aluminum 4032 piston material heat treatment

[rbarile]

Made a piston for a RC Zenoah gas engine out of 4032 alum. Seem to expanding when hot the motor is in a rc twin engine boat. The motor with the factory cast piston is stable runs good.
The one that I made is running hot.
appreciate any heat treat info. to cure my problem. thanks rich.barile

 

[Charles Lamont]

So why not put the original pistons back? What makes you think heat treatment will cure your problem? For useful help you will need to explain what you are trying to achieve.

 

[mu38&Bg#]

You will need to determine the proper piston clearance for the new material. What else is different about the piston design?

 

[rbarile]

So why not put the original pistons back? What makes you think heat treatment will cure your problem? For useful help you will need to explain what you are trying to achieve.

The original engine was side exhaust they dont make rear exhaust engines anymore. You can get a korean piston , but they can take hi rpm. Had to make my own. its working , but its scuffs easy . Heres a photo of my rc hydro plane .
I opted to run rear exhaust, its a twin engine. The rear exhaust application save alot of weight. The side exhaust needs a wider body . and more weight, average weight is 25 lb, mine is 19lb more competive. Heres a photo its called a road runner..

 

[rbarile]

You will need to determine the proper piston clearance for the new material. What else is different about the piston design?

clearance is good , .004 . Made same style piston. seens to scuff easy.
thought it might be the expanding. Or it needs heat treatment for additional hardness.?? The stock piston is cast seems to ware better.
here is what im doing rc hydro plane the Road runner. Oh rpm is 17 to 20,000. Running on reg gas. It will do in the 90 mph area.

 

[lohring]

Those are rear exhaust Quickdraws, not Zenoahs. I have one and the OEM piston in my engine was billet not cast. I bet Quickdraw could make a replacement. As I remember, my piston got scuffed more easily than Zenoah pistons. When I get home I'll measure my piston for its clearance.

 

[mu38&Bg#]

4032, like most aluminum, doesn't heat treat beyond what's done at the mill.

 

[rbarile]

Those are rear exhaust Quickdraws, not Zenoahs. I have one and the OEM piston in my engine was billet not cast. I bet Quickdraw could make a replacement. As I remember, my piston got scuffed more easily than Zenoah pistons. When I get home I'll measure my piston for its clearance.

These are 29s ( 1mm crank) . Zenoah piston dont scuff, or the korean pistons dont. 4032 does ? There is heat treatment options , but they require sending out . It not cost effective for one or two pistons.

It is effective the hardness is raised a few points. I dont know if the scuffing will be cured. Just looking for a simply procedure. I have
small oven and can bring it to temp of 2000 degs.

When i was running nitro made pistons heat treated 4 to 6 hrs at 350 to stop the expandtion.

4032, like most aluminum, doesn't heat treat beyond what's done at the mill.

 

[lohring]

Below are pictures of my piston. My engine dates from around 2005. The clearance on the skirt is about .003" and at the ring grove is about .005" There is only light scoring.

Lohring Miller

 

[rbarile]

Hard to tell if mine has more , running this weekend. Will disassemble and photo to see what you think. I take 500 and clean it up, to check for the next run.
Spoke to jim schaeffer at ABC props very knowledgeable, stated 950 F
for 6 hours and air cool. Seems like high temp, my only concern is the
ring pin. Its pressed in . What do U think?
Used to do A390 for nitro motor high silicon. from henry nelson back in the day., No problems. 4032 is 15 to 20% Not enough or other factors. Or maybe just dont worry about it. What material do you think Quickdraw
made theres out of?

 

[solarenergyadventures]

Why not make the piston out of something that really IS heat treatable like 7075? I don't know if this would work, but it might be worth a shot.

 

[rbarile]

I have tryed 7075 on nitro engine connecting rod, when heated to a certain temperture the bottom end would let go. The bottom was a bushing ( rpm
above 20,000 Gas engines get very hot dont thing it would hold up, maybe hate to have a engine let go, expensive.
In low temp. its excellent.

 

[lohring]

I don't think the scoring is significant. Because Quickdraw uses a steel sleeve, piston expansion is critical. That's the reason for the high silicon. Don't be afraid to run plenty of clearance, especially at the top of the piston. I bet Quickdraw would tell you what material they used. These days they try to run as many mass produced parts as possible. I'm impressed that you made your own pistons. I've done it and it's very time consuming on manual machines.

Are your rods slotted in the big end? The rod big end bearing is the weak point. We dynoed our engines to 25,000 rpm on an inertial dyno and ran to 23,000 rpm on our straight line record passes. the only rod failure I've had was on an M&D cast cylinder engine that I ran over 20,000 rpm for several race seasons. Fortunately, the rod and crankshaft were the only losses. Really good high rev Quickdraws had pretty flat power curves from 17,000 to 20,000 rpm. The peak came around 18.000 rpm. I don't know what your rngines power looks like, but they publish their brake dyno curves. Below is one on a couple of our engines in 2003.

Lohring Miller

 

[mu38&Bg#]

What I meant is that any aluminum alloy with a -Txxx temper has already been heat treated. T6 has been solution heat treated and age hardened at the foundry. 4032 has 11-13.5% Si. A390 has 16-18% Si. Anyhow, it's all out there on the web.

I'd be curious about hardness measurements before and after if you try this. I'm not sure that the temperature you were given is what you want.

 

[kf2qd]

Find an engine rebuilt shop and get a piston removed froma diesel, tend to have larger cross sections. Should be the right grade of aluminum.

 

[rbarile]

What I meant is that any aluminum alloy with a -Txxx temper has already been heat treated. T6 has been solution heat treated and age hardened at the foundry. 4032 has 11-13.5% Si. A390 has 16-18% Si. Anyhow, it's all out there on the web.

I'd be curious about hardness measurements before and after if you try this. I'm not sure that the temperature you were given is what you want.

I'm still researching the temp on hardness , hit up on you guys for additional info thanks.

 

[rbarile]

Find an engine rebuilt shop and get a piston removed froma diesel, tend to have larger cross sections. Should be the right grade of aluminum.

ok thanks.

 

[rbarile]

I don't think the scoring is significant. Because Quickdraw uses a steel sleeve, piston expansion is critical. That's the reason for the high silicon. Don't be afraid to run plenty of clearance, especially at the top of the piston. I bet Quickdraw would tell you what material they used. These days they try to run as many mass produced parts as possible. I'm impressed that you made your own pistons. I've done it and it's very time consuming on manual machines.

Are your rods slotted in the big end? The rod big end bearing is the weak point. We dynoed our engines to 25,000 rpm on an inertial dyno and ran to 23,000 rpm on our straight line record passes. the only rod failure I've had was on an M&D cast cylinder engine that I ran over 20,000 rpm for several race seasons. Fortunately, the rod and crankshaft were the only losses. Really good high rev Quickdraws had pretty flat power curves from 17,000 to 20,000 rpm. The peak came around 18.000 rpm. I don't know what your rngines power looks like, but they publish their brake dyno curves. Below is one on a couple of our engines in 2003.

Lohring Miller

View attachment 130723

Ran this weekend after i cleaned with 500 paper. have photos.
Have slotted rod from performance, .062 slot seems big , but holding up they also gave me a new crank pin over size by 2 or 3 tens. Both engines are running 19000 , to 19500. The engine with my piston started running hot and slower , seem to be up to par now. Orignally had the engines in a andy brown hull. ( nitro type) much lighter and faster, Had to prop down . The roadrunner much heavyer . Ran a 2719 went down to a 2617 will try a 2619.

 

[lohring]

These are the boats we ran. The first is the 110 mph SAW rigger, the second is the 100 mph sport hydro that still holds the record, and the last is Mike Bontoft's Andy Brown 90 rigger that ran a detuned engine at around 80 mph'

Lohring Miller

 

[rbarile]

My passion is the SAWs ran for many years in district 1 with jim allen. I ran a 45 bored to 58 in 60 class, got in the 90s with jim before andy brown set record in the 120s. heres some photos jim and his over bored 90 crap shooter, mine is the silver boat. We both had bar stock motor with roller rods.
Red and yellow rigger is Ed kaulfus 90 with twin pipes. He used to run with us at times before he pasted on.