Speed Density vs MAF

BigSlappy · Mar 7, 2023

Is there a reason why someone would run Speed Density over MAF and vice versa? Im new to these older cars, so im just used to having only MAF, but have heard good things about tuning Speed Density compared to MAF. Ive also heard people would rather have MAF when it comes to upgrades.

Noobz347 · Mar 7, 2023

The speed density computers on these cars were never well supported by the aftermarket. By itself, the Ford SD doesn't tolerate engine mods well to include cam swaps that differ from OEM. Cam swaps are one of the hottest mods for Windsor motors so the OEM SD gets kicked to the curb.

Back in the day, MAF EECs with chips and piggyback programmers are all the rage. In most cases, it's better just to replace the EEC altogether with a stand-alone unit of some kind. This opens up the SD v MAF debate all over again since aftermarket SD units do not suffer the same limitations as the Ford SD.

Mustang5L5 · Mar 8, 2023

The old foxbody 86-88 Speed Density setup wasn't that great when you started changing items that affected manifold vacuum, like camshafts. That's why Mass Air was preferred. Comparing 86-88 SD to 89-93 Mass air, the MA setup wins hands down in terms of modifying.

Now, bring aftermarket ECU's into the mix and it's a different story. These ECU's are faster and more capable of working with modifications. The programming logic has matured. Running speed density with aftermarket ECU's is popular because it eliminates the MAF, which is helpful when running forced induction and trying to plumb the system up for high levels of boost.

A lot of OE's are also going back to Speed Density after decades of Mass Air. For example, the 2010-2018 Ford Taurus was a Mass Air car as you would expect, but in 2019, ford ditched the MAF and went back to Speed Density.

mikestang63 · Mar 8, 2023

There are many aftermarket standalone systems that are SD, as well as Mass Air. They both have pros and cons.

Regarding using the Ford Factory EEC's, I ran a V1, a SD cam. Edelbrock heads all on a SD EEC with a Johnson Motorsports chip- I am sure you can get a tune still burned for an SD EEC if you want. Untill you start running large duration cams or huge amounts of boost, I say you can run a SD EEC. The issue is the stock SD EEC is pre programmed with set AF tables and is not as adaptable as Mass Air. With Mass Air, once you start adding an HCI and/or a power Adder, you will need to match the Mass Air Meter to the injectors as well as getting a tune on the Mass Air EEC. If you make mild changes, the Mass Air EEC will be able to compensate better. In stock form, the SD car is actually faster as it had a more aggressive timing curve if I recall correctly. Ford went to Mass Air for emissions mostly as well as better driveability

Most people will convert to Mass Air as a precursor to making further mods

AeroCoupe · Mar 8, 2023

From my understanding mass air ECU’s have what is called adaptive control and by using the various inputs it receives it can adapt which allows for changes to the motor that allow more air flow. The adaptive control only varies +/- 12.5% so it s its limits which is why at a point you have to tune the car. It cannot compensate for bigger injectors and cannot compensate for a MAF change as those tables are fixed. You can add a larger MAF that is calibrated for larger injectors. By calibrated I mean it provides a signal to the ECU that is scaled so it delivers the correct amount of fuel.

The AFR heads are a bolt on and should need zero machine work. Make sure that you know what the open and closed pressures are for the valve springs that come with the heads as well as the max l as this will be needed when choosing a cam. You may need a different set of valve covers for rocker clearance.

Explorer intakes can still be had at auto recyclers and if removed correctly can be cleaned up at the house and bolted on. You will need to make the provision for the ACT sensor.

The cam is the brains of the operation so once you settle on heads and an intake then choose the correct cam. This will keep it from being a dog.

96pushrod · Mar 8, 2023

I’m just speaking of aftermarket standalone engine management, but speed density really is the way to go. No maf to buy, intake tubing can be ran however you want, if you’re doing something like a blower you don’t need to worry about whether you want to do a blow through or draw through - and you can run an open bypass valve. Sd doesn’t care where air goes before the throttle body.

Really there’s only company that heavily pushes maf based standalone efi for mustangs, and they sell maf’s. All the other ones run sd (with the option for a maf, but 99.99% of users don’t use).

Factory eec are an entirely different story, the maf eec’s are much more tolerant.

BigSlappy · Mar 8, 2023

Currently, I have an 86 GT with the efi and SD. One thing I want to start doing is tuning, but I wasnt too sure how to tune SD let alone OBD1. Anyone have any forums or links to where I could learn to access the computer and start tuning?

Noobz347 · Mar 9, 2023

Aside from a couple of chips mentioned by Mike (if any are even available anymore), you are not going to tune the stock SD or OBD1. The expense is just not worth it for an EEC that is 40 years old.

If you end up tuning SD it will be on an aftermarket system that will eliminate your old EEC and thus OBD1.

You cannot just hook your laptop to your 86 and start ballin'.

Noobz347 · Mar 9, 2023

This may help give you some idea of what is involved with these systems:

mikestang63 · Mar 9, 2023

Noobz347 said:
This may help give you some idea of what is involved with these systems:

ithought they stopped selling them?

Noobz347 · Mar 9, 2023

mikestang63 said:
ithought they stopped selling them?

They might have but in this case, it's not relevant. Just showing what's involved more or less so the OP doesn't think he's going to cord his Windows PC into a 40-year-old EEC and start tuning.

BigSlappy · Mar 9, 2023

Noobz347 said:
They might have but in this case, it's not relevant. Just showing what's involved more or less so the OP doesn't think he's going to cord his Windows PC into a 40-year-old EEC and start tuning.

The discontinuing of these aftermarket ecu's is what I concerned about. The only thing I could find that I can buy is something that plugs into an a9l computer and seems really sketchy. Those megasquirts are still available but never in stock and are close to 1.2k. Ill have to look on ebay and fb marketplace for one.

96pushrod · Mar 9, 2023

BigSlappy said:
The discontinuing of these aftermarket ecu's is what I concerned about. The only thing I could find that I can buy is something that plugs into an a9l computer and seems really sketchy. Those megasquirts are still available but never in stock and are close to 1.2k. Ill have to look on ebay and fb marketplace for one.

PiMPxs Standalone Engine Management (Sequential EFI)

PiMPxs Standalone Engine Management

www.stinger-performance.com

These guys are what you want. Pair it with a aem 30-0300 wideband and you’re set.

95BlueStallion · Mar 9, 2023

I bought a Microsquirt and a wideband for my 347, and my tuner is tuning it via SD. I plan to stick with it with my 363, as my tuner says it will work fine. We'll see. From what I see, the Microsquirt can still be had from EFI Source for $475. That comes with fox specific wiring, and a 3 Bar Map sensor. Wideband set up is obviously separate. My 347 ran awesome with it.

Noobz347 · Mar 9, 2023

BigSlappy said:
The discontinuing of these aftermarket ecu's is what I concerned about. The only thing I could find that I can buy is something that plugs into an a9l computer and seems really sketchy. Those megasquirts are still available but never in stock and are close to 1.2k. Ill have to look on ebay and fb marketplace for one.

We have a whole forum for this. There's at least a dozen different systems out there that you can use to run a Windsor.

I [still] have the chip in the back of an A9L. It's a 4-bank. I'll be ditching that system for a stand-alone once I find my [round tuit].

mikestang63 · Mar 10, 2023

Noobz347 said:
We have a whole forum for this. There's at least a dozen different systems out there that you can use to run a Windsor.

I [still] have the chip in the back of an A9L. It's a 4-bank. I'll be ditching that system for a stand-alone once I find my [round tuit].

FWIW, i have a chip burned by my dyno tuner in my A9P in my 90 Supercharged vert and couldn't be happier. Have it for 7 years and it fires right up, idles and drives well, and makes well over 500 crank hp. It all comes down to the tune. I think people jump to quick to an aftermarket system because that is the latest "thing to do", when us old timer were able to get it done with the factory EEC and harnesses. I would reach out to Matt Leech at Leech Motorsports as he is one of the better tuners on OBDI tuning.

Kid wita 5oh · Mar 10, 2023

Leech is no longer doing tunning unless it's an in house build. (check their FB page)

96pushrod · Mar 10, 2023

mikestang63 said:
FWIW, i have a chip burned by my dyno tuner in my A9P in my 90 Supercharged vert and couldn't be happier. Have it for 7 years and it fires right up, idles and drives well, and makes well over 500 crank hp. It all comes down to the tune. I think people jump to quick to an aftermarket system because that is the latest "thing to do", when us old timer were able to get it done with the factory EEC and harnesses. I would reach out to Matt Leech at Leech Motorsports as he is one of the better tuners on OBDI tuning.

It’s flat out easier long term to go with aftermarket systems.

Never would I ever recommend messing around with stock eec after going aftermarket stand alone.

mikestang63 · Mar 10, 2023

Kid wita 5oh said:
Leech is no longer doing tunning unless it's an in house build. (check their FB page)

Interesting insight from Matt on his FB page. Backs up what I have been saying about the Holley system.

Then things started to get really ugly for me. Holley EFI has been the bane of my existence for many, many reasons. I never wanted to be a Holley tuner. But no amount of trying to convince the public of staying with the stock computer resulted in a customer base where the majority of our work was EEC-IV related. It turned into being about 90% holley efi. And for the types of cars we tune (street cars), it is just not the right decision most of the time. The tuning effort to dial in basic things is often just absurd. Many systems had sever misfires due to harness issues and interference. O2s failing or reading weird constantly. Data logs crashing constantly. And Holley EFI just doesn't have overall not good idle, startup, and idle air logic. We fought through this stuff on hundreds of cars, but man what a task. And not every project succeeded for these reasons.

Kid wita 5oh · Mar 11, 2023

Has me rethinking my plan for my 347& vortech.. Originally planned on quarter horse & leech.... Then changed to termX when those both became unavailable... Now I'm not sure what to do

Speed Density vs MAF

BigSlappy

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Noobz347

Stangnet Facilities Maint Tech... Er... Janitor

Mustang5L5

That is…until I whipped out my Bissell

mikestang63

AeroCoupe

lube between the nut and the face. I know my lubes

96pushrod

I think they're a little easier to get off

BigSlappy

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Noobz347

Stangnet Facilities Maint Tech... Er... Janitor

Noobz347

Stangnet Facilities Maint Tech... Er... Janitor

mikestang63

Noobz347

Stangnet Facilities Maint Tech... Er... Janitor

BigSlappy

Member

96pushrod

I think they're a little easier to get off

PiMPxs Standalone Engine Management (Sequential EFI)

95BlueStallion

My assy trans to myself

Noobz347

Stangnet Facilities Maint Tech... Er... Janitor

mikestang63

Kid wita 5oh

I'm definitely not in the original hole

96pushrod

I think they're a little easier to get off

mikestang63

Kid wita 5oh

I'm definitely not in the original hole

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Speed Density vs MAF

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lube between the nut and the face. I know my lubes

I think they're a little easier to get off

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