Anyone help identify this piston?

[Tyre Smoke]

My grandfather, veteran of two world wars and late of Plymouth used to keep his pipes in this piston that sits on my desk at work.

Legend has it, it's from a WW2 aircraft. But I'm not sure. It's definitely a petrol engine from the slight pitting on the crown. It has no markings at all, is 135mm in diameter and the little end journals are 32mm.

Anybody?

[aeropilot]

I'm guessing Merlin from the looks, and size, although it's missing the bottom part?

Most Merlin pistons though I've seen have a different shape to the top, with flatter surface with a distinct raised lip around the perimeter......but maybe Packard changed the shape and could be a Packard version....?

[Tyre Smoke]

Any chance it could be German? I was thinking the dimensions are metric....

Plus there would have been a fair number of downed German bombers in and around Plymouth.

I've done a bit of searching and there were a couple of Daimler Benz aero engines that had 135mm bore.

[aeropilot]

Tyre Smoke said:

Any chance it could be German? I was thinking the dimensions are metric....

Plus there would have been a fair number of downed German bombers in and around Plymouth.

I've done a bit of searching and there were a couple of Daimler Benz aero engines that had 135mm bore.

Good spot, and yes, the shape of the dome top looks right for a DB605 piston, as is the short skirt........

And Merlin bore was 137.1mm

[3.8 MOD]

Looks like a Packard one, I agree. Diameter should be more like 137mm.
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[Tyre Smoke]

It's definitely 135mm. I can't make it that 2mm more, sorry!

So, aero engine most likely? Grandad was in the RN, but I cannot imagine HMS Newcastle having anything that size.

I'll have a look at the DB605.

[aeropilot]

Tyre Smoke said:

It's definitely 135mm. I can't make it that 2mm more, sorry!

So, aero engine most likely? Grandad was in the RN, but I cannot imagine HMS Newcastle having anything that size.

Aahhhh, if he was RN, it could be a piston from a V12 Packard 4M 2500 marine engine, out of a MTB

Although, at almost 42 litres, I think the 2500 pistons might be a tad bigger than 135mm

Edited by aeropilot on Wednesday 19th December 21:09

[Eric Mc]

My first thought was that it might be a German piston.

[aeropilot]

Well its not from a German Daimler-Benz DB600 series V12 as its too small, bore size on those was 150-154mm, or from a BMW 801 radial as that is also 150mm bore size.

I think were back to looking at our own side.

[Eric Mc]

There is a wreck of a Junkers Jumo engine from a Stuka on display at the Tangmere Aviation Museum and the pistons look like dustbins.

[aeropilot]

I think we're back to looking at it being from a Merlin, its the closest fit in size.

It's too small for any of the Bristol radials such as the Mercury, Pegasus or Hercules, and of course the RR Griffon.

Its too big to be any of the more rare types like RR Peregrine, RR Kestrel, RR Vulture or Napier Sabre, which were all less than 130mm bore.

Its also too small to be a Allison V12 or any of the P&W or Wright radials from the USA.

[RicksAlfas]

The Armstrong Siddeley Deerhound had a 135mm bore!

No, me neither...

[227bhp]

Tyre Smoke said:

It's definitely 135mm. I can't make it that 2mm more, sorry!

Maybe you can as it depends where you measured it, pistons are tapered and oval. The widest point and where pistons are measured in relation to the bore is just up from the bottom on the skirt.
Can you get more pictures from the other (pin) side and underneath?
It's very short for an old piston.

[rednotdead]

I'd say it's a Merlin, here's mine for comparison, also 135mm dia:

[Tyre Smoke]

Interesting!

Certainly looks like a Merlin piston.

[CubanPete]

aeropilot said:

Good spot, and yes, the shape of the dome top looks right for a DB605 piston, as is the short skirt........

And Merlin bore was 137.1mm

Once the rings are on that would take 135mm to about 137.1mm?

[aeropilot]

Its been sliced in half though......

[Tyre Smoke]

I guess it could do.

I'm pleased and a bit disappointed. Pleased that you all seem to have identified it, but I was sort of hoping it came from a downed Dornier or Heinkel giving Devonport Dockyard a pasting.

Don't know why the skirt has been cut off, to make it into an ashtray I guess.

[Krikkit]

Was it originally a development piston and it's been cut up to check the alloy after a heavy run?

[dr_gn]

It could be from a Meteor tank engine I guess. Those pistons were cast rather than forged according to Wikipedia. Any clue as to how it was made from the unmachined bits?