MAF housing restriction?

[mb7050]

How far is the oem maf good for ?

I found this data
55mm (Stock 88-93 Mustang) 275 HP
70mm (Stock 94-95 Mustang) 350 HP
75mm Pro-M Bullet 550 HP
80mm (Stock Ford) 450 HP
Pro-M 85mm Flanged 650HP
Pro-M 95mm Flanged 750HP
80mm Pro-M 800 HP
92mm Pro-M 1500 HP



this is the data I have gathered this far
3s OEM maf = 650cfm = ~433 CHP ? at compressor Inlet Conditions
gm 3.5" MAF w/ screen = 759 cfm = ~506 CHP
gm 3.5" MAF w/o screen = 979 cfm = ~650 CHP
3.75" Zo6 maf = 1202 cfm = ~800 CHP

[Keyan]

speed density = infinite powaaaaaaa

[Atrosity]

speed density = infinite powaaaaaaa

Psht, you're an infinite powaaaaaaa

GM Maf ftw.

[mb7050]

yeah speed density wins but the pro m 92mm supports about 1500hp that is plenty (same size as arc 2 big maf)

[mb7050]

and if you think you need something bigger you can buy the 4"=100mm maf which will flow even more
http://cgi.ebay.com/ebaymotors/4-Inc...item2a0bd0db50
http://www.lingenfelter.com/mm5/merc...gory_Code=C162

[mb7050]

JDM MKIV Supra ECU uses speed density for air-metering there must be a reason why all the others, US and Eurospec supras come with maf air-metering ?

[mb7050]

good reading @ ls1tech.

I think the MAF is definitely the way to go if you can get it to work. Now no doubt that SD setup can run well, but I would still submit that under a variatey of conditions the MAF will come out superiour in drivability, etc. as well as virtually the same in power.

The potential advantages I see for SD are

1) Removing the MAF - "restriction" issues

2) Response time lag (mostly on FI cars with the maf on the intake side).

3) Freedom in routing the intake tract.

A for #1, the maf being a "restriction" - it depends on how much power you are making. On a stock or heads/cam car I don't think it is an issue at all. As for how much power the maf will "support" - well, you can flow as much air as you want through it, as the maf starts becoming a restriction you will just get a larger pressure drop. It's not that you will simply rail out at a certain point. Now as far as air metering, it will max out somewhere from 450-500rwhp normally (depending on your bsac, etc.) - you can easily tune past this point - it will be the same as tuning a SD car at WOT at that point anyway - use the PE vs RPM.

As for #2 I would keep the maf as close to the TB as possible - again, mainly an issue of FI setups. I would just move it to the pressure side. That way you can run a normal BOV also.

As for #3, well - if your intake prevents you from using a maf at all, then you are doing SD - but in a vehicle whose configuration allows for a MAF I would go for it.

SD tuning to me is old school, it's like tuning a an old school controller. You dyno and lock in all the parameters.

99% of our members can use MAF tuning and be very happy, do any of your SD tuners have any 10 second heads/cam cars? Any 9 second motor cars?

I know Ford guys who tune like that because they are using stuff like EPEC (sp?) and it's not because they want to. They end up changing the tunes depending on track weather and altitude.

And we have guys running 105-118mph with stock internals.

I've tuned my car both way's.SD ran a little better on the street but dyno'd the same.SD had a better throttle response for sure,but when the weather changed about 30 degree's the tune went off on me.Decided I liked ussing a MAF and tuned in the VE tables till it was just as responsive as SD.

just to share few posts

[mb7050]

one more

However I feel SD is more suited for the track, than it is for the road. This for someone that just wants to do a few mods and tune it, and leave it for a long time like it is, maybe some minor fiddles, the MAF tune would be better. If you want the most outa your car, race etc and are always changing things, retuning etc then SD is more suited.
Why, one point only really will spend some time and try to explain better than I usually do, think a bit, it hurts however. The purpose of any EFI system is to inject an amount of fuel into the engine. To do this, the PCM must know how much air is going into the motor at ANY given point.
What you should know is how much oxygen is in the combustion chamber at the time of ignition. The only way to tell how much fuel to inject in to mix with the available oxygen ( counting the molecules is hard) So you need to calculate the mass of air in the engine.
The amount of mass of air/gas in a given volume (the cylinder) depends on the temperature and pressure of the air. So SD setups measure the pressure in the intake manifold, and the current engine speed (which gives volume), from calculating these the pcm knows the mass of air in the combustion chamber. Speed density.SD is very fast, pretty accurate, and because it measures the intake charge in the intake manifold (close to the combustion chamber) it gives very good results.
But they have one problem, unless I’ve missing something else. The temperature and pressure of the intake charge in the cylinders wouldn’t be really the same as it is in the intake manifold. The air passes through the cylinder heads and past the valves first, and other factors can reduce or increase the amount of air that actually makes it into the cylinder. To allow for these differences, a speed/density PCM needs more info, the correction table called volumetric efficiency.
With volumetric efficiency (VE), you run the engine at each load point on a dyno, and manually adjusting the table until you get the correct air/fuel ratio as measured by an exhaust gas oxygen sensor. Then, after its is all perfectly tuned and producing nice power anytime after this you do anything else to the engine that changes breathing, you must recalculate all the VE points again.
This means as the engine ages, accumulates carbon deposits, cat converters clog up, etc etc etc, the VE of the engine is constantly changing, the perfect tune is constantly deteriorating. Emissions are also increasing overtime. It also means that if you do something to make a big change in VE - like change catbacks, extractors, intake systems, for example - that perfect SD engine tune will suffer. You need to go and reset the tune again

So holden like GM have used a different method of determining the mass air charge. Instead of the speed density systems, they use a sensor that measures air mass directly, a maf.
From the point of view of the factory, a maf is a great. As air mass is measured straight off the sensor, the maf compensates for wear, or ppl modifing the car to improve it (why you may need to reset the pcm to relearn). Since it has been mapped a given air mass vs RPM in the computer's tables, you can do what you like to the engine's VE and the computer can adjust for it. So you can make small changes and not stuff up your maf tune to much.

So it all depends on what you want to do with the car which tune to get. A maf tune is more forgiving, so could be said to be safer due to the point about VE and SD tunes.

[mb7050]

Speed density is definitely no go up here as the weather changes from ~ -50 degrees Fahrenheit to 100 degrees Fahrenheit and I´m not the kind of a guy who wants to be tuning my car all the time.

[mb7050]

... maybe thats why all the speed density cars run like crap here