EGT at idle Roots with Enderly inj..???

Discussion in 'PSI Superchargers Tech Questions' started by Raymond, Nov 23, 2014.

  1. Raymond

    Raymond New Member

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    Wondering what the average EGT is at idle?? I had my barrel valve set at 70% and the weather changed from 90* to 70* with air from 2050 Da to 800 Da, soon as I went to launch car blowed burst pannel.. so I'm wondering if there is a sweet spot to kinda go by EGT to keep this from happening? ??? I put 2 flats rich in adjustment on barrel valve that day and we ran car with no problems except a serious surge at idle. EGT was at 500 after the adjustment...
     
    #1
    Raymond, Nov 23, 2014
  2. Mike Canter

    Mike Canter Top Dragster
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    Well, the EGT's averaging 500 at idle is ok. The big thing I look for is off ie response in adjusting the BV. If it is blubbering or crisp of hesitates and the EGTs. That DA change from 2050 to 800 was a average of a 12 jet size change to rich required for the main jet. If your foot was to the floor then you were already off the idle circuit and into the mainjet circuit. Did you change the main jet.
     
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    Mike Canter, Nov 23, 2014
  3. Raymond

    Raymond New Member

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    Yes sir I had changed the main prior to blowing burst pannel, had went from a 125 to a 115.. and that's what I ran the rest of the day, I never changed it after I blowed pannel, I just put a couple flats in barrel valve to fatten it up.. But what your saying does make perfect since becuse I was on the floor when it blowed so it was on the main.. Might have been a fluke, I had a old man tell me one time before that the EGT needed to be between 650-700 at idle, and I know mine is pig fat know forsure becuse of the serious surge it has at idle.. Even before when it was set were engine builder had set it soon as u put it in gear it would surge really hard, I hear lots of blown cars at the track that don't surge hardly at all... how is that ??? Mine is a 540 with 380 heads with 10.1 compression with a 1471 Hi Helix blower with big and ugly injection. .I have the blades set at .010 and had by barrel valve set at 70%...
     
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    Raymond, Nov 24, 2014
  4. Mike Canter

    Mike Canter Top Dragster
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    For me safe EGTs are an average of 500 at idle, 625 during stage and 850 at one second out. These are not wild tuneup EGTs but safe guidelines. It could be that the burst panel was fatigued and it was time for it to go. Have you done a leak down on the motor.
     
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    Mike Canter, Nov 24, 2014
  5. sune

    sune Member

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    Mike are those numbers the same for a screw hemi?
     
    #5
    sune, Nov 24, 2014
  6. Mike Canter

    Mike Canter Top Dragster
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    I use them as baseline numbers on both roots and screw if it is a new setup to make sure I am safe through the tshift. Then tune by plugs after that. By no means is that a tuneup. Just a safety check.
     
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    Mike Canter, Nov 24, 2014
  7. Will Hanna

    Will Hanna We put the 'inside' in Top Alcohol
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    head temp

    don't forget about head temp. head temp is mostly a function of how rich or lean you have it at idle. head temp is not always 100% correlated with an idle egt.

    How so? Well there are a number of outside factors such as run time, how long since you made your last run, ambient air temperature and if you made any other fuel system adjustments. How long from the time you warmed the car up to the first run of the day. After you make the first run, how long to the next run. Now the motor has a heat soak so it will gain head temp quicker. A leaner idle mixture will gradually gain head temp the longer the car runs. So if one opponent is quick and the next guy takes his sweet ass time, you can have 5-10 degree warmer head temp swing from run to run with pretty close to the same idle egt.

    If you have done any bracket racing, one of the fundamentals is to have the same water temp every time when you roll through the box for consistency. Well we don't have water in most instances, but we do have a head temp, but most people don't monitor it. If you want your car to act the same, it needs to have the same head temp every time.

    Some people like a hot head, some people like a cool head. Also, some people like cucumbers better pickled.....
     
    #7
    Will Hanna, Nov 24, 2014
  8. Raymond

    Raymond New Member

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    that's good info... thanks !!! No sir I hadn't done a leak down at the time that happen, The motor is out now and at the engine builders shop getting freshened up so everything will be new.. But why do you ask if I had done a leak down ?? What could have been a problem that I could see by doing a leak down that could caused it to do that???? Headgaskets ??
     
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    Raymond, Nov 24, 2014
  9. Mike Canter

    Mike Canter Top Dragster
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    A leaky intake valve will cause the burst panel to blow as will a lean mixture or too much timing.
     
    #9
    Mike Canter, Nov 24, 2014
  10. Raymond

    Raymond New Member

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    Huh. That's good to know. Thank you!!! I run 30* timming but pull any were from 5 to 8* out at the launch for any were from 1 second to 1/2 second just depending on track... thanks for all the advice
     
    #10
    Raymond, Nov 24, 2014
  11. Raymond

    Raymond New Member

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    That's some interesting information too... thanks
     
    #11
    Raymond, Nov 24, 2014
  12. Bjs344

    Bjs344 Member

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    If I ran egts like yall are talking I'd have to change oil after the burnout. I'm five flats off stumble just to get the average barely under 800. I watch head temp pretty close, and that's where my head temp stays pretty stable. I'm not sure why mine is so different.
     
    #12
    Bjs344, Nov 24, 2014
  13. Raymond

    Raymond New Member

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    I know mine is fat fat at 500, I just fattened it up to help try eliminate the burst pannel blowing again that day..I'm gonna lean it back out some forsure becuse it is not very driver friendly with it that fat, it surges way to hard. .
     
    #13
    Raymond, Nov 24, 2014
  14. TADHemiracer

    TADHemiracer Member

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    Surge and Idle

    I don't know about anyone elses engines but if I remember correctly, years ago when I built my FIRST blown alcohol engine, I had a bad engine surge and finally figured out that it was because of a LEAN idle, not because of being too rich. Whether it was too small of fuel nozzles or whatever but when I richened the idle, it now idles SMOOTH even as low as 1450 rpm although I set the idle at 1500. (526 hemi, fuel heads, clutch) I haven't messed with the idle psi since those days but seems like mine is somewhere around 8-11 psi. The port check is around 20. Just saying.
     
    #14
    TADHemiracer, Nov 24, 2014
  15. Randy G.

    Randy G. Top Alcohol

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    Sounds like some screwed up spools.
     
    #15
    Randy G., Nov 24, 2014
  16. Raymond

    Raymond New Member

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    Educate me ??? Not sure what that means
     
    #16
    Raymond, Nov 24, 2014
  17. Raymond

    Raymond New Member

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    That's something to check into.. I know when i fatten BV it gets worse.. when it's set at 70% it dont surge at all idling till u put it in gear then it will but when I fatten it up on BV it will surge hard all the time
     
    #17
    Raymond, Nov 24, 2014

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