to fly.

Motorboy

I has own homemade longstroke engine and here are my engine: http://www.rcuniverse.com/forum/m_2785403/tm.htm

Jens Eirik

Motorboy

I has own homemade longstroke engine and here are my engine: http://www.rcuniverse.com/forum/m_2785403/tm.htm

Jens Eirik

Hobbsy

My Feedback: (102)

Pe Rievers recomended I use a 14x7 APC which it turned at 9,000 when new but after about 4 hours it now turns it at 9,500. I also have MOKI .61 LS with the exact same bore and stroke.

erik58

My Feedback: (4)

I have one.it has a just engines piston + sleeve kit.the engine was worn out when I got it.I used a davis head on it and the carb it came with it runs great. hope to have it in the air soon. will let you know how it performs

erik58

My Feedback: (4)

I have one.it has a just engines piston + sleeve kit.the engine was worn out when I got it.I used a davis head on it and the carb it came with it runs great. hope to have it in the air soon. will let you know how it performs

ddd

I must say i'm really surprised that after over 30 years of constant advertising in both R/C Modeler and Model Aviation and countless articals not to mention to many hobby conventions how many people are still in the dark about our diesel products. We have sold 10's of thousands of diesel systems throughout the world so its really hard to beleive so many people just do not read. For those that care to: www.davisdieseldevelopment.com

AMB

Ok guys will add my 2 cents worth on this one and this is directed to the "new modelers" and maybe the folks who are new to the site
I did notice the ads for the big glow conversions (40 size or so ) to electric which anyone can check the prices on this and by the time you are done
maybe $400 plus. These are not PARK flyers and cannot be safely flown in any small space
Now as an example Supre tiger 40 glow 50 or 60 bucks (yes sometimes a deal from tower at $49,99 Davis head for same $50
thus you are spending $100 or $110 for power 20 or 21 dollars a gallon for diesel fuel which goes almost twice as far a gallon of glow fuel plus the power increase when the engine is converted to diesel. this really the K.I.S.S. principal. Of course there are many engine choices but this comes to mind first .
An other thought the Guys " Down Under" in the UK, and Europe seem much more into diesels than stateside, and Down Under and
Canada "Store bought Diesel "is impossible to obtain, so they go thru hell to get the ether etc and fly their diesels, Here a call to tower or Davis brings it to your door nough said martin

DarZeelon

If someone did not notice, most current engines are close enough to 'square', so minute changes in the bore, or in the stroke, that give any engine the 'long-stroke' name, are not material.

It is all a matter of timing; intake bypass, exhaust port and primary induction timing, that is.


There is a member of RCU, flying a pattern ship of his own design, with an MVVS .61 glow engine + the MVVS tuned pipe and spinning an APC 13x9 prop at 10,800 RPM. This engine is what you would call a long-stroke (actually, the right term is 'under-square'), having a 23 mm bore and a 24 mm stroke. The actual HP output is no less than 1.92 HP.

If this does not seem impressive, read the MAN 05/03 engine shootout, by Dave Gierke.

Most .61 engines make much less power than that. An 80s F3A engine, spinning an 11x7 prop at 14,500 RPM makes only 1.85 actual HP, at much higher RPM...

MVVS selected this engine to make their own big Diesel.

Its bigger brother, the .77 is also an under-square engine, with a bore of 25 mm and a stroke of 26 mm.

The biggest MVVS 'small glow engine' is the .91, which is the real torque paragon... But this engine is NOT under-square, but 'over-square' (short-stroke), using the same stroke as the .77, with a 27 mm diameter piston.
Yet it is this seemingly ~high RPM short-stroke~ engine that is happy spinning props as large as a 16x6, around 9,000 RPM (as a glow engine).
It hates anything over 11,000 RPM, no matter which exhaust you use, or what you throw at it.

MVVS does not offer Diesel versions of either of the last two.

I wonder what it would spin as a Diesel, with an AJC head on it... An 18x8 probably.


So the term 'long-stroke' is just meaningless, useless 'buzz-words'...

meowy84

DDD, I think shipping costs might have something to do with it. When you charge about $7.00 to ship say a Cox reset tool that can actually be shipped for around $1.50 it doesn't win you many friends. It seems sleazy. Furthermore, when a lot of your ads don't mention that for the Cox Babe Bee diesel head conversion for instance you also need a special crank or the engine life can be measured in seconds, that doesn't win you many friends either. When the RJL diesel heads work straight out of the box without any tinkering needed...Well, you get the picture.

meowy84

Apparently the powers that be deleted my post for MFG bashing because I had the gumption to mention that RJL diesel heads work much better than DDD heads and don't require mucho tinkering out of the box to run right.

I would also like to inquire as to why DDD's post wasn't deleted for advertising? Isn't there a rule that says that manufacturers aren't allowed to advertise on the threads? Or is this a case of "there are rules and then there are rules"?

I wonder if something will be done about this or if I'll be silenced again by having my post deleted again.

meowy84

Since when did stating your opinion on a product or manufacturer's conduct become MFG bashing? If my new Ford, Chev or whatever is a lemon should I stay quiet or face corporate wrath?