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Old 05-27-2004, 11:13 AM   #16
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Quote:
Originally posted by rodneybarrett


We also discussed what it really buys us in the RC world since our engines work off of taper. We kinda concluded that yes, the piston may be better than a typical cast one but the sleeve is still the same so you might not gain that much of an advantage.


Who knows, we could be way off base. maybe someone can confirm or discredit it.
From our expirience, piston material is one of the most important element in engine performance. Yes, sleeve material is important too, but I personaly preferd to put in front of everything Piston material.
I am sure you saw already that most of the latest engines ( in RC cars) are used Brass sleeves and only one thing is realy changing is Piston material ( I am not talking about latest work from Novas and Sirio on AAC).
From thousands experiments in Former Soviet Union was found, much better result (performance and reliabilty) are comming from not brass, but from BRB and AAC. As I explaned in some other thread, there are some realy "hot" disadvantages of AAC on particular engine' arhitecture.
So to stay on low cost of manufacturing, the best way is regular brass for sleeves, but the best results been done on BRB so far.
I am not familiar with real engine manufacturing, but I am sure it is realy different aplication and not everything may be just small things can be apply to our engines.
No words about technology of casting pistons
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Old 05-27-2004, 03:07 PM   #17
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Exclamation I have tried the difference....

I had Novarossi NS12S3 (CLASSIC PISTON) AND THEN NSR12S3 (MICROCASTED).
A lot of friend of mine raced this last months with these two engines...... and we all have THE SAME "IMPRESSION" (
It is difficult to say
....but the microcasted piston .... that is presented from novarossi as more durable
It last much less that the classic tipe of piston
Maybe Novarossi had something to correct in the microcasting process.... but this is the reality.
Novarossi .12 microcasted worn more quicker than the classic type NS12S3!!!

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Old 05-27-2004, 03:12 PM   #18
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Default Re: I have tried the difference....

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Last edited by Top Gun 777; 05-27-2004 at 03:17 PM.
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Old 05-27-2004, 04:13 PM   #19
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Default Re: I have tried the difference....

Quote:
Originally posted by mariochi
I had Novarossi NS12S3 (CLASSIC PISTON) AND THEN NSR12S3 (MICROCASTED).
A lot of friends of mine raced this last months with these two engines...... and we all have THE SAME "IMPRESSION".........
It lasts much less than the classic type of piston..............
Maybe Novarossi has something to correct in the microcasting process.... but this is the reality.
Novarossi .12 microcasted wear more quickly than the classic type NS12S3!!!
Putting aside the durability issue, did you noticed any performance difference between the two types???? Or they perform similarly.

AFM
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Old 05-27-2004, 09:04 PM   #20
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Putting all this into a single list plus some

Novarossi's Microcast we believe is a Powdered Metal technology. yes it is common to use alumunium with higher silicon content than can be conventionally casted with a molten alloy. PM provides better dispersal in most cases of the silicon component therefor making the piston harder and more stable.

Hypereutetic and eutetic alloys are similar to what has been used for years as a high silicon content 5/6/7 series type alumunium and silicon dispersal becomes difficult above 23%. Remember SI makes it growth stable and wear resistant but reduces ductility.

Duralcan or Duralumunium is what I believe was being used prior to novarossi's microcasting but I cant be 100% sure.

so all that being said is one better than the rest?? that depends.

yes and no.

you will also notice if you study alot of engines that tapers on the liners change from time to time as does the hone finish on the liners depending on what is trying to be accompolished. You would be suprised how much minor measurements change within runs of one engine. This is the little stuff most people don't know to look for and the difference is a rocket or a turd.

The bottom line to all of this for anyone involved in production engine development is.

Will the engine maintain compression at temp with minimal piston to liner drag, minimal piston mass and survive a reasonable lifespan without exploding.

All that being said
Bottom line is this how good is your engines compression cold after the piston to liner pinch has faded, then how good is it after it is shut down at 250 degrees. If its as good hot as it is cold then the thermal expansion of the piston liner and case is a well balanced combination. The trick is to make it last that way the life of the engine. This will allow the engine to rev hard and have maximum pop off the corners with a stable Idle. That is the bottom line no BS answer to the question you asked and what all the engine manufacturers are looking to achieve

A hard structural bronze with berullium added as a structural stabilizer with a high SI content piston is desirable as TG 777 is producing. The only downside is Berullium is expensive and it is toxic if you were to inhale the dust when grinding on it. Kinda like asbestos (Model boaters know this as we use Berullium copper propellers and take appropriate cautions when preparing them)
I personally had never considered using berullium as a liner material before but it does make sense due to its structural properties (TG nice work) However don't expect to see it in high volume production soon as it is quite cost prohibitive.

I personally have been considering some piston coatings recently in leiu of high Si content. (vapor deposition technology has drastically improved in recent years)

On a sleeve type engine I would not even consider AAC as there are to many draw backs with an alumunium sleeve on an alumunium case particularly aluminum fretting and brinelling causing glow plug contamination.

TAW
an interesting technology we developed to reduce ring pound out even with Hypereutetic pistons was groove welding and remachining. It is used extensively now in the auto industry.
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Last edited by Motorman; 05-27-2004 at 09:13 PM.
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Old 05-27-2004, 09:25 PM   #21
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Motorman: Thanks for the info, that helps explain the technology.

now......

I feel like I have jumped off the diving board on the deep end and can't get back to the top.

Bottom line:

Is this microcasting a bunch of crap of does it have merit?

Can anyone answer that?

I don't want to spend $250 for an engine for it to be a dude. Nor do I want to sacrifice longevity for that extra little 2% performance gain.
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Old 05-27-2004, 10:44 PM   #22
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Rodney,

the engine that I sold to Troy is the fastest .12 I ever laid my hands on and a LOT of people came to me after the race I ran it in and asked me where they could get one.
This motor was faster than any modified .12 I have ever seen, maybe except Swauger's at Ft.Myers.

What makes you think it could be a dud?

No matter what the pro's opinions are here, the microcast piston seems to work very well in this particular set up and all the theory you are asking for won't change a thing.
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Old 05-27-2004, 10:51 PM   #23
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Hey Stefan.

good to hear from you.

I agree, Troy's motor you sold him is very strong. My definition of a "dud" was if it won't last very long then that's not good for me.

Some folks are already saying that they don't even last as long as the normal P/S.


Just wanting to get all the info I can before buying my next engine.

l
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Old 05-28-2004, 12:06 AM   #24
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Hi Dennis. I agree with you 100% on everything. Actualy yuo finalize what I was putting in different treads around.
In our opinion, that microcasting alloys will not add a lot of power.
As I mentioned before there is techology to cast AL alloy with desirable properties and in combination with right leaner material and right tapering it will improove performance tramnedosly.
Yes BRB is very expencive material. but so far we are manged to have at reasonble level. I am not planning to flood with BRB sets, it is my hobby, I love speed and performance and it is so much difference in performance between brass and BRB, hard to belive.
About AAC-in conventional design engines it is totaly nonsence to use it ( it has been prooven years ago) and I have mentioned in the past the reason for it. We discover this interuption back in 1990's.
This is why we came to design Palmaris PS12. I don't have parts which are vibrating and creating AL debry and light up in combastion chamber raise temp, burnglow plugs etc).
I am sure pretty soon more brands will come up to the same schematic ( ones they will find the way how to cast cilinder).
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Old 05-28-2004, 12:28 AM   #25
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Quote:
Originally posted by rodneybarrett
Is this microcasting a bunch of crap of does it have merit?

Well on this question, will be very dificult to answer.
Novarossi very popular brand and to stay on the top, they have to make improovments preety often or they will loos their positions.
I am sure you saw JP's flying and screaming, but also I am sure you saw ( I saw many times) when JP was slow as HPI.
On other hand, I will not sugest to compare team engines to regular poduction engines. Ths is why they are team egines-drivers will show you how fast they are, but pretty often it is driver, not an engine.
Bary Bekker won Speed Line in Las Vegas on Sirio ( I belive this info was correct in other tread) and he was running against Newest team X12 JP ( Mike Swager) and other guys who used newest engines.
So who can answer you this question?
I personaly don't belive in Microcasting, but I might be wrong.
We never were able to get out of powder Alloy results ( not in performance , not in life)which we got from our casting pistons. And it was spent years of trials.
BTW, I am changing conrods after at list 3 gallons of fuel first time
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Last edited by Top Gun 777; 05-28-2004 at 12:35 AM.
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Old 05-28-2004, 07:43 AM   #26
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to prove what i said, picture of piston with traditional casting and other advanced process.
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Old 05-28-2004, 07:45 AM   #27
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sorry how do you post pictures
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Old 05-28-2004, 09:12 AM   #28
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in the post reply window(the windows after you hit post reply), there is a attached file boxed at the bottom. Scroll down and you should see it.
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Old 05-30-2004, 07:12 AM   #29
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Default Re: Re: I have tried the difference....

Quote:
Originally posted by afm
Putting aside the durability issue, did you noticed any performance difference between the two types???? Or they perform similarly.

AFM
Well, I will be sincere
It seems to me that there isn't much difference of power between them.
It seems to me that , after one hour of use, the microcast is more "powerful" but i think more probably is my impression beacuse I bought a new engine after some months of use of the precedent (ns12s3 not microcasted).
TO BE CLEAR:
Now I have purchased the set piston + sleeve NOT MICROCASTED.
BECAUSE :
IT IS CHEAPER (20EUR LESS)
i THINK IS MORE DURABLE......

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Old 05-31-2004, 01:24 AM   #30
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Ciao Mario.

That's just what I've been thinking, I have a NSR12S3, that I bought in Dec. after about 2 1/2 gallons it lost performance. I put the Rex counterpart microcast piston and "fanged" sleeve, mine ,ust've been an early model because the sleeve looked like a MR12's sleeve. It's taken awhile to break in, but it's really coming around now after about 10-15 tanks .

The best thing I've found about this P/S combination,( the micro cast piston and whatever y'all say the sleeve is made out of), is that if you die in a race, when that muther's hot, it fires RIGHT back up and runs well.
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