MVVS 2.5 (.15)    Gallery
View related threads: (in this forum | in all forums)

Logged in as Guest



Users viewing this topic: none
    Search This Thread  
 
Printable Version

All Forums >> Glow Engines, Gas Engines, Fuel & Mfg Support Forums >> Tachometer Readings >> MVVS 2.5 (.15)
Page: [1]

Tower Hobbies Get Coupon Codes Brands  
Login
Message << Older Topic   Newer Topic >>
MVVS 2.5 (.15) - 11/13/2012 4:23 PM   
aspeed


 

Posts: 896
Score: 105
Joined: 7/14/2011
Last Login: 5/19/2013
From: Ruthven, ON, CANADA
Status: offline 		Same 7-5" Master Airscrew as my other .15 tests.  10% nitro, has a rotatable exhaust with the side exhaust being used as the muffler is set up for that.  I opened it up and noticed the ports don't line up properly for side exh. but the rpm's were the same with rear exh. and side exh. anyway.  I am kind of dissapointed it barely made 14,000 rpm.  with or without muffler. My MVVS .21 was so good, I thought this would be too. The muffler is pretty quiet though.  It has an rc carb around .196" dia. with an airbleed that doesn't idle too well either.  Swap meet item, good compression, looks good.

< Message edited by aspeed -- 11/19/2012 9:30 PM >

Hide Signatures
       Post #: 1

RE: MVVS 2.5 (.15) - 11/13/2012 7:44 PM   
Mr Cox



Posts: 2902
Score: 102
Joined: 7/20/2007
Last Login: 5/19/2013
From: Karlstad, SWEDEN
Status: offline 		The half-pipe gives a little better performance than the muffler. I think they stopped making the mufflers near the end, and supplied all with the half-pipe.

Hide Signatures

(in reply to aspeed)
       Post #: 2

RE: MVVS 2.5 (.15) - 11/13/2012 7:59 PM   
aspeed


 

Posts: 896
Score: 105
Joined: 7/14/2011
Last Login: 5/19/2013
From: Ruthven, ON, CANADA
Status: offline 		I think it is the half pipe.  It doesn't lose any rpm with it. It is made of tubing not a casting.  It just seems slow to me,  An OS LA is faster on that prop at least, really everything I have that size is faster except the Thunder Tiger.  Maybe I will check the crank timing, the exh timing is around 160 degrees which should be ok.

Hide Signatures

(in reply to Mr Cox)
       Post #: 3

RE: MVVS 2.5 (.15) - 11/13/2012 9:05 PM   
Mr Cox



Posts: 2902
Score: 102
Joined: 7/20/2007
Last Login: 5/19/2013
From: Karlstad, SWEDEN
Status: offline 		It sounds like there is something wrong, it should do a lot more than 14000rpm on a 7x5 prop.

Hide Signatures

(in reply to aspeed)
       Post #: 4

RE: MVVS 2.5 (.15) - 11/13/2012 10:12 PM   
aspeed


 

Posts: 896
Score: 105
Joined: 7/14/2011
Last Login: 5/19/2013
From: Ruthven, ON, CANADA
Status: offline 		I checked the crank timing, it is likely that.  I think it should usually be 40 deg. after bottom dead centre and about 60 degrees after top dead centre.  It is opening "about" 48 deg. after BDC and 40 deg ATDC closing.  I think the closing should be ground a bit (a lot) and the opening timing is too far to grind.  The headspace worked ok at .015" to .030" with little measureable difference.

Hide Signatures

(in reply to Mr Cox)
       Post #: 5

RE: MVVS 2.5 (.15) - 11/14/2012 6:55 PM   
Mr Cox



Posts: 2902
Score: 102
Joined: 7/20/2007
Last Login: 5/19/2013
From: Karlstad, SWEDEN
Status: offline 		Which engine do you have, is it a very early model?
It might be designed for moderate rpms and then I don't really see anything wrong in those timing numbers. I think the opening is not as critical as the closing is, and the closing depends on the rpm region you want to operate in. Opening at around 50° ABDC is quite normal. Closing at 40° ATDC indicates that it is set up for low revs i.e. <15000rpm. A closing at 60° would then be setting it up for >20000rpm which would be a totally different engine. What are the exhaust and transfer timings?

Hide Signatures

(in reply to aspeed)
       Post #: 6

RE: MVVS 2.5 (.15) - 11/14/2012 8:30 PM   
aspeed


 

Posts: 896
Score: 105
Joined: 7/14/2011
Last Login: 5/19/2013
From: Ruthven, ON, CANADA
Status: offline 		120 deg. transfer and 160 exh.  I am guessing 15 years old, but have no idea. So I guess just run an 8-4 or so on it.

Hide Signatures

(in reply to Mr Cox)
       Post #: 7

RE: MVVS 2.5 (.15) - 11/19/2012 9:29 PM   
aspeed


 

Posts: 896
Score: 105
Joined: 7/14/2011
Last Login: 5/19/2013
From: Ruthven, ON, CANADA
Status: offline 		I changed the closing timing to 55 degrees after, and it goes 16,200 rpm, peak without the muffler, but doesn't stay there.  It sags back to about 15,500.  The bearings are a tight fit too, it needed another shim.  It seems to want to go 14,500 with the muffler.  I guess it isn't worth making a plane for.  It sure looks like a fast motor, maybe someday I will try some different props or something.  Blew a plug too, Probably my fault for squeezing it too lean for some numbers.

Hide Signatures

(in reply to aspeed)
       Post #: 8

Page:   [1]
All Forums >> Glow Engines, Gas Engines, Fuel &amp; Mfg Support Forums >> Tachometer Readings >> MVVS 2.5 (.15)
Page: [1]





Jump to:


 
Google 



Search | Marketplace | Event Calendar | Local Clubs | Magazine | Product Ratings | New Products | Discussion Forums

Photo Gallery | Instructor Search | Field|Track|Marina Search

Advertisers | Hobby Vendor Resources | Rate Manufacturers | Sign In/Sign Up

SITE MAP!   : :   FORUM RULES

RC Universe is a service of Internet Brands, Inc. Copyright © 2001-2013.

Charities we support that also need your help
Yorkie Rescue | Humane Society | ASPCA | Crohn's-Colitis America


1.500RCU1