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 Post subject: CC'ing Cylinder Head
PostPosted: Tue Jun 02, 2009 10:36 am 
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1098cc
1098cc
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Joined: Thu Jul 15, 2004 9:53 pm
Posts: 1768
Location: Lake Macquarie NSW
As I was going through this process at the weekend, I thought I'd take a few pictures, I know a lot of you will be familiar with this, but hopefully for those who have not seen this before it will be of assistance :)

Firstly I made a plate from a free offcut of 4mm perspex, then drilled a 3mm hole:
Image
This is how it will fit and seal the head:
Image
Seal the face with a little grease:
Image
Then run in liquid (I used kero) from the burette to measure ther volume:
Image
This being a 12G295 head, I added 5ml (CC) to start with, then measured:
Image
So 5 plus 22ml is a total of 27.0 ml for this head which has had a clean up skim (12G295 usually 28.3 ish..)
Final picture of full set up:
Image
Burettes are available from Lab supply places.
I also did the same excersise on the block with the piston at tdc, the dished piston and area above the piston yielded 9.5ml, so total volume on this 0.060" over 1098 is 36.5ml, plus say 1.7ml for gasket (tot 38.2)...

So, question time! what's the current compression ratio! :?

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 Post subject:
PostPosted: Tue Jun 02, 2009 11:19 am 
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Bimmer Twinky
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Joined: Mon Sep 06, 2004 4:36 pm
Posts: 8602
Location: Brisbane
CR = total combusted volume(CV) + the swept volume (SV),,, divided by the swept volume (SV)

or,,, CV divided by SV +1

so,,, "IF" your head gasket holds 1.7ccs (i`d say it will be more like 2.5mm actually but you should measure it) & if you have actually got 38.2ccs total

then 1098 + .060 oversize is 1150cc

divide by 4 for one cyl = 287.5cc

ok,, so our CV is supposed to be 38.2 divided into our SV which is 287.5,,,which then = 7.526..... Plus our "1" which then = 8.526 -ish

but i`d guess that your head gasket holds more than 1.7cc so i`d say thet you comp ratio is actually slightly less than 8.5:1

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 Post subject:
PostPosted: Tue Jun 02, 2009 11:21 am 
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Milatsmadmini
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Joined: Mon Nov 12, 2007 6:57 pm
Posts: 6221
Location: the inner west of sydeney!
TheMiniMan wrote:
CR = total combusted volume(CV) + the swept volume (SV),,, divided by the swept volume (SV)

or,,, CV divided by SV +1

so,,, "IF" your head gasket holds 1.7ccs (i`d say it will be more like 2.5mm actually but you should measure it) & if you have actually got 38.2ccs total

then 1098 + .060 oversize is 1150cc

divide by 4 for one cyl = 287.5cc

ok,, so our CV is supposed to be 38.2 divided into our SV which is 287.5,,,which then = 7.526..... Plus our "1" which then = 8.526 -ish

but i`d guess that your head gasket holds more than 1.7cc so i`d say thet you comp ratio is actually slightly less than 8.5:1


translated *blah blah blah... comp ratio 8.5:1 GET A TURBO ON THAT!!!

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