# 4032 Aluminum for pistons



## fltenwheeler (Aug 27, 2010)

Hi

Would 4032 Aluminum be a good choice for I/C engine pistons? It has a 11-13.5% Silicon content.

Thanks

Tim


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## bentprop (Aug 28, 2010)

OS engines have a certain amount of silicon in their alloy,so I don't see why yours wouldn't be ok.Try it and see.


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## waynes world (Dec 31, 2010)

you need material with a silicon content 25%-30% anything less would be a gamble and would require greater clearances on your set up. ;D


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## Jasonb (Dec 31, 2010)

A lot depends on the type of IC engine you are talking about, Judging by your crankshaft post you are looking at a relatively low reving, low compression, cool running hit & miss engine in which case it will be fine. If it were a high reving aero or boat engine then maybe something a bit special would be required.

I've got hit and miss engines with alloy pistons with less than 1% silicon HE30 (6082) and they run fine, these high contents are for 20,000rpm high tollerance RC engines.

Jason


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## Tin Falcon (Dec 31, 2010)

Air force manual 1-1a-9 gives metal specs
http://www.robins.af.mil/shared/media/document/AFD-091006-039.pdf
Tin


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## stevehuckss396 (Dec 31, 2010)

fltenwheeler  said:
			
		

> Would 4032 Aluminum be a good choice for I/C engine pistons? It has a 11-13.5% Silicon content.



Most model builders use 6061 an some use 7075 if you want a tighter fit. I use 6061


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## mu38&Bg# (Dec 31, 2010)

If building an engine that will be running under load and experiencing high temperatures the 4032 will be appropriate. Display engines with low load and temperature requirements will get by with common alloys. 20-30% silicon alloys are only required for ringless tapered bore designs with brass or aluminum sleeves. I have 4032 for making some custom pistons for OS FS-52 engines I'm working with.

Greg


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## Swede (Jul 30, 2011)

I know this topic is old, but if anyone wonders, my radial engine uses 6061 pistons in 12L14 jugs, cast iron rings, and about 0.0025" clearance between pistons and cylinders. This less-than-optimum combination has run well for many, many hours, an when torn down, there was no noticeable wear except some shiny rings and bores.


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## stevehuckss396 (Jul 30, 2011)

Swede  said:
			
		

> This less-than-optimum combination



This is a very good combination. What would be optimum?


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## mu38&Bg# (Jul 31, 2011)

How many hours at what power levels would you say?


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## Swede (Aug 4, 2011)

> This is a very good combination. What would be optimum?



Well, 12L14 would be considered about the softest steel imaginable for a cylinder. The 6061 pistons could have been made out of a harder alloy. The CI rings are appropriate. Most IC engines designed for hard or lengthy running are going to use better alloys.



> How many hours at what power levels would you say?



I've demo'd the engine many dozens if not well over a hundred times, w/lots of full-throttle running. The engine runs cooler than I thought it would, not sure why. As far as total hours, I honestly don't know, but it's no shelf queen. Still, the components seem to be in great shape. I did take care to use correct steels for the cam ring and tappets. The tappets are NOT roller tappets, and without proper heat treatment and lubrication of cam and tappets, they'd shred themselves. As it is, there is nothing more than a shiny path on the cam surfaces, and the tappets still have a full hemispherical profile. Cam is 4340 RC 40 or so, tappets A-2 hardened and tempered.


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## karolh (Aug 27, 2014)

I know that this is a very old thread but I just found this site and joined up as I am in urgent need of advice as to as to which aluminium would be most suitable for machining a piston for a 26cc R/C gas engine with a 11,000 max rpm. Thanks

 Karol


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## windy (Aug 27, 2014)

karolh said:


> I know that this is a very old thread but I just found this site and joined up as I am in urgent need of advice as to as to which aluminium would be most suitable for machining a piston for a 26cc R/C gas engine with a 11,000 max rpm. Thanks
> 
> Karol



Just a thought my 14cc flash steam engine under load is doing between 10.500 to 11.000 rpm 129.33 mph with laps over 131 mph and it's a cast iron piston in steel liner.
The crankshaft bob weight is fairly heavy for balancing.
How many high performance IC engines use cast iron pistons?

 Paul


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## karolh (Aug 27, 2014)

Thanks for your response but I specifically want to use an aluminium piston, however there seems to be two schools of thought regarding using 4032 aluminium as some think that it's a good piston choice while the others do not. I would really appreciate someone advising me on exactly what to use for machining a piston for my 22cc engine as I've been told to use 4032, 6061, 7075 and even 5042.

Karol


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## John Rus (Aug 28, 2014)

Nice to have you on the forum but it would be nice to introduce yourself in the welcome section and tell us a little about yourself. As the Brits would say it "It's the done thing.".

Cheers,
John.


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## Jasonb (Aug 28, 2014)

Does your engien have piston rings?

I'd go with 6081/6082 works on my glow engine that does not have rings and will run at 9000rpm under load.


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## karolh (Aug 28, 2014)

John Rus said:


> Nice to have you on the forum but it would be nice to introduce yourself in the welcome section and tell us a little about yourself. As the Brits would say it "It's the done thing.".
> 
> Cheers,
> John.



Will do.

Karol


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## karolh (Aug 28, 2014)

Jasonb said:


> Does your engien have piston rings?
> 
> I'd go with 6081/6082 works on my glow engine that does not have rings and will run at 9000rpm under load.



Yes my engine uses a single ring and has a skirt dia. of 1.338". Sending you a PM.

Karol


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