I found this for people that has a supercharged 5.0 mustang

This is a few tips and tricks for supercharged 5.0 mustangs. It will answer ALOT of questions. It may take a while to read, but it helped me hope it helps you ENJOY!!!!

O.K., you've made the plunge, spent the hard-earned bucks and are now the proud owner of a supercharged 5.0 Mustang. Congratulations and welcome to the club! Now the real work begins. No, not the installation, as most superchargers are straightforward and their manufacturers have usually spent considerable time working up a good set of instructions. No, I mean the care and feeding of your new huffer. If there was ever a time to get real adept at tweakin' your fuel-injected engine, its electronics, and everything that makes it tick, your time has now come!

While running any naturally aspirated performance vehicle is certainly challenging, a blown application can make even the most knowledgeable of us (of which I am not one) weak in the knees. Though tech magazines write numerous articles on supercharging, I have found that this info seems to focus more on new products and considerably faster Mustangs than myGT. What I needed was more info on the "little things." You know-- how your boosted performance is affected by everyday driving situations, not just banzai, power-crunchin' blasts down the 1320. And how to read my sensor outputs like I did my spark plugs when I was running a Holley double-pumper. I wanted to know how to get the most out of my supercharger on the street, and how to troubleshoot the little irritations that seemed to crop up when you drive your Mustang to work and back every day. I generally stayed away from recommending bolt-ons like throttlebodies, headers, etc. So, here we go with some tips and hints gleaned from racing, reading, driving, beating and just plain living with my 8# Vortech blower over the last three years.

Now the usual qualification... Keep in mind that these tuning tips worked for me. Each engine has its own unique operating characteristics. Some things work and some things don't. You be the judge. And for those of you who know what you're doing, great. You probably don't need to read any further--But, for those who have wrestled with a problem with your blower into the wee hours of Monday morning, read on...

Tip 1: Know thy engine. Get the manual by Charles O. Probst on Ford Fuel Injection & Electronic Engine Control, and read it cover to cover. There's no substitute for knowledge these days. Even if you think you are pretty good with a wrench--check it out!! Many advertisers in our national Mustang publications carry this manual for around thirty bucks. [Note: I am assuming here that you can interpret your diagnostic engine codes when they occur. If not, you really need to read this manual.]

Tip 2: Fuel and Boost gauges--get em!! I tried to go too long without really knowing what my fuel or boost pressures were. Not swift! The gauges will really help you at some point. Trust me on this one.

Tip 3: Run a Fuel Management Unit (FMU) (also called a boost-indexed fuel regulator). I know some people say, "you can run without one--just go with larger injectors." Yes, you can do that. But, remember, I am talking about running (and idling) your supercharged engine in rush hour traffic, not the racetrack. Lots of manufacturers' reseach and development bucks don't often go wrong. You need fuel when you go into boost, and lots of it. Stick with the FMU.

Tip 4: You never have enough fuel. Can you spell D-E-T-O-N-A-T-I-O-N, boys and girls? I don't need to tell you what uncontrolled combustion can do to your head gaskets, pistons and engine, do I? With a supercharger, err on the side of too much fuel. Actually, detonation can be caused by a whole slew of reasons including ignition timing (too much, wrong curve, etc.), combustion chamber problems, spark plugs, compression, ad nauseum. It would be nice if we all had access to an air/fuel monitor like a "pocket Horiba," but how many of us can afford a quick eight grand off the top?

Tip 5: Match your Mass Air Flow Sensor (MAF) to your injectors. (See Tip 6.) Assuming you have mass air (as opposed to the speed density system used in 1987-88 (California - 1987 only), make sure that whatever Mass Air Flow sensor you do use matches your fuel injectors. Otherwise, idling and full throttle will leave you less than impressed in a hurry. I have had luck with sensors which are calibrated by either an air sampling tube (C&L, Vortech) or electronically (ProFlow). Also, remember that the stock MAF is only 55 MM. A switch to a 73 or 75 MM will generally give you an extra pound of boost--not bad.

Tip 6: Make sure you are using the right fuel injector. I could write a volume here. There are formulas for determining proper fuel usage, and any number of opinions to help you interpret your answers. The equations look at such things as your Mustang's weight, your fuel consumption (called brake-specific fuel consumption or BFSC), fuel pump capacity, etc., etc. Putting a larger fuel injector on your Mustang won't necessarily make it run quicker. Rule of thumb seems to be that if you are running anything higher than 7-8 lbs. of boost and have bolted on a few extras like intake manifold, headers, etc., you better be thinking about moving up to a 24 lb injector (or a 30 lb injector if you also have a good set of heads). Some people suggest going even higher, like 36 and up. I
suggest you really check things out before making the leap to larger injectors. Your stock 19 pounders do seem to work in many cases, especially when you are running just a supercharger, 5-6 lbs of boost, and no extra engine goodies.

Tip 7: Make sure your exhaust is breathing as good as you are: No time to skimp on a restricted exhaust system. Your supercharger flows a lot of air and it all has to go somewhere! Make sure you have a good 2 1/2 exhaust system. Otherwise, you will be losing lots of ponies between Point A and Point B. Ever tried running a 200-meter sprint with an apple in your mouth?

Tip 8: Make sure your FMU has an unrestricted flow of boost pressure: This one really stumped me early on. I was experiencing detonation in third or fourth gear during a long RPM blitz. I suspected fuel delivery, not spark, but everything checked out. Eventually, I found I had routed the boost-vacuum line to both my compressor by-pass valve (you do have a by-pass valve, don't you?) as well as my FMU per the original installation instructions. Not that this is wrong; but, in my case I did not get enough response from my FMU. I decided to run a 3/8 "fuel" line ( instead of the original line) to the top of my FMU. I also changed the 90-degree boost fitting on top of the FMU (which connects to the 3/8 line) from the original 1/8 inch inlet fitting to a barbed 1/4 inlet fitting. My FMU is much more responsive as I spool up. (Oh, almost forgot. I used a dedicated line to my by-pass valve too.)

Tip 9: On the subject of gas and fuel filters: Good gas always helps. Simply put, octane and blowers go hand in hand. Make sure you fill up with at least 92/93 or higher. Your ignition retard, if your kit came with one (and many do), cannot make up for excessive cylinder pressures if you skimp on the octane. AND, be sure to change your fuel filter at least twice a year!!

Tip 10: Run a colder spark plug: Fuel injected cars, blown or not, seem to tolerate colder plugs than do carbureted cars. A colder plug helps stave off detonation by running just a tad cooler. The result may not be all that noticeable, but its the little things which add up. Also, gap `em anywhere from .035 to .045. With your cylinder pressures up under boost, the spark needs a little help in jumpin' the gap. I have had varying degrees of success by staying within those numbers. If you use a larger gap, like your stock .052-.056, you may find your engine cutting out at higher rpm's as if it just had its fuel line cut. (Actually, if your engine does cut out momentarily, your boost pressure probably just blew out your spark just like you do to your birthday cake.)

Tip 11: Get rid of the heat! This one isn't so much a tip as a comment. Boost pressures create heat--lots of it. Do everything you can to eliminate heat. Try three and four-core radiators, 180-degree thermostats (160 is usually too low), and special service cooling fans like the fan pictured in one of the other tech articles in the CORRAL. Summers are hard on blowers because of the natural heat build-up in the discharge tube anyway as you make a few runs. Air is less dense and your air charge will heat up considerably more than in the winter months--no secret here. Short of an intercooler (big bucks), do what you can to reduce heat.

Tip 12: Make sure you have enough fuel pump, enough voltage to the pump and enough pump volume: Superchargers need plenty of fuel to run well, and to cool the combustion chamber; enough voltage (minimum 12 volts) to deliver a full shot; and enough volume to ensure your engine doesn't detonate and decide to go south on you permanently. Many will say that the bare minimum pump capacity is the 155-liter pump, and that you should run a 190, 200, or higher-rated pump. Again, it is better to err on the side of too much fuel rather than too little fuel.

Tip 13: Run "Loc Wire" head gaskets if you plan to boost it past 8 lbs: Like all tips, this one is optional. Of course, the wisdom of this will usually come home only after you decide to try a smaller supercharger pulley in hopes of getting a little more boost out of your blower. Actually, I have always felt that the head gasket is cheap insurance. I don't use Loc Wires--just a good quality gasket like FelPro Blue. In spite of the teardown time, I would still rather blow a head gasket than to blow a hole in one of my pistons! With higher than 8#, I would definitely "Loc Wire" my heads.

Tip 14: Run an ignition timing retard: This is another one where the reseach and development guys know more than most of us do. Most kits come with some sort of ignition retard. Use it. Under supercharged boost, your stock combustion chamber pressures act much like an engine with higher compression. This results in a quicker burn rate. You generally need less ignition advance as you get into boost, not more. And if you have a manual boost retard system (like the MSD), and decide to experiment with the boost retard dial, remember that your engine may detonate before you actually hear it. So, dial it down cautiously.

Tip 14 1/2: Run a high energy ignition: If your kit does not come with this item, get it. Some good ones exist on the market. I use a MSD 6A. You need a strong spark since cylinder pressures are greater. Just make sure you check out your distributor cap and rotor frequently. A high energy ignition is tough on them.

Tip 15: Common sense is good enough for up to 8 lbs of boost. After 8 lbs, things get a little dicey unless you really know what you are doing: This one is simple. You are playing the odds when you go past 8 lbs. of supercharger. What I mean is that beyond 8 lbs of boost, your Mustang is becoming tasked to the limit--beyond original factory high-performance specs (good as it is). Your "performance checklist" has just multiplied from ignition and fuel to a whole host of items including your trans, clutch, driveline, rearend, frame, AND ignition and fuel.

Tip 16: Belt Slippage? I do not have a 8-rib or 10-rib on my supercharger. But, according to my boost gauge, I do not really slip much as I am able to make my 7-8 lbs even under a heavy first-gear assault. I do change the belt and tighten it regularly though. I also use a little bottle of "Insta Boost" from McClure Motorsports which seems to work by making the belt more pliable and soft. I have not experienced any premature belt failures. At least that's my story with the belt issue.

Tip 17: Oil Fill Vent Tube Routing: This one is more subtle. Vortech routed the hose, which originally ran to the throttle body from the oil filler vent tube, to the air filter fitting as provided in the installation kit. I always felt that the oil filler venting should stay between the MAF and the supercharger intake instead, as the system is a closed PCV system. (I do not have a oil filter on my oil filler tube either although I know racers who feel this is O.K.) So, I have routed the oil filler vent tube line to my blower's intake inlet elbow. Seems my engine idles smoother with this mod. I have since found as many people (including Saleen) who do the same--decide for yourself.

Tip 18: The pros and cons of blowers: Superchargers, while expensive, make a lot of horses for relatively little wrenchin' time. There are many good ones on the market today, thanks to the 5.0's popularity. Blowers are pricey to a degree, but hey, what price speed, huh? It would take quite a few bucks (other than squeeze) to duplicate your horsepower level otherwise. Blowers do seem to stress my driveline harder because of the pulleys, on-off boost, etc. On the other hand, it's easy to attract admiring attention when you pop your hood. My list could go on and on, but I can sum up everything by saying that If I had it to do all over again, I would.:nice: :Track:


Founding Member
Jan 20, 2000
Detroit, MI
Decent article that covers the basics, however I don't agree with the stock injector and FMU theory. My 95, stock engine and a ProCharger running 7-8 psi, had the stock 19#er's maxed. As for the FMU, you can get by with one but ideally a bigger set of squirters and a good dyno tune will be better.
Decent article that covers the basics, however I don't agree with the stock injector and FMU theory. My 95, stock engine and a ProCharger running 7-8 psi, had the stock 19#er's maxed. As for the FMU, you can get by with one but ideally a bigger set of squirters and a good dyno tune will be better.

yeah I agree. I have a set of 42s and a 80 mm MAF on the way and then a tune, BUT for the people out there that doesnt have the money to do that then the FMU is the way to go