AIT or MAF

[NeilC]

I've done a couple logs of my BMC and modded air box to see which is best and i still cant decide!
I'm wanting to go to the modbox as the bmc looks a bit naff and makes daft 'whootish' noises all the time.

Anyhoo's i've noticed that the bmc seems to be pulling more g/s whereas the airbox has lower air intake temps so which is the one to go for? The temp diff between the days according to the AIT at the start was box 37 bmc 39. The g/s look a bit diff to last time i logged my car when i was seeing 220. I'm putting this down to the hotter weather as i've checked and all my hoses seem tight.

Logs are revo stg2 on T6B8 with 0 timing pull (i dont have an sps3 to up it ATM)
Engine mods are upper and lower IC hoses plus forge FMIC.

BMC log:

Group A:	'002				Group B:	'115				Group C:	'004			
	RPM	Load	Inj. On Time	Mass Flow		RPM	Load	Absolute Pres.	Absolute Pres.		RPM	Voltage	Temperature	Temperature
TIME					TIME					TIME				
STAMP	 /min	%	 ms	 g/s	STAMP	 /min	%	 mbar	 mbar	STAMP	 /min	 V	°C	°C
419.26	2520	106.8	8.84	59.19	418.66	2400	73.7	1390	1110	418.96	2480	13.93	84	27
420.17	2800	162.4	13.26	106.31	419.56	2600	121.8	2210	1530	419.86	2720	13.93	84	27
421.07	3200	188.7	15.64	119.86	420.47	2920	190.2	2260	2350	420.76	3040	13.86	84	27
421.98	3600	191.7	17	140.17	421.37	3320	191.7	2330	2310	421.67	3440	13.93	84	26
422.88	3960	191.7	17.68	156.58	422.28	3720	191.7	2390	2370	422.58	3840	13.93	84	26
423.79	4360	191.7	17.34	169.69	423.18	4120	191.7	2430	2420	423.48	4240	13.93	84	27
424.69	4680	191.7	17.34	174.92	424.09	4440	191.7	2440	2370	424.39	4600	13.79	84	28
425.6	5040	191.7	17.34	189.25	424.99	4800	191.7	2400	2350	425.29	4920	13.93	84	30
426.49	5320	191.7	17.34	201	425.9	5160	191.7	2370	2310	426.2	5240	14	85	31
427.41	5600	189.5	16.66	200	426.8	5440	191.7	2350	2270	427.11	5520	14	85	33
428.31	5840	179.7	15.98	202.97	427.71	5680	191.7	2320	2230	428.01	5760	13.86	85	34
429.22	6080	183.5	15.98	209.56	428.61	5920	178.2	2290	2220	428.92	6000	13.86	85	35
430.12	6240	172.9	14.96	208.56	429.52	6120	171.4	2260	2240	429.82	6200	13.86	85	36
431.03	6440	172.2	14.96	208.33	430.42	6320	175.9	2250	2160	430.73	6360	13.93	86	37
431.93	6640	169.2	15.64	210.58	431.33	6520	170.7	2250	2120	431.63	6560	13.93	86	38
432.84	6760	157.9	15.64	210.42	432.25	6680	165.4	2250	2170	432.54	6720	13.93	86	39
433.74	6880	157.1	15.64	207.92	433.14	6800	161.7	2250	2140	433.44	6880	13.86	86	39
434.65	7040	157.9	15.3	211.25	434.05	6960	160.9	2260	2120	434.36	6960	13.93	87	39
435.56	7160	152.6	14.28	212.08	434.95	7080	173.7	2260	1990	435.25	7120	13.93	87	40
436.46	7240	145.9	13.26	121.53	435.86	7200	169.2	2190	2200	436.16	7240	13.86	87	41

Airbox

Group A:	'002				Group B:	'115				Group C:	'004			
	RPM	Load	Inj. On Time	Mass Flow		RPM	Load	Absolute Pres.	Absolute Pres.		RPM	Voltage	Temperature	Temperature
TIME					TIME					TIME				
STAMP	 /min	%	 ms	 g/s	STAMP	 /min	%	 mbar	 mbar	STAMP	 /min	 V	°C	°C
418.04	2040	15	1.36	2.06	418.33	2080	15.8	1010	1090	417.73	2040	14	84	21
418.94	2120	77.4	6.8	37.06	419.25	2160	93.2	1810	1180	418.63	2120	13.93	84	22
419.85	2320	112.8	9.52	57.58	420.15	2400	124.8	2080	1560	419.55	2240	14	84	22
420.76	2640	154.9	12.92	91.03	421.05	2720	175.9	2230	2200	420.45	2520	14	84	21
421.65	3000	182	15.3	100.28	421.96	3120	184.2	2280	2220	421.36	2880	14.07	84	22
422.56	3400	191.7	15.98	128.11	422.87	3520	191	2350	2250	422.27	3280	14	84	21
423.47	3800	191.7	17.34	150.33	423.77	3920	191.7	2410	2440	423.17	3640	14	84	21
424.38	4200	191.7	18.02	162.83	424.68	4360	191.7	2420	2420	424.08	4080	14.07	84	21
425.28	4600	191.7	17.68	172.31	425.59	4720	191.7	2390	2400	424.98	4480	14	84	23
426.19	4960	190.2	17.34	180.75	426.49	5080	191.7	2360	2290	425.89	4840	14	84	24
427.09	5280	191.7	17.34	192.11	427.4	5360	188	2340	2290	426.79	5160	14	85	25
428	5600	184.2	16.66	194.69	428.3	5640	178.9	2310	2210	427.7	5480	14	85	27
428.91	5840	174.4	15.98	196.19	429.22	5920	172.2	2270	2150	428.6	5720	14	85	28
429.81	6080	175.9	15.98	197.81	430.11	6160	162.4	2250	2190	429.51	6000	14	85	30
430.73	6280	157.1	14.28	197.47	431.02	6360	156.4	2220	2190	430.41	6200	14.07	85	30
431.62	6480	160.2	14.62	199.31	431.92	6560	157.1	2230	2170	431.32	6400	13.93	85	32
432.53	6640	154.1	13.94	200.06	432.84	6720	151.9	2230	2140	432.22	6600	14.07	85	33
433.44	6840	160.9	15.3	198.92	433.73	6880	154.1	2230	2120	433.13	6760	14	85	34
434.35	7000	160.2	15.98	200.14	434.64	7040	163.2	2240	2070	434.04	6920	14	86	34

 

[Tallpaul]

A temp diff of 2°C is not signicant as the temp sensor is only accurate to +/-1°C. It could easily be reading on the high end one run and the low end the other.

If you don't like the sound then go back to the airbox. Personnaly i always thought my BMC looked cool - but i'm easily impressed.

 

[Feel]

IAT has a surprising effect on power, I remember someone (Wilko?) somewhere quoted some relationship between the rise in IAT and loss in power.

I would say though, that as the BMC starts off 6°C hotter that you can ignore the temp difference, if you have a cold feed going into the BMC that is...

Is the standard airbox totally standard? Standard filter, air feed etc?

Slightly more boost out of the stock airbox though

 

[Tallpaul]

As logs were done on differant days, the atmospheric air pressure could have changed too.

From everything i've read and noted myself from using OE airboxes/OE airbox with Green Filter and 80mm Air Feed/BMC CDA/Carbonio. The differances are in the most part cosmetic and audible. I've never been able to say to myself, yes this filter/CAI is definately better than that one.

 

[NeilC]

I've smoothed out the airbox and put a panel filter in. I've only done a couple hundred miles on it tho. Do these things need to bed in?
I was just a little surprised to see such a diff in MAF, i expected them to be virtually the same. Maybe i'll do another run with the modbox later to see if it was a one off.
I think i'm going to try T7B7 next to see if can get it to hold a bit more boost for longer. What do other peeps see on stg 2? I've got a log of a std lcr exept remap somewhere that shows 2400+ through most of the rev range.

 

[Feel]

On the BMC Adjusted, I took the temperature difference of the starting point figures (5°C) off the range off values.

 

[Tallpaul]

Are those the airflow logs you took using two differant MAFs as well as changing the filter?

 

[Feel]

No, they're graphs of the logs NeilC posted above.

I was going to mash them all together with the ones I did, but work got in the way

 

[PhilW]

Just goes to prove that a simple panel filter can be just as good as a 160 quid bit of carbon.