What many car enthusiasts don't
know, or simply overlook, is that you can get more performance out of the power
you already have.
Many car enthusiasts believe that the path to better performance is through
engine modifications. The problem is that engine modifications often don't work
out exactly as you hope. Modifying a daily driver's engine can be tricky business,
sacrificing one benefit in favor of another: low-end torque for top-end horsepower,
fuel economy for acceleration, or even worse, reliability for that newfound
performance.
What many car enthusiasts don't know, or simply overlook, is that you can get more performance out of the power you already have. Power (more accurately, torque) is never delivered directly from the flywheel to the pavement, without first being multiplied by gear ratios in the transmission and differential. The math is pretty simple: A car with a 4.0:1 gear ratio puts 33% more torque to the wheels than a car with a 3.0:1 gear ratio with no increase in engine torque.
However, changing gear ratios is another one of those compromises. Driveablity is adversely affected because the engine revs higher at all speeds, uses more fuel and simply wears itself out faster. Bottom line: Gears will help your car accelerate quicker-you'll just hate the added rpm if you drive your vehicle any distance.Top
Torque
Multiplier
If your car has an automatic transmission, it has an additional torque "multiplier"
above and beyond the trans and differential gears. This unit is called the torque
converter-a fluid coupling that disengages the engine from the transmission
at idle so that you can pull to a stop or shift gears without stalling the engine.
The torque converter is actually a misnomer-it should be called the "torque
multiplier" because it doesn't simply provide a one-to-one connection to
the transmission like a clutch does with a manual transmission.
A torque converter will actually double engine torque on takeoff. This torque-multiplication factor remains in effect until the vehicle speed catches up with engine speed. A purpose-built high-performance torque converter can multiply torque even more, up to 2.5 times. OEM torque converters can vary greatly in the amount of torque multiplication and stall speed. Replacing your stock torque converter with a high-performance torque converter can decrease 1/4-mile times by .4 to .5-seconds with no other changes. Installing a high-performance torque converter should be the first step in any performance upgrade program.
Today's new cars have some very efficient torque converters, but they lack the necessary stall speeds for optimal performance.
Torque multiplication is just one important parameter for selecting a torque converter. Stall speed-the speed at which the converter slips under full throttle, full-load operation-is important as well. Early race/street type converters focused solely on stall speed. As long as the converter slipped enough to get the engine into the torque peak, it was considered a success. Not very efficient, but it worked. Today's new cars have some very efficient torque converters, but they lack the necessary stall speeds for optimal performance.Top
Custom
Converters
That's where custom torque converter manufacturers like Pro Torque come in.
They analyze your vehicle-items such as horsepower, torque, weight, transmission
type, gear ratio and tire size-and then design a custom torque converter specifically
for your vehicle. Pro Torque custom machines the internal components to provide
the correct stall speed (slip), and the company also modifies the unit for increased
durability by furnace-brazing the impeller and turbine vanes in place in addition
to installing a larger ceramic-impregnated lock-up clutch.
Typically, Pro Torque builds torque converters with stall speeds of 2,400-2,800 rpm versus OE factory stall speeds of 1,300-1,700 rpm.
What's the down side of installing a high-performance torque converter? With today's lock-up overdrive transmissions, the answer is not much. Typically, Pro Torque builds torque converters with stall speeds of 2,400-2,800 rpm versus OE factory stall speeds of 1,300-1,700 rpm. In normal driving conditions, you won't notice much difference; under heavier-throttle scenarios, you may notice that the engine revs a little quicker. But as soon as the vehicle hits the higher gears, the torque converter locks up and the engine and transmission become solidly coupled.Top
Real-World
Test
We found a perfect vehicle to do a Pro Torque custom torque converter installation.
Tommy Pierson, President of K&P Engineering in Irwindale, California (one
of the nation's oldest Go-Kart manufacturers), was tweaking and testing a 2000
supercharged Ford Lightning F-150 pickup truck. He'd installed the usual bolt-ons,
including an 80mm thottle body, a Swanson Performance engine management chip
and a set of 26x11.50-16 Mickey Thompson slicks. The sum of these changes had
reduced his 1/4-mile times from the low 14s to 13. 33 @ 102.5 mph. However,
the Lightning still felt lazy off the starting line. Pro Torque had just the
solution: a 10.5-inch diameter 2,400 rpm stall-speed lockup torque converter.
Tommy took his truck to a local transmission shop, where the stock torque converter was removed and the Pro Torque installed in approximately seven hours. (See step-by-step installation tips.) The results were pretty impressive. His 1/4-mile times dropped to 12.86 @ 104.6 mph with no other changes. That's a .47-second reduction in 1/4-mile performance. Tommy reports virtually no loss in driveability and the ability to smoke the rear tires at will.
A torque converter is something a well-equipped do-it-yourselfer can do if he has a transmission jack and the means to raise the vehicle up high enough to use it.
A torque converter is something a well-equipped do-it-yourselfer can do if he has a transmission jack and the means to raise the vehicle up high enough to use it. Most enthusiasts are better off having a local transmission shop do this heavy work. Tommy had San Dimas Auto Repair in San Dimas, California do the changeover that took approximately seven hours and cost $500.Top
What does "new technology" mean?
Torque converters have been around for over 50 years and converters continue
to evolve at the pace automobiles have. PROTORQUE utilizes only the latest technology
for both the core product and our modifications. Car manufacturers have spent
a lot of time and money in developing vehicles that meet today's CAFE standards.
One of the ways they have done this is through drive line advances, and the
torque converter is one of the key components in this development. Many of our
competitors use torque converters that were designed in the 70's; some even
use converters that were developed in the 60's.AtPROTORQUE, we use converters
that have been developed in the 90's; made to withstand the hi-tech, high horsepower
of today. These torque converters are far superior in design because they have
better torque multiplication rates and are more efficient. For example, the
torque converter we use for our 4L60/700R4 was originally designed to go behind
a 300hp late-model engine that is still in production today. The question you
have to ask yourself is: What torque converter do I want to use for my 1998
Corvette, or my 1992 Camaro or my brand new Dodge truck, or my high-dollar street
rod, or my hi-tech import? Certainly not a unit designed 30 years ago!Top
What is stall speed and how do I determine what stall
I have now?
Stall speed is a term used to describe the rpm at which the torque converter
transfers the power from the engine to the transmission. There are different
ways to test stall speed. "Foot brake stall" is when you press the
brake pedal and then press the gas pedal. When the car doesn't go anymore or
the tires start to spin that is "brake stall". (DO NOT TRY THIS! THIS
MEASUREMENT IS MEANINGLESS AND POTENTIALLY DANGEROUS TO YOU AND THE TORQUE CONVERTER!)
"Flash stall" is when you, from a dead stop, press the gas pedal to
wide open throttle (wot). Watch your tach needle, you will see the needle jump
to a certain rpm, that is "flash stall". A drag racing-style trans
brake will give you closer to the true stall speed of a torque converter. Top
What is torque multiplication?
Torque multiplication is a term used to describe the amount of torque the torque
converter will multiply. A torque converter is basically a fluid coupling between
your engine and transmission. There is no direct mechanical link until the torque
converter is in lockup mode. The pump assembly of the torque converter is directly
linked to the crankshaft of the engine, however the turbine assembly of the
torque converter is not. It is connected to the transmission input shaft. When
the oil is pumped to move the turbine it is actually pushing the turbine at
a higher rate. Each torque converter pump and design pushes the fluid differently,
therefore giving you different rates of turbine speed . All of this only means
that different torque converters will give you different torque multiplication
rates simply by design. Our goal is to design the best torque converter using
the highest multiplication rates for your application. Top
What does torque converter efficiency mean?
Once the torque converter does it's job multiplying torque for take off, the
function of the torque converter is to be a link (sometimes called a fluid coupling)from
the engine to the transmission. Keeping in mind that the pump assembly and the
turbine assembly spin at different speeds, every torque converter has a different
rate of slippage between the two. The amount of slippage is what determines
efficiency. This is why auto manufacturers created lockup torque converters.
Rather than having a torque converter that is let's say 92% efficient, they
mechanically link the engine to the transmission, giving it a 1:1 ratio or creating
100% efficiency. This lowers the rpm of the engine, therefore increasing fuel
efficiency. Top
Why do I need a higher stall speed converter?
Theoretically, for maximum acceleration the stall speed of the torque converter
should match the peak torque rpm of the engine. A good explanation for the way
it works is this: when you go outside jogging you start to breathe in and out
faster and harder. Well the same thing goes for a performance engine. The engine
is breathing in and out harder and faster, at a higher rpm. If a high performance
engine makes power at a higher rpm, then a higher stall speed torque converter
is what you need to put more power to the ground quicker. Top
Why is
a torque converter the best performance upgrade money can buy?
Theoretically, for maximum acceleration the stall speed of the torque converter
should match the peak torque rpm of the engine. A good explanation for the way
it works is this: when you go outside jogging you start to breathe in and out
faster and harder. Well the same thing goes for a performance engine. The engine
is breathing in and out harder and faster, at a higher rpm. If a high performance
engine makes power at a higher rpm, then a higher stall speed torque converter
is what you need to put more power to the ground quicker. Top
How do I determine the best converter for my vehicle?
This can sometimes be a difficult question to give a general answer to. In many
cases performance and driveability are somewhat of a trade off. Generally with
a higher stall speed you loose some of the driveability, and the driveability
increases with a lower stall speed. Our goal is to manufacture a torque converter
that will increase performance without sacrificing driveability. The most important
thing to keep in mind, when selecting a torque converter, is that you want to
match stall speed to the engine's powerband. Most cam manufacturers will give
you a minimum and maximum rpm range. This minimum rpm really should determine
what stall speed that you will need. Top
Why use a "Custom Built Torque Converter"?
You have your heart and soul into your car. You have spent countless hours planning
all the modifications. You have spent as much time making these modifications.
You have picked the best of everything. Are you going to call a company that
will sell you something off the shelf, because they have it stock, that only
kind-of fits your application? I don't think so! We put as much care and workmanship
into helping you decide what product you need as we do into developing the product
you put in your car. And if that product is something we haven't developed yet,
you can rest assure that we will take the time to develop a specific torque
converter for your application! Top
How do I make a final decision on a torque converter?
Use a company that offers you as much information as possible. Use a company
that offers you a warranty. Use a company that utilizes all the technology available
today. Use a company that will help you make a decision on what product that
you need for your vehicle. And most of all, use a company that you know is building
the best torque converter on the market today! Top
Are there any other upgrades that I should consider
when installing a new torque converter?
You might want to consider a performance tire upgrade such as a "drag radial"
tire. Traction will be your biggest problem. Take for example the testing we
did with our 1998 Corvette. After the torque converter swap, we couldn't believe
the amount of tire spin. By putting power to the wheels, at a higher rpm, you
begin to realize that a suspension upgrade might be a necessary upgrade as well.
The only other recommendation is, depending on the application, some performance
torque converters create more heat and long term heat kills transmission life.
A light bulb that burns twice as bright burns half as long. This is why we carry
a full line of "stacked plate" transmission coolers. Tests have shown
that these coolers can increase your cooling capacity by 100%.
Is installation of a performance torque converter difficult?
Again this can be a difficult question to give a generic answer to. In most
rear-wheel-drive cars installation is relatively simple for someone who has
some mechanical background and the proper tools. In cases such as the new C5
Corvette or a 4WD Eclipse Spyder installation is better left for a professional.
In depth installation tips follow and can be downloaded from this web site.
© 2002 PRO-TORQUE.COM All Rights Reserved.
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