Pistons for m20 Stroker

[.n0iz4!]

Ok, back to the Pistons.
Offset Wiseco should be X+5.9 Y-6.05 (~6)

Merry Christmas :D

[.n0iz4!]

So start a new thread and show us your work on the rocker arms.

I already started a new thread in our german e30-talk Forum :D

https://e30-talk.com/topic/202157-kevin-allein-zu-haus-baut-nen-motor/

There you can watch it. But its not finished yet. The Problem ist the strength / how much Newtons go into the rocker-arm etc.

But i'm on the way... maybe :D

[E30-325iS]

Didnt had the time for the Piston "measure".

I'm too busy buildin my own Rocker arms, sorry.

Will get back to the pistons soon!

So start a new thread and show us your work on the rocker arms.

[.n0iz4!]

Didnt had the time for the Piston "measure".

I'm too busy buildin my own Rocker arms, sorry.

Will get back to the pistons soon!

[digger]

I had It closer to 7mm but hard to measure. Small variation Doesn't matter much though

[.n0iz4!]

for the 9.7:1 +0.5mm piston it is, R100 convex (dome) and R107 concave (dish)

Thanks alot!

I'll check this on thuesday/friday at the cnc.

It is correct that the Offset is x8 y-8 ?

[digger]

for the 9.7:1 +0.5mm piston it is, R100 convex (dome) and R107 concave (dish)

[.n0iz4!]

Yea this looks pretty accurate. Would you share your work with me? When you dont want to, no problem.

My last two problems are that i have to measure the Radius of the "Piston Ball - the convex shape" and the position and Radius of the Concave/Dome Ball.

I think its x+8 and y-8 but this is too unaccurate for me. Also the Radius at the 9,7 - somthing from 200mm-210mm(Diameter) could be correct but... for me its tooo unaccurate :?

Some idea is to clamp the piston on the CNC and take a dial indicator and "drive" above the piston. Write down the Points and get the Radius :D

[digger]

the is a stock 9.7:1 piston i modeled a while back

[.n0iz4!]

example of how they are spec'd often

This looks good to me

hmm..I think could be it. (please correct, if its wrong :D) the length is also ok. (43,318 - deeper than original)
(the Radius makes the difference!)

Thanks for your fast help guys!

[digger]

example of how they are spec'd often

[.n0iz4!]

I can see the difference it your plotting and your actual pistons. However you keep referring to Mahle piston specs (pin center to valve etc). Do you have all specs for Wiseco dimensions?

Typically, valve relief depth is measured vertically from the deck to the deepest part of the valve relief radius. That makes my picture above not exactly precise (red line needs to be vertical). I didn't know you are trying to reproduce it precisely when did that pic. Just tried to convey the idea explanation about TE measurement and where it starts from.


P.S. What are you trying to figure to? If Wiseco pistons match your desired spec?

No i just have the Mahle Specs. (And of course the specs from the kit. But theres no other info about the valve pockets etc..)

The Vertical option seems good to me, but that even looks not right..
Unfortunately..

I wanna offset the whole "surface" and lower it. Maybe -1mm.
But not the Dome depth. This increases the CR of the Pistons.
1mm should end up around 10,5:1.

[zaq123]

I can see the difference it your plotting and your actual pistons. However you keep referring to Mahle piston specs (pin center to valve etc). Do you have all specs for Wiseco dimensions?

Typically, valve relief depth is measured vertically from the deck to the deepest part of the valve relief radius. That makes my picture above not exactly precise (red line needs to be vertical). I didn't know you are trying to reproduce it precisely when did that pic. Just tried to convey the idea explanation about TE measurement and where it starts from.


P.S. What are you trying to figure to? If Wiseco pistons match your desired spec?

[.n0iz4!]

This is how it should looks

[zaq123]

I'm getting inspired with my art skills now. Definitely need to explore it further