I think the real gains are in the fuel and spark tables, not necessarily from sequential injection. It would be interesting to see what effect just changing from batch to sequential fire makes (maybe I could test this on the FSAE car next time we dyno the motor). I think all of the mustangs that weren't CFI and aren't mass air are sequential speed density. I'm not sure how those cars compare either ('88 to an '89).

 

FosterJohnson,

I don't really like that article you posted because I disagree with of it's statements.

"Mass air EFI is usually what is called SEFI (Sequential Electronic Fuel Injection), which has one separate wire for each injector and fires them twice for every power stroke of the engine. This makes the injector timing more accurate and will help emissions along with power."

Mass air is not called SEFI. Also, SEFI does not fire the injector twice for every power stroke of the engine (according to a few of the Ford EFI books I read, and threads on FTE). What I've found to be true, is that with non-sequential SD, it fires a bank of injectors at a time...vs each of 8 injectors when necessary. So it fires 4, then fires the other 4...etc etc...

The sequential injection is when each injector is fired at the exact time the intake valve is open. This means that the fuel is sprayed directly into the combustion chamber, and spends very little time in the intake port. The fuel hits the back of the hot intake valve, and provides better atomization (more power, efficency, etc).

Like I mentioned, there were SD mustangs that had sequential injection, it doesn't have to be MAF to be sequential, so MAF is certainly not called sequential. With SD, sometimes injectors are fired when the intake valve is closed, so the fuel is sprayed into a closed area. Also, my sequential efi has 3 wires going to the injectors.


"Speed density EFI will usually run well with just about any exhaust modifications."

Just about? Any exhaust modification, including headers, cat work, hi-po mufflers, dual pipes, larger diameter tubing..etc...will cause absolutely no affect on the airflow through the engine, therefore no affect on the SD. As mentioned, a turbo is different.

A better flowing exhaust just simply makes it easier for the engine to get rid of exhaust gases. It doesn't affect the amount of air that flows through the engine. The piston still only sucks in that same amount of air through the intake ports.

"One list member is running the stock speed density computer/intake with Windsor Jr. heads and a stock 351W lightning cam. Claim is that it runs very well and the key is the lobe separation of the cam, which should be kept above 113 degrees."

Those heads flow a lot more air then stock, I don't see how the stock SD would work with it. Most likely, the SD computer was tweaked, its common. Most people say no less then 114 lobe sep. My cam is 112 but its MAF. It is important to keep the vacuum correct by having the right lobe sep, but it's not the only thing that determines whether or not the EFI is able to run it appropriately. I felt as though the article gave that impression.


Just read a little more on tuning a SD, decide on whether or not you want SD or MAF, decide how you're going to tune it (tweeker, pms, SCT dyno tuning etc), tune it and enjoy

You'll need a wideband 02 sensor if you're going to tune it yourself, around $400.

 

One thing I try not to do is group our rigs in with the stang crowd. They are two totally different animals.
However, your are right and this has been done. The GEN 1 Lightning guys do this with the Pro-M MA conversion, larger injectors, and matching MAF and no additional tuning. What I'm talking about is a factory installed MAF on a full size pickup with 19lb injectors. Like I said before it'll run, just not very well.

 

Regarding that engine combo FosterJohnson mentioned, I doubt that member is running that combo without some type of tuning, even though he is using the stock PCM. I've been tuning and running a SD/boosted combo for some time now and can tell you that SD tuning requires a little more than just keeping the LSA above 113, and a stock Lightning cam isn't even flirting with that.

In my experience, the mass air combo I had was easier to tune than the SD set up I'm currently running. I have it tuned properly now, but it required a little more time and understanding to get it there...SD is a totally different animal. Either system is going to need some type of tuning to get the most out of your combo. If you're going to spend the moeny on better parts, then spend the money to make them perform at their peak.

 

Will the above with bone stock MAF and 19lb/hr injectors run a 300-320 HP Windsor without tuning, thats my goal?


Wasn't trying to group us with mutang people other than the motor they use for swap sometimes. Same chunk of cast iron since '69

 

It'll start, idle and run but I'd say the stock fuel system will fall short. Also, I don't know what the stock MAF will support either since every application is different. You could keep it on there and take it to a dyno for some datalog runs and see what everyting is doing.

However, with right parts, aftermarket tuning will help you reach your goal. Look at it this way, if your gonna spend your hard-earned money and time to install better components on your rig, then why not spend a little more for some aftermarket tuning and allow these components to reach your goal? Some people have the wrong idea when it comes to mass air, and I've seen it before...they build their motor with excellent aftermarket parts, and don't go after any aftermarket tuning. They end up being disapointed with the results until they get a chip to tie their combo together. My two brothers went through this as well, one has a Mustang and the other has 94 F-150/5.0.
When tuned properly to a modified combo, mass air is a "set it and forget it" type of system. It'll even adapt to a few other minor modifications without any additional tuning. If you plan on doing your own tuning, then get the right devices to allow you to do so: wideband O2 that will datalog, tuning software, fuel pressure gauge, etc...

 

It's probably a combination of the changes made when I converted to MAF that are responsible for the improvements I've experienced. Better fuel curves calculated with more accuracy, sequential firing and for me the ability to use my MSD have made improvements that might be greater than the sum of each improvement seperately.

I didn't see a drastic increase in power (at first) but throttle response and idle improved immediately. It's taken some time but I'm starting to see a definate improvement in mileage. Right after the conversion I was at about 12 mpg (about the same as before the conversion) But now after nearly a year I'm up to about 17 mpg.