I have a 88gt that's speed density. Ive been wanting to get a little more power out of the car so far its a 306 with a e303, shorty headers. how adaptive is SD versus MAF? Some people say SD is better and some think MAF is the way to go...

 

Go carbed or MAF is the only way to go for more power & tuning!

 

Speed Density cars can be Animals but For Sure harder to make run smooth when compared to Mass Air!

 

It cheaper to convert to mass air & be done with it!

 

whats the cost of the swap?

 

if you keep it speed density just keep the stock cam or a small one at that.

 

i have a small cam and if the cars cold it will have erratic idle for about 30secs then it will clean up and idle normal, most of the time.. the reason i ask is because id like to swap heads and upper and lower intakes.

 

I'm no expert on EFI. But I like to be technical with only give out correct information. Usually bias'd from my own personal experience or my own personal likes and dislikes. So take what I say with an open mind. Its not always the 'proper' or only way to do something.

They way I understand Air Density vs MAF 5.0 cars is like this.

The 86 - 88 cars have 3 main components for engine management. The MAP sensor which reads manifold vacuum, the TPS sensor which read throttle position and the O2's which read oxygen levels in the exhaust. The problem with trying to modify an Air Density car is not the fact that it doesnt have an MAF. The really fast prostock guys running EFI do not use a Mass Air Meter. They use something like a FAST system which is indeed Air Density Based. But they tune their car for WOT,.. and Air Density is the easiest to tune for WOT. You set your fuel and timing tables per RPM level. Its preprogrammed that at a said RPM level it should have a known amount of air coming into the engine. The fuel and timing is set accordingly. And that is pretty much how Ford Air Density works,.. except the map sensor and O2's try to compensate some of the variables for drivability. The stock computer has a preset table it reads as the RPM's climb it knows how much air should be coming into the engine. If you alter that with a cam, larger intake and TB, and then throw headers on it so the engines breaths better,.. the computer does not have the ability to read and compensate for all of it.

With a MAF meter the computer can now adjust fuel and timing because the MAF sends voltage signals that tell it how much air is coming in. It can compensate for more variables at different RPM levels that an Air Density system is just not capable of doing.

For an all out race car,.. Air Density is cheaper and easier to tune. For a street driven car.. an MAF provides more information to the computer to adjust the engines needs. But an MAF can only read so much air before it becomes (Pegged out) voltage limited. Once more air passes through the MAF than what it can read,.. you run into the same problems that you had with Air Density.

Converting an Air Density car to MAF is really pretty easy. There are detailed how to's with step by step pictures all over the net.

What you need:
An MAF housing with a 4 pin meter set for 19lb injectors (if your stock)
An MAF 4 pin pig tail to tie into the computer and wiring harness.
And lastly you need an 89 - 93 computer. The A3M and A9L are the two most desirable. They are essentially the same thing.

The computers go for about $100.
the MAF meters run anywhere from $25 to $250 depending on where and what you buy.
The pig tail can be free if you steal it from a junkyard or $45 to $65 for ready made ones from online vendors.


I hope that was understandable in laymens terms,.. and I hope most of it was correct. Those who really know and understand this better then I do,.. please feel free to correct me if anything I said was incorrect.



Peace,..

Hurst

 

I added a H/C/I combo to my 88 LX and kept it SD for over a year. It ran great and if I had not gotten greedy and started on the horsepower trail, it would still be SD. It was always a DD and I had no problems with it. Like Hurst said, dont go overboard, especially with the cam. SD needs to keep good vacuum. I went with a Comps XR264HR, it has mild duration, wide lobe separation and great lift. Added GT40P heads with bigger valves and a Cobra intake w/ 65mm TB and a cold air fender kit. Underdrive pulleys, offroad exhaust, all the ussually goodies.

Car ran awesome. Idled like stock and reved like a bitch. It didn't even loose any MPG.. I wish the damn thing had of come that way.

And if you want you can still change to mass air after you build it. It isnt hard at all.

Anyway, good luck.

 

Thank you all for some very insightful information i'm still not sure wich way i want to go. But i think ill use the current SD and then later on swap over like you guys suggested since it seems to be fairly cheap. Could i just bolt up a set of gt-40 heads on stock injectors, or would i need a tune and everything else?
Hurst, thank you for taking some time and giving me a basic run down.