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Old 10-31-2005, 12:23 AM   #1051
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Quote:
Originally Posted by Hesky
It does allow for 20-25% higher silicon content.
I noticed both my jp and rb mod motors have mc pistons with areas of the piston machine finished like the inside of the piston skirt and the piston face, I guess as accurate the micro casting process is it will never cast to desired tolerances.
I feel the micro casting process is a way of reducing manufacturing costs and manufacturing time. more of an economic solution not a performance solution.
Its lighter and is also cheaper to produce but doesnt last as long... All plus points as far as Novarossi is concerned
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Old 10-31-2005, 06:06 AM   #1052
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yup, micro casting is here to stay
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Old 10-31-2005, 07:40 AM   #1053
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This is my take on the microcast piston,
First, most pistons are cast oversize then CNC ground to shape on the outside to achieve the familiar finish. Not CNC'd from billet, as that doesn't give decent performance.
Most cast pistons however have a lower silicon content, as it is very difficult to achieve the ultra high silicon percentages using a std casting method (the blending of silicon to aluminum becomes very difficult above 22% as the silicon doesn't want to blend after this ratio, and requires very costly techniques to force the silicon to bond to the aluminum).
Microcast pistons on the otherhand, begin as a powder with the high silicon content dispersed as a powder with the aluminum powder along with a bonding agent(this allows the silicon molecules to bond properly to the aluminum molecules under extreme pressure). This mixture of powder is poured into the mold and compressed under extreme force and heat to fuse the molecules together to make a piston (in this case microcast could be compared to forging). The benefits to this process is the piston contains a high silicon content (probably around 26-27%) and the piston performs quite well. The downside to this process is the pistons dont last very long.
I'm sure the companies that use this process arent trying to build a product that only lasts a short time, but they are trying to cut costs of production. While truly casting pistons with high silicon content is very expensive, microcasting the same silicon content can be done much cheaper.

I may be wrong on some or all of this, but this is how it was explained to me. Take it with a grain of salt.

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Old 10-31-2005, 10:32 AM   #1054
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Quote:
Originally Posted by mxwrench
This is my take on the microcast piston,
First, most pistons are cast oversize then CNC ground to shape on the outside to achieve the familiar finish. Not CNC'd from billet, as that doesn't give decent performance.
Most cast pistons however have a lower silicon content, as it is very difficult to achieve the ultra high silicon percentages using a std casting method (the blending of silicon to aluminum becomes very difficult above 22% as the silicon doesn't want to blend after this ratio, and requires very costly techniques to force the silicon to bond to the aluminum).
Microcast pistons on the otherhand, begin as a powder with the high silicon content dispersed as a powder with the aluminum powder along with a bonding agent(this allows the silicon molecules to bond properly to the aluminum molecules under extreme pressure). This mixture of powder is poured into the mold and compressed under extreme force and heat to fuse the molecules together to make a piston (in this case microcast could be compared to forging). The benefits to this process is the piston contains a high silicon content (probably around 26-27%) and the piston performs quite well. The downside to this process is the pistons dont last very long.
I'm sure the companies that use this process arent trying to build a product that only lasts a short time, but they are trying to cut costs of production. While truly casting pistons with high silicon content is very expensive, microcasting the same silicon content can be done much cheaper.

I may be wrong on some or all of this, but this is how it was explained to me. Take it with a grain of salt.

BK
It seems like we have our information on the MC piston from the same source with a russian accent

This is exactly how it was explained to me. The main reason to microcast is that you can get more silicon into the alloy than with aluminum stock.
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Old 10-31-2005, 02:11 PM   #1055
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sometimes microcasting doesn't require machining the microcasted piece, but I don't think our pistons are just casted........
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Old 10-31-2005, 07:07 PM   #1056
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so the bottom line is, will it be faster?????????

i don't care about the microcasting
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Old 11-01-2005, 12:05 AM   #1057
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It is possible to make an engine much faster but it will only last one heat! Is this what you want?

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Old 11-01-2005, 12:22 AM   #1058
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Yes, basecaly it is possible to make engine pretty fast and it will last really short time.
Just take brand new p/l set, washed very well in some sort of thiner to make sure there is no any oil left at all, stick piston to sleeve till it stop and can't move further by pressure of finger, that mesure distance from the top of sleeve to top of piston. On different models it is different numbers, but they are always within 3-4 mm. Then take piston and lap it to size 1.9-1.8 mm, make sure after every laping clean piston with thiner so no any lapping compaund left. Make always sure that before final assembly piston and sleeve must to be washed perfectly. then put motor together and run couple of tanks and motor is ready for it best performance possible, but it will not last really long, but defenetly will work much better then motor run in out of the box. This size works on any 12 size with head button dipness 1mm.
If motor was start ones this technics will not work any more, so P/L set must to be brand new.
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Old 11-01-2005, 04:54 AM   #1059
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Hi Ed, pretty interesting! so basically when you lap a p/s the surface finish will be superior to that of an engine broke-in normally on the bench??? I know if you lap correctly all machining marks will be removed from the metal surfaces and it can obtaining very close fits between mating parts, but will it produce an even better fit than breaking the engine in on the bench?
Also why exactly does the engine loose compression so rapidly when prepared in this way?
I've heard of people lapping engines but I dont know in detail how the process is carried out, is the helical lapping method used on 2-stroke motors to?

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Old 11-01-2005, 05:58 AM   #1060
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Quote:
Originally Posted by Hesky
Hi Ed, pretty interesting! so basically when you lap a p/s the surface finish will be superior to that of an engine broke-in normally on the bench??? I know if you lap correctly all machining marks will be removed from the metal surfaces and it can obtaining very close fits between mating parts, but will it produce an even better fit than breaking the engine in on the bench?
Also why exactly does the engine loose compression so rapidly when prepared in this way?
I've heard of people lapping engines but I dont know in detail how the process is carried out, is the helical lapping method used on 2-stroke motors to?

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if you look surface on new engines you will find that finish on chrome palting is look like very small tiny scratches. It is resut of honning fitting process. In big manufacturing it is basecaly one way to keep cost low, the rst of process will make it much more expencive (in exchange of quality). Those scratchs are working as cutting tool during the run in. Ones engine run in and you look inside the scratches looks much smaller and smoother, so the piston. So main porpose of run in is to smooth that finished surface. Any company can make engines which will required less run in period ( i am talking about piston fitting), but they use us to finish technology which they can't afford. Sorry, may be somebody will not like this sentance.
If you take brand new set, and we are assuming that you have right tools to lap in and polish first sleeve for best mirror surface, then you lap piston to best fitting, which is 1.9-1.8 mm and you will try that engine, you will be ammazed in difference of performance and power, but as long as sleeve is nt finished to mirror, normal fitting will add perfomance,but scratches will shave piston and wear it out, this is why life will be pretty short.
Edward
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Old 11-02-2005, 04:24 PM   #1061
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edward.........

does it have anything to do with engines that require less breaking in time?? i.e: The fastest engines I ran or tuned were the ones that required 3 or 4 tanks to be broken in............

what are your thoughts about the discussion (microcasted piston)?????
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Old 11-03-2005, 06:02 AM   #1062
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Quote:
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edward.........

does it have anything to do with engines that require less breaking in time?? i.e: The fastest engines I ran or tuned were the ones that required 3 or 4 tanks to be broken in............

what are your thoughts about the discussion (microcasted piston)?????
In our engines, which winding around 40K on track every interuption is very important and some of them can kill performance really badly. When engine required a lot of brak in process, on end of it, sleeve will not be leanear straight on top where the main friction happening. So here is answer. Take one of used liner and use prcesion gauge to mesure OD and you will find how much wear there is, also brass which comonly used for sleeve, is expending too (balooning) in the top area of sleeve. So ones that tough fitted type of engine brokne in and ready to go, the sleeve is out of its geometry and will not perform as good as the same engine, but prepared (laped) to right size.
About microcasting, everybody has their own idea and technology on piston material (remember please-piston material is about 70% power). While developing piston material, everybody is basecaly having the war with NATURE to insert more Si to Al alloy. Microcasting is one of the way to do it, but it is already been proven over the years it works pretty dicent, but life is too short-it is due how the Si dispers in alloy. From be our friend (Silicon) in some point it became our enemy-it doesn't make alloy slikier, it prematurely going out from alloy and works as lapping compaund. We did try that type of material years ago and it did give us a lot perfomance, but life is really short. There is companies (I will not mentioned names, industry, countries) around the world, who makes very good material which will suit to our aplication and we did try it-very good results, but still our bar stock casting gives better peformance-Si there is completely desolved and did not exsist as particulars at all. The piston manufacturing more expencive ( more machine time involve then with Microcasting), but our target is power and dependability, not super profit, so we stay with that.
Edward
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Old 11-03-2005, 06:29 AM   #1063
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Ed

As the liner is tapered towards the top it would be inpossible to hone the liner with a honing tool along its axis, it would have to be done radially. This will give the liner scratches in the radial direction and this would make the wear rate worse!

If the engine was ran in noramlly the surface lines would run in the same direction as the movement of the piston so dont see how a honed liner could out perform a ran in liner.

When I was at college we called lapping the process to make a smooth FLAT surface and HONING to make a smooth BORE

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Old 11-03-2005, 06:40 AM   #1064
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Quote:
Originally Posted by ziggy12345
Ed

As the liner is tapered towards the top it would be inpossible to hone the liner with a honing tool along its axis, it would have to be done radially. This will give the liner scratches in the radial direction and this would make the wear rate worse!

If the engine was ran in noramlly the surface lines would run in the same direction as the movement of the piston so dont see how a honed liner could out perform a ran in liner.

When I was at college we called lapping the process to make a smooth FLAT surface and HONING to make a smooth BORE

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You are right about honning make smoth bore. Honning is dicent process to make pricision liners, barrels etc for mass production and it has pretty low cost. But surface finish after honning is not the best. Grinding is much beter, but defenetly much more expencive specialy on mass production, Lapping gives really fine surface, but posability to make oval is really great and it is required very good skills to do that and a lot of patients.
Edward
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Old 11-04-2005, 03:16 PM   #1065
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any new engine coming out soon from novarossi (.21)
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