348: OK, new compression #s | FerrariChat

348: OK, new compression #s

Discussion in 'Technical Q&A' started by 348SStb, Oct 24, 2005.

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  1. 348SStb

    348SStb F1 Rookie
    Owner

    The Ferrari dealer re-did the compression test on my 348 after they discovered that the tool they had used the first time was inaccurate.

    The new compression #s are:

    c1 195
    c2 198
    c3 195
    c4 196
    c5 198
    c6 194
    c7 196
    c8 196

    I know these numbers look good because they are very close together, but should they be above 200?
     
  2. Ferrari_tech

    Ferrari_tech Formula 3

    Jul 28, 2003
    1,527
    UK
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    Malcolm W
    Compression figures depend on many things , the main thing is consistancy accross the cylinders - I would be quite happy with your figures
     
  3. Ken

    Ken F1 World Champ

    Oct 19, 2001
    16,078
    Arlington Heights IL
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    Kenneth
    Wow, that's so much higher than my car! My Lotus is 168, 168, 170, 170 for a 9.5:1 comp. ratio 1.6L 4 banger.

    What's the factory spec on a 348?

    Ken
     
  4. tbakowsky

    tbakowsky F1 World Champ
    Consultant Professional Ferrari Technician

    Sep 18, 2002
    19,344
    The Cold North
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    Tom
    Looks good! Now ask how the numbers jumped so high so fast. Did they squert oil in the cylinders? Did they warm up the car better?,did they use a different gauge?, did they use a different car?<--;)
     
  5. Miltonian

    Miltonian F1 Veteran

    Dec 11, 2002
    5,966
    Milton, Wash.
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    Jeff B.
    I wouldn't expect to see compression readings that close together on a brand new engine with a brand new tester. Something stinks. I have my suspicions that they just made up the numbers. Are you SURE that they really re-did the test? There's no way that the original compression test numbers were right, they had to know that numbers like that did not match your leakdown numbers. Why didn't they recheck their numbers in the first place? I think you need a good long hard talk with the service manager.

    Perhaps one of the pros like Rifledriver has an opinion on this. Would you EVER expect to see numbers that close together on a used car?
     
  6. 348SStb

    348SStb F1 Rookie
    Owner

    Well, I will say that I do treat my engine with the utmost care and respect :)

    As far as trusting the service technician is concerned, I guess I should investigate further; but I will say that I have a very good relationship with the service advisor and with the technician himself. These people are very trustworthy.

    It's true that he should have re-did the test himself without my questioning.

    Apparently the first gauge he used was not accurate, so he used a "Mag" (or Mac?) guage the second time around.

    Rifledriver... your thoughts?
     
  7. Miltonian

    Miltonian F1 Veteran

    Dec 11, 2002
    5,966
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    Jeff B.
    Let me tell you a little story that may explain my suspicious attitude about this. Back in the 80's, I worked as a QCI for the service department in a busy VW dealership. As part of each major service, the tech was supposed to do a compression test. It was quick and easy when the spark plugs were out anyway, and just 4-cyl engines. Took maybe 5 minutes to do, and they were paid to do it. I was constantly having to bug the techs to write down the compression numbers on the repair orders, so the service advisor would be able to pass the information along to the customer, and would KNOW that we hadn't just done a full service on an engine with a dead hole. Finally, one day, this particularly lazy tech failed to write down the compression numbers for about the 50th time, and I got in his face about it. He shouted at me, "You want compression numbers, HERE, I'VE GOT A WHOLE PEN FULL OF THEM!!!!" And he proceeded to write down the number 150 all over the back of the order. He obviously never did the checks, he just gave me numbers to get me off his back. Real professional.
     
  8. Joe G.

    Joe G. Formula 3
    BANNED

    Dec 9, 2003
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    Joe Gazzani
    sumthing weally weally scewy
     
  9. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
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    10.4:1
     
  10. Rifledriver

    Rifledriver Three Time F1 World Champ

    Apr 29, 2004
    33,736
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    Brian Crall
    Just saw this and had to go back and find and read the other thread for context.

    I don't know how many miles the motor has on it but for background I will say with the exception of the cam drive system the 348 was as robust a motor as Ferrari ever built. TR is the same in many ways and I just went for a drive to up close to the Oregan border with another TR that had 212 k miles and it ran as good as ours with 200 less.

    Compression tests are like prostrate exams, you have to have a lot of faith in the guy doing it. The equipment and methodology also varies a lot. Those numbers are pretty close and I will also say the gauges usually are marked in 5lb increments and some people just round off to the nearest 5, others try to estimate the individual pounds. Then there are those that just make numbers up. I can't say they are not legitimate but I would like to have been looking over his shoulder.
     
  11. No Doubt

    No Doubt Seven Time F1 World Champ

    May 21, 2005
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    #11 No Doubt, Oct 24, 2005
    Last edited by a moderator: Sep 7, 2017

    That's a $125 guage. I say buy it yourself and use it to test 2 cylinders. If your numbers match your shop's, then no problem.

    These 348 engines are clockwork, so I wouldn't be too surprised at your great numbers, though.

    Here's the Mac leakdown tester: http://www.mactools.com/ProductDetails.aspx?ItemNum=CLD200M
    Image Unavailable, Please Login
     
  12. Rifledriver

    Rifledriver Three Time F1 World Champ

    Apr 29, 2004
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    That's a leak down tester.
     
  13. No Doubt

    No Doubt Seven Time F1 World Champ

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    #13 No Doubt, Oct 24, 2005
    Last edited by a moderator: Sep 7, 2017
  14. fatbillybob

    fatbillybob Two Time F1 World Champ
    Consultant Owner

    Aug 10, 2002
    26,291
    socal
    Just for curiosity...why compression numbers? A leak down test is what you really need. For those medically inclined like the difference between a breast exam and a mamogram. For you lawyers like the difference between a will and a family trust. IMO snapshot compression numbers so mean much.
     
  15. Rifledriver

    Rifledriver Three Time F1 World Champ

    Apr 29, 2004
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    I am a firm believer in both in certain circumstances. They provide different and important information.
    He already got good leak down numbers (listed in another thread) but the original compression #'s were way off suggesting a problem with the test. The second compression numbers are so good and consistant it is causing some disbelief.
     
  16. Ken

    Ken F1 World Champ

    Oct 19, 2001
    16,078
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    Kenneth
    That's the compression ratio, not factory spec for compression PSI...but that answers my question as to why a 348 is higher than my car! (Most?) older Ferraris than a 348 all have lower ratios and lower compression numbers.

    No regular gas for you! LOL

    Ken
     
  17. fatbillybob

    fatbillybob Two Time F1 World Champ
    Consultant Owner

    Aug 10, 2002
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    socal

    Ah-So....I did not get the whole story. Thanks!
     
  18. Zulf

    Zulf Rookie

    Jan 16, 2019
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    Irvine California
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    Zulf Ali
    Hi gents, I’m new to this forum. I’m currently looking at buying a 1990 348. This particular car has just over 13000 miles and just had a major service. Here are the compression test results. Please let me know your thoughts.

    #1- 160
    #2- 154
    #3-160
    #4-162
    #5-160
    #6-162
    #7-150
    #8-168

    If these are low or an issue can these be remedied on my next major if I bought it. Thanks
     
  19. greyboxer

    greyboxer F1 World Champ

    Dec 8, 2004
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    See post #2
    I'm sure others will comment further in your main thread
     
  20. Meister

    Meister F1 Veteran
    Silver Subscribed

    Apr 27, 2001
    5,516
    Duluth, MN
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    The Meister

    Zulf I think you and I chatted about lotus esprit wheels via ebay a while back. Welcome to fchat.

    If anyone is going to follow this thread...my ex 348 with 43k miles and last major service date (completely) unknown pulled comp #'s very consistent to the ones in the first post done by a very reputable shop. Personally when I saw the #'sI was surprised, tech wasn't and buyer was happy so it was all good.
     
  21. Ferrari Tech

    Ferrari Tech Formula 3

    Mar 5, 2010
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    Wade Williams

    Drive it and enjoy it.
     
    steved033 likes this.

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