davidfox280585

trying to calculate my ratio but it confuses the hell out of me

my engine is a 94 2.0 silvertop

crank stroke is 88mm
piston dish -9
bore size 85mm
head chamber led to beleive is 48cc
st170 head gasket squashes to 0.9mm
eagle rods with larger diameter gudgeon pin

if there is anything else needed please post many thanks guys

the_frozen_one

iTrader: (1)

Does the piston protrude out of the block at all?

davidfox280585

i have not built it up yet just had my acl bearing delivered so i shall pre assemble this week some time and see, i bought the parts second hand new for a zetec turbo if ya get me

many thanks

the_frozen_one

iTrader: (1)

Assuming the pistons are flush with the deck, you'll have approx 9:1

marty24

Here you go

http://www.johnmaherracing.co.uk/enginecalc.htm

the_frozen_one

iTrader: (1)

Too much missing data for a 100% accurate calculation but I'd say between 8.8-9.2 without doubt

davidfox280585

is this accounting the valve cutouts in the pistons
this is the link for the pistons i can find which state my pistons are the top ones part numbers on the boxes for them,
http://www.nolimitmotorsport.com/supertech/pistons.html

the_frozen_one

iTrader: (1)

I'd assume the -9cc 'dish' value would incorporate those. The only way to ever 100% know is too measure everything with bore gauges, DTIs, cc fluid and complex maths. Then you'll know each individual cylinder to three decimal places. But you cant.

Those pistons list a cr of 8.7:1 with a 48cc head volume.

davidfox280585

firstly can i say THANK YOU for taking the time to help with this
it certainly sounds pretty good for a zetec turbo,i had tried using google and just head pickled myself lol,
i tried the link earlier marty posted and either i got it wrong as it came back as 3.3 lol

the_frozen_one

iTrader: (1)

No worries chap, guessed the ZT might be destined for your S1. Was known on S1T a few years back, recognised the name. It is a confusing thing. I do it day in day out at work so I kinda got it down these days lol.

Best thing to do to comp check it once built. Then you'll know

davidfox280585

will do,
another query is the pistons i have got are stated for the svt ie st170 with the smaller combustion chamber so im guessing in a zetec turbo silvertop with a bigger combustion chamber will drop it down a little more
though im confused as i thought the stroke on a st170 were different