more compression!

[ALLNOVA]

got a 20SE in ma nova and want the head skimmed for more oomph, does anyone know how much should come off so that the compression is the same as the SEH?? cant find any stuff in the haynes.


cheers!

[m.d.]

well ive skimmed 40 thou of mine and it made hell of a difference

[ALLNOVA]

any idea what the limit is? or do you think 40thou is sufficent?

[leebo]

hey sorry i cant help as im new to the whole moddin thing but what do u mean by 40thou. i will be undertakin a few changes in the near time to come cheers

[burgo]

40 thousenth of an inch mate



p.s. he he

[leebo]

cheers, i gathered it was a thousenth (spl lol) but i wasnt sur off what

[ALLNOVA]

enuff of the chit chat ladies, whats the bloody limit!

[Stuart]

its usually a couple of mm

and dont get shirty

[ALLNOVA]

okay usually not really good enuff, cheers anyway but i need to know the exact limit as there are vital horses at stake! :o

[Aragorn]

depends on lots of factors

the limit with std cams is going to be different to the limit with high lift long duration cams due to piston valve contact issues

a decent machine shop should be able to tell you

some will also recommend skimming the block face too which raises compression without fucking up the squish zone

[Chris Astley]

there are a few deciding factors on how high you can have your compression.

1/ need to ensure you adequate fueling and high octane(optimax/super unleaded)
2/ may need to adjust timing to prevent detonation.
3/also depends on if your running a high lift cam or not, if not then you want to be running about 10.5 or 11:1 but if the motor is cammed you can run more compression upto 11.5:1

sometimes you can easily skim 2mm(80thou) off head to achieve the desired compression ratio.