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F40 Boost loss question

Discussion in '288GTO/F40/F50/Enzo/LaFerrari' started by WILLIAM H, Sep 12, 2004.

  1. WILLIAM H

    WILLIAM H Three Time F1 World Champ

    Nov 1, 2003
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    I think my wastegate sometimes opens prematurely releasing all my boost bcus sometimes when I punch it it stumbles really bad. Other times the car just accelerates like the Starship Enterprise going into Warp :)
    I know the problem is bcus the turbos are loosing boost but why does this happen intermittently?

    Mr Scotty, I need Warp drive now dammit LOL

    Thanks
     
  2. cmparrenzo

    cmparrenzo F1 Rookie
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    You have an overboost issue, when this happens, the wastegate opens to avoid handgrenading the engine.

    This happens alot with the addition of a Tubi or other non-stock exhaust. You need to adjust the wastegate which you can do with a simple wrench. You just screw the adjust bolt a 1/2 turn and try the car, keep adjusting till the overboost goes away. In an extreme case you may have to have the wastegate machined, but that is rare.
     
  3. PCH

    PCH F1 Rookie

    Apr 7, 2004
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    Just curious as to why the addition of only an aftermarket exhaust would result in these symptoms
     
  4. cmparrenzo

    cmparrenzo F1 Rookie
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    Well it is not exclusive to aftermarket exhausts, but it usually happens because a Tubi will breath better than a stock system. Better breathing results in QUICKER turbo spin, the car simply builds too much boost too fast.

    The car will act like it lost all power when this happens because the overboost shuts off the ignition till the overboost goes away...
     
  5. Rifledriver

    Rifledriver Two Time F1 World Champ

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    You should contact Dave Helms (he contributes to this board occasionally)about this as he is more familiar with it than I. But to give you the short version, overboost is a computer calculated figure taking into account not only manifold pressure but also a variety of temps to be sure the motor is properly warmed up. With the size of the various coolers, in some conditions the engine management sys senses that the motor is not warm enough to handle hard running (even though you may have been driving for an hour). It was a programming glitch that does not in my experience, effect all cars but one that Ferrari has known about from the start and they at that time defined it as normal. As I said, Dave has delt with it more than I and if he doesn't chime in here I can help put you in touch with him.
     
  6. cmparrenzo

    cmparrenzo F1 Rookie
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    Good answer, but.... in this case the problem is caused by pressure, not temp. Dave and I have talked about this before, I would welcome his comments. Chris Hill at Autosport has alot of F40 experience as well...
     
  7. WILLIAM H

    WILLIAM H Three Time F1 World Champ

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    So will this get even worse when I add test pipes ?
     
  8. cmparrenzo

    cmparrenzo F1 Rookie
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    the simple answer is yes.... but the fix is easy and does not cost anything, usually just a simple adjustment to your wastegate...
     
  9. triXXXter

    triXXXter Formula Junior

    Nov 11, 2003
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    Hope this isn't a stupid question. But does the F40 have a bypass valve or blow-off valve or neither? Do many people opt for aftermarket Blow-off valves?

    Just curious.
    Thank you.
     
  10. F40

    F40 F1 Rookie

    Apr 16, 2003
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    Wastegate=BOV.
     
  11. davehelms

    davehelms F1 Rookie

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    There are a couple of different issues in play here. I have seen the waste gates stick open before but it is not the norm. As Brian was stating, the computer cut out is something the two of us have discussed at length.
    The drive train, radiator, and coolant tubes being made of aluminum are able to dissipate a great deal of heat. The cooling system was designed to handle the heat generated when the car was being run quite hard. When it is not working hard it cools down too far and this is when the problem surfaces. It is a computer (Weber Marelli injection / ignition) calculation that senses the boost present vs. the engine temp and it cuts the ign / injection for a moment if the temp is not high enough. The most common time this happens is when driving at a steady speed on the highway and then put the foot into it looking for boost. Under all but the hottest ambient temps the engine runs too cool to allow it. This was a point of frustration for a number of customers when the cars were new, as Ferrari's reply was "this is a normal condition". If I recall correctly both Brian and myself chased this problem down on customer’s cars when they were new. It doesn't happen on all of the cars. This is a software issue as I have replaced temp sensors and thermostats when trying to eliminate the problem, and found that some of the ECU's simply have the "temp window" lower than others. I remember ordering 6 t-stats and boiling them in a bowl on the bench and installing the one that opened and closed the quickest. Did the same for the coolant temp sensor and installed the one that read the hottest. This is a point where attention to the finest detail can make the difference. A little scale on the coolant temp sensor bulb can be the difference between being thrown back in the seat or forward against the shoulder belts. Frustrating little quirk!
    Dave
     
  12. cmparrenzo

    cmparrenzo F1 Rookie
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    Dave, I understand what you are saying, but the sympton sounds like an overboost. We have delt with this on several F40's at the shop, we corrected by making an adjustment to the wastegate. We were seeing the boost gauge peg out too quickly and we documented this on the dyno, before and after the adjustment. Am I wrong in thinking what you are describing is seperate but similar symptom?
     
  13. triXXXter

    triXXXter Formula Junior

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    Umm... no. Wastegates control the amount of exhaust gas that hits the turbine blades. But the Blow-off valves and bypass valves allow compressed air going into the Intake manifold to "blow off" when the throttle plate closes. This helps extend the life of the turbo so the compressed air doesn't buildup back pressure against the turbine. If you have ever raced an aftermarket car that was turbocharged you have probably heard it. It's the swoosh sound with most shifts.
    Here is a explaination for wastegate from www.howstuffworks.com

    "The Wastegate
    Most automotive turbochargers have a wastegate, which allows the use of a smaller turbocharger to reduce lag while preventing it from spinning too quickly at high engine speeds. The wastegate is a valve that allows the exhaust to bypass the turbine blades. The wastegate senses the boost pressure. If the pressure gets too high, it could be an indicator that the turbine is spinning too quickly, so the wastegate bypasses some of the exhaust around the turbine blades, allowing the blades to slow down."

    From HKS USA
    "Blow-Off & Bypass Valves have one goal, prevent compressor surge. Compressor surge occurs when the throttle plate of a turbocharged engine closes and the pressurized air is forced back into the turbocharger’s compressor housing causing the turbo to slow down. Compressor surge not only decreases the spool of a turbo but can also damage its center cartridge. HKS Blow-Off and Bypass Valves prevent compressor surge by venting the excess pressure when a throttle plate closes, thus improving spool-up & longevity."

    BOV then Wastegate pics
     
  14. WILLIAM H

    WILLIAM H Three Time F1 World Champ

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    Shelton is adjusting my BOV now, should have the car back on Fri, just in time for Hurricane Jeannie :(
     
  15. SefacHotRodder

    SefacHotRodder F1 World Champ

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    :(
     
  16. Rifledriver

    Rifledriver Two Time F1 World Champ

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    F40's have blow off valves built into the intake tract after the turbo. On the F40 it is very noticeable, just close the throttle quickly on high boost and you will hear a loud woosh, almost like a low grade explosion outside the car as the extra air is blown off. These are in addition to the waste gate and perform a different function.

    And Dave, as I recall (it's been a long time since I delt with this problem) oil temp may have been a factor in the calculation as well. The original car we experienced the problem with was the first car delivered and the weather was cold in this area, I could get good water temps but not oil temps. But as I said that was quite a few years ago.
     
  17. davehelms

    davehelms F1 Rookie

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    Chris,
    You may well be correct. I got the mental image that the break up happened as soon as the throttle was mashed and not after the turbos spooled up. The over boost can be seen on the gauge and the red light flashing like you say. I assumed this was not the situation as that was not part of the description William gave, BUT.... we all know what assuming makes me look like (my daughters / co-mechanics point this out to me daily)!
    You have a very valid and accurate point.
    William, give us more info on this problem.
    Dave
     
  18. johnnyferrari

    johnnyferrari Karting

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    Dave, William & Chris:

    I do believe that it is the over boost problem. When I went on the Players Run, I had very similar problems. Since I left the mile high city and went down to sea level at New York, I was hitting the “Over boost Lockout” very early in the spooling. I really do believe that this was due to the denser air at sea level. So, I feathered the throttle during the boost cycle as we made our way to Kansas.

    At the Heartland Park track in Topeka, I had no fun with the car until I started to take a half turn at a time out of the waste gate. After about 1 ¾ turns out, I had the car boosting at full throttle in the 20-21 psi range with no “over boost” problems.

    When I returned to PPIR in Colorado, the car was only boosting to between 15 – 18 psi at full throttle. So, I started to systematically dial the waste gate back in, ½ turn at a time, until I got the car back to the 20psi +/- range.

    This seems to be working quite well. Dave knows what this “Evil Thing” of mine is capable of at sea level and it is quite fun and scary at the same time. In Fact I think Roland would even agree that I have been able to give him a run for his money from time to time as well.

    John.
     
  19. rexrcr

    rexrcr Formula 3

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    Nope :)

    TriXXXter is correct.
     
  20. rexrcr

    rexrcr Formula 3

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    Right on target.
    Just picking nits here, it's actually the injectors that are shut down, no dumping of unburned fuel into the exhaust.
     
  21. rexrcr

    rexrcr Formula 3

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    This issue can be tuned out by an experienced tech. Either wastegate and/or solenoid valve (plastic duty-cycle valve located on the RR shock tower, bleeds boost at high rpm to flatten the torque curve and protect the turbos from overspeeding) adjustment.

    Best regards,

    Rob
     
  22. cmparrenzo

    cmparrenzo F1 Rookie
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    thanks Rob, I knew WHAT was happening, but I guess not HOW it was happening!

    Chris
     
  23. Steve

    Steve Formula Junior

    Nov 1, 2003
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    I know I'm ressurecting an old thread here, but I got some first-hand experience with this issue (and solving it) today so I thought I'd share.

    Earlier this morning, I had my F40 on a dyno in Redmond, WA for a sound recording session with Microsoft for an upcoming video game (not allowed to say which one, but it's got at least one Ferrari in it!). The torque and hp curves looked ok, and the chart showed average boost was about 18, with peak at 20. The tech running the dyno noted that the boost curve was really "jagged" - meaning that the wastegate was opening and closing too slowly and inefficiently. I came across the parking lot to their office and searched for this thread, then printed it out and took it to the tech. We talked about it, and decided it was worth a try.

    No exaggeration here - I have the dyno charts to prove this (and will scan and post them when I get a chance). One turn of the wastegate adjustment screw yielded an additional 10HP. Just by turning a screw! I was amazed. When we were done fiddling around (three full turns) we had a net gain of 17.6 HP, with average boost of 20 and a peak at 22, and the boost curve was much more smooth. I'll post the before and after graphs (and the runs were separated only by a few minutes, so changes in atmospheric conditions were not a factor).

    For those who are interested, I have the LM turbos, Tubi Sport Exhaust, Tubi muffled bypass tubes, and the Carobu LM ECU chip - and we were using a DynoJet. When I bought the chip, Vince at Carobu said not to mess with the wastegate screw, but these results can't be denied.

    Comments?

    Steve

    P.S. My 512 TR is currently on the dyno now. I'm in the office wasting time on the computer :)
     
  24. Suneal

    Suneal Rookie

    Dec 7, 2003
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    Just curious, Steve - what kind of numbers did you put down?
     
  25. bobafett

    bobafett F1 Veteran

    Sep 28, 2002
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    Steve: amusing about MS. A friend of mine is the lead on PGR2 and 3, and they want my 550 with exhaust for the game. Hopefully we can get more FCers into the game... would be cool.

    --Dan
     

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