This is an
introduction to the first steps to take for increasing your 5.0L
Mustang’s performance. Although this article is built around the
fuel-injected 5.0 liter Mustang most of what’s here applies to other
Mustangs and many other cars.
Read all you
can before you dive in. If you ask 50 people their opinions on what you
should do you’ll get 50 different answers! There’s lots of information
on the web and in Mustang magazines. Note that these specialty
performance car magazines are not only there to help you enjoy the
potential of your car more, but to sell their advertisers' parts. Look
at the return on your investment before buying. Lots of parts suppliers
are on the Web.
like most people you’ll want to jump in first with straight-line
performance enhancements. If you do then later you’ll discover the
weaknesses in the other areas of your car.
This is a
balanced approach, not just looking for the best quarter mile times,
but a car that can turn and slow down too.
be necessary to rob a bank to afford these enhancements.
streetable, reliable, legal car.
meant to be all-inclusive on how to buy a particular part, or even why
you should do this instead of something else. It’s just meant to give
you an idea of where to start researching.
If you want
to accelerate hard or corner hard the Fox bodied chassis needs to have
the flex taken out. If you have a convertible you should do this now
whether you make any other changes to your car or not. When you corner
hard and you car’s body flexes the tire contact patches change and your
alignment is thrown off.
Subframe connectors. This is the single
best thing you can do for you chassis. Get weld-on connectors, not
Strut tower brace. Get a three-point that
bolts to the firewall, also.
G Load or K member brace. For bettr turn-in.
together make a good basis for future modifications.
improvement you can afford to make is good. Most Fox bodied Mustangs
have inadequate brakes. They fade too quickly in performance driving
and lock up prematurely.
Cheap braking improvements:
your brake fluid. Put in a good quality
Put on new
brake lines. Stainless steel
if you want, but just new rubber ones will help.
the front Ford pads with something better.
the front calipers.
front wheel bearings while you're in
the rear drums to discs. This is
an expensive undertaking, but worthwhile for performance applications.
the front brakes. If you go to
the expense of putting discs in the rear think about upgrading the
fronts also. About 80% of your braking is done with the fronts.
Install a brake bias valve to allow manual adjusting of
the front-to-rear brake bias.
better master cylinder.
Running racing pads on the street. This is a quick way
to ruin your expensive rotors. And racing pads don't stop very well
when cold. You could be surprised some winter morning.
Hard pads have to heat up before working their best, but they don't
fade with repeated hard braking. Softer pads don't have to warm up much
and are best for street conditions. Investigate and find the proper
pads for your needs.
Straight line performance
makes power by pumping air. In general, the more air you can flow
through the more horsepower. At some point you may have to improve the
fuel and the ignition systems.
rule is cubic inches equals more HP so if your displacement stays the
same as you increase HP with modifications then something has to give.
Modifications to increase HP usually moves that horsepower higher up in
the RPM’s and you may be robbing torque. This is OK for the drag strip,
but not so good for the street or road course. You can fix this by
changing you rear gears to bring that power back down to where you want
on increasing the flow of your intake and exhaust before getting into
the engine. That is, look at the air intake, fuel intake and exhaust
before worrying about cams and new cylinder heads. I don’t cover
superchargers or nitrous because they can cause too much stress on an
engine if not done correctly. There’s a lot of reading you need to do
if you’re interested in one of these options.
More is not
always better. Increasing one part too much will create a bottleneck
elsewhere that can actually bog you down. Think of your engine as a
Once you go
over about 300 HP you need to upgrade your fuel delivery and spark.
Also, over 300 HP is where you’ll find other weak links like your
tranny, driveshaft and rear-end so this is where it starts getting
expensive as the stress levels on your engine increase.
Cheap horsepower gains:
Tune up – good quality plugs, wires, cap, rotor
Remove air silencer -- it's
under the air box in the wheel-well
K&N air filter
Advance timing – experiment to see how high you can
advance it and not have pinging.
Synthetic fluids. Not a lot of HP gains, but
definitely a good idea for you performance car’s longevity. Change the
motor oil, tranny and rear end to synthetics.
Underdrive pulleys. Slows down your
accessories, your alternator and A/C, that rob power. Warning: This may
slow down your alternator enough to where it discharges at idle.
(numerically higher) rear gear. 3.55 or
3.73’s are good all around gears.
Tuned cat-back exhaust. Just mufflers don’t make much
difference in HP.
H pipe and high flow cats.
Your state’s emissions laws determine what you can do.
Extrude Honed or new, and a bigger throttle body.
Stock TB is 60mm. Go to 65 for lightly modified cars. Then new cylinder
the Speed Density air intake to mass air metering. 1989-up ('88 for Calif.
Mustangs) came with MAF. This probably only needs to be done for more
highly modified cars, especially when increasing the air flow with a
better intake, heads or cam. Even then, in many cases, Speed Density
can work OK if you have a custom computer chip made for your
modifications, but then if you change your car you may need to
re-program the chip.
Too big of anything. Too big of a throttle body
or carburetor, too large diameter of headers, etc.
Ram air using hot under the hood air – cold air
is denser therefore better. Draw the air from outside. Warning: Drawing
air from under the car is a good way to suck up water, road kill, etc.
octane than you need can
actually rob power and will at least waste money.
Colder plugs – Maybe for the race track only
lot of money into fuel flow (fuel pump,
injectors) and after-market ignition on a
nearly stock engine.
Computer Chips - Putting a chip on a stock or
nearly stock engine is a waste of money. You can advance your timing
yourself! Once you go into fairly heavy modifications then it's time to
think about having a custom chip made to fit your particular engine,
especially if you're experiencing drivability problems. Don't bother
with an off-the-shelf chip on a stock engine -- put the money into
So how much horsepower do you gain?
Part vendors make unsubstantiated claims. Other
improvements move the horsepower way up in the rpm's so the car may
actually feel slower around town. And since your engine is a system you
may not realize the full potential of a particular upgrade until you do
something else. All that said, here's a shot at estimates of horsepower
increases for some popular modifications:
pulleys -- 5 to 10 hp
exhaust -- 10 hp
air filter and remove air silencer-- 5 hp
body -- 5 to 10 hp
manifold -- 15 hp
forget about gears. No HP increase, of course, but the most performance
"streetable" really comes into play with getting the right compromise
between corning ability and a decent street ride. It’s easy to make the
car ride so hard you actually lessen your car’s ability to handle on
the street as every little imperfection in a corner sends the car
skittering off in the wrong direction.
alignment. Get rid of the
factory spec positive camber (causes understeer). Go for minimal toe
in. Find a good alignment shop. Try –.5 to -2 deg camber, 1//16th
Stiffer bushings at front sway bar, lower control arms
and steering rack. These will be noisier than the stock rubber bushings
(the newer polygraphite bushings don't squeak). If you have a higher
mileage car just replacing these with new rubber ones would be helpful.
Lowering springs and new struts
and shocks. This is a package. Do
it all together. You probably shouldn’t lower more than an
inch-and-a-half if you use your car on the street. Don’t get springs
that are too stiff. Progressive rate springs are best to retain a good
ride; linear rate will provide sharper turn in on the track.
Camber plates to fine-tune the alignment on a
Aluminum steering rack bushings help control bump-steer,
especially on a pre-90 lowered car. These later cars have redesigned
tie rods that take care of this problem.
Stronger control arms
for better rear end bite when accelerating from a stop or out of a turn.
Tires. If you want lower profile or wider tires
get bigger wheels fitted with tires of the same circumference (called
Lowering the car too much. Gets into other
problems with your suspension. Puts too much stress on the wrong parts
of the chassis; can’t get a good alignment. There’s ways to fix this,
but it’s expensive.
Too stiff springs
Cutting the stock springs. OK if you're doing it just for looks, but this
doesn't work if you are interested in performance.
old struts and shocks
when putting in new lowering springs. Likewise, putting expensive Konis
in with high mileage springs.
sticky tires with an otherwise old, stock
suspension. It looks good, but it’s a waste of money performance-wise
on a soft suspension.
you have a mostly stock 5.0L Fox bodied Mustang with a few miles on it
and you want to enhance the performance, but you’re not quite sure
where you will end up. This is a pretty typical starting point. So what
do you do first?
First step recommendations:
Tune up. Plugs, wires, cap, rotor as needed.
Clean injectors if it hasn’t been done in over
Change to synthetic fluids.
air silencer and put in a
K&N-type air filter.
New brake lines, fluid
and better fade resistant front pads.
If you were
to have a shop do all of the above for you it would be about $800.
Second step recommendations:
the chassis stiffening with a strut tower brace
and G Load brace.
straight line performance:
Exhaust headers and a cat-back tuned exhaust system
looking at about $2000 for all of these.
When you get
into moderate improvements unless you know what you're doing think
about buying a package whether it's a complete disc brake conversion or
a suspension package. As I said before your engine, brakes and
suspension can be thought of as a complete system. Changes to one part
may cause problems elsewhere. If you go with a reputable company that
has maybe engineered and at least tested all the components together
you may have fewer problems then if you do things piecemeal. The
disadvantage is a larger outlay of money at one time.
Do Your Homework!
Have a plan
if you go beyond the simple, basic changes. Where do you want to end
up? Are you modifying for street use, drag racing, autocross, or open
track? How important is a street drivable car? There will always be
someone faster than you at the track, but they may not be able to drive
their car on the street. If you commute 40 miles on the freeway
everyday you may not want the 4.11 gears and the loud exhaust. If air
conditioning is a necessity and you sit in stop-and-go traffic a lot
then the cam and underdrive pulleys may be a bad idea.
modifications have a trade-off. You have to be aware of what they are
so you can make an informed decision as to what's worth doing for your
needs. There's a reason the Ford engineers built the car with the parts
they did. Often it's just a matter of money, but their decisions may
also be based on reliability and NVH (noise, vibration, harshness).
The Corral: Late model Mustangs web
Muscle Mustangs and Fast
Mustang Works online magazine