well, here is the background to the story: last night, I played with an M5 just for fun, misshifted from 6th to 3rd coming around a corner, and I mechanically over-revved for appr. 1.5 seconds... Anyways, to make sure that the F20 doesn't blow, I heard it's a good idea to get the engine checked, which I did and the results are as listed below, I would really like some input on this:

According to Tire's Plus' computer:
Nominal: 1,570kpa 228psi (!!)

Minimal: 930kpa 135psi

Max. Variation: 200kpa 28psi

now, I think that 228 psi is approaching a 14 compression ratio ... correct me if I'm wrong, but we all agreed that that number seemed a little out there.. anyways, here are my results (I'm N/A):

Cyl 1- 150 psi

Cyl 2- 160 psi

Cyl 3- 157 psi

Cyl 4- 155 psi

do those numbers look normal, or am I in trouble? Thanks for any input!!

 

Look fine. You dont want more then 10 variance between cylinders

 

I would suggest you get your valve retainers checked. Unless you have a bent valve, a leak down test will not show the results of a slighlty cracked retainer. Fixing this will prevent the valve from dropping and destroying your motor.

Here's a post by billman that shows the results of an overrev:

https://www.s2ki.com/forums/index.php?showt...&#entry10340216

 

yep, all look very low, we'll assume you had fuel wash away oil etc. and the gauge registers low. Since they're all fairly close

STILL you need to add oil and do the same test....that is drop oil right down the spark plug hole,

THEN YOU NEED TO leak down test it.

-G

 

Compression won't tell you much about the condition of the valves. Leak down test or just skip it and get all the intake valves replaced.

 

this test should not give you assurance.

you should replace your retainers for peace of mind.

after i over-revved, dealer and mechanic both said my compression #'s were fine...

i replaced all my retainers anyway for peace of mind.

about a year later i had low compression in cylinder 3 from warped valve guides and valve face.

perhaps the damage can also appear later gradually, i dunno how or why.

 

^^ how much is a retainer per unit??

 

you can get all retainers and keepers for less than $150 i believe...

 

What was your speed when you shifted into 3rd? And do you have stock gears?

 

I also got around 160 ish on my compression test. Does that mean something is wrong?