Cold compression test after rebuild... should I be worried?

[MidnightR32]

Welp, this is where my compression lands after my rebuild. Thoughts? I have ~6 hours on the motor. 

[MidnightR32]

This is for an RB20DET. Sorry for not including that. 

[Duncan]

How have you run it in / what has been done in those 6 hours? Also, you need to do the test hot.

You have to load the new motor pretty hard to bed the rings in quickly and properly, doing it on the dyno is best and only takes an hour-ish

The other question is.....what were the measured clearances post machining and do they match the specs for the piston and rings

[Murray_Calavera]

1 hour ago, Duncan said:

what were the measured clearances post machining

$50 says no measurements where done post machine shop. 

[MidnightR32]

1 hour ago, Murray_Calavera said:

$50 says no measurements where done post machine shop. 

Nope and I only have myself to blame here. I hired the shop and didn't do my due diligence.

[MidnightR32]

3 hours ago, Duncan said:

How have you run it in / what has been done in those 6 hours? Also, you need to do the test hot.

You have to load the new motor pretty hard to bed the rings in quickly and properly, doing it on the dyno is best and only takes an hour-ish

The other question is.....what were the measured clearances post machining and do they match the specs for the piston and rings

 

The first hour or so was not on a dyno, but 2 of them were on a dyno and it was pushed hard enough to get tuned. 

[Duncan]

My suggestion would be, even with 6 hours on the engine already, take it back to a dyno and give it a good high load run in, then test again when warm.

I've learned through experience that fuel glazing bores is very easy on a new engine but both times it was saved by pushing it harder. You just can't get that sort of good load on the road