TAW

iTrader: (18)

Can anyone comment on the advantages that the new Microcasted pistons provide and exactly what it means. I have a motor that has this and a friend and I have been discussing this and just wanted to know what the big deal is with it.

thanks

EdwardN

iTrader: (1)

This technology givers ability to add Silicon in quantity more then 22-23%. It is pretty old technology ( as far as I know). Also been calling poweder metall technology. If you look in internet, you will find it is widely used for years. It has some advantages and disadvantages. From what I know this techology been use in engine for military aplication in Russia since 1980"s. We try and used this kind of materials for pistons back in 80's and 90's but later it was find the way how to make casting alloy. Alloy made by this technology is still bridall.
One of the big advantages is-economical-you can form almost any kind of configuration without wasting machine time and material ( it is beside Si content).
more info you can find on the web.
Edward

ERL2004

I might be wrong, but from what I know. In the past some of the pistons were machined from aluminum bars . Nowdays they are casted, giving the advantages of lightness and complicated intrisic design possible. I am not sure whether you can use powder metal technique because I think they can only use one type of metal and it is not the type of aluminum alloy we use in RC engine, it looks more like steel or iron.
The biggest problem with casting high silicon content alloy is getting porosities in the casting. Si particles don't disperse uniformly in alluminum. To control the particle size it has to be heated to a certain temp, let it cool down at a specific rate.
But it is all aluminum manufactured secrects.
A newer technique is spray forming process which give you high density Si-Al. It can incorperate upto about 50% Si. but the piston will cost more than an engine you can get now.

EdwardN

iTrader: (1)

This is the one of the reasons ( secret of casting) we will never realiese and ( as I noticed-you are pretty familiar with airmodeling) you will know what Russian piston material is.
About poweder Al alloy with 35 % Si, I can supply you by tons, with realy good dispersed Si in alloy, but it is not going to work as material we use on our engines and P/S sets.

rodneybarrett

iTrader: (50)

ok. I'll bite, so why would the newest engines use this technology? There has to be some advantages to it.

EdwardN

iTrader: (1)

First of all, we tryed about 20 years ago and since we found different way to make what we want to, we never went back to that type of metalurgy. Second, why just this year Novarossi makes AAC, and AAc very well known for last 25 years?
Why would I make my own engine and don't buy Novarossi ( it is much easier, just pay $300+ and be happy for while)?
They probably developed something new, I guess.
Everybody choose their own way.

TAW

iTrader: (18)

Ok, we are not really interested in knowing why you don't use this technology in your engines. What I would like to know is what if any are the advantages in the engines that are made with this technology. This seems to be the newest trend from Novarossi and it seems that no one knows just excatly what the deal is other than it's New.

EdwardN

iTrader: (1)

I am very interesting in everything, specialy if it is realed to metalurgy.
I didn't have chance yet to work with any of those pistons, but all development in piston materials is to improve expantion rate, reduce friction, improve stability of piston geometry under temeprature, reduce wear and make naterial more durable.
To achive all this points ( except durability) in one shot, nees to increase Silicon content in Alloy. Novarossi using this way to do so.
I think it is pretty simple.
Oh, forgot to mention big part of it-marketing

AMGRacer

From my understanding/discussions with local importers here the main advantage being touted is that these types of pistons can take more heat before they get out of the usable range. These engines can supposedly take up to 150 celcius before damage starts occurring.

EdwardN

iTrader: (1)

Any Al alloy can take way more then 150C before they start damaging. 150 C isn't critical temperature.
On tether cars, when they come from race, temperature some times reach up to 420 F.

AMGRacer

I dont race my R40 on a tether.

TAW

iTrader: (18)

My buddy pointed me in this direction which talks about Hypereutectic pistons in full size engines, is this what Microcasting is all about?

Contains 12.5 percent_or more silicon content. Special melting processes are necessary to ‘super-saturate’ the aluminum with additional silicon content. Special molds, casting and cooling techniques are required to obtain finely and uniformly dispersed silicon particles throughout the material. Our hyper-eutectic material is also being used in light and medium diesel engines to replace some of the eutectic pistons with iron groove inserts used for additional heat and wear resistance of the ring groove. Heat and wear in the ring groove contribute to groove ‘pound-out. In the Sealed Power hypereutectic pistons, the hard, finely dispersed silicon particles serve as ‘micro-inserts’ at the surfaces of the piston, especially in the surfaces of the precision-machined ring grooves. The increased strength, heat and wear resistance provided by the high-silicon content hypereutectic piston material allows for elimination of the groove inserts in several piston applications.

rodneybarrett

iTrader: (50)

http://www.ttp.net/0-87849-908-3/165.htm

afm

Resuming what has been posted, and talking with some people in the business, and explaining it with simple words.
These "new" MCP pistons used by Novarossi or others, can sustain better the higher temperatures posed by the high rpm's at which they operate, without loosing performance. Of course they bennefit from it for marketing purposes, Am I right???

AFM

rodneybarrett

iTrader: (50)

afm:


I think that's what we are truly trying to find out.

Are they really better or is it just marketing hype?

I have been talking with a friend who races SCCA and knows a great deal about building real engines.

From what I have told him about the high Silicon content, he believes it is a variation of the hypereutectic form of making pistons for real engines.

Best to worse in this order for real engine pistons.

Machined
hypereutectic
cast


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.