Considering a 2012 458 Italia with 11k miles. Ferrari dealer compression test results as follows: 1-152 2-150 3-148 4-152 5-150 6-145 7-145 8-148 Dealer says results are fine. Reading other threads I know differential between cylinders reasonably low more important than actual PSI levels. But when I bought my previous 2005 7k mile F430 the tests were 195-200. Should I be concerned about horsepower loss? Dealer say no leakdown test needed given the compression test results and they are selling vehicle with a 2 year Ferrari warranty. What do tech experts think?
If they're selling the car with a 2 year warranty , i don't think you have reason to be concerned....lots of variables go into a compression test and the readings that come out of it.
There are different types of gauges and measurements that will produce different results. The important thing is that the compression numbers between the cylinders are pretty close. Now, if you had one or two at 175 or a 130 I'd be concerned. But with those uniform numbers you have nothing to worry about.
152psi is about 10,5bar. It’s very low. This engine cant work on cylinder under about 9bar. This engine should show at least about 12-12,5 bar on each cyl. First I’ll check if the measurement was properly taken. If yes, the numbers are low. But as others said, one thing is good, that there are no big differences between cylinders. Wysłane z iPhone za pomocą FerrariChat
FWIW , for New Power Warranty inspections we run an electronic compression test. Under special circumstances we can run a mechanical compression test. I’ll take a look at the last few inspections to see how their numbers compare with yours. I can tell you, Ferrari would not allow the 2 for 1 New Power if the test were not to their spec. S
Did they manually open the valves in the throttle body during the test? That can negatively affect pressures sometimes. Also, were all the plugs out during the test or did they go one by one? Was the gauge calibrated prior to testing? Usually as long as the readings are all within a few percent of each other then you're ok. Also was the motor hot or cold? Ray
Hey folks: here is the answer to the questions from Rayjohns: Throttle value isn’t touched to do compression test. If reading are with in 10PSI of each other all is good. Proper process is one by one Motor is cold. Thoughts?
As you note your grouping is fine - nothing else matters as there are so many other variables including technique equipment and ambient - this is a positive result
I would think that if your compression readings were supposed to be up around 200psi, at least one of your readings would be near there. The fact that they are all close together at 150ish, it seems to me that the motor is in good shape. I’ve never seen cylinders that wear evenly from 200ish down to 150ish. If there’s a problem with the motor, there’s usually one or two cylinders that read low, with the others reading high. Usually the low cylinder(s) is the one that ran the hottest. I’m sure you are fine and shouldn’t worry. Sent from my iPhone using FerrariChat.com mobile app
