ESE's works engine tuner

[SwePatrick]

I have successfully done this in the past with a product called scotch weld by manufacturer 3m. You roughen up the piston (do undercuts if you can), clamp an aluminium stripe around it (pour it in soapy water before so that it does not stick as much to the epoxy - use spit if you forgot to prepare the soapy water), then put it in the oven to dry and harden (@120-150°C iirc). Before use, do re-work on the new outer shape of the piston if required.

I did several of these and all held up perfectly well for many hours at full load on the dyno on an engine with about 12k red line rpm.

Today, I would, however, roll a small aluminum sheet, cut out the required shape and have it laser welded to the piston.


.

I ended up doing almost that, i´ve got a different epoxi from Loctite, cant remember the name as we speak, but it has been really good earlier when i have modified other things in aluminium.
However, i drilled a hole into the piston and locked a kevlarstrengthened m4 nylonscrew with the same epoxi(special ordered at my work long time ago, i work at ABB and are a 'toolmaker')
I heated up the piston to about 70 degree celsius after blasted and cleaned it, i did also undercut as you describe.
The heat makes the epoxi very low viscous so it grabs the blasted surface really good.
Then i use 'package tape' as a mold and filled half the pit, i don´t need to fill the whole pit.

It takes about 36 hours for this epoxi to fully cure.
I have noticed that those faster epoxies aren´t as good when it comes to 'adhesive', stick to aluminium, in other words.

[SwePatrick]

it seems like millenium once told me they could apply plating to .36mm thick. this may let you go back to any common 66.4mm 250 piston. other wise devcon titanium putty may be the way to go

Good info, but i got a cast iron liner.

[TZ350]

Good info, but i got a cast iron liner.

You can plate an iron liner. Some have done it here to extend the life of the liner.

[SwePatrick]

You can plate an iron liner. Some have done here to extend the life of the liner.

if needing to revert back for 66.4 bore, i can always buy an new liner and port it the same as mine is now, it's cheaper as i can bore and hone the liner myself.

[andreas]

I ended up doing almost that, i´ve got a different epoxi from Loctite, cant remember the name as we speak, but it has been really good earlier when i have modified other things in aluminium.
However, i drilled a hole into the piston and locked a kevlarstrengthened m4 screw with the same epoxi(special ordered at my work long time ago, i work at ABB and are a 'toolmaker')
I heated up the piston to about 70 degree celsius after blasted and cleaned it, i did also undercut as you describe.
The heat makes the epoxi very low viscous so it grabs the blasted surface really good.
Then i use 'package tape' as a mold and filled half the pit, i don´t need to fill the whole pit.

It takes about 36 hours for this epoxi to fully cure.
I have noticed that those faster epoxies aren´t as good when it comes to 'adhesive', stick to aluminium, in other words.

This epoxy you mention, is good for transfer ducts and what not? I've used Hagmans for this usually but if you find the loctite name I'd like to try it.

[SwePatrick]

This epoxy you mention, is good for transfer ducts and what not? I've used Hagmans for this usually but if you find the loctite name I'd like to try it.

I can look it up this afternoon, i´m at work now, and yes it works fine modifying transferducts.

[andreas]

I can look it up this afternoon, i´m at work now, and yes it works fine modifying transferducts.

Ok, great..

[SwePatrick]

Ok, great..

https://www.henkel-adhesives.com/us/...e_ea_9497.html

I mix it up with some 'aluminiumdust' from grinding a part of the same quality.

[andreas]

https://www.henkel-adhesives.com/us/...e_ea_9497.html

I mix it up with some 'aluminiumdust' from grinding a part of the same quality.

Like "engine concrete" then, Thanks man.

[wobbly]

I want to fill a piston cavity exactly like the sample shown to test the effects of short circuiting.
Anyone found a supplier of 9497 in NZ.

[lohring]

On dyno correction factors; I've raced model boats from sea level to 5000' (1500 meters) and up to 40* C at that altitude. The nitro engines (60% nitro) lost a little power, but could pull the same diameter propellers thanks to the oxygen in the fuel. Gasoline engines lost a lot of power and needed to run much smaller props. We always dynoed and test ran at around 450' (140 meters) and in cool weather. Los Angeles was only a little lower, but warmer. We always could count on 2 or 3 mph (around 2%) more speed. Since boat speed is related to power cubed, that's a bigger difference than I would expect. Gasoline engines wouldn't pull sea level props starting around 2,500' (750 meters). Of course we couldn't change pipe length much or ignition timing. However, it seems that two strokes loose or gain power more drastically than conventional correction factors would suggest.

Lohring Miller

[husaberg]

I want to fill a piston cavity exactly like the sample shown to test the effects of short circuiting.
Anyone found a supplier of 9497 in NZ.

This is the NZ distributer and they don't list it.
https://www.shuk.co.nz/major-products/loctite-products/

they list

CTITE® EA 9017 (known as FIXMASTER® FAST CURE POXY PAK™ EPOXY) is a 2-part, room temperature curing epoxy adhesive used for high strength, permanent bonding of metals, ceramics, concrete, wood, glass and most plastics. This product can withstand temperatures up to +300 °F (+149 °C).
Premeasured resin and hardener for easy application, consistent strength and time savings - no waste, no mess, no clumping
Bonds virtually any material
Repair, fill and seal holes, cracks and worn surfaces
May be drilled, tapped, sanded, or machined and painted after cure
Reaches handling strength in 4 to 6 mins, fully cures in 45 to 60 mins
Easy to use in a syringe applicator

VS

9497
2-part, medium viscosity, high performance epoxy adhesive offering heat resistant bonding and filling characteristics.
LOCTITE® EA 9497 is a 2-part, grey epoxy adhesive for structural bonding that offers high technical performance. The product provides a high temperature resistance up to +180°C for heat resistant bonding and filling. It is thermally conductive and delivers high compression strength. It is ideal for bonding metal components.
High temperature resistance
Ideal for heat dissipation
Ideal for metal parts
High compression strength

Blackwoods have

Loctite Epoxy Adhesive 3805
Term Description
Steel and aluminium epoxy filler in dual tubes. High strength, fast cure. Ideal for fitting shaft repair sleeves and surface filling. Resistant to fuel, oil, anti-freeze, water etc. May be drilled, filed, tapped, etc. Temperature range
-55°;C to +150°;C, +175°;C (intermittent).

[AndreasL]

The adhesive/filler with the highest peek temperature (if it matters much I don’t know) from Loctite I could find was 3479.
Filled a crank case with it an it’s very hard and seems to adhere really well. Haven’t used it in anger though yet so no real prof.

9497 sounds really interesting though.

[yatasaki]

Same stuff here, tested on aircooled cast iron

[AndreasL]

Same stuff here, tested on aircooled cast iron

Good results? No issues?