Rb26dett Compression Test Reads High

[BoostedBarge]

Hey guys,

I'm in the process of buying an Autech Stagea 260RS. I got a mechanic to do a compression test last week and the results came up as:

174 178 178 182 182 179

If I'm not mistaken, the quoted maximum for an RB26DETT is 171psi and normal is around 160psi. I was there when the mechanic did the test and he used a good quality Blue Point digital compression tester. The test was done when the engine was hot and throttle was closed. The mechanic didn't tell me to open the throttle. I later read that it should be open. Anyway, I'm not overly concerned since the readings are all fairly close to one another. I was just wondering if someone could explain the high readings? Perhaps the gauge was a bit out? Would the hot engine make a difference?

The engine looks dead stock (except for exhaust) and is running standard boost. From the exhaust it sounds like it has a slight miss or pop at idle, but it holds a good steady idle. I'm not sure if this is normal for an RB26. Perhaps it's the aftermarket exhaust that gives it this sound or perhaps it's in need of a service and timing adjustment (has just come off the boat). It revs cleanly to 7000rpm.

Cheers,

Simon

Edited March 24, 2008 by BoostedBarge

[Adriano]

Comp test should always be done hot, either inconsistency in the gauge which is very common, or the head may have had a skim at some stage.

[Duncan]

yeah probably been rebuilt nice and tight with either head shaved or block decked. don't worry it sounds nice and healthy

[MYRB30]

I once comped at 1jz which showed around 250+ psi....lots of carbon in the chamber will do this

[BoostedBarge]

Cool. Thanks guys. Lets hope it's just the gauge.

I'll test it again with a mate's gauge once I get the car.