Quote:
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Originally Posted by cody
I have a custom tune. MBC's are bad on a stock ECU, but a good MBC should really help my boost response and isn't dangerous with a tuned map. Ed suggested it and assured me there's no need for a retune.
Thanks for the info.
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Quote:
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Originally Posted by sperry
Well shit, with logic like that, you should just reflash back to stock and run the MBC and UniChip I've got rolling around in my workbench drawer. I'll sell it to ya for only $50!
Think of it this way: if you install a MBC and set it to say 15 psi, sure you'll run right up to 15 psi in 1st and 2nd gear as soon as possible, and you'll avoid some of that boost wobble due to the factory EBC, but you're not going to be able to taper boost at high rpms. If you think you can run a stock turbo at 15 psi at 6500 rpm in 4th gear down the backstraight at RFR all day long, I've got a 2.0L shortblock in my garage I'll sell you, 'cause you'll need it. So, you're going to have to set the MBC to say 13 psi. Granted you'll have a nice rock solid 13 psi all day in every gear (well until the weather changes and you're under the hood w/ an allen wrench), but I'd rather have that 15.5 psi when it's safe and the taper to 13 psi on the top end making sure my motor will last.
If MBC's were so great, I'm pretty sure Subaru would have put one on the car to begin with 'cause they're about 1/50th the cost of the EBC.
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As per Ed's reccomendation, I'm now running a Hallman Pro RX Kit MBC (he runs one too). Boost tapers as it should. Spoolup and response are remarkably better.
Here's some supporting data from a log I took today.
Code:
RPM Manifold Relative Pressure (PSI)
1968 -8.996
1926 -8.996
1926 -8.996
1926 -8.996
1921 -9.141
2051 -0.435
1980 0.145
1968 0.435
1983 0.725
2004 0.871
2005 1.161
2036 1.451
2055 1.741
2100 2.031
2108 2.176
2142 2.467
2154 2.757
2187 2.902
2208 3.192
2242 3.482
2247 3.627
2285 3.918
2315 4.208
2330 4.353
2356 4.643
2401 4.933
2448 5.224
2455 5.659
2502 6.094
2498 6.384
2550 6.82
2580 7.255
2625 7.835
2679 8.416
2693 8.706
2730 9.576
2781 10.447
2827 11.463
2849 12.624
2906 13.929
2948 14.8
2961 15.816
3050 16.396
3104 16.541
3146 16.541
3193 16.541
3278 16.396
3308 16.396
3351 16.396
3439 16.541
3461 16.396
3558 16.396
3588 16.396
3639 16.396
3702 16.251
3769 16.251
3811 16.251
3874 16.251
3922 16.251
3935 16.251
4011 16.251
4067 16.251
4112 16.251
4173 16.106
4230 16.106
4256 16.106
4308 16.106
4406 16.251
4456 16.106
4454 16.396
4548 16.541
4568 16.686
4638 16.686
4696 16.541
4714 16.541
4777 16.396
4867 16.251
4902 16.251
4908 16.106
4960 15.961
5020 15.816
5081 15.671
5137 15.525
5133 15.38
5205 15.235
5271 15.09
5330 14.8
5372 14.8
5380 14.655
5478 14.51
5515 14.51
5519 14.365
5601 14.22
5580 13.929
5660 13.929
5695 13.784
5725 13.784
5800 13.639
5850 13.494
5905 13.204
5905 13.204
5943 13.059
6010 12.914
6053 12.769
6083 12.624
6068 12.769
6107 12.624
6142 12.478
6178 12.333
6260 12.333
6313 12.188
6340 12.188
6324 12.043
6367 12.043
6454 12.043
6432 12.188
6527 12.043
6510 12.043
6510 12.043
6602 11.898
6637 11.898
6667 11.898
6655 11.898
6745 11.898
6745 11.898
6726 12.043
6818 11.898
I had Ed look at my logs and they look good. He thinks it's probably running a bit rich in open loop based on my low EGT's at full throttle and next time he's up here, he'll bring his wideband and lean it out a bit for this elevation. But this has nothing to do with me adding the MBC. My tune was good before and after adding the MBC, no tweaking necessary. Ed says you can probably run this MBC on any tuned map, maybe even Cobb's canned maps. DO NOT RUN AN MBC ON A STOCK MAPPED SUBARU EVER.
He used one of my logs (maybe the one above) to make the following graph. Numbers aren't great, but this is at ~5,200 feet of elevation. I'm just glad to get rid of all the lag I was seeing at this elevation.