RE: MVVS 58cc Gasser - 9.25HP?!?!?  
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    • All Forums >> Glow Engines, Gas Engines, Fuel & Mfg Support Forums >> Gas Engines >> RE: MVVS 58cc Gasser - 9.25HP?!?!?
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    RE: MVVS 58cc Gasser - 9.25HP?!?!? - 9/29/2003 4:18:36 PM   
    Volfy



    Posts: 3227
    Joined: 1/4/2002
    From: Houston, TX, USA
    Status: offline     		Above a certain displacement, the greater volumetric efficiency potential of a twin will overcome the addtional parasitic drag compared to a single. Likewise, above a yet higher dsiplacement range, a twin will loose favor to a 4cyl for the very same reason. Good design can stretch that break even point, but there is no defeating the inevitable.

    Still, none of this matter to the single most important aspect of any engine - price, which accounts for a great deal of ZDZ80's popularity. I hope MVVS prices this 58cc comparable to the 50-55cc crowd.

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    (in reply to joelsaxton)
           Post #: 26

    RE: MVVS 58cc Gasser - 9.25HP?!?!? - 9/30/2003 2:51:41 PM   
    f2racer



    Posts: 1167
    Joined: 12/7/2001
    From: Bedford, MA, USA
    Status: offline     		Just a quick note. I spoke to Robert at Morris and supposedly the 58s will be in either next week or the following week. He also said that those "crazy" Czechs are working on something completely new (at least in this hobby) as well... A liquid cooled version of the 58cc, supposedly for applications where cooling is an issue!

    (in reply to joelsaxton)
           Post #: 27

    RE: MVVS 58cc Gasser - 9.25HP?!?!? - 9/30/2003 2:58:45 PM   
    Herby 1


     

    Posts: 10
    Joined: 4/26/2003
    From: Northern Arizona
    Status: offline     		Nothing new about water cooling..Zenoah makes water cooled engines for model boats..Bruce Hnson's 50cc water cooled racing twin is 12.87 HP and turns 18,200 rpm..
    The G26 marine engine turns 12,000 rpm stock...

    < Message edited by RCIGN1 -- 9/30/2003 4:05:31 PM >

    (in reply to f2racer)
           Post #: 28

    RE: MVVS 58cc Gasser - 9.25HP?!?!? - 9/30/2003 6:10:11 PM   
    Flypaper 2



    Posts: 4337
    Joined: 3/29/2002
    From: Kingston, ON, CANADA
    Status: offline     		Wish they would come back with the torque, hp graphs that they used to put in the old mags. They didn't lie. For instance, high performance engines,ducted fan,etc, the hp rise was very slow till it got to a high rpm, then an abrupt rise to high hp.at, say 18000 rpm. When you backed up to 10,000 rpm, not a lot of hp, or torque. The only way it would be usefull would be with reduction gearing, then throttled back, would be pretty useless. With the graph you could see the actual HP and torque at, say, 7500 rpm.

    _____________________________

    Gord
    Dreamed I was a muffler. Woke up exhausted.

    (in reply to joelsaxton)
           Post #: 29

    RE: MVVS 58cc Gasser - 9.25HP?!?!? - 9/30/2003 7:02:28 PM   
    pe reivers



    Posts: 2980
    Joined: 1/23/2002
    From: Arcen, , NETHERLANDS
    Status: online     		Mmmm..

    Maybe that is why Mr Svajda was so curious about the construction of the watercooled converted 1.60 engines that I had made for a twin hull boat. We had an opprtunity to exhange a few words and ideas when at the show in Dortmund.

    I will receive <one> 58 test engine and <two> new type red heads in a few weeks time. Morris gets the rest :-(

    _____________________________

    Pe, Dealer for MVVS, MTW and Mejzlik; www.mvvs.nl
    There is sanctuary in analisys.

    (in reply to f2racer)
           Post #: 30

    RE: MVVS 58cc Gasser - 9.25HP?!?!? - 9/30/2003 8:46:44 PM   
    ketil


     

    Posts: 168
    Joined: 11/22/2002
    From: , ,
    Status: offline     		I Wonder And i Wonder?

    When you have an engine,you start it let it go fore a bit,and reads the rpm on full throttle.
    1 is this the rpm the factory reads?

    2 when the plane is airborne and make top speed,the rpm is a lot higher than when its on ground, is it possible that you have a higher hp in air than on ground?

    3 in a dive ,can you over run the engine on rpm?

    4 how do you know what rpm you have in a top speed plane ?

    some one thought about this?

    Ketil

    (in reply to pe reivers)
           Post #: 31

    RE: MVVS 58cc Gasser - 9.25HP?!?!? - 10/1/2003 3:12:55 AM   
    DKjens



    Posts: 2086
    Joined: 2/10/2002
    From: Pasadena, CA, USA
    Status: offline
    quote:

    I Wonder And i Wonder?

    When you have an engine,you start it let it go fore a bit,and reads the rpm on full throttle.
    1 is this the rpm the factory reads?

    2 when the plane is airborne and make top speed,the rpm is a lot higher than when its on ground, is it possible that you have a higher hp in air than on ground?

    3 in a dive ,can you over run the engine on rpm?

    4 how do you know what rpm you have in a top speed plane ?

    some one thought about this?

    Ketil


    1. Who knows what the factory reads, should be a cold and a hot reading.

    2. I doubt the unwinding of the engine in flight has great significance in this/these particular applications, being aerobatics and 3D. In racing and with pipes, it most definetely has significance, and yes, a 2-stroke "on the pipe" has more HP than not "on the pipe".

    3. Again, I really doubt you can over run a 2-stroke engine. With 4-strokes it's a different matter, again especially if on a race application where the plane will fly at a significant speed. That is why you should not underprop a 4-stroke glow engine.

    4. I suppose you get one of the new 3W ignitions and record the rpm range throughout the flight ha ha.

    DKjens

    (in reply to ketil)
           Post #: 32

    RE: MVVS 58cc Gasser - 9.25HP?!?!? - 10/1/2003 2:49:11 PM   
    dick Hanson



    Posts: 10186
    Joined: 12/12/2001
    From: slc, UT, USA
    Status: online     		That is one interesting HP reading --for a 50 -
    Ihave a new ZDZ50 NG which really sparkles -but I doubt it is even remotely close to 9 hp -
    One point about porting ---
    even tho a twin has more porting area - the business of EFFECTIVE flow rears it's head -
    this is kinda confusing stuff -unless you look at how fluids flow thru large and smaller "tubes".
    Hot rodders and NASCAR guys figured out how to make flow benches many years ago -that told em what was really going on.
    I played about with watching how water changes flow rates when the shape of inlets/outlets were radiused differently. Learned a bit from that ---
    These little air pumps (our engines) can be made to deliver unbelievable flow if all is set up to do it .
    four stroke engines in cars now use variable length intakes /valve openings etc -and the flow is stabilized over broad rpm ranges.
    simply tipping the ports to different outlet angles changes the whole picture.
    The thing that must drive the engine designers nuts, is the habit -in the USA anyway --of putting an abysmal piece of plumbing on the exhaust outlet - which wrecks any real performance flow setup.
    Some setups will tolerate this -others will not .
    my new NG engines tolerate it pretty well but after a fair bit of doodling with the good /bad and the ugly exhausts - I noted some interesting (to me ) performance changes .
    The use of a more restrictive muffler - still affects rpm on bigger props -more than it does on smaller props .
    Adding a correctly tuned setup - makes the entire rpm band smooth out and run harder - a lot - and throttle response at low rpm is even faster --
    this is a bit of a surprise - the exhaust timing is quite low - but the intake porting is very directional and is of a different relationship to exhaust timing than previous designs.
    So - maybe - the MVVS really has a trick setup which really cooks - we will see.
    Looks like we all win -we get more power for same size setups .




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    Libby

    (in reply to joelsaxton)
           Post #: 33

    RE: MVVS 58cc Gasser - 9.25HP?!?!? - 10/10/2003 1:11:24 PM   
    f2racer



    Posts: 1167
    Joined: 12/7/2001
    From: Bedford, MA, USA
    Status: offline
    quote:

    Maybe that is why Mr Svajda was so curious about the construction of the watercooled converted 1.60 engines that I had made for a twin hull boat. We had an opprtunity to exhange a few words and ideas when at the show in Dortmund.


    Pe, looks like Morris has the scoop on the liquid cooled 58s... Check this link out:

    http://morrishobbies.com/mvvs/58cc_gasser_liquid.html

    (in reply to pe reivers)
           Post #: 34

    RE: MVVS 58cc Gasser - 9.25HP?!?!? - 10/11/2003 9:58:06 AM   
    pe reivers



    Posts: 2980
    Joined: 1/23/2002
    From: Arcen, , NETHERLANDS
    Status: online     		Mmmm..\
    That looks a lot better than the liquid cooled 1.60 conversions I did last year. In fact, it looks great!
    The clean-cowled Spitfire now is within grasp, using functional heat exchangers. Another up-side: The "speed" I build with, enables them ample time to market the engine.
    I just wish, MVVS would spend more time producing engines, so I get my full orders, instead of small parts of it.

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    _____________________________

    Pe, Dealer for MVVS, MTW and Mejzlik; www.mvvs.nl
    There is sanctuary in analisys.

    (in reply to f2racer)
           Post #: 35

    RE: <span class= - 12/16/2003 9:54:50 PM   
    pe reivers



    Posts: 2980
    Joined: 1/23/2002
    From: Arcen, , NETHERLANDS
    Status: online     		Small update on real life numbers on the MVVS 58

    I acquired a few engines, so now I can publish results.
    Since MVVS still does not provide a dedicated tuned pipe, I tried two setups:

    The first (not recommended) test was with a very restrictive pitts muffler as produced for the 2.15 engine. Using this muffler and a 22x10 Menz-S prop, the engine turned a happy 6300 rpm. Throttle response excellent, idle quite low, below 1500 rpm. This was used for running in, and no prolonged full throttle runs were asked for.

    The second was using a friend's Krumscheid tuned pipe for the ZDZ50 engines, and a long header. According to the Krumscheid manual the chosen total length would tune the engine between 6500 and 6800. This is the rpm that MVVS quotes as max power output.
    With this setup and the same 22x10 Menz-S prop, the engine now turned 7450 rpm cold, 7400 warm. Thrust was 31lbs. This is 600 rpm over the top for this engine. This could also be judged by the "snoring" sound of the membrane intake, indicating reeds closing under less favourable conditions due to mass momentum. (BTW, the Carbon reeds are very thin and flexible.)
    Absorbed power for this prop and rpm is an esimated 7.5 hp, and in line with the thrust measured.
    This pipe was not produced for the 58cc, but rather for the smaller 50cc ZDZ. It may be possible, that Krumscheid will produce a pipe for the MVVS soon, and that MVVS will produce the headers.
    Since the 22x10 prop is too small, I have ordered a 24x12 prop to try next, in order to get rpm down to about 6500. (8.26 hp and 50 lbs thrust acc to my spreadsheet)

    Conclusion:
    The engine likes to breathe, and will then produce loads of power. If restricted, power will decline sharply, though the engine seems to accept it willingly.

    (typo 41 lbs thrust corrected to 31 lbs)

    < Message edited by pe reivers -- 1/12/2004 9:47:12 PM >

    _____________________________

    Pe, Dealer for MVVS, MTW and Mejzlik; www.mvvs.nl
    There is sanctuary in analisys.

    (in reply to pe reivers)
           Post #: 36

    RE: <span class= - 12/17/2003 1:42:40 AM   
    dick Hanson



    Posts: 10186
    Joined: 12/12/2001
    From: slc, UT, USA
    Status: online     		Thanks for the report!
    I have the new ZDZ50NG-which is a comparable engine .
    Ijust put the 50 thru in cowl muffler tests -to see how well it responded to very restricted breathing.
    I have, 22x10 and a 22x8 MenzS props which Ikeep as referrence.
    on the Supersonic muffler - I got 6400 on the 22x10 and 6900+ on the 22x8.
    adding proper tuned systems to these ZDZNG engines really allows them to run ---howevr -in the US , most modelers do not use them as it typically requires some airframe fitting.
    The 50 NG also performs better on larger tuned systems
    I
    have a wide assortment of pipes and tuned cans etc., but when I do rpm readings on these - I get much dis belief from some modelers --
    The rotary valve breathes very well -as you know -at high rpm .
    I have not run the KS full length tuned pipe on this one -but I expect it will show a sizeable increase--
    I presume you used the KS 1070 pipe .

    _____________________________

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    Libby

    (in reply to pe reivers)
           Post #: 37

    RE: <span class= - 12/17/2003 3:15:09 AM   
    David_Moen



    Posts: 1405
    Joined: 10/5/2002
    From: Salmon ArmBritish Columbia, CANADA
    Status: offline     		Looking at my two-stroke dirt bike, it seems that other industries have adapted to the fact that a tuned pipe does not have to be straight. We should be able to come up with some sort of turned pipe that folded back on itself to provide the length required and still fit in front of the firewall. Anyone out there have some talent with a TIG welder who wants to build the next "must-have" giant scale RC product should get busy!

    (in reply to dick Hanson)
           Post #: 38

    RE: <span class= - 12/17/2003 3:15:16 AM   
    Herby 1


     

    Posts: 10
    Joined: 4/26/2003
    From: Northern Arizona
    Status: offline     		Sorry guys, I don't get the BIG deal..... An old loose G62 will turn a 22-10 Zinger 7000 rpm all day long, with no pipe at all....40 lbs thrust ? My spring scale on a G62 at that rpm with that prop shows 28 lbs.....How come a 22-10 Menz has 40 lbs thrust ? A good customer told me his G62 shows 34 lbs thrust with a 24-8 prop, don't know the rpm..
    FWIW..The ThrustHP chart shows about 37 lbs thrust, and we all know it's wildly optimistic...
    Color me confused
    And the "top" for a G62 is 13,500 when it's in the chainsaw...
    We run G62s in our racers at somewhere around 9000, no pipe, just an 8 inch straight pipe...
    I guess the extra 4ccs puts it in a different class....
    Just got a report from a customer..G62, 22-8 prop, Mac's pipe not really tuned yet, 8000 rpm...

    (in reply to dick Hanson)
           Post #: 39

    RE: <span class= - 12/17/2003 4:15:32 AM   
    DKjens



    Posts: 2086
    Joined: 2/10/2002
    From: Pasadena, CA, USA
    Status: offline     		Well, here are my engines for the next 3 planes. The MVVS2.15Gas on the 35cc Macs pipe turns the Mejzlick21x8 at 7000 and is going on an OMP 80" Edge540P that I will be building over tthe holidays. The DA50R has only has 14 oz of fuel through it, and will go on my 3rd DiablotinXL that I am getting in January/February. The can is a KS60. The MVVS58i is going on my Wild Hare 28%Edge540T, that I should receive this week. I hope I can fit that can in it, it's a JMB80/70/400 so it should let the engine breathe quite freely and be quiet.
    DKjens