Dan Vincent

Every now and then I see someone say the MVVS .09 is very powerful while others say it is of average power.

I have two of these nice little engines.

The one with the aluminum back-plate appears to have a standard cylinder intake port.

The one with the black back-plate and pinch-type venturi appears to have three intake ports in the cylinder which tells me it's Schneurle-Ported.

Perhaps this explains the power difference.

Any comments?

ffkiwi

There seems to be a number of versions out there-and on top of that the worksmanship on some seems a bit variable. There is ample evidence of variable transfer passage sizes, for example. One of the UK magazines (AMI? RC Model Flyer?) published an article on reworking the MVVS 09 to improve output. My feeling is that the plastic backplate version is the later one, but there is evidence (see pic below) of a later version still (this information came from Czech collector Jiri Kalina)-the exact timeline and dates is uncertain. Personally-though I have one, I'm not that impressed-too hard to start. For FF use, I need an engine that starts quickly so I connect with the thermal-not one that takes minutes to get running-and that's been my experience with 4 or 5 examples of the MVVS/Modela 09 over the past 20 odd years.

ChrisM
'ffkiwi

ffkiwi

I suppose we also need to consider that 'average power' has crept up over the years as well-so we need to be certain we're singing from the same song sheet when it comes to this sort of discussion. For many years a 'sport' plain bearing 1.5 diesel (DC Sabre, Frog 150, Elfin 149, ED Hornet etc)produced around 0.10-0.12 BHP and a contest one about 0.15-0.18BHP (AM 15, PAW 149, ED Hawk, Oliver Tiger Cub, ED Super Fury)-meanwhile a good 1.5 glow (TD 09, Cipolla, Rossi) produced around 0.3BHP. Then the current generation of contest 1.5 diesels arrived-the tuned PAWs, the various Russian/ukrainian Fora,Parra CTAHs etc which are producing at least 0.3BHP. By current standards, the Modella is rated at about 0.22BHP-about the same as an ED Super Fury-so in that sense is above average for a plain bearing 'cooking' or sport diesel-but only average by current 'performance' 1.5D standards-but these are twin BB, schneurle ported and generally AAC or ABC........
It depends what yardstick you're using for measurement.........

ChrisM
'ffkiwi'

AMB

Dan I only have the one with the plastic back plate the spec sheet in the box reads prop size 100 by 200mm or 100x180mm ( 7x4 or 8x4) max rpm ``17000
think I ran a 8x4 wood zinger maybe 11K-11.5K thus "sport speed" its been several years since run I had it in a used plane I bought that was just a just high wing sport the plane electric I repowered it with the MVVS was destroyed in a crash when the wing came apart the guy never put the joining spar in just glued the 2 wing halves martin

I just consider it a sport engine not a barn burner no attempt was made for max revs

note the engine came thru it with no damage


I was also lucky got it with the factory muffler and U bolt no mods need to fit a muffler

Chris sums it up well not a cooker by todays standards

Dan Vincent

Sure, there are plenty of engines out there, mostly newer stuff, that have more power than an MVVS.

My point was that the Schneurle-ported MVVS should have more power than the older cross flow MVVS.

ffkiwi

Indeed it should-but how do you distinguish them externally? This would help people buying on Ebay or elsewhere-which is about the only source for this model of MVVS/Modela these days.

ChrisM
'ffkiwi'

AMB

Chris the pix Dan shows the one one the right shows the pinch bar on the venturi, thats the one have I have fitted I have fitted with r/c carb I would guess if it has the pinch bar it is the schneurle ported one
is so thats what you would look for to tell them apart my guess

correction the head is plain not black had it on the counter next to the MPJET 061 thats the black head

AMB

delete dup

AMB

delete dup

ffkiwi

Its possible-but by no means certain or definitive that the external changes correspond to porting changes. we'd need comment from someone close to MVVS (pereivers perhaps?) to confirm this. There is too much proven variation from batch to batch with a lot of manufacturers to be absolute without very good-ie someone who actually worked at the factory corroboration. Case in point-the ST X15 schneurle glow-the first ones had G15 innards in an X15 case-and weren't schneurle at all.

Much though I'd like to accept the premise, I'm not sure it's valid-something as trivial as a carb retaining method might have been introduced randomly, or on a batch basis. (though in this case a small change was obviously made to the casting die). No argument that somewhere along the line a 'schneurle style' of porting was introduced-but did it also correspond to a slight change in crankcase? Maybe, maybe not.

ChrisM
'ffkiwi'

Mr Cox

Are you taking about the intake port or the transfer channels?
I only have one, it has a black plastic backplate and it is schneurle ported, but without a boost port.
As far as I can tell, this is the same as on the one with an aluminium back plate that was improved upon by Dave Clarksson (there was an assymetry in the size of the two transfer channels).

Dan Vincent

Look in the exhaust port at the far side of the cylinder. My older MVVS has a single horizontal slot in the cylinder whilst the newer one has three ports.

Another difference is the prop driver on the newer engine is larger, giving a better grip to the prop hub.

Mr Cox

As I tried to say above, I have one with the black plastic backplates and it is schneurle ported (two transfer channels).

In the engine review and reworking of the transfer channels they had an engine with aluminium backplate, and it too had two transfer port (i.e. schneurle type);

ffkiwi

Mr Cox's last post confirms my point-you cannot simply go by the backplate material as a guide-as the adoption of schneurle porting in the MVVS 1.5 obviously predates the use of a plastic backplate. So somewhere along the line-I'm guessing here-but I'd say probably in the 1980s, MVVS went from cross flow to a type of schneurle for this motor. Did they change the crankcase die significantly in the process. I would say no-such changes were largely internal, based on Dan Vincent's description of his early one-it would have to have an internal transfer passage matching the horizontal slit. This would have been produced either by machining or the use of cores in the die [the later schneurle model obviously used cores to produce the front and rear transfer, as the rework article indicates]
I would not put any faith at all in a prop hub as a diagnostic tool-I can show you engines from all sorts of manufacturers where examples of the same engine model have prop drivers with different dimensions. Prop drivers, comp screws and NVAs are usually produced in large batches (at least hundreds-more likely thousands)-on high speed repetitive operation lathes (capstan lathes in the early days, CNC stations these days) and batch to batch variation is to be expected.

ChrisM
'ffkiwi'

qazimoto

My Feedback: (1)

The Dave Clarkson MVVS 09 "hotup" article should be attached.

Although it doesn't quite say it, there is the strong inference within the article that reinforces the old adage about not being able to make a silk purse out of a pig's ear.

With similar attention, any of the current Oliver Tiger Cubs, CS Cubs or TBR PAWs would have easily reached 17K on an APC 7 x 4.

A "blue headed" plain bearing PAW 09 would have been well into the 16K range.

The 09 MVVS is a straight forward easy to use beginners diesel and that's about it.

AMB

Works for me in sport flying its a John Deere not a Ferrari flip fuel go Martin

trfourtune44

I bought a couple of MVVS 1.5 diesels on fleabay. I like what I got BUT, both had casting flaws in the cases. one had a pin hole in the bottom of the case and the other near the intake. I cleaned them up with laquer thinner and brake cleaner, then pressure fit some JB Weld through the pinhole(s). result, 2 perfectly good engines. run like a top. nice plain bearing sport engine, with mufflers, no ear piercing scream.
The PAW engines I have, all have excellent cases-perfect.
conclusion: check the mvvs engine cases very carefully before buying. I could not see any of this in the pictures on fleabay.

trfourtune44

one more note, an MP jet 06 diesel will match an mvvs 09. they are available at:
http://www.icare-rc.com/diesel.htm

quietflyer

My Feedback: (1)

I have one with the black composite backplate. It is still being run in, has an r/c carb , and so far has been a joy to play with! The accompanying link shows it's third run without the muffler on home brew fuel.
https://www.youtube.com/watch?v=iEaA81SJb4I
trfortune44, where do you fly in the Lower Mainland?
Min

AMB

QUIET FLYER Looks like about 12500 ?? on tach not bad the the MVVS it is a sport engine the MP jet 061 will do the same or a bit more on the same prop but also a modern design engine. Hums along quite nicely if just fun flying a small one will work fine most of my stuff at 9500-10500 flys fine my bigger ones with an irvine 40 or 53 diesel ( the 53 a conversion)
fly at the same revs, bottom line you have a winner martin

Recycled Flyer

Just looking more closely at the transfer port arrangement, is this really a 'schneurle' device or variation thereof?

I know that there are two ports but they are hardly angled towards the rear of the cylinder like the pic attached.

AMB

Those ports seem huge was this a glow design to begin with?? martin

AMB

[quote]ORIGINAL: AMB

Those ports ( bypass) seem huge was this a glow design to begin with?? martin

no not a quote hit wrong key

fiery

My Feedback: (2)

David Owen's opinion is that the porting is not Schnuerle.

It is a variation of "vortex" porting as originally patented by the Garofali's (Super Tigre) in the early 1960's.

This permits the Modela Junior 2 cc (similar porting) to be used in C/L Phantom racing in Australia, where Schnuerle ported engines are not permitted.

Recycled Flyer

Iagree Derek, it just didn't seem right to me.

I have a Rustler/Merco 51 control line stunt engine that has a boost port in the classic diametrically exhaust opposed position and two side ports much like the featured MVVS here but all three ports live behing a piston baffle!

So I won't call that 'shnuerle' ported either.