1988- pre mass air meter vs. 1989+ mass air metered cars

Discussion in 'Fox 5.0 Mustang Tech' started by I candy, Sep 28, 2010.


  1. I candy

    I candy Founding Member

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    I'm sure this has been covered alot of times. but when i search it doesn't have what i'm looking for. there are alot of help threads and conversion threads but nothing to tell me the difference between the 2.

    what i want to know is what is the difference between the two?

    Which is better and why?

    pros and cons?

    modifiying is it easy?
    (not talking converting)


    I found a car on CL and its a 88 GT I want get it to put into Rallycross and have a car to use on the street once in a while. I don't want to get it if there is alot of issues with non mass air metered cars or if moding them takes more money or they are limited with out converting them.

    someone please help.
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  2. Rick 91GT

    Rick 91GT SN Certified Technician Site Sponsor

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    The Speed Density cars are actually just a tad faster in most cases in stock form, however they do not adjust well to aggressive modifications. That is the main reason guys swap to MAF, aggressive cams, power adders, etc make tuning much easier.

    Really depends on what modifications you plan to do, if you keep the cam under say 224 duration and a 112/114 LSA the SD cars respond and run very well, even with heads/cam/intake changes.
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  3. walmic679

    walmic679 New Member

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    1988 GT

    This is true. I stuck a E303 cam in a stock engine and after about 200 mile on a brand new engine, it fouled up both o2's, would surge at idle, just did not work right. After installing a mass air conversion, problems stopped and the car ran fine. The good thing about having a mass air instead of speed density is that you can do ALOT more mods with out a ton of problems. Besides, if the computer is measuring the air before it goes into your engine it gets a more accurate reading. Go with the mass air conversion, it won't do you wrong.
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  4. Mustang5L5

    Mustang5L5 Car used in adult film "Highway Gangbang-InDaButt" SN Certified Technician Founding Member

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    I wouldn't pass over a good speed density car because it wasn't mass air. I didn't. I've owned my car for 13 years and it's still speed density and I have a healthy list of mods. It runs great.

    The conversion to mass air is cheap. $100 fpr a computer, $45 for wiring kit, and $50 for used mass air meter and air intake hoses...the job is simple.
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  5. Kdubslugga

    Kdubslugga Active Member

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    Basically Speed Denisty measure airflow by vacuum and adjusts accordingly. Mass Air measures airflow electronically through the mass air meter, which is a much more accurate way to measure airflow. As stated above. Stock for stock there essentially the same. When you start modifying your car beyond the exhaust and bolt on parts, your going to need to convert to mass air! Since you said your looking to build an autocross car, your not going to need gobs of horsepower, so if you find a Speed density car, thats really nice, id go for it. Worst case scenario you have to convert, and thats been done a million time!!
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