How much taper on a 4032 piston skirt?

[digger]

page 32 has some info

http://randolphtoom.com/ENSAIS/Pistons% ... esting.pdf

[the_crack_fox]

That document is gold!! Thank you Digger

[DCal]

No don't send me a PM because I'm not just going to give you what we have invested millions of dollars into. However, I admire you're giving it a try and would like to pass on some suggestions. Considering you have Solidworks and the capabilities of reverse engineering I think you'll not fail.
I will tell you what I did for my own engine and you can see if that is logical for your situation. I took a CP forged piston that would be 2618 and normally set up for .004 clearance and just followed that profile on a 4032 forging. I set the clearance up for .002 , worked great.
I can say nothing about the cam shape but I will caution you on your box forging to add an extra .0005 to .001 clearance where the struts join the thrust faces on all 4 corners. Biggest thing, if your clocking tabs will allow it, is to cut your ring lands and ring grooves last. That's paramount.

[the_crack_fox]

Thanks DCal, the advice is much appreciated!

[novafornow]

Sorry to overstep my bounds dcal, but you did give him something. That is what makes these sites worthwhile. I would not expect someone to "sell the farm".

[Mark O'Neal]

Pistons were measured in cam and taper in the 1980s. Skirt designs are now far more complicated than that.

Mine were smaller at the bottom and under the oil ring than they were at the gauge point ... for example.

[DCal]

Sorry to overstep my bounds dcal, but you did give him something. That is what makes these sites worthwhile. I would not expect someone to "sell the farm".

Don't think twice. Didn't bother me at all and this site is helpful for sure.

[the_crack_fox]

Pistons ready to install. After much thought I decided to get an expert to finish the skirt and ring grooves for me.
I will definitely have another go at completing a set by myself. I'm pretty confident I can do it, but not confident enough to risk trashing the engine in my daily driver. Next time I'll do a single cylinder motorbike engine.
Thanks to everyone who offered advice!

[DCal]

Pistons ready to install. After much thought I decided to get an expert to finish the skirt and ring grooves for me.
I will definitely have another go at completing a set by myself. I'm pretty confident I can do it, but not confident enough to risk trashing the engine in my daily driver. Next time I'll do a single cylinder motorbike engine.
Thanks to everyone who offered advice!

good move !!!!

[the_crack_fox]

Engine is running! No rattles, no smoke. If anyone ever says "you can't make your own pistons", they're wrong

[the_crack_fox]

BRZ 2.2L FA20 making 190kw/255HP at the wheels on 9psi boost (harrop supercharger) with billet 4032 pistons.