4A-GE engine mix - question

[Bean]

Uzelac Wrote:Continued


Measured my chamber cylinder 1, only 32cc!
I'm sure head was cut 1mm, but measuring was done good, friend who is a professional engine builder did it.
It is a smallport head, 100% no porting/enlarging chamber.

Does it make sense ?
Where would i end up, 13+ CR zone ?

with a 1.2 HG shy over 12.6:1 (static)CR
a nice and easy (allows metric or imperial) CR calculator you can find here: http://www.csgnetwork.com/compcalc.html

when you say no porting at all, does that mean the hotspots in the combustion chamber are still there? if yes in combination with the wiseco pistons you'll be in big trouble.

Also although a lot of people choose the HG simply to get their desired CR, they often forget that, in combination with the deck height, the choice influences the effectiveness of the squish area (this should be idealy some where ~1mm on a high CR engine, run too low and your pstons will hit the head, when the rods/rodbolts stretch, piston expands; too big and the effect will suffer)

At the end of the day SCR is only half the story - what you want to know is DynamicCR to calculate that I would need to know at what ° ABDC (AfterBottomDeadCenter) your intake valves fully close, as only then the engine will start compressing. with your wild cams it'll be fairly late so you will need a higher SCR but mind you, depending on fuel quality and engine running temps you wouldn't want to run much above 9:1 DCR


just as a guideline - oh and if your oil gets easily to 100°C+ on track forget about the lower two lines