compression test

[bhp-mad]

hi all, iv got a evo5 done 70.000miles what would be a good pressure to have or can someone tell me the compression in the pistons when they were new???thanks

 

[HermaN]

When fully warmed up on WOT it should be...

Minimum - 9.7 bar (140psi)

Standard Value - 11.5 bar (167 psi)

Limit between cylinders - 1.0 bar (14.5 psi)

 

[jamie@evotune]

Normal comp pressure you will see on a Evo engine is 120 psi across the cylinders.

Anything bellow 100 psi and I would be investigating it further I would also carry out a cylinder leakage test as a comp test will not always show a fault on the engine.

 

[HermaN]

Normal comp pressure you will see on a Evo engine is 120 psi across the cylinders.

Anything bellow 100 psi and I would be investigating it further I would also carry out a cylinder leakage test as a comp test will not always show a fault on the engine.

120psi?! When warmed up with the throttle wide open?? None of the engines I have tested have been that low. The last 8MR I checked was 175, 170, 180, 175

The figures I posted above are also directly from the service manual. 120psi is too low on a fully warmed up engine on WOT.

 

[bhp-mad]

test done

hi thanks for the replys...i was getting 150 psi on all pistons with the throttle closed on 6 turns of the engine is this good or not .

 

[jamie@evotune]

120psi?! When warmed up with the throttle wide open?? None of the engines I have tested have been that low. The last 8MR I checked was 175, 170, 180, 175

The figures I posted above are also directly from the service manual. 120psi is too low on a fully warmed up engine on WOT.

Well all the ones we see are around that figure I know what Mitsi say but it is very rare that you will get a Evo engine that has above 155 psi per cyl.

 

[HermaN]

.....but it is very rare that you will get a Evo engine that has above 155 psi per cyl.

I always do a compression test as part of my pre-mapping checks and not had any below 140psi yet, all are 150+....

@ op, 150 per cylinder with throttle closed seems good, but the test should be done with the engine @ operating temperature with the throttle wide open.

 

[bhp-mad]

I always do a compression test as part of my pre-mapping checks and not had any below 140psi yet, all are 150+....

@ op, 150 per cylinder with throttle closed seems good, but the test should be done with the engine @ operating temperature with the throttle wide open.

the engine was at operating temp , but i will do it again with the throttle wide open ...how many times do i need to turn the engine over ????thanks

 

[HermaN]

...how many times do i need to turn the engine over ????thanks

Until the gauge stops rising. Also make sure all plugs are out when doing the test, don't remove them 1 by 1.