Mvvs .49
 

After helping a friend run-in his new Green-Head, 3219 carb, MVVS .49, we tached it.

On 5% nitro 20% oil Model Technics (UK) fuel with the 3248 tuned muffler installed, unaltered, this engine spins a Master Airscrew G/F 11x6 prop at 14,800 RPM.

Is this a bear, or what?

Mvvs .49
 

11*6 apc @ 11000 on ground , using 80/20 fuel.

tried the 10*6 at 13000 rpm but could not fly because it would unload further and lean out.

also tried a 11*7 but dropped rpm to 10000 only and really bogs down the engine.

exhaust is quiet type 3245A.

still pretty new (not even a gallon through yet) . maybe it will a bit better as my other engines did .

this is the newer version with the blue heat sink head.

MVVS .49
 

Bobi,

How did you break you engine in??? If it is not broke-in properly, even 3 gallons will not get it to run right.

Read this:

http://www.rcuniverse.com/showthread...59&forumid=145

If you didn't do it that way, do it. You may have damaged your engine. All the "experts" who have learned everything they know from breaking-in ringed engines, cannot help you and do not understand why non-ringed engines need a hot break-in.

An ABC/ABN engine is fully broken-in within one QUART of fuel, sometimes a little more. It gains virtually no power afterward.

Your engine should get about 12,300 with the #3245 and an 11x6. Maybe a little less with the quiet #3245A type.

Sincerely,,

Mvvs .49
 

Zar

i did the break in for 4 tanks ( 320cc ) on ground and then i am flying it already. about 10 flights to now.

the carb is a 3216 and not a 3219 so the rpms will be a bit lower .

Break-in of ABC engines
 

Bobi,

The question was not about the amount of fuel used during break-in, but about the technique.
ABC engines, like your MVVS, need a hot break-in, like I described in the thread. If you did a cold, four-cycle break-in, your engine is not broken-in. It may even be broken-down.

Do read the thread.

My .49 has the #3216 7mm carburettor, just like your's.
This unit is prefered for fun-fly, because it has better transition.

My engine's performance is typical.
What you now have is substandard.

Sincerely,

Mvvs .49
 

Dar
been running it 2 cycle speed at various speeds at wot.
i was expecting it to do ~12000 with 11*6 after seeing 13k with a 10*6.
Peak is ~11.4k but back off to 11k.
i am running a #4 enya .. maybe it is not hot enough ... had this on hand.
need to change to enya 3 or os8 and will check again.

MVVS .49
 

Bobi,

My engine (it is mounted in my daughter's WM Worldstar 40) is still running with the originally supplied plug. I believe it is a Novarossi No.5, or 6. It has over 30 hours on it and it has not shown any signs of its age yet. BTW, I am using fuel with 5% nitro and a synthetic+Castor oil mix (20% total).

I don't think the Enya 4, 3, or the OS No. 8 will have such a profound, negative effect on RPM.

I cannot believe the quiet #3245A muffler has so much negative effect. Can you borrow a standard #3245 muffler from someone, just to check the RPM with it?

I once added an exhaust deflector (Hobbico) to the muffler outlet and got 1,000 RPM less; 11,300. Maybe it is the quiet muffler after all.

Please elaborate on how the engine feels; cold compression, cold "pinch" at TDC (remove the plug to check), hot compression, are you using pressure from the muffler?

Sincerely,

Mvvs .49
 

The extra muffler chamber on the A-types is very restrictive.
This is not a bad thing, because it helps us save our fields.
However, if you start comparing rpm with non-muffled engines, things get hairy.
The extra muffler chamber is glued to the silencer. Once you remove the three screws, and carefully file away the end crimp, you can heat the assembly, and wiggle it off.
If you do not like the unmuffled noise, you can always glue it back on again.

Mvvs .49
 

Gentlemen, I have a question, if I may... I've got a .49 w/the 7mm carb. I saw 15,100 w/ an 11x5 MAS after the 2nd tank...That's w/no muff. (rear exh.) Then I added a Mac's fuse. top header, and saw the same R.P.M. My question is, is the header too long? Should I have seen an increase? Do I start trimming it down 1/4" at a time and look for an increase in R.P.M.? Any suggestions? (that's w/ 10% nitro, 18% oil, synth./castor blend) Thanks. (p.s. I plan on using an APC 10x7 or 8, in a modified G.P. Patriot)

Nitro...
 

Proptop,

MVVS are high compression engines, recommended to be run with no nitromethane at all. It is us, poor Asians and Europeans you should blame for that....

10% nitro is borderline high and I would say a little too high for this engine.
The maximum you should use is 5%, for added reliability. It will lower your fuel cost also.

About your pipe. Why would you use a Mac's? MVVS makes full length pipes and tuned-silencers, especially suited for this engine.

The MVVS exhausts are claimed to be effective in the 10K-14K range.

My own experience tells me the range is larger and you can add a little more RPM and still be in the range.

I would also say the engine is built to be at its best at about 14K; all timing numbers and sizes taken in account. You should load it so it will spin at about 14 K, 11x7, or 12x5 will do that.

Generally speaking about lengths of tuned exhaust systems; if you are getting the same RPM from the piped setup, that you got from the open exhaust, you are quite close to the right length.

It shows that the pipe (which is also a restrictive muffler, with a very small outlet) does not affect the RPM. So it is boosting enough to overcome its own restrictiveness.

So had it been any other engine, because you are close to ideal length, I would suggest cutting 1/8" at a time, off the header and moving the pipe forward to take up the amount cut.

If you see an increase in RPM, cut 1/8" more and try again, until the next cut gives no increase, or a very slight drop.

You must judge by the needle; if you have to lean the mixture to get on the pipe, but must then richen it back to prevent a lean run, your system is too short and your engine's life is in question.
You must lengthen it until it "naturally" gets on the pipe, even when about 1/4 turn rich.

Because this is an engine I would not think of hearing at 17K, I used "had it been any other engine".

Sincerely,

Mvvs .49
 

Dar, and other posters,
I would like you to take notice, that the engine is designed for the lower RPM range, at around 12000, using props 11x7 12x7 12x6. That is where the engine is most happy. All extra option pipes from MVVS are carefully tuned around that figure, and allow the appropriate amount of unwinding in flight, up to around 14000.
If you prop the engine this way, it has massive pulling power, only bettered by high performance engines screaming at the top of their lungs.
Idle can be as low as 1000 rpm once dialed in right.

Mvvs .49
 

Thanks for the Tip Darzeelon. Just last week I was thinking about acquiring the MVVS 49. I didn't realize it was a high compression, low to no nitro burner. I guess one could always shim the head.

Anyways, I decided on that new Magnum XLS-52. :)

Happy Flyn...

MVVS .49
 

PepeJ,

I know I was not telling you anything that you didn't know before... Yes, you can shim the head, but what for? To use more expensive fuel, just for the sake of it?

Pe,

I know most MVVS engines are not intended for very high RPM.
The .49 excels with largish props at low and mid RPM.
Although it is rated by the manufacturer at 17K, it is really a waste of time to race this engine against Rossi .53, YS .45, Jett .50 and the like.

Apart from the MVVS .61-.91, which really excel in the up to 12K range, the .40G S/R to .49G S/R are great up to about 15K, even with the OEM tuned pipe, or silencer. You can always shorten the header a bit to fully awaken it, if it is a bit drowsy.

Since Proptop wants to get the very best from his MVVS in the top of its range, I was trying to best coach him on this issue.

Sincerely,

Mvvs .49
 

Dar,
Please do not get me wrong; I did not doubt your good advice so far, and you seem to have lots of personal experience with MVVS engines.
My experience is, that the .40 and .45 gladly turn higher rpm, and that the .49 I ran liked to be set up around 12000 static for good all round performance.
I noticed that the newly delivered .49 engines have the top of the exhaust port widened and the port bottom narrowed, with the transfer ports area increased snug against the exhaust port.
I have not tested it yet, but it may be a power and power range inprovement in an engine that was not bad at all to start with.

MVVS .49
 

Hi again, Pe,

Of all the engines I have seen from MVVS the .49 came in more varieties then the others. I have one, in my daughter's 170cm span trainer, with an annular, side ribbed, neutral head and a #3216 carburettor. I broke-in one with a green anodized, lengthwise ribbed only head, and a #3219 carburettor.

It showed 14,800 RPM with a MA 14x6 prop (#3248 tuned silencer).

Now the new models have the blue head and the I-don't-know-what's-new carburettor; maybe you can elaborate on that.

My .49 gets 12,400 RPM on the MA 11x6, with a #3245 muffler.

I would put its ability at "low to medium-high" RPM, not into Jett territory.

Sincerely,

Mvvs .49
 

I'm a little (?) confused now...I didn't think this was a "torquer" engine! Wasn't expecting screaming R.P.M. either, but somewhere around 15 to 16,000. I read, in the engine forum, that the newer batch of .49's made since mid '02 have a harder piston? And were more capable of handling up to 15% nitro...The smallish (7mm) venturi did suggest tho that hi rpm should not be expected. I matched the transfer ports in the upper cyl. case to the crankcase when I rotated the cyl. 90deg. for R. exh. and am pleased w/ 15,100-200 w/the break-in 11x5 prop it had on it. Would a pipe intended for a 7.5cc eng. be better for torque, or a slightly larger one? I didn't get the MVVS one because it wasn't available at the time, and I already have a Mac's pipe for a 7.5cc eng. I think I'll have to experement w/ different props to get just the right one(naturally) but was wondering what you all might have to say...Thanks, Tom.

MVVS .49
 

Proptop,

15K-16K IS screaming RPM.

Most sport engines are between 9K and 14K.

You can listen to replies in the thread, especially to Jan K and you can, or should, experiment yourself.

Why would you waste your time and your money, forcing an engine designed to run on inexpensive, no-to-low nitro fuel, to run on more expensive higher nitro fuel?

If you have dead cash lying around, just send it to me. I will have much better use for it.

A 7.5cc pipe will do the job, although it sounds smallish, for an 8.0cc engine, but most pipes are made for a range of sizes.
This size should be good for 6.5-8.5cc engine (.40-.53"), unless its manufacturer specifically says otherwise.

Sincerely,

Mvvs .49
 

Good post Dar,

I will check out the engine and post a picture of the sleeve. It has the 7mm , new 3216 design carb with the "trumpet mouthpiece" tapered inlet.
Reports on this carb have been very positive.

Proptop,
MVVS always has used quite hard materials. That is why they are so long-lasting, and need a bit longer to run in well.

Mvvs .49
 

The complete engine

Mvvs .49
 

The sleeve and combustion chamber.
The top of the exhaust port is arched, with apex in the middle.
The very wide transfer port directs the flow to the cylinder centre line

Mvvs .49
 

Thanks for the info guys...I just want to get max performance out of it...I wish I had extra cash lying around, but then, it wouldn't be lying around very long!:) preivers, that looks like mine, but my head and prop driver are natural alum. Wish I had the blue anodizing, that looks cool! I run everything on 10%, because it's the most common fuel 'round here, it's not too much, but enough to do something, ya know?! I'm going to prop it for best over-all perf. w/o working the eng. too hard, or wasting it...10% goes for 12.95 per gal. in central N.Y. what do you guys have to pay?(just curious, if you don't mind me asking) I know nitro is hard to come by, or even illegal in some countries, isn't it?

MVVS .49
 

Proptop,

Like you, I also have the previous .49, with the neutral head.
It is a great engine, but as Preivers elaborated, the new model is a redesign, not only a paint job.

If MVVS went into the trouble to redesign this engine, with it being such a great engine before, it must be a real world improvement.

Sincerely,

Mvvs .49
 

Proptop.
Nitro is easy to come by in the Netherlands, but price is about $22.00 a quart, and often it is sold per weight unit, so you get even less volume for the buck. It is expensive, but not prohibitive.
I could trace many tuning problems in notoriously balky MVVS engines to the use of nitro.
Regressing to fresh and plain FAI fuel mostly was the cure-for-all.

I do not know yet what the new porting and toroidal combustion chamber does to performance, but I sure am about to give in to curiosity.

Mvvs .49
 

I have been flying mainly with 2 units of MVVS 45 with a tuned silencer (long black colour) for the past 1 year. And have not facing any problem at all with the exception of the bolt screw at the muffler always keep losing. Almost majority of the flyers in my club are using MVVS 45.

I have been using own blend FAI fuel ie. 0% Nitro, 10% pure castor oil and 90% methanol.

This is so far the best blending for the engine. I have tried using a 10% nitro, 20% oil (synthetic plus castor) and 70% methanol but it is just too hot for the engine to handle. It will cease at midair and this could lead to detonation too.

I am using the engines on World model super sport 40, Hangar 9 super stick, whilst my friends have been using it for Mentor 34, Mustang 40, Super Stunt and a lot more without so much hassle.

My MVVS 45 with a prop of Master Airscrew 11x8 will produced a max of about 11,900 - 12,200 RPM while the idle is around 2,200 - 2,500. As I am not a racing flyer, I would normally fly at a below half throttle and it is good enough for the plane (super sport and stick).

To further keep the engine in good condition, I have been using after-run oil each and everytime after end of the day. For me its better to have oil rather than nothing inside the engine for added protection.

The after-run is also owned blend ie 50% car gasoline fuel injector cleaner and 50% regular automatic transmission oil.

Based on my experience so far with the engine and what I believe is the most important thing to know about the engine is that ---- MVVS really performs best with a 0% nitro and less than 15% oil, in my case it is a 10% pure castor.

Mvvs .49
 

Hi Pe. On the photo it seem there are screws without heads for fixing of the silencer. Is it so?