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Old 02-07-2007, 10:19 PM   #21
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Sorry about opening a can o' worms on the LIM

Quote:
Originally Posted by Foghorn
What parameters and methods were you using to calculate VE?

Cheers,
I used MAF, rpm and IAT data from Scantool capture data during WOT runs. For the VE% computations, I used only data from captured points where the rpm'* were between 4000 and 4500, the TPS showed 100%, and O2 sensor 1 showed 0.920v to 0.950v. I used the formulae on this site to calculate:

http://www.installuniversity.com/ins...n_9.012000.htm
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Old 02-07-2007, 10:43 PM   #22
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Quote:
Originally Posted by agrazela
Sorry about opening a can o' worms on the LIM
And a can of worms on VE...

What was your LTFT for these runs?

Interesting how GM approaches the VE for the L36 and L67 from 97 and up. The PCM VE table is 80% across all MAP/RPM combinations for the L36 but varies for the L67. You know that the PCM VE table is a multiplier value for the MAF?

Cheers,
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Old 02-07-2007, 11:05 PM   #23
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Oh i know, i am not going to jump into it. I plan on doing a few more little things before this even crosses my mind. I am just saying that i have my eye on it and i am going to continue to read about it and what not. When i do my HV3, i am going to do probably do this since i will have it half way apart. I will be in contact with all of you guys about this around spring time. I want a 14 second pass before i do anymore mods. I know the car has one in it and i want to push the mods i have now to the limit before i add more. But come spring i plan on doing the HV3, the ported LIM, and having some work done to my TB, and some custom computer work. Ohhh i cant wait til spril to get back to the track lol
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Old 02-08-2007, 12:05 AM   #24
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Quote:
Originally Posted by 95naSTA
When I swapped my home ported heads (summer 05) for MMS heads I polished the runners in the LIM.
Polishing the runners will be nearly a negligible effect in flow improvements. It'* the port-matching where you gain the flow.
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Old 02-08-2007, 12:37 AM   #25
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Quote:
Originally Posted by willwren
Polishing the runners will be nearly a negligible effect in flow improvements. It'* the port-matching where you gain the flow.
Thats obvious from the obstruction of the ports. I figured I might as well lightly polish the runner to match what I did with the port matching.
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Old 02-08-2007, 12:40 AM   #26
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Quote:
Originally Posted by Foghorn
Quote:
Originally Posted by agrazela
Sorry about opening a can o' worms on the LIM
And a can of worms on VE...

What was your LTFT for these runs?

Interesting how GM approaches the VE for the L36 and L67 from 97 and up. The PCM VE table is 80% across all MAP/RPM combinations for the L36 but varies for the L67. You know that the PCM VE table is a multiplier value for the MAF?

Cheers,
I did not record LTFT'*, but the last run is still captured on my ScanTool. I just checked it and the LTFT was 10.1%

Please explain more about your comments regarding the PCM...are you saying the PCM limits the VE to 80%?
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Old 02-08-2007, 01:01 AM   #27
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Quote:
Originally Posted by agrazela
Quote:
Originally Posted by Foghorn
Quote:
Originally Posted by agrazela
Sorry about opening a can o' worms on the LIM
And a can of worms on VE...

What was your LTFT for these runs?

Interesting how GM approaches the VE for the L36 and L67 from 97 and up. The PCM VE table is 80% across all MAP/RPM combinations for the L36 but varies for the L67. You know that the PCM VE table is a multiplier value for the MAF?

Cheers,
I did not record LTFT'*, but the last run is still captured on my ScanTool. I just checked it and the LTFT was 10.1%

Please explain more about your comments regarding the PCM...are you saying the PCM limits the VE to 80%?
Interesting LTFTs. No I'm not saying the PCM limits the VE, but 80% is a realistic maximum value.

Still, I was drifting on a tangent about VE. You can compare changes with the methods you used, though 4% variation between runs is quite a bit, just that they may not be actual VE values.

Cheers,
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Old 02-08-2007, 01:51 AM   #28
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Please, pursue the tangent regarding the PCM VE table and a multiplier for the MAF...I want to learn more about that.

(BTW, I think the variability in this data was well within expectations...if you propagate error and assume that each input is accurate to +/-1%, there would be an expected error in the VE calculation of almost +/-3%)
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Old 02-12-2007, 01:21 PM   #29
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Quote:
Originally Posted by agrazela
Please, pursue the tangent regarding the PCM VE table and a multiplier for the MAF...I want to learn more about that.

(BTW, I think the variability in this data was well within expectations...if you propagate error and assume that each input is accurate to +/-1%, there would be an expected error in the VE calculation of almost +/-3%)
Just as a quick aside, it looks like you used Excel to figure out your standard deviation... but you need to use stdevp(), not stdev(). stdev() is only an approximation to standard deviation, whereas stdevp() is the calculated value. I think the only reason they provide both functions is for calculation time on very large data sets... but they should have made the more intuitive stdev() the real calculation, and not an approximation.

Given that, your original standard deviation for your groups were 1.58% and 1.54%, respectively.

Anyway, curious to see what comes of all of this -
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Old 02-12-2007, 03:36 PM   #30
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Quote:
Originally Posted by mkaake
Just as a quick aside, it looks like you used Excel to figure out your standard deviation... but you need to use stdevp(), not stdev(). stdev() is only an approximation to standard deviation, whereas stdevp() is the calculated value. I think the only reason they provide both functions is for calculation time on very large data sets... but they should have made the more intuitive stdev() the real calculation, and not an approximation.
IMO, I did not have enough data points to use the stdevp() function. i would only use that function if I had at least 12 data points.
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