Compression figures

[gazareth]

How will they read lower with cam & head job? The valves are closed so no difference in compression

145 is too low, try a different gauge

so why do you think when you put in a cam with more duration and overlap they recommend upping the static compression ratio??? its because low rpm cylinder filling isn't as effective.

[Gambit]

Lairy cams yes but fast road cams no

[gazareth]

any uprated cam will make a difference. with a long duration cam the inlet stays open longer as the piston rises on the compression stroke pushing back out some of the air it has just drawn it.

[Gambit]

As i said lairy cams yes fast road no

 look at kr, abf & autotech cam profiles. One has more lift, the other more duration and the later more of both and neither effect compression ratio

what cam is sgt_lemon running? Itd need to be a seriously big cam to have that much effect on compression.

[gazareth]

kr and abf are 16v so you cant use them in a comparison between a standard 8v and a cammed 8v. not sure what cam the sergeant has but he reckons that once it was fitted his idle got very lumpy.

[danny_p]

his gadge dosent stay up tho,  if it dosent have a valve init where it screws into the cylinder the colume of the pipe can be considerd to be part of the combustion chamber,  that will lower the compression ratio shown  LOTS.

145 is enough to run tho

[notenoughtime]

I have a classic mini running a very lairy cam my compression gauge figures are about 280 per cylinder the overlap doesn't really affect reading

Op needs to use a gauge that works and then put his results up and we wouldn't all be going on about low readings in the engine

[Sgt_Lemon]

I have acquired another tester to settle it haha  if the sun comes out later I will test it again.

[gazareth]

I have a classic mini running a very lairy cam my compression gauge figures are about 280 per cylinder the overlap doesn't really affect reading

Op needs to use a gauge that works and then put his results up and we wouldn't all be going on about low readings in the engine

ok now we are veering of in a completely different direction again with talk of mad mini engines. but just out of curiosity. what is the static compression ratio of said mini?

[JC]

shall we get back on track 

Sarge, different compression Gauge required, then new readings please.