04 gto ls1 was tuned with stock MAF, wanting to change ito the ls2 or truck 85mm. How hard is it to tune, The car runs great as is. Is there a calculation for changing the MAF?
Thanks Kyle.

 

When I changed over my stock one to 85mm I based my maf table off the z06 maf table. I then dialed in the MAF with data logging and found it to be within 2-3%. Results will vary depending on intake tract setup.

 

If you're using the stock side intake or an aftermarket "cold" air intake that sits in the same spot, copy-paste the maf table from an LS2 GTO or a Holden VZ LS1 for a starting point. It should be pretty close. They both use the 85mm maf with side intake.

Also if you still have the stock crinkle-cut maf pipe throw it away, they're restrictive crappy Holden parts. 4" maf pipe is the way to go.

 

I used the stock '02 truck table for a while and had no
accuracy problems, after heads & cam swap it moved a
little and the Z06 table was a better fit (by wideband AFR).
I use the stock bellows which ends up fully compressed
(w/ blackwing lid setup and 85mm TB) so it's "effectively
smooth".

 

I found the z06 maf table to be very close when I did my dyno tune. I also ended up keeping my stock bellows too as it was a perfect fit and near compressed.

 

maf diver is talking about the intake tube on a 04 GTO. Not a F-body.

 

okay thanks guys, Im using ramair setup, Ill be working on the tune this up coming week once I get the wide band back in the car.

 

Just for information, the 85mm maf table looks very rich from the get go, just a bit less than the stock f-body table which is a 75mm maf. Both the vette and f-body have fairly "straight through" designs. Either way, you are going to calibrate it with a wideband, so no worries where you start, just good to know that from previous experience that the z06 table seems be the most accurate for a 85mm maf, the bends after the fact should affect it but not as much as what difference at 12000hz 511 vs 428 and 423... I mean, with that difference, you are thinking the elbow design flows more air than the straight through z06 vette?

All from 1500hz to 12000hz.

85mm 04
2.14 2.59 3.07 3.59 4.15 4.74 5.4 6.1 6.85 7.67 8.55 9.48 10.5 11.59 12.76 14.02 15.34 16.95 18.66 20.52 22.29 24.16 26.16 28.26 30.48 32.83 35.3 37.91 40.66 43.54 46.57 49.74 53.06 56.55 60.19 63.98 67.95 72.09 76.41 80.91 85.58 90.45 95.5 100.74 106.2 111.84 117.7 123.76 130.04 136.54 143.26 150.2 157.38 164.79 172.44 180.32 188.46 196.84 205.48 214.38 223.53 232.95 242.64 252.6 262.84 273.37 284.17 295.27 306.66 318.34 330.33 342.62 355.21 368.13 381.35 394.9 408.77 422.97 437.5 452.37 467.58 483.13 499.02 511.99 511.99

01 Z06
1.48 1.8 2.13 2.49 2.89 3.33 3.8 4.34 4.91 5.54 6.22 6.95 7.73 8.56 9.45 10.38 11.38 12.45 13.6 14.85 16.21 17.7 19.32 21.02 22.77 24.54 26.43 28.41 30.49 32.66 34.95 37.36 39.9 42.62 45.48 48.5 51.66 54.98 58.44 62.05 65.82 69.73 73.8 78.03 82.4 86.94 91.63 96.49 101.51 106.71 112.09 117.63 123.35 129.24 135.3 141.53 147.87 154.41 161.15 168.08 175.22 182.58 190.23 198.21 206.34 214.8 223.52 232.52 241.83 251.34 261.13 271.19 281.53 292.15 303.05 314.25 325.73 337.51 349.59 361.96 374.64 387.63 400.92 414.53 428.46

02 Z06
1.42 1.76 2.1 2.48 2.86 3.26 3.7 4.18 4.71 5.31 5.97 6.68 7.43 8.23 9.08 9.97 10.91 11.93 13.05 14.27 15.59 16.98 18.47 20.05 21.72 23.48 25.34 27.28 29.34 31.48 33.74 36.11 38.62 41.3 44.17 47.2 50.4 53.77 57.3 61.01 64.88 68.91 73.12 77.47 81.97 86.63 91.45 96.43 101.59 106.9 112.36 118.01 123.83 129.84 136.05 142.48 149.13 155.98 163.06 170.38 177.92 185.7 193.73 201.99 210.52 219.3 228.34 237.64 247.23 257.06 267.16 277.56 288.25 299.25 310.55 322.2 334.16 346.49 359.16 372.22 385.66 399.51 413.77 428.45 443.6