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Old 08-01-2005, 07:34 AM   #1
dudical26
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Default Will MAF voltage get pegged?

I am about to purchse a td06-20g, and plan to boost about 22-23psi.
I am wonder if the maf voltage will get maxed out.
If it will, do i have to run something like the perrin big maf (which I have heard is a pain to tune.)
Or can I just run something like a K&N typhoon.
Also will a new trubo inlet hose be necessary?

Please only reply if you have experiance or are very knowledgeable in the area.

Thanks

EDIT---
I was just thinking, does it really matter if my MAF voltage gets pegged at high RPM, since i will be using a UTEC in Open Loop Fueling, and tunning AFR w/ a wideband.
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Last edited by dudical26; 08-01-2005 at 08:12 AM.
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Old 08-01-2005, 10:06 AM   #2
RiftsWRX
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Quote:
Originally Posted by dudical26
I am about to purchse a td06-20g, and plan to boost about 22-23psi.
I am wonder if the maf voltage will get maxed out.
If it will, do i have to run something like the perrin big maf (which I have heard is a pain to tune.)
Or can I just run something like a K&N typhoon.
Also will a new trubo inlet hose be necessary?

Please only reply if you have experiance or are very knowledgeable in the area.

Thanks

EDIT---
I was just thinking, does it really matter if my MAF voltage gets pegged at high RPM, since i will be using a UTEC in Open Loop Fueling, and tunning AFR w/ a wideband.
Personally, at 22-23 PSI you have other issues to consider as well (like surging) but that wasn't the question. Yes.. I'd imagine you'd be well on your way to maxing out by then.

Jorge (RiftsWRX)
www.ProjectWRX.com
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Old 08-01-2005, 12:50 PM   #3
ebeck
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On my JDM 2.0 and pump fuel, I find that at 357whp my MAF is maxed and the CEL comes on. On pump fuel the USDM 2.0 won't get anywhere near that. The USDM 2.0 on 91 seems to get stuck at 320whp reagrdless of turbo and I have seen several T66 and other big ones tuned. On 93 you may make more but your nowhere near 360 on pump fuel with a USDM motor.

You'll be fine. Enjoy!
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Old 08-01-2005, 01:00 PM   #4
ride5000
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according to my calculations, the oem maf will max out, voltage wise, ~ 450chp. that jives with ebecks observations.
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Old 08-01-2005, 02:21 PM   #5
dudical26
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Thanks
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Old 08-01-2005, 02:52 PM   #6
ebeck
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I realized that I run alot more timing than USDM so I suspect Ken's ride5000 calculation is more accurate.
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Old 08-01-2005, 04:58 PM   #7
ride5000
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here's a little table of values for mafv vs. mass. i used the equation posted by Jeff Sponaugle for the mafv translation.
mass(g/s)=3.5906*mafv^3-4.0038*mafv^2+2.2571*mafv-0.4089
the first three columns are pretty accurate. the last is a VERY rough hp estimate following the 10hp/(1lb/min) rule of thumb.
Code:
mafv	g/s	lb/min	 hp
2.00	16.81	2.22	22
2.05	18.33	2.42	24
2.10	19.93	2.64	26
2.15	21.62	2.86	29
2.20	23.41	3.10	31
2.25	25.30	3.35	33
2.30	27.29	3.61	36
2.35	29.38	3.89	39
2.40	31.58	4.18	42
2.45	33.89	4.48	45
2.50	36.31	4.80	48
2.55	38.85	5.14	51
2.60	41.50	5.49	55
2.65	44.28	5.86	59
2.70	47.17	6.24	62
2.75	50.19	6.64	66
2.80	53.34	7.06	71
2.85	56.62	7.49	75
2.90	60.04	7.94	79
2.95	63.59	8.41	84
3.00	67.27	8.90	89
3.05	71.10	9.41	94
3.10	75.08	9.93	99
3.15	79.20	10.48	105
3.20	83.47	11.04	110
3.25	87.90	11.63	116
3.30	92.47	12.23	122
3.35	97.21	12.86	129
3.40	102.11	13.51	135
3.45	107.17	14.18	142
3.50	112.39	14.87	149
3.55	117.79	15.58	156
3.60	123.35	16.32	163
3.65	129.09	17.08	171
3.70	135.01	17.86	179
3.75	141.10	18.67	187
3.80	147.38	19.50	195
3.85	153.84	20.35	204
3.90	160.49	21.23	212
3.95	167.33	22.14	221
4.00	174.36	23.07	231
4.05	181.58	24.02	240
4.10	189.01	25.01	250
4.15	196.63	26.01	260
4.20	204.46	27.05	271
4.25	212.50	28.11	281
4.30	220.74	29.20	292
4.35	229.20	30.32	303
4.40	237.87	31.47	315
4.45	246.76	32.65	326
4.50	255.86	33.85	339
4.55	265.19	35.09	351
4.60	274.75	36.35	363
4.65	284.53	37.64	376
4.70	294.54	38.97	390
4.75	304.79	40.32	403
4.80	315.27	41.71	417
4.85	325.99	43.13	431
4.90	336.95	44.58	446
4.95	348.16	46.06	461
5.00	359.61	47.58	476
5.05	371.31	49.12	491

Last edited by ride5000; 08-01-2005 at 05:01 PM. Reason: added hyperlink to post
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Old 08-01-2005, 06:16 PM   #8
ebeck
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I had 360whp calculated which calculates to 496chp before I hit max MAF on the Dyno which is what that log shows as well. You should be OK with a 20G and pump fuel. Pretty good calculating Ken. Seems quite accurate.
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Old 08-01-2005, 06:54 PM   #9
hondaeater69
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but you don't want to go to the max right?? What is an acceptable voltage to go to?
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Old 08-01-2005, 07:22 PM   #10
ebeck
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Right up to it is fine actually. Once you hit max the ECU will stop compensating by adding fuel etc... so if you keep turning it up, the reults will be catastrophic for the motor. None of that happens until you hit Max voltage though. Eitherway a USDM 2.0 is not likley to get anywhere near it on pump fuel.
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Old 08-01-2005, 08:35 PM   #11
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that chart is awesome; i've been looking for something to calculate MAFv to actual air flow.

regarding MAFv on a 20G, i'm running a TD06H/20G and depending on temperature, i can hit anywhere between 4.6-4.7 MAFv. i'm still working on the tune... and anxious to see what happens when winter comes around.
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Old 08-01-2005, 10:45 PM   #12
ride5000
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Quote:
Originally Posted by rewt
that chart is awesome; i've been looking for something to calculate MAFv to actual air flow.

regarding MAFv on a 20G, i'm running a TD06H/20G and depending on temperature, i can hit anywhere between 4.6-4.7 MAFv. i'm still working on the tune... and anxious to see what happens when winter comes around.
that's some good air, rewt.. enough for ~300whp, imho.

i wish i could take more credit for the chart, but the hard work was all jeff's. i just put his equation in a spreadsheet, put in some sample values for voltage, copied a few cells, and pasted them here.
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Old 08-01-2005, 11:16 PM   #13
ride5000
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also it's important to note a few of jeff's comments:

Quote:
The 02 WRX ECUs have a hard internal limit of 300g/sec of metered air, regardless of the MAF voltage. The stock WRX MAF table falls slightly short of this limit at 292g/sec. One can use the reflash software to extend this to 300, but that is as far as it can go.
of course, he's not talking about an sti ecu, and it doesn't take into account the presense of a utec.

see also:
http://forums.nasioc.com/forums/showthread.php?t=773994
http://forums.nasioc.com/forums/showthread.php?t=608153
http://forums.nasioc.com/forums/showthread.php?t=661756
http://forums.nasioc.com/forums/showthread.php?t=535211
http://forums.nasioc.com/forums/showthread.php?t=475758
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Old 08-02-2005, 10:19 AM   #14
dudical26
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awsome help......thanks again
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Old 06-15-2007, 11:57 AM   #15
mefarri
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edit.
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Old 06-15-2007, 01:41 PM   #16
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the MAF in its stock pipe will be able to read up to 370gr/s as Ride stated, Not more. Beyong this limit, a big MAF is required. Going over 300gr/s will require some work on the 16 bits ECU maps to overcome the 300g/s limitation.
300g/s corresponds to about 330whp while 370g/s corresponds to about 380whp on 93ron and corresponding mods.
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