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348 - Power loss & service work

Discussion in '348/355' started by angelis, Mar 7, 2007.

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  1. angelis

    angelis F1 Veteran
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    Jun 18, 2004
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    #1 angelis, Mar 7, 2007
    I recently did a rolling road test and power output was down to 305bhp, although torque was only down 8 lbs. The top speed was still an indicated 172 bhp. I was told yesterday by QV, that on a de-catted car there is a loss of torque for some reason so that may explain the loss.

    With a decat and tubi, power should have been around 330bhp (on a new motor), which means 25 bhp has disapeared. Suppose it's not bad for a 13 year old motor, but I'm going to undertake extensive checks to see if everything is okay. If after the service/checks and cambelt timing, it comes out with the same bhp, then I'm happy with it and it's probably more to do with the rolling road. Bearing in mind it lapped fractionally faster than a 355 around a short circuit (no high speed straights).



    Next week work will finally start on my 348. My mate George and I (well mainly George :D) will be taking the engine out and doing various things to the car. I have a nagging suspicion that I've forgotton something.


    Here's what we'll be doing.


    - Compression & leak down test

    - Carry out 30K service (cambelts/spark plugs etc) as per 348 book

    - Replace water radiators & fans
    - Replace all coolant hoses with silicon ones
    - Replace fuel lines
    - Replace suspension springs with 10% stiffer 355 ones
    - Replace anti-roll bar bushes
    - Replace suspension bushes with 355 bushes (10% stiffer than 348)
    - Replace water pump (got one off ebay)
    - Change gearbox oil with redline
    - Do the cambelt timing
    - Replace leaking cam seal (replace all seals)
    - Replace tensioner bearing (wiyth Hills Engineering ones)
    - Check clutch/repack flywheel

    - Paint cam covers
    - Clean engine

    - Adjust valves (thanks Ernie)


    Anything else I need to do?

    Any idea what may have caused the 25bhp loss?
     
  2. ernie

    ernie Two Time F1 World Champ
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    #2 ernie, Mar 7, 2007
    Don't forget to adjust the valves
     
  3. angelis

    angelis F1 Veteran
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    #3 angelis, Mar 7, 2007
    Thanks ernie. :D
     
  4. PAP 348

    PAP 348 Ten Time F1 World Champ
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    #4 PAP 348, Mar 7, 2007
    Make sure you take heaps of pics ;) :)

    Maybe time to go on a diet :p
     
  5. gothspeed

    gothspeed F1 World Champ

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    #5 gothspeed, Mar 7, 2007
    Isn't that stock?? 325BHP were the "later" models, right? What measuring device were you using?
     
  6. angelis

    angelis F1 Veteran
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    #6 angelis, Mar 7, 2007
    Mine is a later one with 320 bhp standard.

    Not sure what Roling Road it is, but it's used by Ford to test some of their vehicles. When I was there, they had an original GT40 owned by Ford Motor Company on it. So it is fairly reliable...well as much as rolling roads can be I suppose.
     
  7. gothspeed

    gothspeed F1 World Champ

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    #7 gothspeed, Mar 7, 2007
    My guesses:

    1. Early stages of clutch slipage
    2. Humidity
    3. Fuel octane variations
    4. Dirty air filters
    5. Worn spark plugs
     
  8. angelis

    angelis F1 Veteran
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    #8 angelis, Mar 7, 2007
    Could be. I'll know for sure after the service.

    This is England..... it's always cold :D :D

    I used Shell V-power which is 99 octane.


    There is one other potential cause and that's a faulty 02 sensor.

    A few months back I was getting slow down lights and half my engine shutting down. I swapped over the ECU's and the problem continued on the same side of the engine. I removed the ECU's and thought nothing of it.
     
  9. angelis

    angelis F1 Veteran
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    #9 angelis, Mar 7, 2007
    Last edited by a moderator: Sep 7, 2017
  10. chrisx666

    chrisx666 Formula Junior

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    #10 chrisx666, Mar 7, 2007

    Are you confusing the oxygen sensors and the CAT temp thermocouple (that triggers the slow down lights)?? I can't imagine either causing a loss of power as the M2.7 does not use the oxygen sensor data at W.O.T (IIRC..).

    More importantly, how did they calculate the driveline losses? May be worth comparing the wheel power with another 348 run (PAP?).
     
  11. No Doubt

    No Doubt Seven Time F1 World Champ

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    #11 No Doubt, Mar 7, 2007

    Very possible. Other possibilities could be reduced alternator output (e.g. bad alternator ground, failing rectifier, failing diodes, missing heat shield, etc.) or reduced coil output (e.g. failing wires or failing power transistors or failing coils or even dielectric grease placed on the coil connections instead of just on the spark plug end) or failing 1-way check valves for the air injection or exhaust leak or clogged muffler/cats (OK, OK, he said de-cat).

    Could be a catching brake/caliper/rotor/pad/parking drum or a dying wheel/engine/tranny bearing, too.

    Also, keep in mind that the Motronic 2.7 software retards engine timing if your water temperature is being reported to the ECUs as progressively too high. M2.7 also changes your fuel-air mixture at WOT based on your battery voltage...ditto for your intake air temperature (e.g. MAF signal).

    Further, M2.7 will attempt to use your "learned" fuel-air maps, which are subject to error (e.g. your system learned your car when the ambient air was cold/humid but you ran your dyno test on a day when the air was different).

    If you want consistant accuracy in dyno tests, you've got to reset your main ECUs prior your dyno runs. That reset will clear the "learned" air-fuel curves.
     
  12. No Doubt

    No Doubt Seven Time F1 World Champ

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    #12 No Doubt, Mar 7, 2007
    Is your AFR reading around 13 to 1?! Bit lean, if so. I'd expect best power down below 12.5...possibly even down to 11 to 1.
     
  13. ernie

    ernie Two Time F1 World Champ
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    #13 ernie, Mar 9, 2007
    Just for kicks I would have a look at the resistance of the MAFS. Then when you have the engine out make sure that you time the cams very well. Oh yeah and be sure to put in new fuel filters too.
     
  14. PAP 348

    PAP 348 Ten Time F1 World Champ
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    #14 PAP 348, Mar 10, 2007
    All my runs were done on a Dyno Dynamics dyno. Driveline loss is calculated at around 15%-18% by memory. :):)

    Here is the related link.
    http://www.ferrarichat.com/forum/showpost.php?p=136321185&postcount=1

    I lost around 5HP due to the hotter weather. :)
     
  15. gothspeed

    gothspeed F1 World Champ

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    #15 gothspeed, Mar 12, 2007
  16. PAP 348

    PAP 348 Ten Time F1 World Champ
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    #16 PAP 348, Mar 13, 2007


    No no, would still be around 18RWHP in this cooler weather. :)
    Just higher power figures, still would make around 18RWHP. :):)
     
  17. angelis

    angelis F1 Veteran
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    #17 angelis, Apr 1, 2007
    Cars been dropped off and work on it will start tomorrow.

    Compression & leak down tests first.
     

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