Compression Test Results

Discussion in '96-04 - 2V Specific' started by 97stanger, Apr 3, 2016.

  1. 97stanger

    97stanger Legend

    Messages:
    5,880
    Likes Received:
    95
    Joined:
    Mar 22, 2006
    I mentioned in one of my other posts about some issues I was having with my car when I recently put it on the dyno. To make a long story short...My wide band was showing pig rig (10.2) at WOT, so I wanted to get it on a machine to see what was going on. So a little bit ago I got the car on a dyno. My tuner's wide band was showing 11.2 the entire pull up to 6400 or so, which mine was showing 10.0, so it seems my o2 sensor is bad. I had no spark blow out, the car was not going lean suggesting I have plenty of fuel, and the car was seeing 19 or so psi, but is WAY down on power. We did 3 pulls and after the 3rd the car was barely making 400rwhp. So today I started with a compression test, thinking I may have a bad head gasket or possibly something going on with a piston ring or maybe even something in a head...so wanted to start with a compression test and next I'll do a leak down test. My results are below:

    #1 - 130
    #2 - 143
    #3 - 133
    #4 - 135
    #5 - 140
    #6 - 135
    #7 - 140
    #8 - 135

    After doing some research online, I'm seeing some guys getting a lot higher numbers, but obviously different setups may result in different findings. I'm running a 97 romeo block, PI heads, Manley 18cc pistons, Permatorque MLS 3.625 head gaskets...so I should be around 9.5:1 compression. My cams I am running are overall a pretty mild blower grind, .220/.230, 533/571, 114. I'm thinking next I'll do a leak down test to see what kind of results I get, but just wanted to get any input or advise on my compression results, this is the first time I've done a test on this car. Thanks in advance.
     
  2. Thomas_W

    Thomas_W Well-Known Member

    Messages:
    1,478
    Likes Received:
    44
    Joined:
    Jan 25, 2007
    Location:
    Capon Bridge, WV
    Was the test with the engine hot or cold?
     
  3. 97stanger

    97stanger Legend

    Messages:
    5,880
    Likes Received:
    95
    Joined:
    Mar 22, 2006
    That was hot. Let the car get to about 160. Probably took a half hour to get all the COP's off and plugs out, but even fitting on compression tool was still warm when removed
     
  4. Thomas_W

    Thomas_W Well-Known Member

    Messages:
    1,478
    Likes Received:
    44
    Joined:
    Jan 25, 2007
    Location:
    Capon Bridge, WV
    Hmm. They are all similar in numbers which is good.

    How much power does your tunee think your missing?

    what head bolts are you using?
     
  5. 97stanger

    97stanger Legend

    Messages:
    5,880
    Likes Received:
    95
    Joined:
    Mar 22, 2006
    The car makes 600rwhp consistently . This past dyno number was dropping after each pull, ended with it barely making 400rwhp, so it's down about 200rwhp. I run head studs
     
  6. Thomas_W

    Thomas_W Well-Known Member

    Messages:
    1,478
    Likes Received:
    44
    Joined:
    Jan 25, 2007
    Location:
    Capon Bridge, WV
    Holy smokes.. Thats a huge loss.

    Do you notice any coolant loss? It could be that under boost the head is lifting allowing some blowby
     
  7. 97stanger

    97stanger Legend

    Messages:
    5,880
    Likes Received:
    95
    Joined:
    Mar 22, 2006
    No noticeable coolant loss. I haven't thought about that, I started thinking possible timing issue. How would I ever determine if lifting a head was the issue?
     
  8. 96blak54

    96blak54 Legend

    Messages:
    7,471
    Likes Received:
    781
    Joined:
    Feb 21, 2011
    Location:
    Ky
    What oil weight do you run?
     
  9. Thomas_W

    Thomas_W Well-Known Member

    Messages:
    1,478
    Likes Received:
    44
    Joined:
    Jan 25, 2007
    Location:
    Capon Bridge, WV
    You could lose coolant over time, the best way to rule that out is to just retorque the heads
     
  10. 97stanger

    97stanger Legend

    Messages:
    5,880
    Likes Received:
    95
    Joined:
    Mar 22, 2006
    Valvoline 5w30
     
  11. 96blak54

    96blak54 Legend

    Messages:
    7,471
    Likes Received:
    781
    Joined:
    Feb 21, 2011
    Location:
    Ky
    man...im gonna sound like a broken record here, but the lash adjusters can really break an engine and at your power levels its really noticeable. These things are so high tolerant made, anything can cause them to lock or not operate as they should, ultimately hanging the intake valve open at the wrong times. This is only a suggestion towards the problem, but all the parameters being spot on and power down reminds me of my buddies issues. Can you take out the lashers and squeeze the oil out? Using heat gun helps to thin the oil so that they can collapse easier. Hope this helps bro. Keep us posted otherwise
     
  12. 97stanger

    97stanger Legend

    Messages:
    5,880
    Likes Received:
    95
    Joined:
    Mar 22, 2006
    Thanks for the input and advice man. I'm going to try a leak down just to be safe and see what the results are. After that, I'll start working on getting the valve covers off and taking a look. If it's anything top end related I'd be happy.
     
  13. hondarocks61

    hondarocks61 Active Member

    Messages:
    568
    Likes Received:
    19
    Joined:
    Jul 5, 2012
    Location:
    MA
    I'll be very curious to see what is wrong. Seems like a solid setup.

    Sent from my LGL22C using Tapatalk
     
  14. 97stanger

    97stanger Legend

    Messages:
    5,880
    Likes Received:
    95
    Joined:
    Mar 22, 2006
    So started the leak down test today...got 5 cylinders done and couldn't spend any more time on it. Kind of stumped with it. Now because I had the spark plugs out and all the COP's off, I did the test cold. I have the OTC leak down tester, and used a consistent 80psi for my reference on the left gauge. Here are my results so far

    #1 - 35% leak
    #2 - 25% leak
    #3 - 37% leak
    #4 - 25% leak
    #5 - 27% leak

    The only thing I don't know is how wide of a gap my piston rings are. When I bought my rotating assembly years ago from a local engine builder, I told him I was going to be running fairly high boost, so I would imagine he went a bit wider on the gap. The only other thing I didn't like was #1 and #3 there was a very loud and noticeable air leak coming from the hose to the tester. Could this potentially mean I have cracked or broken timeserts? Just trying to think of all possible things that could be going on
     
  15. 96blak54

    96blak54 Legend

    Messages:
    7,471
    Likes Received:
    781
    Joined:
    Feb 21, 2011
    Location:
    Ky
    Surely the rings arent broke! Do you remember the rings you used?
     
  16. 97stanger

    97stanger Legend

    Messages:
    5,880
    Likes Received:
    95
    Joined:
    Mar 22, 2006
    Unfortunately I don't. I dug up the invoice and no luck either. I'm really starting to get stumped with what is going on. What about something stupid like a bad o2 sensor? Would this cause the extreme loss of power I'm seeing at WOT...or the opposite b/c it would be in close loop at WOT?
     
  17. 96blak54

    96blak54 Legend

    Messages:
    7,471
    Likes Received:
    781
    Joined:
    Feb 21, 2011
    Location:
    Ky
    Any gas smell on the oil dipstick?
     
  18. g36 monkey

    g36 monkey Moderator Staff SN95 Supporter

    Messages:
    14,057
    Likes Received:
    539
    Joined:
    Nov 15, 2008
    Location:
    Orlando, Fl
    Did you timesert every cylinder plug?
     
  19. 97stanger

    97stanger Legend

    Messages:
    5,880
    Likes Received:
    95
    Joined:
    Mar 22, 2006
    Nothing really noticeable, and no fuel on plugs
     
  20. 97stanger

    97stanger Legend

    Messages:
    5,880
    Likes Received:
    95
    Joined:
    Mar 22, 2006
    Yes, car has had timeserts for probably 5 years now