18rgu compression rating

[Hemmer]

Hi all I was wondering what is a good compression reading for an 18rgu?

[MorGo]

Err.. you mean compression pressure;not ratio?
If pressure the BGB gives 12,7 bar as std and 10 bar limit.These for 9,7:1 comp 18R-G;for 18R-GU somewhat less (being lower compression model)

[Omegaman]

do you mean the piston combo like 18rg=9.7.1 18rgu=8.7.1 and 18rgeu 8.3.1
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[Hemmer]

Well the compression ratios were helpful but the pressure was what I was after thanks as I did a comp test and got fairly bad readings.

[Willofan]

Depending on the compression ratios, a good engine will give a compression reading between 140 to 180psi and no more than 10psi from lowest to highest.

On an old used engine, if the lowest is 145 and the highest is 155 then it's OK. When I rebuild a motor, I aim for zero variance.

[MorGo]

Bad readings? So be prepared to shop valves..

[Hemmer]

Readings were
1:133
2:97
3:135
4:126
Then I did a wet compression test and the readings were
1:165
2:200
3:190
4:160
So I'm thinking most likely piston rings?