Piston Design
Turbo Mini Forums

Ok guys taughts on this,

Attached is a pic of a drawing I have been doodling with, (I relay need to learn CAD) I have just finished Dishing out my pistons and got to thinking is there a possibility of bad flame prop and uneven burn as the piston moves of TDC with the current design (the left hand side of the attached drawing in cross section view) and would I be better radiusing the outside wall (as in the right hand side of the drawing again cross section view) ??

You’re taught greatly appreciated

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I would say so yes, sharp edges and quick/even distribution rarely goes together....

is this for a 5 port head?

I did mine the classic "D" shape (a "D" on its side but with a large flat bottom).

I retained the flat top around the outside because (after everything I read) it seems to be important, along with deck height, for getting the "squich" right.

Assuming it's a standard head of course.

Whether I'm right or not remains to be seen....

Schrödinger's cat - so which one am I ???

I recognise that large flat bottom !

Sore lads I ment to say its for the bmw 16v racer

Edited by PaulH on 30th Oct, 2008.

I dont see any OEM pistons like that so I would say there is nothing in it other than expensive machining?

what about making them more like this: http://www.minimania.com/web/item/RE-A1117...%20PISTON%20SET

have you got any pictures of this?

Drives
-Ford S-max Mk2 Ecoboost
-Rover 100 VVC #2 - track project

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do you mean radiusing it Sprocket I think you are right I have been on the Omega, AE and wiseco as well as a few other ones and the all show pistons with my current design but none with my proposed design

I will be doing the dry build during the next two weeks Paul and I check clearence but I suspect I will still need cut outs

BTW here are my wiseco pistons for my NA 16valver:

Schrödinger's cat - so which one am I ???

yeah i couldnt really get in my head an imaged of what you ment a D on its side with a flat bottom. tbh i still dont :) but atleast i know i need the edges for my pistons when i get them and machine them as im going to have a 5port head :)

(_) piston shape like that for the chambers or like _/ ?? i think i get what you ment now lol

Edited by Paul R on 30th Oct, 2008.

Drives
-Ford S-max Mk2 Ecoboost
-Rover 100 VVC #2 - track project

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miniminor63 what size ae those pistons ?

i would say 73.5 as it is a N/a

Drives
-Ford S-max Mk2 Ecoboost
-Rover 100 VVC #2 - track project

Searching is all you need on TurboMinis

why 73.5 mm? its 72.5 mm pistons as a matter of fact, so I do not make the block "useless" when worn at 73.5 mm

i was meaning a 1380cc i thought they used 73.5mm pistons :) as your doing a n/a build i assumed it would be 1380.
apologies

Drives
-Ford S-max Mk2 Ecoboost
-Rover 100 VVC #2 - track project

Searching is all you need on TurboMinis

:) its not a 1380, its a 1343cc engine.

+60 long stroke? or custom pistons and bore size?

Drives
-Ford S-max Mk2 Ecoboost
-Rover 100 VVC #2 - track project

Searching is all you need on TurboMinis

pistons are wiseco ones, so custom. one can get 72.5 mm pistons from different other places now though. The stroke is standard 1275.

Here are my STD Powermax pistons with 16v cuts. Note the cuts are all identical across the pistons because of the special boring carried out

I have a set of STD turbo pistons where I have opened out the dish, but I have a large radius at the bottom of the dish, pretty much similar to these Powermax pistons, just a bigger dish, by about 10cc more!







The only thing im concerned about with your design is the short radius at the bottom of the dish. There isnt much suporting the crown around the top ring land?

Sprocket could you tell me the thickness of the center of the crown in the pic with the sectioned piston

7mm. Those turbo pistons are tough old boots!!

:lol that they are,
On my omegas there is 11mm so from that point of view im not to bad