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View Full Version : just did a compression test..



dave j gtt
14-10-2009, 20:35
Was board

1 - 160psi

2 - 160psi

3 - 164psi

5 - 163 psi

Is this normal for skimed head :scared:

Did test by taking sprak plugs out individually is this ok ?

cranked with full open throttle untill reached its peak .

cheers dave

Markey Mark (BD)
14-10-2009, 20:44
There all about the same so no prob's with it loss of compression but abit higher then normal, how much was skimmed off the head? Do you know the head thickness now?

dave j gtt
14-10-2009, 23:10
wrote it down somwhere :scratch: it was defo mid 73mm i had it accuateley measured as well 73.56 rings a bell, that was after the skim tho.

dave j gtt
14-10-2009, 23:12
yeah just got Receipt out 73.56mm after it was skimmed ;)

cheers for input mark :)

Theres no problems as of yet , its been runing 10-20k miles no probs, i played with my carb and had it road tuned a while back all was well.

just digging b4 i decide what the best course of action is with future of car engine :D

dave j gtt
15-10-2009, 22:31
am feeling this is maybe to high :confused: any one :wasntme:

Alex
16-10-2009, 11:56
It's fine. :)

Andrew Cooke
16-10-2009, 13:28
mine was 175psi, don't worry about it.

Jimmy_GTT
17-10-2009, 18:11
There all about the same so no prob's with it loss of compression but abit higher then normal, how much was skimmed off the head? Do you know the head thickness now?

What should be the normal value?

redrocket29
17-10-2009, 18:45
hi i had mine done on the 07/10/09
1 was 6%
2 was 13%
3 was 10%
4 was 8%
the guy said to be worried over ten but even the rolling rod place said dont worry about anything 20 and under then i got my car rolling roaded the same day
there.
an old engine you will always get a bit of leakage .

Jimmy_GTT
17-10-2009, 20:07
hi i had mine done on the 07/10/09
1 was 6%
2 was 13%
3 was 10%
4 was 8%
the guy said to be worried over ten but even the rolling rod place said dont worry about anything 20 and under then i got my car rolling roaded the same day
there.
an old engine you will always get a bit of leakage .

But how many psi is the normal value?

redrocket29
17-10-2009, 21:35
he done it in % thats all i no but my engine is strong and made good bhp

Jimmy_GTT
17-10-2009, 21:42
he done it in % thats all i no but my engine is strong and made good bhp

That's a good news.
What was the result of the rolling?


II have measured my friend's GTT today and the value was around 150psi. Is it good?

dave j gtt
18-10-2009, 05:43
mine was 175psi, don't worry about it.

Cheers for the chill pill Andrew ;), least i have good even compression.

Just trying to way up my next move for more power.

jonnyshaw49
19-10-2009, 21:00
when doin the compression test on the gt turbo is it right to take king lead off then leave plugs in the other 3 cylinders and use tester on them indicidually. on cylinder 4 nearest to flywheel the plug is black like its fouling and the rest clean does this seem suspicious? the engine was rebuilt only a few months ago with new rings just want to check my compression see if there ok.y wud only one cylinder foul?

Andrew Cooke
19-10-2009, 21:13
hi i had mine done on the 07/10/09
1 was 6%
2 was 13%
3 was 10%
4 was 8%
the guy said to be worried over ten but even the rolling rod place said dont worry about anything 20 and under then i got my car rolling roaded the same day
there.
an old engine you will always get a bit of leakage .

that sounds like leakdown rather than compression

Adam L
19-10-2009, 21:48
hi i had mine done on the 07/10/09
1 was 6%
2 was 13%
3 was 10%
4 was 8%
the guy said to be worried over ten but even the rolling rod place said dont worry about anything 20 and under then i got my car rolling roaded the same day
there.
an old engine you will always get a bit of leakage .

That wasn't a compression test, that was a leak down test.

Oh, Andy already mentioned it...