Q: Which is the best supercharger for the Ford 5.4L truck?
Q: What supercharger do you recommend for the 4.6L 2V Thunderbird?
Q: I just bought a used Kenne Bell but it is missing some parts.
Where can I get Kenne Bell parts?
Q: What is the best supercharger kit for the 4.0L Explorer/Ranger?
Q: Which is more important, horsepower or torque?
Q: Why do you prefer positive displacement blowers so much?
Q: What is an FMU?
Q: What is more efficient, a supercharger or a turbocharger?
Q: Why is inter cooling such a good thing?
Q: How much power could I expect to gain with a turbocharger or supercharger?
Q: How much engine life can I expect to loose when I
Q: How much fuel economy can I expect to loose when I
Q: I have a blower from a Super Coupe. Can I bolt it on my engine?
Q: I have a supercharged or turbo charged engine and it
have a problem with detonation (ping) under boost. What is the best
way to handle it?
Q: Which is the best supercharger for the
Ford 5.4L truck?
A: Fortunately there are 3 very good positive displacement
systems out there. The most expensive is the Holley Thunder kit. It uses a Holley Roots
style blower and a water-to-air inter cooler. The kit sells for
just under $6,000 I heard. A guy installed one last fall and emailed
me. He was quite happy with it. Holley bought the supercharger
line from B&M Racing a few years back. B&M had been building
these blowers since about 1980. See the Thunder kit at:
My personal choice would be the Magnuson kit (sold through Magnacharger http://www.magnacharger.com/). It uses
the proven Eaton Roots style supercharger and is also water-to-air inter
cooled and bypass valve. It has a superior intake manifold design
as well. It sells for $3845. It looks identical to the Allen
superchargers of which I have completed 2 installs last year. I
was very impressed with the Allen kit. http://www.magnacharger.com/ford_5_4.htm
The other system is made by Kenne Bell.
This uses a Lysholm (or screw) type supercharger. These blowers
are actually more efficient than a Roots. It is not inter cooled
and does not include a bypass valve. I have installed many KB kits.
They are much better than any centrifugal but not quite the quality of
an Eaton blower. KB kits usually run about $3500.
Q: What supercharger do you recommend for the
4.6L 2V Thunderbird?
A: The AED kit is by far the best choice for your
car, hands down. The Allen kit uses the best quality (Eaton) blower,
comes with a bypass valve, fuel pump, and inter cooler, and has a superior
intake manifold design. The Allen comes complete with everything
you need, no custom fab work required. It is also the recommended
kit of the National Thunderbird club. The Allen uses the same blower
you had on your Super coupe and it has the same boost characteristics.
I would definitely recommend you go that route. It is well worth
Installation of the Allen kit is time consuming. If you have done basic
wiring and mechanics repairs, you should be able to do it yourself. If you
don't want to tackle it, Allen installs them in California, I have friends
(professionals) who install them in Seattle and Eastern Washington, and of
course I install them here in central Illinois.
Q: I just bought a used Kenne Bell but it is
missing some parts. Where can I get Kenne Bell parts?
A: I have heard that Kenne Bell does not do
business with people who buy used kits. I have no idea why they are that way but
I have had several people tell me this. I don't know what KB's
problem is. You could ask on http://www.kenne-bell.com/ . eBay is another possible source. Good
Q: What is the best supercharger kit for the
A: The only positive displacement kit I know of
is the BBK. Explorer Express
sells that same kit. These kits use the Eaton Roots blower for instant
boost across the entire rpm range. I have not yet installed one of these
kits but they appear to be a solid design.
Q: Which is more important, horsepower or
A: Horsepower is a rate based measure of an
engines ability to do work. In order to accelerate a given mass from 0 to
60 mph for instance, a certain amount of horsepower is needed. Torque, on
the other hand, is merely a force. Torque can exist with no motion.
Therefore a torque rating really does not tell you much without an RPM that the
torque was measured at. If you have torque and RPM, you can calculate
horsepower HP=(torque ft*lbs x RPM)/5252. So you may wonder why people get
so hung up on torque. Well, given a peak torque and RPM, and the peak HP
rating, you can tell some characteristics of the engine performance you won't
get with just HP. If you have an engine with a peak torque above the peak
HP, you have an engine that does not care to rev but instead has good power at
low engine RPM. If you have an engine with torque (ft*lbs) and HP ratings
about the same, it is a typical automotive engine. If you have an engine
with high HP ratings and low torque ratings you have an engine that has poor
power down low but can rev very high. Bottom line however, any performance
estimates will require the HP, not the torque. More important yet is what
is often called "power under the curve". This is the area under the power
curve throughout a given rpm band. Best case would be to have the most
area under the curve to provide the best acceleration.
Q: Why do you prefer positive displacement
blowers so much?
A: When was the last time you saw a professional
race team use a centrifugal blower? How about a new vehicle
manufacturer? Sure, if you look real hard, you can find a few instances
here and there but they are very rare. Why do you suppose that is?
While centrifugal superchargers will give you the peak HP numbers you are
looking for on the dyno, it is only the peak that you really get. A
typical 6psi to 9psi kit will not give you any real boost until about 3000RPM.
Q: What is an FMU?
A: An Fuel Management Unit (FMU) is a special
rising rate fuel pressure regulator placed in the fuel return line of the fuel
injection system. This is a very common approach to handling the increased
fuel demand required by supercharger kits. It does work. It will
make the injectors flow more fuel than their rating. These are used in
addition to the factory fuel pressure regulator and only have an affect under
boost. They are rated by the ratio of fuel pressure to boost
pressure. For instance, a 10:1 FMU will give you 100psi fuel pressure at
10 psi boost pressure. The problem here is that the extra pressure on the
fuel pump decreases the flow capacity of the pump. That is the last thing
you need on a supercharged engine. You can offset that by installing an
in-line fuel pump in addition to the in-tank pump.
Q: What is more efficient, a supercharger or
A: Turbochargers have an adiabatic efficiency in
the range of 70% to 80%. Centrifugal superchargers are usually closer
to 70%. The Eaton Roots blower is typically 60% and the screw type
blower (Whipple or Kenne Bell) can be as high as 75%. Conventional
Roots blowers, like the GM 6-71, is about 40% to 50% efficient.
What does this mean? The lower the adiabatic efficiency, the more
heating of the discharge air you will get. That means less density,
less power, more detonation problems. An inter cooler can pull the
heat back out but there is a price for that too. Now if you want
to look at total efficiency of the system, the turbo wins. It will
give you the highest power gain potential of any forced induction system.
Notice that the Pro-Mod 5.0 class now uses more turbochargers than anything
else. If you really want peak power, get a turbo and inter cool
it. I still like the Roots or Screw blower for many street applications
since there is no lag or cut-in speed to worry about (although my daily
driver is turbo charged). Most centrifugal blowers will have
an even higher cut-in speed than most turbo's and will not offer anywhere
near the mid-range power gains of either a turbo or a roots or screw blower.
Superchargers all draw power from the crankshaft where turbochargers draw the
power from the exhaust flow and heat. Both rob power but much of the power
the turbocharger uses would otherwise be wasted out the exhaust. The
turbocharger is also more efficient at applying the power to the
compressor. Overall, the turbocharger is the most efficient method of
Q: Why is inter cooling such a good thing?
A: Anytime you compress air, it heats up.
Even at 100% adiabatic efficiency (which is impossible), the air will heat up
quite a bit. The inefficiency of the compressor (turbocharger or
supercharger) will heat the air up even more. As the air is heated, the
density of the air drops. Engine power is a function of the amount of air,
and fuel, you can get into the cylinder during the intake stroke. It is
not really the volume of air but rather the mass of air that is the key.
As the air is heated and the density drops, the same volume will supply less air
mass to the cylinder. The key is to not only compress the air, but to cool
it back down as well to achieve the maximum mass of air, and therefore maximum
In addition to this, the hotter the inlet air, the more tendency the engine
will have towards detonation and pre-ignition (spark-knock, ping). These
are very damaging to the engine and they rob power.
Q: How much power could I expect to gain
with a turbocharger or supercharger?
A: Roughly, you can expect to gain about the same
power difference percentage as you gain induction pressure percentage.
The equation is HPafter = ((14.7 + boost)/14.7)*HPbefore. For instance,
if you have a 200HP engine and you add 7.5psi boost, you can expect to
have about 300HP. This is an estimate, not an exact calculation
so take it for what it is worth. In reality, it will likely be just
a bit less than that due to inefficiencies and air density losses due
to heating. If you are inter cooled, you will get closer to this
Q: How much engine life can I expect to
loose when I supercharge/turbo charge?
A: You should not loose much at all as long
as you properly maintain the engine. The amount of time you will
be in boost on a daily driver will be very small in most cases.
Even on cars that have small turbo charged/supercharged engines, the engines
generally last quite long these days. Engine technology and engine
oil has significantly improved over the years. Fuel injection has
also made a big difference. Most modern engines should last 250k
miles or so. I would recommend Mobil One engine oil with oil changes
every 10k miles. I had a 1985 Thunderbird Turbo Coupe with the boost
set at 17psi. I ran the car very hard. The car was totaled
in an accident at 177k miles but it never used any oil in it's life.
It ran like new to the end. This was not an isolated case.
I have seen many of those cars last over 200k miles with the original
engine and turbo.
Q: How much fuel economy can I expect to
loose when I supercharge/turbo charge?
A: You may loose about 5% or so for a good
system. The amount of time you will be in boost on a daily driver
will be very small in most cases. A good design with a bypass valve (for
superchargers) will draw about 1/3HP on Eaton supercharger based kits under
normal driving conditions. Most other types will still be under 1HP under
most driving conditions when not in boost. If you drive with your foot
buried in the throttle all the time you can loose quite a bit of fuel
economy. Most people will not loose much at all.
Q: I have a blower from a Super Coupe.
Can I bolt it on my engine?
A: The Super Coupe used the Eaton M90 blower.
While this blower is the proper size for 3.0L to 5.0L engines, the installation
parts for the Super Coupe will not fit on other engines. You would
need to develop and build your own mounting, ducting, and blower drive
to make it work. It can certainly be done, and has been done many
times, but this is a completely custom thing. You had better know
what you are doing. Even the Eaton based kits for other applications
(BBK, Allen, SVO) use different drive arrangements. The Super Coupe
blower will not fit any of those I know of either. I have not heard
of anyone offering the kit parts to make a Super Coupe blower fit any
other applications. Magnuson has more information about
Eaton blowers and kits available on their web site. They also sell
Eaton blowers for custom applications.
Q: I have a supercharged or turbo charged
engine and it have a problem with detonation (ping) under boost. What
is the best way to handle it?
A: First of all, always use the best premium fuel
you can buy in any forced induction engine, and make sure the engine has plenty
of it. The few pennies you save buying regular are not even worth
it. In order to allow your forced induction engine to run on regular, you
must remove so much timing you loose more fuel economy than you ever gain in
savings from cheaper fuel. Besides, if you are that interested in fuel
economy you should be driving some econobox anyway. If you are running
high compression (relatively speaking, like over 10:1) you may want consider
using octane booster along with premium in every tank. The air fuel ratio
should be around 11.5:1 to 12:1 under boost. Make sure your fuel system
will support this.
If you have a distributor type ignition system, the MSD Boost Timing Master if my personal
favorite. This comes in 2 forms, one is a complete MSD module with boost
retard (about $350), and the other is just a boost retard (about $170, MSD part
number 5462). Both have a remote control knob that you mount in the
drivers compartment. The knob allows you to adjust retard relative to
boost pressure, up to 3 degrees per psi. I would not recommend using it
for more than about 1 degree per psi however or you will loose power. Crane sells a similar device (called TRC)
that is very easy to install of TFI Fords and other makes. It connects
into the connector where the timing check plug plugs in and has the driver
compartment adjuster knob like the MSD unit. The nice thing about it is if
it fails, you can just pop the timing plug back in and drive off. It can
be configured to control boost like the MSD unit if you buy the optional
pressure sensor. It can also be configured to be a base timing adjustment,
or to have a step adjustment in timing (great for nitrous). These systems
let you keep your normal timing strategy when not in boost.
Timing control can also be done through software (chips or flash
programming). Some aftermarket engine controls (like the Extreme Performance Engine
Computer that SVO sold) can also connect to a boost pressure sensor and
retard timing based on boost pressure. Some more advanced ignition systems
can even be set up to use a knock sensor. I would caution you on the use
of a knock sensor however. While this sounds like the ultimate way to go,
it has drawbacks. First of all, they can be very tricky to set up so they
don't retard timing when there are other noises present. Even if you get
past that issue, the strategy is a matter of trade-offs. If you always
start off with advanced timing and let the detonation (knock) sensor sense the
ping and back the timing down, you are letting it ping too often. If you
take the knock information to develop maps so you don't let it ping again, then
you could be retarding the timing too much and loosing power if noise enters the
picture. A knock sensor is best used to develop optimum timing
curves. It can be used to help prevent engine destruction in continuous
use as well but it is tricky to really optimize it.
Inter cooling is always a good idea with forced induction and it will reduce
detonation as well. Lower compression ratios will not ping near
as bad either. Combustion chamber design play a big role in detonation
too. High squish or high swirl chambers will reduce detonation.
Some modern engines with advanced chamber designs can run 10:1 compression
and 15psi boost on pump premium fuel. Camshaft design also plays