Schrader

My Feedback: (1)

Novayusa,
Did you use an internal baffle to seperate the two sides?

Schrader

Super08

My Feedback: (2)

Their may be no gain but no loss either. It would be an excellent design for fitting inside of cowls.
Did you experiment with the diameter of the resonator or exhaust stacks?

I see you did run into interference with the carb and had to reverse the cylinders though.

unit53

it appears the rpm,s in novay,s assesmentare on the lower side,,,then im wondering with such a high oil to gas mix,,is he diluting the fuel too much and reducing its combustible power,?,,who knows,,so far it seems the best numbers are coming from using the stock exhaust...and since thers been some changes with the engine what batch did his come from??

PlaneKrazee

My Feedback: (14)

novayusa,

Did you use a baffle to split the muffer in half? I didn't on my first aluminum one but will on the stainless one. Also, did you use 2" or 2 1/2" pipe? My headers are about 2-1/4" longer than yours putting the muffler 1/4" from the firewall in my AW Extra 300.

I'm thinking of bending up a 2-1/2"x2-1/2"x6" stainless box rather than using a tube. It will give a little more volume.

novayusa

Before I post the muffler design drawing here, I'd like to tell the how simple the muffler make is. Just need 2 type diameter of aluminium tube and 1 aluminium plate. One is 22mm, the other is 58mm and 1.5mm thin plate. No baffler in muffler. My purpose just want everyone can build this muffler by yourself  easily.

PlaneKrazee

My Feedback: (14)

Novayusa,

Do you think dividing the muffler in two with a solid baffle would give higher rpm? Larger volume with the same back pressure as the stock mufflers should give the same or higher rpm and lower db.

tomyrcmodels

with plane about 18lb total weight and more than 35LB thurst . much more than enouth power for this plane. so modeller need is the uniqe sound that like big motocycle . power are not the first concer now

novayusa

Lower the noise just need to drill many small holes on tube and smaller the tube exit diameter to produce back pressure to engine. The rpm is decide by the length of exhaust input tube. keep the two input tube at the same condition is important like tube length, numbers of small holes and exit diameter
By the way, The muffler Imade sound like Harley Davidson motorcycle. I think that is not loud and great sound to me

PlaneKrazee

My Feedback: (14)

I see Clive is selling a kit version of the 35 on his website.

PlaneKrazee

My Feedback: (14)

I prefer the sound of tubes thru a baffle vs. drilled holes. Drilled holes have a resonator effect whereas properly sized tubes thru a baffle tune the sound.

novayusa

more device add into muffler need re-calculate more datas and effects. Here Ijust introduce people the simple way to make the muffler to maintain the same rpm with stock muffler at least. You can develope it farther by your own thinking

kochj

I went on MTengine usa, and saw only there 80cc single for sale...

Q....
Anyone one know what there headers are made out of??
THe ones on the website??

I wanted this one...

http://mtenginesusa.com/products.asp...ne+Accessories

If it isn't stainless steel, I am not going to buy it...
No info on the webpage...

Thanks.

jedijody

My Feedback: (1)

Aluminum

mausolfh

My Feedback: (19)

Has anybody had some recent experience with the MT-70 twin. I found out that they are no longer being sold in the USA due to quality issues. I bought two of them from ValleyView RC and they basically rebuilt them before they were shipped to me. This latest revelation casts some doubts on using them on my 120" TigerCat project. The last one I built I used two Fuji BT-64s. They ran great, but had low rpm vibration problems.
Thanks
Hank

tomyrcmodels

when engine runing . vibration make prop hub move up and down or left and right . if prop hub not doing this . maybe the over torque of engine bring this out .

jst

Hi,

Yes I have. I bought MT-70 twin last August 2010 and bolted it straight out of the box on a 1/3 scale cub 2 weeks ago.
I had to reset the engine timing to 28 deg and used a starter for the first few flights but engine ran right off the bat and never missed a beat.
This engine cruised the cub at 1/4 to 1/3 throttle on a 23 x 10 prop. Power was super. I don't have any rpm readings at this time as engine still breaking in.
A bit too early to tell but no problems experienced so far.

Hope this helps, ciao..

unit53

well as one of the first owners in america,,,i can confidently make this statement,,,if,,,,, thats if,,you got one of the engines from valleyview,,you stand a good chance of having a dependable engine,,because its been gone through,,and checked out,,otherwise,,you run a chance of any number of the problems listed in this thread,or in other threads on this particular engine,,and even some that arent listed as well,,,now it would be nice if you had a pair of those g-62 s that ralph c reworks but i can assure you that when the mt70 is defect free,its a reliable good running engine,it would be a real heartbreaker to spend months and thousands of dollars to have one engine sag out a fail on a touchy twin like a tigercat,,i had an esm tigercat with a crappy pair of rcv.s that caused its demise,,one weak engine caused a spin during a turn .

unit53

huh????

72

I have yet to see the manufacturer come on here and say "yes I am fixing all the problems you owners have identified and will sell a reliable engine" I'm still waiting because I would really like one- a reliable one.

libralouis

MT Engine is take action to implement QA procedures in factory now.

unit53

as a mt owner ,,previously stated,,,i would like to know where your source of information comes from? are you associated with mt engines ? and if so this is good news but might be ,what we call over here,,,a little too late,,the qc issues along with potential dealers was shameful..we have been saying all along,,if tommy has the ability to deliver what we have asked for,,he will have a happy customer and dealers waiting to recommend the mt line..

aussiesteve

QA - the statement means nothing by itself

The best that any of the QA systems around the place do is guarantee consistency within defined parameters. That consistency can also be consistently terrible if those parameters are such that they allow a poor end product to be supplied.

What matters is not only that there is a documented QA system in place (which is a great beginning and if the factory does in fact implement it, kudos to them) but also that the QA system sets measurable acceptance and rejection parameters for materials, manufacturing tolerances and assembled items.

Then, and only then, will the product have any hope of being genuinely good.

Tomy - you have my e-mail address - E-mail me if you want me to explain any of it off line to you. I have offered to help you set up useful QC before and that offer still exists.



Here are some guidelines for the factory to consider and I truly hope they heed these

What material is used for each component and are the suppliers of that material trustworthy and with acceptable QA processes in place?
.
Are the materials "Batch recorded" and traceable to point of origin as well as point of exit from the factory?

What manufacturing tolerances are applied to each part? All parts outside those tolerances need to be rejected, no matter how "close" they are.

What Assembly techniques are used for each part of the assembly and are critical tools calibrated by qualified people?

And finally, is the finished item inspected for compliance with the documented processes and procedures and rejected if it is outside of those processes and procedures?

Simple "checks to make sure all the bits are in the box" are not even close to QC - it needs to go far deeper than that and parts need to be traceable and rejected if they do not comply with the requirements.

What has been seen to date is what appears to be a great designed engine that has been a big let down due to a lack of detail on the implementation of that design.

Fix those problems, give confidence to the end users and you wil have a successful product that could wel dominate the market.

Check, double check, measure, reject as necessary and document - those are the key words.

And yes, I AM involved in a company that holds a series of ISO 9000 series (plus others) of QC certifications.

jedijody

My Feedback: (1)

If I had a nickle for every time I've...........

apalsson

My Feedback: (1)

So very true!

ISO9000 and other quality standards on their own do nothing but to at best, lock into place existing practices. The more recently issued standards also include continuous improvement but by merely adopting ISO, you are not fixing underlying quality issues with manufacturing, sourcing or supply.
Quality methods must be established before adopting quality systems like ISO to ensure quality remains consistent and doesn't slip.
Manufacturers that rely heavily on external supplies of parts or materials must also demand the same standards from their suppliers or their own internal quality systems become compromised

unit53

irregardless of the technical aspects of proper manufacturing,,does anyone think they can get tommy to implement theese standards?i can allmost guarantee anyone with the whit and mentality to design and build a model aircraft engine,,should know better