Quote:
Originally Posted by D-IV
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Div, actually +/-0.3 is quite a high number when you talk about combustion chamber volume. I only needed like 1+cc to go from 10.5CR to 11CR on my b16A. I did that with S2 high comp flat valves. They're heavier than type R, but I just modded in the most convenient way as my valves were too worn to be reused. With pistons, the cc variation can be bigger, as valve pockets can be made deeper to compensate for high dome. Then there's the issue of wrist pin height (or the C/D = compression distance), which is more accurate(or inaccurate, depending on who you ask) view/number (you have to convert, that's the inaccurate part, because 1 inch doesn't exactly = 24.5 (or was it 25.4?) when measuring compression. If our cars were measured in cubic inches, it'd be easy, but they're not :P
So if the wrist pin height is different, then have to measure the piston to deck height (which can be a positive number, means the piston stick out slightly from the bore. I don't really like this method for rod stretch reasons, but it's one way to get higher compression)
Using mugen/spoon metal gasket also nets around that 1cc number, as it can be considered part of the combustion chamber calculation.
It can be considered a quick and easy mod to get power. Install on stock engine, observe if the engine runs lean or not, and then up the fuel pressure if it's too lean.
simple and no so cheap at RM500 a piece (dunno the current price, I'm guessing)
About measuring.
To measure accurately, have to measure a couple of times and get the averages. if too much variation between readings, then the reading is invalid, and measured again. I measured 3 times and got 3 same numbers each time, so it was a clear cut thing.
using liquids means there will be water tension, that's what the perspex is for, to break the water tension when it hits the brim of the combustion chamber. It's not for show, lol.
(okay...so I used to think it was for show..
.)
Then you need a beaker, and plasticine to get the volume of the valve pockets. that one is a bit of calculator work, as you will need to mold the plasticine to the shape of the piston to that is't perfectly round and square. (round like the piston, square means the top is FLAT, that sounded so weird/oxymoronic lol.)
DC2 cylinder head VS EK9 cylinder head
