I've got a 91 351W with exhaust mods, but the rest of it is stock and I want to pull some more power out of it. I've read about mass air and I just think it may be a bit "extravagant" for me right now. I know I can do a SD cam and air intake, but what else will my computer accept, intake manifold, pistons, roller rockers, anything else? What's the biggest SD cam out there? I've heard some people say you can put cylinder heads in an SD engine and others who say you can't, so...?

Thanks.

 

Heads, cam and exhaust will work on the SD system but the motor won't make quite as much power as it would with a tunable PCM driving it. Technically all Ford PCMs are tunable but in reality only a small selection have been "decoded" to work with the available tuning systems. A Gen1 Lightning SD computer is on that list so you can get some of the benefits without a full MAF conversion, but you could also use a MAF 5.0/E4OD computer for example because once a tuner module is plugged in it doesn't matter what motor the box was originally programmed to run.. you can change all that.

 

So really it's just better to spend a bit more and go for a mass air conversion, I've gotta get a computer and a wiring harness, anything else?

 

You will also need the actual MAF meter, and any ductwork that goes with it.

 

So, that's in the air intake right?

 

It's likely that you can keep speed density with a SD friendly cam and CIA. You may need to install an adjustable fuel pressure regulator to make up for the fueling needed at WOT though. You shouldn't need a mass air swap unless you experiencing a tip-in-lean condition and/or the fuel pressure regulator can't suffice for the added fuel that is needed.

 

The air intake ductwork I refer to are the big rubber tubes that run from the throttle body to the MAF sensor. Since you're now metering the air right at the air cleaner box, you don't want to lose or gain any air as it flows into the engine. The tubes made for MAF engines will obviously be shorter than those made for SD engines.

 

There are some SD systems that can be tuned, I don't know much about them. But this means you can change things like the injectors and then make the proper tune changes.

That being said, the community tuning with MASS Air is much larger and you'll have more support, which is good when making these types of changes. My suggestion would be the MASS Air conversion. Read my post here - https://www.ford-trucks.com/forums/1...l#post12924071

The conversion isn't that hard, I have two harnesses on my workbench that I converted and will install. You can also do the conversion w/o removing the wiring harness.

 

How do I keep the harness?

 

In looking at your signature, I see you have an E40D. If you convert to MASS Air, you'll need to first decide how to address this. You can either get a MASS Air computer that can control the transmission or you'll need to get an aftermarket solution.

First option doesn't cost any extra money for that type of computer, but less people use that type. There may be some questions that you have trouble answering but it's sure possible, a friend of mine does it this way. Would also need to verify what tuner supports this. Makes the MASS Air conversion easy.

Second option is more expensive but will give you as much control as possible with your trans (shift points, line pressure, etc). Also means you can get one of the most widely used MASS Air computers used, which is good when needing help. A little more involved for the MASS Air conversion.

If you still want to proceed, the wiring you'll need to do depends on the option.