155mm rods and oem pistons for 2.5l, how many uses this?

[x6rs]

is this a good reliable combination in a tall deck?

and what compression rate do you get using standard pistons, 155mm rods in a diesel bottom?

[aronmatic2]

http://www.s2forum.com/forum/showthread.php?t=34352&highlight=155mm

[x6rs]

so with 155mm and oem pistons 8,71:1 compression rate or am i reading something wrong? whats oem compression rate?

is there alot of people using stock pistons on a 2.5l machine with good results?

[Jamo]

I disagree having calculated and having my pistons remade by JE, I spoke also to CP and using the stock pistons put the CR about 10.7:1

[x6rs]

ok, i guess a little extra compression cant hurt in worst case scenario, less boost means cooler exhaust valves i guess. heard that the new wrc engines had a cr about 11,5-12:1 and 2bars of boost

what happens if i skim of a little to lets say, the valve grooves in the piston dissapears? what cr would that be?

[x6rs]

how do you calculate the CR?

[RallyQuattro]

155mm and oem pistons it will be 9.8:1

Here in Swedish:
Blockhöjden ökar med 236-220=16mm
Staklängden ökar med 155-144=11mm
Den ökade slaglägden gör att kolven kommer (95,5-86,4)/2=4,55mm högre upp.
Alltså kolven kommer att svänga 16-11-4,55=0,45mm lägre ner än orginal.
Orginal förbränningsvolym 81²*pi*86,4/4000/(9,3-1)=53,6cm3
Förbränningsrummet ökar med 81²*pi*0,45/4000=2,3cm3
Nya kompet blir (81²*pi*95,5/4000/(53,6+2,3))+1=9,8