Just in case you have never seen one before

I found this Merlin piston in a basket on my door step and took a picture of it next to a Ferrari piston to give you a sense of scale.


One is from a 137 inch cylinder designed to go 3000 RPM and the other is from a 22.5 inch cylinder designed to go 7500 rpm
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Wouldn't that make it a Moses piston?

 

Is that a ring groove at the bottom of the skirt?

 

Yes, for an oil ring to lube the skirt. Lots of old timey motors had them.

 

Clean running Merlin...you can tell by the shine.

 

Not surprised with those high BLING pistons.

 

Redline's are to be observed. Ferrari states " do not exceed 7,500 RPM" Here is what you get at 7,501!
Gary Bobileff
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LOL!

 

very cool!!

What is the weight (approx)?

 

I don't have a scale that big but I will see what I can do.

 

Nice stuff.

But tell us the truth, Brian.

This is actually for the 308 big-bore kit you are developing.

 

Thanks Gary,

Thats the paperweight nobody really wants on their desk. LOL

The Merlin one must be for those really big jobs.

I saw here somewhere a report of what happens in an unlimited race motor during a very brief time(maybe one or two seconds) and it was SHOCKING even for me.

 

You mean like this one?
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Rifledriver, do you know if the Merlin had 4 valves per cylinder, or was it two? There was an article on this engine in a classic aircraft magazine last month, but the way they drew up the shadow view illustration it is almost impossible to tell.

I was greatly amused by their story of how the first models were plagued by flooding when you put on negative Gs...the Me-109 could just push forward and get away while the Spitfires were either choking and sputtering or else had to roll inverted to dive after them.

Finally, one of the ladies in the engine department of R-R came up with a restrictor flange which solved the problem -

Everyone disrespectfully called it "Miss Tilly's Orifice".

 

4 valves. So did the Allison.


The Daimler Benz motor had fuel injection. Negative G's dont bother it. With the exception of the B29 all the Allied recips I am aware of had carbs. Dont care what you do to them they need gravity of the correct kind. You can delay the inevitable just a hair but the gas needs to be in the bottom to work.

The fuel injection system on the Mercedes 300SL's of the 50's had a fuel injection system that was a direct decendant of the one used on the airplanes. It was very rudimentary in operation but for the type of duty an aviation motor sees made good sense. Automotive fuel delivery systems actually need far greater abilities due to their type of use.

 

Pix of cyl head. Easy to see the 4 holes per cyl.
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I was gonna ask about the weight as well.

Pretty shiny thing there Brian........keep it away from the wife, she might confiscatae it.

 

Brian, didn't we develop the diaphragm carburetor near the end of the war that solved the float chamber problem?
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I think we could reshape those chambers to unshroud the valves and get you some more HP.

 

You would know better than I but it can't cope with sustained inverted flight can it?

 

That is the beauty of a diaphragm carb. Since the fuel and atmospheric pressure is separated by the diaphragm, the fuel chamber stays full all of the time providing your fuel pump has enough pressure to pop off the needle and seat when the fuel chamber gets low. They can be mounted in any orientation I.E Downdraft, Side draft, or up draft.

Mikuni BN and Super BN carbs worked so well on jet-skis that some EAA types started to use them on there A/C. Mikuni responded by placing stickers on all non OEM carbs stating that they were "Not Certified for Aviation Use"

 

When I first started working at Allison there were tons of old V1710 pistons that were cut down or modded to be really neat ash trays. Nice and heavy and if you cut it thru the wrist pin you could stick a cigarette right there when you weren't smoking it..... I saw a picture of the old Allison school for tech reps and each desk had a upside down piston sitting on the ground beside it being used as an ash tray... When the war stopped there were a lot of V1710 pistions that weren't needed so they got recycled....

Not many of them around anymore since they banned smoking in the buildings, the ash trays kinda walked away.......

 

The Merlin 51s had big two barreled diaphram pressure carbs that injected the fuel up stream into the area just aft of the 1st wheel case through a defuzer nozzle. UMSLOPOGAS really likes that stuff. Has an ravenous appetite. What a way to convert dollars to noise.

 

You want to see a REAL PISTON take one out of an R1820. They were about nine inches across and you could take a bath in one of them. About 125-130 HP out of each one. Get one shot up and you lost most of the engine. Not so with an R1830 or an R2800, they still ran. Reminds me of the patter that we did with the announcers at air shows when we were doing the clown act. When the announcer asked why we couldn't get the engine started we told him " That the carburetor wouldn't carb, the generator wouldn't gen, the starter wouldn't start, and the pistons wouldn't ....run either." Always got a laugh out of the crowd.

 

I was going to say something about making it into a really *****in ashtray........But that one is soooooo pretty! very cool piece.