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Turbo engine compression test


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step 1 - pull all plugs out

step 2- hold compression tester in plug hole -very firm

step 3- put foot on accelerator-flat

step 4- swing engine at least 4 to 6 times

step 5 - check compression should read between 8 and 10



Technically sound ...Theoretically poked !

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The main thing you are looking for is a similar reading across all 4 cylinders. For an LC, they should ideally be around 135psi, with no more that 10% variation between cylinders. Anything less than 90 is bad news. Also anything over, say 150, may also bad news as the head has been overskimmed, potentially leading to detonation.

cheers Steve

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Here are my compression readings cold vs 1/2 hot (+/- 45 deg)

cyl. cold (PSI) at 45 deg (PSI)

1 120 122

2 118 120

3 116 120

4 115 120

measured with Motometer compression tester range: 250 PSI (

Open throttle is essential to get a proper reading.



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