how are pistons machined, for example a cast piston.

are they turned on a lathe, ground with a bench grinder or milled???

any info appreciated

 

Do you mean when they are made, in which case they tend not to be, or do you mean when someone wants to lower the compression of an engine etc?

In which case, generally they are milled in my experience.

Sadly though that normally involves bending the squish over and giving it 8" up the wrong'un

 

cheers chip.

basically, say you were to take a flat piston from a n/a engine, and as, you said, to lower the comp, mill a bit off.

flat pistons dont have squish areas do they?

 

Oh yes they do!

Squish is the area between the head and the piston... no not the combustion chamber... the other bit round the edges!

alex

 

http://www.motorsport-developments.c...products_id=66

Totally untouched squish area.

 

don't grind aluminium, tends to bind up

i would personally turn a piston on a lathe, but you will have to be careful of fixturing.

Millling is just as easy depending on the setup used

 

ok cheers alex.

so then, if i wanted to build an experiment zetec turbo engine, by taking the pistons and machining them, it would be best to dish the middle and leave say a 5mm ring around the edge at std height? like proppa low comp pistons.

although the area machined will be minimal, will it have a drastic effect being 1-2mm lower?

and for this experiment before anyone says it will go pop - i dont care, it wont be in my car, and 1.8 zetecs are rather cheap to buy so no great loss.

just to see exactly how much power it will make at what ever boost on a std engine with machined pistons.

 

yes it would be best to leave squish in there

The porblem is as soon as you remove material from the top of the piston (called the crown) you weaken it!

It not idea to weaken a componant in an engine you want to extract more power from.

Alex

 

Fugdeass have you ever seen that being done?? Hope not lol

 

Just use a thicker headgasket and ignore squish on that application, you dont want to go turboing an engine with weak cast pistons made even weaker by machining.

 

well, to be honest i know of a guy that builds ZVH's and he skims 2mm off the pistons, and runs them at 20psi with circa 250bhp....

and hasnt had one fail yet

 

cant beat precision engineering.. hahah

 

you dick, thats what the big fookers are called!

personnally, id crack out the angle grinder

 

there called 'surface grinders'