TeamRX8

iTrader: (25)

it only measures actual pressure

you are way over thinking the situation, the standard for seal level is considered to be 1013.25 mb and you just reference everything from there to get a normalized reading, it varies due to atmospheric conditions as we have already discussed

if you really want to ****-yze it, take your compression reading and barometric reading, using the std sea level of 1013.25 mb convert your barometric reading to effective relative altitude, and then use the foxed.ca calculator to spit out your theoretical standardized compression reading

Ian_D

Guys, again, thanks.

I want to say clearly that this is more than an academic exercise as the differences between corrected and non-corrected values will frequently make the difference between pass and fail on the worn engines most RX8s have now.

I am on my 6th RX8 and have always bought and sold privately. I like to have compression figures when I sell so, like many others who don't want to spend $2,000 on a Mazda tester, I have a system that measures the output of an off-the-shelf pressure gauge. The gauge manufacturer is understandably wary of going outside his area of expertise so doesn't say how to manipulate the raw output values into figures at the same basis as Mazda's 6.9 pass/fail limit.

I am honest and want to be confident of compression values I give to the buyer of my 6th RX8 when I sell her to get the next one in my quest for a full house of RX8 colours. Using absolute rather than gauge pressure would boost the figures by 1.0, great when selling a car, and not adjusting for atmospheric pressure/height where I am would reduce the values by 0.4+, great for buying a car.