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Go Back   IWSTI.com: Subaru WRX STI Forums > IWSTI Engine & Drivetrain > ECU Tuning & Performance Electronics > Cobb Street Tuner


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Old 01-12-2006, 07:17 PM   #1
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Default Anyone running a Perrin Big MAF???

If anyone is, your settings for the ST would be GREATLY appriciated!


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Old 01-14-2006, 08:01 AM   #2
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The basics:
1. Find a mustang dyno for an hour.
2. Open the dash board with load, STFT, and LTFT
3. Set a fixed RPM on the dyno.
4. Steady the car on a load point and let the STFT stabilize. (Watch engine oil and water temps, keep them in check!!!)
5. Modify the intake calibration until the LTFT is close to 0 (+-1-2%) (Let the STFT stabilize between changes)
6. Move to the next load point on the intake cal map and goto #4
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Old 01-14-2006, 08:54 AM   #3
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it should not be hard to calibrate it with bigger injectors, they will almost cancel eachother out with the stock fuel map, adjustments must be made though.
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Old 01-14-2006, 09:36 AM   #4
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Quote:
Originally Posted by XfactorSTi
it should not be hard to calibrate it with bigger injectors, they will almost cancel eachother out with the stock fuel map, adjustments must be made though.
They only 'cancel' each other out if you have the perrin modded stock injectors.
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Old 01-14-2006, 10:26 AM   #5
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Quote:
Originally Posted by STirish
The basics:
1. Find a mustang dyno for an hour.
2. Open the dash board with load, STFT, and LTFT
3. Set a fixed RPM on the dyno.
4. Steady the car on a load point and let the STFT stabilize. (Watch engine oil and water temps, keep them in check!!!)
5. Modify the intake calibration until the LTFT is close to 0 (+-1-2%) (Let the STFT stabilize between changes)
6. Move to the next load point on the intake cal map and goto #4

Thanks for the tips. Unfortunately there isnt a Mustang dyno anywhere around me.

Does this make sence? Say if i take the measurment of the stock intake and compare it to the Big MAF. And then rescale the intake calabrations accordingly compared to the stock intake.
IE: Stock intake size is: lets just sat its - 2"
Big MAF intake is - 3:

Take that ratio and apply it the the intake calabration table.

It makes sence that it would work however im still uncertain.
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Old 01-16-2006, 08:44 AM   #6
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Quote:
Originally Posted by 1FastSTi
...Does this make sence? Say if i take the measurment of the stock intake and compare it to the Big MAF. And then rescale the intake calabrations accordingly compared to the stock intake.
IE: Stock intake size is: lets just sat its - 2"
Big MAF intake is - 3:

Take that ratio and apply it the the intake calabration table.

It makes sence that it would work however im still uncertain.
I don't think that's gonna work. You might be able to get away with fixing a couple of points on the low side then fix a couple up top. Then (I think wolfplayer did this) use the top and bottom correction factors to scale the original numbers. I think the amount of correction will be different as you flow more air. But I haven't done it so don't listen to me.
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Old 01-17-2006, 08:22 AM   #7
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Default

Quote:
Originally Posted by 1FastSTi
Thanks for the tips. Unfortunately there isnt a Mustang dyno anywhere around me.

Does this make sence? Say if i take the measurment of the stock intake and compare it to the Big MAF. And then rescale the intake calabrations accordingly compared to the stock intake.
IE: Stock intake size is: lets just sat its - 2"
Big MAF intake is - 3:

Take that ratio and apply it the the intake calabration table.

It makes sence that it would work however im still uncertain.
It is a ratio, but a ratio of the cross sectional area of the MAF. I think that should get you close, but you're still going to need tuning. Air flow around the MAF is probably not optimal with what intake you are running.

My little disclaimer: I'll say it now, if you are not 100% confident in what you are about to do, don't do it. Take the intake off and go to a professional. You could seriously damage your car.
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Old 01-17-2006, 05:21 PM   #8
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I am going to just run a stock size short ram intake to drive to the tuner and let him work his magic.
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Old 01-17-2006, 06:24 PM   #9
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It is not a linear relationship.
http://www.pdxtuning.com/nasioc/BigMafvsStockMAFVol.gif
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Old 01-17-2006, 06:28 PM   #10
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Quote:
Originally Posted by RSVCHAD
Thanks for the chart, yea for the most part im going to leave it to my tuner to get it right.


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