Piston oilers for cooling

[Esprit Aviation]

Does anyone know if Lotus utilized piston iolers/sprayers for cooling the piston crowns in any of the Esprit engines, V8's included????

Thanks, Lee

[t70]

dunno... but mitsubishi does, toyota does on the 7mgte and 2jz and 1jz, I tried to build my own for my 5mge but i was unsuccessful and discovered that forged pistons are able to distribute heat sufficiently for my 550hp goal. As I understand it, our pistons are chrome covered because they aren't forged.... I could be wrong... but after talking to my piston manufacturer... I felt that forged pistons wouldn't require the chrome coating. Oil squirters require an oil journal to be right next to the cylinder wall as well... You could use the ones from the Mitsubishi 4g63 -- they have a spring loaded ball valve in them so that they won't rob the top end of the engine of oil pressure at idle and low rpm...

[Vulcan Grey]

dunno... but mitsubishi does, toyota does on the 7mgte and 2jz and 1jz, I tried to build my own for my 5mge but i was unsuccessful and discovered that forged pistons are able to distribute heat sufficiently for my 550hp goal. As I understand it, our pistons are chrome covered because they aren't forged.... I could be wrong... but after talking to my piston manufacturer... I felt that forged pistons wouldn't require the chrome coating. Oil squirters require an oil journal to be right next to the cylinder wall as well... You could use the ones from the Mitsubishi 4g63 -- they have a spring loaded ball valve in them so that they won't rob the top end of the engine of oil pressure at idle and low rpm...

Its all in the manual.

The 89SE-S4s Chargecooled cars do have forged aluminum pistons, and chrome coating on the dome. DO NOT soak them in Simple Green, it will strip the chrome!

The GT3 920 engine has Nickel plating.

The non charge cooled 912, 910 engines have forged pistons, but no coating.

There are oil holes on the skirts of my pistons (89SE 910 Chargecooled)

[USAndretti42]

Aren't those holes in the skirt for controlling skirt expansion or draining the oil from the oil control ring?

[Vulcan Grey]

Aren't those holes in the skirt for controlling skirt expansion or draining the oil from the oil control ring?

Yea, they aren't active cooling holes, as there are no oil galley paths through the forged glued in cylinders.

[t70]

Lol!! no, but in the case of Arias pistons there are oil galleries that lubricate the floating pins and I think there are 16 oil holes along the oil rings... I am however, now confused as to why they coat the pistons if they are already forged? Does it reduce detonation? Evenly distribute heat? what does it actually do? and if you coat the top of the pistons then why not the cylinder dome too??

[USAndretti42]

I suspect the chrome coating on the piston top is to reduce the heat transfer into the crown. There is no need to coat the inside of the chamber as the head is water cooled but the piston is not. It gets rid of its heat through the rings into the walls and through any oil cooling but it appears that the engine doesn't have any cooling jets. The jets will reduce the piston temperature by only about 10 C. Not much but it can be the difference between a piston cracking and one staying in one piece.