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finally got my cobra tuned with 2.93 upper + 4lb lower but...

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SnakeBite2k3

SnakeBite2k3

Pray For The Dead To Rise
Nov 1, 2005
1,632
0
  • #1
    i only made 465rwhp and 485rwtq unported eaton

    I think I got wrong belt. Damn it! The car runs really strong but I know my TQ numbers have to be way up there like you guys that run this. right?
    i used a gates K080816 which is 1-3/32" x 82-1/8" to big?????????

    check my dyno graph out below. mods are 2.93 upper, 4lb lower, 3.2 alt pulley,sct2400maf and bolt ons. what do u guys think. Thanks


    BTW Thank you Bob k for the awesome tune and also thanks to speed inc :headbang:

    02-21-2007120031AM87.jpg



    now to go belt hunting. :)
    Click to read more...
     
    Bob_Kurgan

    Bob_Kurgan

    Flyin_Hawaiin
    Feb 16, 2005
    3,013
    0
  • #15
    hj16 said:
    TQ numbers definately seem 20-30rwtq too low, but dyno numbers mean squat...just a tool to achieve the best results at the track :D
    Click to expand...

    i was also hoping for higher TQ numbers but I think the belt being as loose as it was kept the boost down... I could literally twist the belt 3/4 way around when i grabbed it... thats probably why the torque curve was so flat and less peaky.. I tried adding as much as 2-3 more degrees with no effect too... also, Speed's dyno has always been known to read conservative.. this has been proven time and time again when you guys have been there for a dyno day and been disappointed... As I told Joel, the numbers are the numbers.. thats where they ended up with a safe tune...
     
    Dana

    Dana

    Bluesmobile
    Mar 2, 2004
    2,619
    0
  • #19
    [email protected] said:
    i was also hoping for higher TQ numbers but I think the belt being as loose as it was kept the boost down... I could literally twist the belt 3/4 way around when i grabbed it... thats probably why the torque curve was so flat and less peaky.. I tried adding as much as 2-3 more degrees with no effect too... also, Speed's dyno has always been known to read conservative.. this has been proven time and time again when you guys have been there for a dyno day and been disappointed... As I told Joel, the numbers are the numbers.. thats where they ended up with a safe tune...
    Click to expand...

    The belt tension is a function of the tensioner, not the belt. That belt, when installed was at the center of the indicator on the tensioner. Just where it's supposed to be. You can put on a smaller belt, but that won't change the tension. It still relies on the spring contained inside the tensioner.
    There is a high probability that the spring in the tensioner is fatigued and may need to be replaced.
    I honestly don't expect to see any difference if Joel changes belts.
    Also, if you look at the power curve, you can see a little slippage around 5600 RPMs.
    You can only get so much out of an unported Eaton. I don't think he did too bad. Nice tuning work Bob.

    Dan
     
    Bob_Kurgan

    Bob_Kurgan

    Flyin_Hawaiin
    Feb 16, 2005
    3,013
    0
  • #20
    Dana said:
    The belt tension is a function of the tensioner, not the belt. That belt, when installed was at the center of the indicator on the tensioner. Just where it's supposed to be. You can put on a smaller belt, but that won't change the tension. It still relies on the spring contained inside the tensioner.
    There is a high probability that the spring in the tensioner is fatigued and may need to be replaced.
    I honestly don't expect to see any difference if Joel changes belts.
    Also, if you look at the power curve, you can see a little slippage around 5600 RPMs.
    You can only get so much out of an unported Eaton. I don't think he did too bad. Nice tuning work Bob.

    Dan
    Click to expand...

    i understand the tensioner etc.. thats why i prefer solid screw tensioners... but the first few pulls, you could feel the motor almost bog after the initial hit... I went out and felt the tension on the belt and it was extremely loose... One thing that I have noticed after years of running renegade (with 8rib serpentine belts and making 30psi boost) is that belts tend to stretch upwards of 1-2 inches after drive time and especially after making a few dyno runs... its the nature of hte beast as its made from rubber.... I just told Joel that the belt was "loose".... I figured the next smaller size would help quite a bit but i do understand your statement about the tensioner being out of its range..

    thanks for the props!
     
    Dana

    Dana

    Bluesmobile
    Mar 2, 2004
    2,619
    0
  • #21
    I told Joel that I have a 797 belt here that he could try. He said that was the next smaller size from what he was currently running. I can't remember the number of the belt that was installed.
    We'll see what happens.
    If he knocks the stop off of the tensioner and installs a really small belt, it might increase the tension some, but even that is a big if, just because the way the tensioner is designed.
    Bob is already aware, but for those that aren't, the tensioner is supposed to provide a fairly linear amount of tension or pressure on the belt, regardless of the amount of wear or length of the belt. Pushing the tensioner past it's designed upper limit (by installing a much smaller belt) MAY increase the pressure/tension slightly.

    I also use a RR manual tensioner. For the high load levels these belt systems see, that is the only reliable way to go.
    Time for the RR tensioner. HA! HA!
    It's something that can be used regardless of the blower setup.
    Dan
     
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