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It can be low or high for forgies. my engine read 120 in all cyl for a rb30det with forgies.

hey guys just running a compresion test from home whats the comp sposed to be i hear 140-160????now will it be lower for forgies???
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Forgies or not.. It doesn't matter. What matters is what comp ratio the given piston returns.

Cam timing, engine temp, piston/bore clearance and the gauge its self all vary the read out.

Mine with was up over 150psi in all cylinders, all exactly the same apart from cyl 3 or was it 4!? :laugh: that was only 1psi down. BUT the motor was stone cold.

I'm just about to give it another comp test *with the same guage* after 50,000km's so it shall be interesting how it comes up.

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Raa told me 5 percent in their little box on the report. whatever that means. RB25Det was at 125,000kms. enlighten me...
Probably the compression results are within 5% of one another which is acceptable but, they should've still provided a reading for each cylinder in their report. Results for a stockish RB25DET in good condition are generally between 140 - 170psi(newish engine).
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Its just a comp guage with 5 little lines between the big numbers. :( I crank until it stops moving.

Unsure on the brand have never taken notice. The old man bought it many years ago, he's not one to buy cheap, he always spends the little bit more to get the better one.

The guage reads out both in bar and psi.

I'm not concerned on the actual final number as it doesn't mean a lot, I'm just stoked how spot on each cylinder is. :D

The old rb20 varied by 5psi when it had supposively done 67,000km's.

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