f2racer

Just visited the Morris Hobbies and saw that MVVS is doing a 58cc gas engine!!! Site says that it's going to be as powerful as most 80cc and only weigh 3lb 13oz.

Charley

My Feedback: (2)

I took a look, since I have a 1.6 & a 2.15. The 58 is rear intake & looked good to me until I realized it has reed valves. I don't care much for reed induction.

The engine will compete directly with the ZDZ 60cc which has disk induction, a thing I believe to be better than reeds.

My .02,

CR

Diablo-RCU

My Feedback: (1)

Thanks for the news. Looks like it has great potential. Guess it will have either a Vlach or Falkon ignition from the plug shield. I wonder if the weight is engine bare.

captinjohn

Charley: What are the downsides of reed valve engines? On motorcycles the reeds give lots of torque. Thanks John

Charley

My Feedback: (2)

Captin,

The downside of reed valves to me hinges on maintenance issues. Reeds can break, or go soft and leak, or stick shut when the engine is stored for a long time, etc. When I was a Go-Kart racer I ran into all the above at one time or another.

Rotary disk valves don't have these issues, give more precise timing and allow higher engine RPM. However, disk valves add complexity, weight and cost. Tradeoffs.....

Before someone tries to start a war, I'm aware that there are plenty of reed valve engines out there and I'm not going to argue about it with the reed valve proponents. ;^)

Cheers,

CR

captinjohn

charley: I was just wondering. I have had only piston with port timed RC engines. Except for Saito 4 strokes. I wish a engine like a 4 stroke connley with 4-5 valves per cyl and equiped with needle and ball bearings would be developed. The sound of a good four stroke, with power and would burn gas instead of high priced glow fuel. In time it may happen. Space age materials will make it possible. Any Ideas???? Thanks John

Jemo

My Feedback: (5)

How do you make a 58cc engine more powerful than a current 80, such as the ZDZ 80.

Diablo-RCU

My Feedback: (1)

More power is possible through better porting, assuming it's going to operate in the same rpm range. You can make power from displacement, cylinder filling, or rpm. I doubt it will have the power of the ZDZ-80. Maybe equivalent to a Zenoah-80? Time will tell. The claim of 7,000 rpm on a 22x12 prop for the MVVS-58 is about the same as figures posted on the Amelung Modellbau site for the ZDZ-60. More choices are always good.

f2racer

I spoke to Robert over at Morris Hobbies regarding this engine. It's still in early stages of development, but shows enormous potential. The engine uses some design elements (especially porting) from high performance 2 stroke motorcycle and carting engines. It is designed by an engineer who also developed engines in the European carting circuit. A weed whacker convert it ain't. It'll be a while before any production units are available, but Robert is very optimistic about this engine. He realizes the limitations of MVVS's prior gas engines and says this offering should put MVVS in the same category as the likes of ZDZ... Ain't competition great?

Charley

My Feedback: (2)

Captin,

Aw, don't mind me, I din't mean to offend. I just didn't want to get into it with reed valve lovers.

I loooved that hype on the Morris Hobbies site about this 58cc being more powerful than an 80cc. Riiiggghhhttt! Typical...

A flying buddy bought a Fuji BT-50 (actually a 46.5cc). I looked it over carefully. The carb is mounted on the side of the case and there are no reeds. It uses the piston skirt to open and close the port into the crankcase, under the carb. Interesting.

I had a Conley 1.20. It was serial # 27. I flew it in an Ace 4-120 bipe. Adequate power, started easily and it got a lot of comments at fly-ins. The down side was that the timing belt would jump a tooth now and again. Then I'd have to take it off the airplane and retime the cams. Bummer!

I got sick of that and sold the engine to a German collector. Got a Saito 1.5 on the bipe now.

Cheers,

CR

Antique

My Feedback: (4)

UH...The carb on a fuji 50 is mounted on the side of the cylinder, just like every other piston ported engine ever made...

captinjohn

:surprised Double uh uh!!!!

Charley

My Feedback: (2)

Huh,

Now I'm going to have to go back and look at it again. It open the port under the carb as the piston is on the way up and it was fully open at TDC. Looked to me that the port was into the crankcase. Are you sure you guys aren't splitting hairs?

CR

Antique

My Feedback: (4)

Could be..The carb is on the cylinder..There is a passageway in the cylinder that goes into the case, Hence "piston port"..
Any carb mounted to the case would need a reed valve underneath it.....

captinjohn

charley: Did you go back and look at that engine again. Was wondering what you came up with. CaptinJohn

Charley

My Feedback: (2)

Hi Cap,

Iwas over to my friends houde yesterday PM. He needed a long drill bit that I have and somwe help making a servo mount in hisnGP Pitts.

I looked down thru the carb, can see the base of the piston and the ring, can't see the crown or skirt. There's a phenolic block under the carb which seems to have curved passageways in it to match the cylinder casting underneath.

I think you guys were right, the carb is ported into the cylinder. I wish the engine was mine. I'd have that carb and block off there in a flash.

I've been searching the net for typical specs on this kind of setup. I get the impression that this works well for engines that don't have to have a large power band.

Vat'cha 'tink?

CR

captinjohn

What I think is this.... The insulator block is needed so heat does not soak back into carb after you shut down the engine. If the heat gets to the carb it will perkolate the fuel and restarting will be hard untill carb cools down. Now, when running the carb and intake should be the coolist part/place of engine. The incoming air and fuel does the cooling. Charley what did you have in mind when you said" I would have that carb and block off there in a flash?? You may have a good idea, lets here the rest of the story. Paull Harvey AKA Captinjohn

Charley

My Feedback: (2)

Cap,

I know why the insulator block is there but I guess I didn't make myself clear. Here's the point. Because of the angle of the opening in the block and the intake passages, one can't see into the cylinder or crankcase. I meant I'd remove the carb and block to satisfy my curiousity if the engine was mine.

I've been building and modifying engines for most of my adult life, so I'm not afraid of a little disassembly.

CR

captinjohn

charley: Maybe there is a website that shows a exploded view of the insides of the engine. Happy hunting.......Cap.

f2racer

I just saw on the Morris Hobbies website that the new 58cc gasser will use DIRECTIONAL PORTING CHANNELS. What are they and why will they make this engine more powerful than others in it's displacement range?

Diablo-RCU

My Feedback: (1)

Directional porting is advertising lingo. ALL porting is directional, designed to direct the fuel mixture into the cylinder so that the cylinder gets filled and not too much escapes out the exhaust. Only time will tell if the MVVS porting is any better than the rest.

When I checked your weblink I saw that they are trying to differentiate thier porting design from the "open port" design shown for one of their competitors. Not sure who uses that "open port" design, but it's not a 3W. It's interesting that MVVS is using an aluminum connecting rod - others use a hardened steel rod so that caged needle bearings can ride directly on the rod surface. MVVS must use a bearing with an outer shell of steel. Also, I notice what appears to be a nylon stuffer plate bolted to the crankshaft web - to reduce crankcase volume and to help pump mixture into the cylinder.

Charley

My Feedback: (2)

F2,

The above means that the passages (channels) to the ports are shaped for optimum flow to the intake ports. Also the ports will be shaped to swirl the intake charge into the cylinder, sort of up and around, so as to fill the top of the cylinder, avoiding the exhaust port, to help scavenging.

Did you ever hear of the HB engines with Perry Directional Porting, or PDP? I have a .40 PDP.

Cheers,

CR

captinjohn

MY guess is that some of the chainsaw engines are ported for high power. Of coarse a person can always enlarge, polish match carb and gaskets to intake better. Anything you do to get the fuel/air mixture in the engine better and out with a good exhaust system will help performance. Tunned pipes can really help too. I wish more was offered in the way of super good and lite exhaust parts. Also they got to be compact as possible. Thanks Captinjohn

rmh

The ZDZ rods are all aluminum --at least all I have seen - original were cut from bar stock - current are formed.
Porting is interesting subject - I was frankly amazed when I looked in, at the porting on the new ZDZ50 - also the latest 210-
-The new MVVS looks to be from same school of thought.
Way back when - the new Perry porting and the Scneurle engines wer "assumed" to be rpm engines and the old simple square cut ports were "torquers" - because they ran at low revs.
The old stuff was just slow .
I LOVE these new designs - -I would have a hard time accepting less.

captinjohn

Dick: For the rest of us that does not have a 50 to look at the ports....please post some photos if you can. Thanks Captin John