compression numbers, how bad are these Options

[mobymutt]

Just did a compression check, here's what I measured:

108, 120, 96, 85

I've got a stock 1.8L, but would like to build a 1911 or 2056 in the relatively near future. Hopefully I'll be ok for another year or so with the current setup.

[mobymutt]

Full disclosure: I did just have the engine apart, but (for a number of reasons) I didn't replace the pistons, cylinders or rings.

There was actually a pretty big 'pocket' in one of the cylinder walls (looked like a casting void), so having at least one cylinder with low compression doesn't surprise me.

Is there an actual spec for what the compression numbers should be on a good engine?

[rgalla9146]

Full disclosure: I did just have the engine apart, but (for a number of reasons) I didn't replace the pistons, cylinders or rings.

There was actually a pretty big 'pocket' in one of the cylinder walls (looked like a casting void), so having at least one cylinder with low compression doesn't surprise me.

Is there an actual spec for what the compression numbers should be on a good engine?

Uniform numbers is the goal.
The actual number is dependent on engine configuration.

[Morrie]

Full disclosure: I did just have the engine apart, but (for a number of reasons) I didn't replace the pistons, cylinders or rings.

There was actually a pretty big 'pocket' in one of the cylinder walls (looked like a casting void), so having at least one cylinder with low compression doesn't surprise me.

Is there an actual spec for what the compression numbers should be on a good engine?

Uniform numbers is the goal.
The actual number is dependent on engine configuration.

Exactly. I have run engines down below 100 PSI compression numbers so long as the numbers do not vary dramatically. 10% of highest compression subtracted from highest number is a reasonable rule of thumb. For example, if your highest compression cylinder is 100, lowest should be 90. This is a quick real world rule of thumb, not a textbook number. Problem with large variation is it places uneven stresses on the lower end of the engine, and can cause problems in the bottom end sooner than later.