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Old 04-13-2007, 04:01 AM   #1
BlackSTI2006
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Default Perrin Big MAF-Open Ecu/Enginuity Help

Does anybody have the info on rescaling the MAF for the perrin Big MAF intake?

I am upgrading to Fp Green 2.4" inlet, 7cm housing, iwg. Going with fuel pump, one step colder plugs, big maf,perrin turbo inlet,and 816cc modded stock injectors.

Anyone got a good base map for me maybe?

Just looking to see if anyone has the info for rescaling?
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Old 04-13-2007, 01:00 PM   #2
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it's funny you brought this up because i was talking to a guy about this last night. I have a copy of his map on my laptop(which broke while we were working on it) and we noticed that the MAF was scaled kind of odd. I was wondering if anyone else has got a map for a Big MAF that it could be compared to.

Jeremy
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Old 04-13-2007, 03:48 PM   #3
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multiply the map by 1.1459. tune accordingly from there.

Last edited by WeldingHank; 04-13-2007 at 04:02 PM.
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Old 04-13-2007, 04:36 PM   #4
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I had lots of troubles with the Perrin big MAF. The pipe starts to heat up from the engine bay heat which causes it to go soft and change shape, causes all sorts of funky MAF problems. In the end I gave up and we used a solid pipe instead. Even back to back MAF logs were not consistent. Just my 2c.
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Old 04-13-2007, 08:39 PM   #5
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On an FP Green 2.4" inlet, 7cm, iwg with perrin turbo inlet and front mount, should i go with big MAF or keep my k&n tyhpoon?
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Old 04-13-2007, 10:25 PM   #6
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I woud say so, the stock MAF tops out at 300 G/sec. The Green is more than capable of flowing that much air and more.

edit: did a little digging for you, the green is capable of flowing up to 48lbs/min. Which equates to about 362 g/sec

Last edited by WeldingHank; 04-13-2007 at 10:42 PM.
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Old 04-14-2007, 03:14 AM   #7
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mulitply which map? the fueling map?

or are you talking about the MAF Scaling?
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Old 04-14-2007, 05:25 AM   #8
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You will be chasing MAFV dips and spikes forever. Good luck.

TMS
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Old 04-14-2007, 09:41 AM   #9
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I've posted my bigmaf calibration before. If you can't find it by searching, I can try to dig it up. Mine idles good, and achieves target AFR at WOT... but there are occasional dips and spikes like TMS mentions.

edit... I searched for 2 seconds and found it. Obviously, use at your own risk.

Code:
0.94	0.98	1.02	1.05	1.09	1.13	1.17	1.21	1.25	1.29	1.33	1.37	1.41	1.48	1.56	1.64	1.72	1.8	1.88	1.95	2.03	2.11	2.19	2.27	2.34	2.42	2.54	2.66	2.77	2.89	3.01	3.13	3.24	3.36	3.48	3.59	3.71	3.83	3.95	4.06	4.18	4.3	4.41	4.49	4.57	4.61	4.65	4.69	4.73	4.77	4.8	4.84	4.88	4.92
1.50	1.72	1.97	2.24	2.53	2.85	3.22	3.64	4.07	4.54	5.06	5.60	6.19	7.43	8.83	10.36	12.06	13.94	16.01	18.26	20.87	23.87	27.21	30.96	35.16	39.64	46.93	55.19	64.33	74.10	84.67	96.13	108.61	122.20	137.01	153.07	170.36	189.26	210.00	233.39	258.37	284.06	310.48	328.83	348.85	359.88	371.18	382.74	394.22	406.06	418.17	429.56	441.16	452.99
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Old 04-14-2007, 10:45 AM   #10
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Quote:
Originally Posted by HndaTch627 View Post
mulitply which map? the fueling map?

or are you talking about the MAF Scaling?
the maf scaling, not the voltage part but the G/S part.
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Old 04-14-2007, 10:58 AM   #11
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Quote:
Originally Posted by darthvader666 View Post
I had lots of troubles with the Perrin big MAF. The pipe starts to heat up from the engine bay heat which causes it to go soft and change shape, causes all sorts of funky MAF problems. In the end I gave up and we used a solid pipe instead. Even back to back MAF logs were not consistent. Just my 2c.
The Perrin BigMAF housing is metal - Are you saying that your engine bay gets hot enough to warp metal
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Old 04-14-2007, 11:09 AM   #12
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its aluminum. Leaving aluminum in the sun on a nice hot day is enough to distort it.
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Old 04-14-2007, 07:18 PM   #13
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Quote:
Originally Posted by WeldingHank View Post
edit: did a little digging for you, the green is capable of flowing up to 48lbs/min. Which equates to about 362 g/sec
Is there an equation to go from lb/min to G/sec?
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Old 04-16-2007, 01:33 AM   #14
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1 lb/min = 7.56 g/sec
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Old 04-16-2007, 12:34 PM   #15
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The one I used had a silicon tube before the filter and that was too soft.

Quote:
Originally Posted by mick_the_ginge View Post
The Perrin BigMAF housing is metal - Are you saying that your engine bay gets hot enough to warp metal
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Old 04-22-2007, 09:18 AM   #16
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when adjusting the maf table,
adjust to read for lambda values
read lt & st fuel values (compare to what is acceptable from stock)
then adjust maf table values
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Old 04-26-2007, 10:21 PM   #17
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Quote:
Originally Posted by WeldingHank View Post
edit: did a little digging for you, the green is capable of flowing up to 48lbs/min. Which equates to about 362 g/sec
this might be out of context, but at what PSI does the green flow 48lbs/min?
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Old 04-27-2007, 01:36 PM   #18
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Quote:
Originally Posted by WeldingHank View Post
multiply the map by 1.1459. tune accordingly from there.
where do u get this number from. I am trying to figure it out but cant, then again I don't even know how the MAF truly works, but....

if the stock intake radius is 2.5/2 or 1.25in

and I think the perrin big maf is 3.25/2 or 1.625in

If its proportional to the square of the radius then it's about 1.7 times bigger?


Someone please explain because I really want to know how the MAF works
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Old 04-28-2007, 01:39 PM   #19
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Default 70mm big maf help on 2.0 ecu

I am also battling to come to terms with the BIG MAF from Perrin and the APS 70mm cold air induction
scaling - adjusting injector size all seem to be band aids - surely mathematically we can do this properly ?

just how ?
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Old 04-28-2007, 05:20 PM   #20
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you take the size in millimeters and turn it into a percentage larger than the stock intake tube. On the Cobbforums you can get a spread sheet that will do the calculation for you.
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Old 04-30-2007, 08:19 AM   #21
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Welding Hank - got a clicky ? to that sheet on cobb forums - I signed up there and searched with no joy
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Old 05-02-2007, 06:55 PM   #22
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I cant find it either. (the spreadsheet) Anyone have a link?
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Old 05-03-2007, 12:44 PM   #23
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Jeff Sponaugle from PDX tuning did a bench test with a Perrin BigMAF and a stock MAF back in 2004 that described the flow characteristics. It is not as simple as bumping every flow value up by the increase in open area.

I did a google search and looked at the cached page. I think I saved the document if someone wants it. PM me.
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Old 05-07-2007, 03:28 PM   #24
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I can't seem to find that test data from PDX anymore. You cannot simply increase all the flows by the increased cross-sectional area (40%). The Big MAF flows more like +20% at low loads and up to +30% at high loads.

Anyway, it was almost dead on with the MAF table posted in this thread in post #9. Seems to be a very good starting point.
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Old 05-12-2007, 10:24 AM   #25
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Here it is... although in practice, this didn't help me a bit.

http://forums.nasioc.com/forums/show...t=BigMAF+scale
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