stock MAF choking engine?

FoxGT87 · May 30, 2010

i got a stock MAF and 19lb injectors. i also got a trickflow track heat upper/lower intake and 75mm throttle body. i started thinking about it and i was thinking that if i added some more air the intake would really come alive. is my 55mm MAF choking my engine because of the much larger intake? if i were to switch MAF what would be a good choice in size? should i upgrade to 24# injectors?

HISSIN50 · May 30, 2010

A 94-95 Mustang Maf is 70mm and functions with your stock 19's.

FoxGT87 · May 30, 2010

thats a good thought, thanks maybe i can find one in a local U-pull it.

Mustang5L5 · May 30, 2010

You will need and adapter to make it work on a fox.

But when I swapped from a 55 to a sn95 75 maf...I felt a difference

stang&2Birds · May 31, 2010

You'll get ~3 to 5HP. Don't expect anything more. IMHO, any other difference is due to dirty MAFs, the calibration differences that exists between all MAFs, etc.

Also, don't put in a foolish cone filter on the end of the MAF. They are great for Dyno runs where the hood is open and cold air is blown into the engine bay. They are a joke in real world driving.

So.., is it worth it?
Hmm, free 3-5HP. Better MPG (very slight), more HP, better response (slight) all for under ~$100. With no downside? What do you think?
And, why do you think that Ford when with the more expensive MAF (bigger costs more in raw material and machining) for sn95s?

Good Luck!

FoxGT87 · May 31, 2010

you think i would only be picking up 3-5 ponies moving up to say a 73mm or a 76mm which flows almost 800 cfm, running into the bigger Tbod and upper lower intake? i was expecting something a little better.

also would i see a gain if i went with the 24# calibrated MAF and and bought new injectors?

Mustang5L5 · May 31, 2010

You would only see a gain with injectors if your original combo was running lean due to undersized injectors. They only provide fuel, they don't make power. So if your current combo has adequate fuel, nothing to gain.

FoxGT87 · May 31, 2010

Mustang5L5 said:
You would only see a gain with injectors if your original combo was running lean due to undersized injectors. They only provide fuel, they don't make power. So if your current combo has adequate fuel, nothing to gain.

easiest way to check this is with an air/fuel guage right? or is there an easier way, honestly it smells like i am running rich often.

my goal is after bootcamp and A school to do TFS heads/cam swap at that point i would assume that 24# would be necessary. for my Bday hoping i can get a new MAF and im wanting to get them calibrated for 24# injectors. reason being i don't want to spend money twice. is this a good plan with the TFS top end i plan on installing?

stang&2Birds · May 31, 2010

You're fine with 19# and your combo.

As for the MAF, my favorite quote: "It's all relative".

The 55mm MAF is an air restriction at ~180+HP. Think of it as a dirty air filter. A dirty air filter restricts air, and that limits HP (makes the engine "air pump" work harder to suck in air).

Let's say the car is on a dyno. If you replace your clean stock air filter with a mega ricer 100foot air filter, would expect a big HP gain? I hope not!

So, the size of the air filter, the size of the MAF, the size of the air intake tubing are all relative to the air needs of a specific engine. In other words, "It's all relative".

I like to remind people that the engineers that designed the cars do know something. But, there is always a trade-off in cost/ performance/ profit/ market desire/ MPG/ HP/ smoothness/ etc/ etc/ etc.

The 55mm MAF was used for cost reasons in the Fox Stangs. It has only a small HP detriment, and was much cheaper than going to a 70mm MAF. Don't forget that a $30 added cost over a million cars is $30 million dollars of extra expense. :-O

stang&2Birds · May 31, 2010

[on soapbox]
I also want to add:
A bigger MAF makes it harder to get accurate readings at idle. That effects smog, smoothness, MPG, etc.

People are more than welcome to design a 300mm MAF and intake that is super accurate over the full range from idle to 1000HP, and is super cheap. Until they do, maybe they shouldn't bash the MAF design choices.

Engineers have to design for the real world. Many forum posters and ricers seem to design for their own mega screwed up perception of reality.

Also, the analysis and verification tools available from the design start of the EFI 5.0 (~84) to the sn95 upgrade (~92) are very different. And, the analysis and verification tools available today (2010) are much different than they were in 92.

Air flow patterns vary a lot depending on temp, air pressure, amount, etc. The differences between a Fox MAF and an sn95 may look "minor", but they have a huge impact on the air flow pattern.

So, cost, and available air flow analysis where major reasons for a 55mm MAF in a Fox.
[off soapbox]

FoxGT87 · Jun 1, 2010

is the 94-95 cobra MAF bigger than the 94-95 GT MAF?

i got someone offering me a 94 GT MAF for $30 shipped and then another guy saying he has a 94-95 MAF calibrated for 19# injectors.

also can someone post a link to the adapter i will need? i havent been able to find it. finding adapters for the huge MAF but not for a fox/94-95 MAF conversion.

EDIT: is this the part i am looking for? found an old post with Jrichter saying i could get an aluminum adapter from Autozone for 13 dollars. just making sure this is the right thing so when i go down there i can verify thats what i need to buy.

HISSIN50 · Jun 1, 2010

All 94-95 Mustangs use the same MAF.

They are not calibrated for any injector (the same MAF functions for 19's, 24's, and whatever injectors are in a V6).

FoxGT87 · Jun 1, 2010

thats pretty cool to find out, thanks Hissin. i am slightly concerned about running too lean when i do the heads/cam in the not so near future. but if i can swap in bigger injectors w/o needing to change MAF that is nice.

1990MustangLX50 · Jun 1, 2010

I was considering the same deal, planning on one day doing possibly an explorer top end and a cam with 24lb inj. So a 94-95 MAF would be able to handle that kind of change?

HISSIN50 · Jun 1, 2010

No, the MAF is not calibrated for any injectors. It simply reports airflow to the EEC.

If someone wants to change injector size, of course the EEC will need to be tuned or some trickery will be needed to fool the EEC.

FoxGT87 · Jun 1, 2010

okay so hypothetically if i went with new parts it would run me $380 for a new MAF censor and new 24# injectors (C&L MAF, Venum injectors)

but if i got a 94-95 MAF i would need a tune for the vehicle aswell? so, 50 for the MAF and another 450 for the tune? doh! bah seems like i will be waiting some more before i do this mod. i guess im setting my mind back on a 73-76mm MAF calibrated for the 24#.

i know i can find 24# injectors on corral all day long, seems kind of hard to find a MAF censor that i want on corral.

HISSIN50 · Jun 2, 2010

The short answer is no, the 94-95 MAF will not require any extra tuning that the stock 55 MM MAF would have.

None of the OEM MAF's are calibrated for any size injector. They report airflow volume to the EEC. The idea of calibration comes from the aftermarket.

That said, to make this understandable, we will say the stock 55mm A9* EEC's MAF is calibrated for 19's. The 94-95 MAF (any stock MAF from a GT, V6 or Cobra), when used with an A9* EEC, is calibrated for 19's.

If you want to run 24's, you need to either tune the car (just as you would with a LMAF or any other factory MAF not using the injectors and EEC that were married to it from the factory), use an aftermarket MAF, or use a device that changes the MAF transfer curve (there are other more obscure options as well).

Think of the 94-95 MAF like the stock 55 MM Maf. If you used 24's with the stock MAF (and kept your current EEC), you'd need to change the MAF. The same is true with the 94-95 MAF.

Good luck.

tmoss · Jun 2, 2010

5-10 HP for an SN 70mm swap is worth it my book.............

FoxGT87 · Jun 2, 2010

tmoss said:
5-10 HP for an SN 70mm swap is worth it my book.............

kind of... but when a tune i have to turn out 450 everytime i go to get a tune, i might as well just buy a bran new 73 or 76mm C&L for 160 and pick up a set of used 24# injectors for around 90-110.

i was going to get used SN 70mm for 30 + $15 adapter from AZ but the tune it would take puts the cost way more then i would like it to be. seems like waiting a little bit longer will be better for me rather than trying to go "cheap" now. in the long run it just doesn't seem worth it to me.

tmoss · Jun 2, 2010

I can't tell you how many guys I see saying they for with more intake/head and TB with 19s but leave the stock 55mm MAF - when for cheap they can get the 70mm SN unit - I'd do it everytime in that case.

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