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Thread: ETC area scalar

  1. #1

    ETC area scalar

    102 mm tb having problems with hanging idle like 4000 rpms hanging idle 09 z06. Any one know how the factory number is calculated. I have tried the math and it does not add up to the factory has in the table.
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  2. #2
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    That's a good question that I'm hoping Chris, or another, can answer, as it would help to solve all the issues with going with larger aftermarket TBs.
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  3. #3
    I have did all the math calculations and it is not even close to the mathematical number for the area of a circle. I did a search and found nothing, I have been trying to just fuge it but it is not really working.
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  4. #4
    90mm tb is 6341 mm2, and 102tb is 8141 mm2, and the number in Hp tuners is 4725mm2 wtf. i have also noticed that some files have different ETC scalars even thought the blade is stil the same 90mms?????????????
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  5. #5
    I believe the car I tuned with the 102mm tb required me to max out the ETC scaler but I can check the file you tomorrow.
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  6. #6
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    Have you tried stock setting * 8141 / 6341 ? This would adjust the value by the % of area increase.

  7. #7
    Advanced Tuner eficalibrator's Avatar
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    You guys are forgetting to subtract the area blocked by the shaft even when the blade is open. The real formula for area is:

    [Total bore area] - [shaft area]

    -or-

    [pi * r^2] - [(diameter) * (shaft thickness)]

    This should get you much closer before you covert it to [(mm^2)/(% rotation)] units as seen in the calibration data.

  8. #8
    Senior Tuner DSteck's Avatar
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    Wait wait wait... There's a 102mm TB that works on C6 Z06s now???

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  9. #9
    Yes, nick williams.

    I checked my file and etc scalar is maxed at 8191
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  10. #10
    Tuner Kelp's Avatar
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    The ETC Scaler is not the problem. Among other settings, I set my 102mm TB to Effective Area min = 50 more or less.

  11. #11
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    Quote Originally Posted by Kelp View Post
    The ETC Scaler is not the problem. Among other settings, I set my 102mm TB to Effective Area min = 50 more or less.
    Why is it not the problem? I haven't looked at the logic, but if it if is anything similar to Ford's ETC logic, then just modifying the ETC Scalar parameter with the correct values should allow the pcm to compensate correctly. Naturally, there may be other areas to tune for, but the ETC Scalar is the main starting point.

    I'm going to shoot an email to Nick Williams to see if he can't give the values for the formula Greg posted above.
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  12. #12
    I have mine around 7800 or so. with some timing tweaks, and airflow table corrections its driving like the 90mm was

    Nick told me i would have to max it out or come damn close.

  13. #13
    I did the same thing I ended up with 7900 I think thanks guys. Car drives like stock and went 10.99 on factory tires, in 100 degree heat.
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  14. #14
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    Quote Originally Posted by Tunning @ LMR View Post
    90mm tb is 6341 mm2, and 102tb is 8141 mm2, and the number in Hp tuners is 4725mm2 wtf. i have also noticed that some files have different ETC scalars even thought the blade is stil the same 90mms?????????????
    Which 90mm are you referring to? Even tho they were labeled as such, I do not believe the '05-'08 TBs were true 90mm (can anyone confirm)? The '09 TBs was actually slightly larger area wise, and this can also been seen in the '09 calibrations (5636 for LS3 and LS7, and 5060 for the LS9). At least in the '05-'06 GTO, and '05-'08 C6, they all had the same ETC Area Scalar value (4725).

    As for how GM derives the values, possibly such: Take an '05 SSR for example, it's set to 4391. The ETC opens to approx. 83% at max throttle. Then take an '05 GTO, it's set to 4725. The ETC opens to approx. 88% at max throttle. 4391 / 4725 = 0.92931216931216931216931216931217. Then take 88 * 0.92931216931216931216931216931217, which equals 81.779470899470899470899470899456. That's more than likely why the ETC Area Scalar is different on the SSR and TBSS, since they open less.

    So if the '09 TB is really approx. 90mm, then [pi * r^2] of 90mm is 3.1415926535897932384626433832795 * 45 * 45 = 6361.725123519331307886852851141 * 0.88 = 5598.3181086970115509404305090041. As I mentioned above, the factory ETC Area Scalar on the '09 is 5636. More than likely the difference between this and what I just calculated is the blade thickness being accounted for (as Greg stated).

    Quote Originally Posted by Nick@Newtech View Post
    I have mine around 7800 or so. with some timing tweaks, and airflow table corrections its driving like the 90mm was

    Nick told me i would have to max it out or come damn close.
    Quote Originally Posted by Tunning @ LMR View Post
    I did the same thing I ended up with 7900 I think thanks guys. Car drives like stock and went 10.99 on factory tires, in 100 degree heat.
    Can you two tell me how you arrived at this value?

    As Greg said, it should be [(mm^2)/(% rotation)]. Without having the actual blade thickness to account for area of, I'm coming up with approx. 7190.x. So [pi * r^2] of 102mm is 3.1415926535897932384626433832795 * 51 * 51 = 8171.28249198705221324133543991 * 0.88 = 7190.7285929486059476523751871208.
    Last edited by RWTD; 08-25-2009 at 10:58 PM.
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  15. #15
    Advanced Tuner eficalibrator's Avatar
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    Anything over about 82 degrees of rotation is basically WOT since the blade is "shadowed" by the shaft when view from the entry. Rotating any further doesn't really open up any more significant airflow area or reduce the pressure drop any more, so there's no real benefit to going all the way to 90*.

    That said, you still effectively get 100% area opening at either 82, 83, or 88 degrees; which should equal roughly the area of the bore minus the area of the shaft. The PCM uses this maximum as a reference from which it will reduce down toward zero (in a nonlinear fashion, determined by another table you don't see) as it controls idle airflow.

    Obviously, larger starting areas will need a smaller % of that area to get the same desired effective area at idle for normal operation. This is why adjusting the area scalar is so important if you change the ETC module and want normal drivability and idle control.

    Going from 90mm up to 102, I'd first solve for the ratio of areas (with an ASSumed 10mm shaft):

    90mm = (pi*45*45)-(10*90) = 5458.5
    102mm = (pi*51*51)-(10*102) = 7147.1

    Ratio = 1.30936

    Multiply this by the reference scalar and I get : (5636*1.30936) = ~7380

    Any smaller errors from here will just get baked into the RAF adjustments or idle airflow PID corrections. This of course ASSumes that you've nailed both the MAF and VE (or Virtual VE, as it were) airflow models and ignition timing before adjusting target idle airflows.

  16. #16
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    Quote Originally Posted by eficalibrator View Post
    Anything over about 82 degrees of rotation is basically WOT since the blade is "shadowed" by the shaft when view from the entry. Rotating any further doesn't really open up any more significant airflow area or reduce the pressure drop any more, so there's no real benefit to going all the way to 90*.

    That said, you still effectively get 100% area opening at either 82, 83, or 88 degrees; which should equal roughly the area of the bore minus the area of the shaft. The PCM uses this maximum as a reference from which it will reduce down toward zero (in a nonlinear fashion, determined by another table you don't see) as it controls idle airflow.

    Obviously, larger starting areas will need a smaller % of that area to get the same desired effective area at idle for normal operation. This is why adjusting the area scalar is so important if you change the ETC module and want normal drivability and idle control.

    Going from 90mm up to 102, I'd first solve for the ratio of areas (with an ASSumed 10mm shaft):

    90mm = (pi*45*45)-(10*90) = 5458.5
    102mm = (pi*51*51)-(10*102) = 7147.1

    Ratio = 1.30936

    Multiply this by the reference scalar and I get : (5636*1.30936) = ~7380

    Any smaller errors from here will just get baked into the RAF adjustments or idle airflow PID corrections. This of course ASSumes that you've nailed both the MAF and VE (or Virtual VE, as it were) airflow models and ignition timing before adjusting target idle airflows.
    Do you mean for reference scaler is what HPT shows as 4275? Then all we do is multiply it by 1.3?

  17. #17
    Advanced Tuner Sébast19X's Avatar
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    Quote Originally Posted by eficalibrator View Post
    Anything over about 82 degrees of rotation is basically WOT since the blade is "shadowed" by the shaft when view from the entry. Rotating any further doesn't really open up any more significant airflow area or reduce the pressure drop any more, so there's no real benefit to going all the way to 90*.

    That said, you still effectively get 100% area opening at either 82, 83, or 88 degrees; which should equal roughly the area of the bore minus the area of the shaft. The PCM uses this maximum as a reference from which it will reduce down toward zero (in a nonlinear fashion, determined by another table you don't see) as it controls idle airflow.

    Obviously, larger starting areas will need a smaller % of that area to get the same desired effective area at idle for normal operation. This is why adjusting the area scalar is so important if you change the ETC module and want normal drivability and idle control.

    Going from 90mm up to 102, I'd first solve for the ratio of areas (with an ASSumed 10mm shaft):

    90mm = (pi*45*45)-(10*90) = 5458.5
    102mm = (pi*51*51)-(10*102) = 7147.1

    Ratio = 1.30936

    Multiply this by the reference scalar and I get : (5636*1.30936) = ~7380

    Any smaller errors from here will just get baked into the RAF adjustments or idle airflow PID corrections. This of course ASSumes that you've nailed both the MAF and VE (or Virtual VE, as it were) airflow models and ignition timing before adjusting target idle airflows.

    If my car is a C6 Z06 2008 and the area scalar are 4725.
    If I put the NW 102mm, my new area scalar should be :

    4725*1.30936= 6187

    ???

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  18. #18
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    Quote Originally Posted by Sébast19X View Post
    If my car is a C6 Z06 2008 and the area scalar are 4725.
    If I put the NW 102mm, my new area scalar should be :

    4725*1.30936= 6187

    ???

    Thank you
    Re-read the posts by myself and Greg. You can also read my post here:

    http://www.hptuners.com/forum/showthread.php?t=25561
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  19. #19
    Advanced Tuner Sébast19X's Avatar
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    Quote Originally Posted by RWTD View Post
    Re-read the posts by myself and Greg. You can also read my post here:

    http://www.hptuners.com/forum/showthread.php?t=25561
    James, sorry for my ignorance, but I don't understand very well.

    Why the 2009 C6 Z06 are a different ETC area scalar than my 2008 C6 Z06 ???

    If I started with my 4725 ETC area scalar that would be my calculation:

    90mm for the 2008 TB: (3.1416*45*45)-(10*90) * 0.88 = 4806 that would be close to the 4725 into my stock hp file .

    102mm for the NW TB: (3.1416*51*51)-(10*102)*0.88 = 6293 right ?

    Or just multiply 4725 by 1.30936 =6187

    Help needed
    Last edited by Sébast19X; 09-22-2009 at 02:01 PM.
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    DA for this pass: 0'

  20. #20
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    Because, as I stated, your '08 TB has a smaller effective area than the '09 TB.

    Why don't you just try the value I gave in my post, or the one Greg gave in his post. They are within 200 of each other.
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