"Dual Power Adders"

by

Kennedy's

Others talk about it or just think about it, but at Kennedy's we make dual power adder setups practical for the first time! We have the experience and equipment to add nitrous oxide to a supercharged vehicle and make it live. The key to our success with dual power adders is our experience and the use of the Dynojet chassis dyno. We strongly recommend Dynotuning to ensure safe and reliable use of dual power adders. And, of course, Dynotuning ensures maximum horsepower.

How does nitrous work
How a supercharger works
Why use dual power adders
How Kennedy's makes dual power adders practical
Camshaft selection for dual power adders
Engine control systems for dual power adders

How does nitrous work 

Nitrous oxide is an oxygen bearing compound. Nitrous oxide is injected into the combustion chambers of an internal combustion engine as a way to increase power output. The first extensive use was in the Second World War. Smokey Yunick rediscovered nitrous oxide injection in this country during the 1950s. NASCAR banned nitrous after they discovered Smokey was using it! In the late 1970s nitrous oxide began to be used by amateur drag racers and hot-rodders. Nitrous is a colorless, non-flammable gas. It has a slightly sweet taste and odor. It is non-toxic but if it is inhaled in a high concentration it causes asphyxiation and death. At high temperature though, above ~565F, nitrous oxide breaks down into nitrogen and oxygen. When injected into a running engine the oxygen is thus available to combine with added fuel and more power is produced.

Nitrous oxide has a number of operational and practical characteristics that make it impractical for continuous use. Perhaps the most obvious is that nitrous is relatively expensive. The current price is in the range of $4.00-$5.00 per pound. As a rule of thumb, it takes one pound of nitrous to make 100hp over ten seconds. This would make it impractical for continuous use. In addition, finding space for a bottle big enough to store the quantity of nitrous needed for continuous use would also be impractical. As a result of these factors and numerous others, nitrous is typically activated intermittently at full throttle when maximum power is desired.  

How a supercharger works 

A supercharger is the most versatile form of power adder. It can be thought of as an air compressor or fan that increases the amount of air that fills each cylinder during the intake stroke. Just as with nitrous, more air means more oxygen. With more oxygen filling each cylinder, more fuel may be added. When this fuel combines with the added oxygen, more power is the inevitable result. 

With a supercharger, the power is available "on-demand" at all times, unlike systems such as nitrous oxide. Under light load conditions when the supercharger is not making boost it takes only minimal power to spin the blower. As a result in normal driving gas mileage does NOT decrease significantly. This common myth is just that, a myth. In fact, some of our customers report a slight IMPROVEMENT in fuel economy under highway conditions after a blower installation. Most likely this is due to the careful tuning that we do for our own installations. 

Why use dual power adders

 As can be deduced from the above, a supercharger and nitrous are complementary systems. The supercharger is there at all times and adds no operational costs to using the vehicle other than additional fuel when operating at wide open throttle. If a nitrous system is added, even more power is available when it is needed at the track or to pass that pesky Viper or Porsche Turbo! 

The maximum horsepower available with either a separate nitrous or supercharger system is essentially the same. This theoretical limitation is a function of the octane of the fuel used and the mechanical strength of the basic engine components. A rule of thumb for small block type V8's is that stock parts will tolerate up to ~1.3-1.5hp/cubic inch while a motor built with premium components can be reliable with up to 2.0hp/ci or more. "Billet" race components are needed when the 2.5hp/ci threshold is approached. When considering these numbers, you must keep in mind that a supercharger is a "hidden" source of power consumption. Depending on the type of supercharger and the boost level, it will take 50-100hp or more to drive the blower. You will never see this hp at the flywheel or at the rear wheels. But the stress on the internal engine parts is still there. 

If power up to the 1.5hp/ci range (~500hp for a motor in the 350ci range) either a SC or nitrous may be selected depending upon the owners preference and intended use. When more power is desired it is necessary to upgrade the entire short block assembly. Either a very large supercharger or a large port nitrous system (in the range of 300+hp) would be needed to achieve the maximum horsepower potential of the upgraded short block. There are advantages and disadvantages to each type of system. 

A very large supercharger and the attendant plumbing and components (especially the large intercooler that is needed) are difficult to package. When a typical centrifugal supercharger is used the setup may be relatively weak on the bottom end because of the low compression needed to accommodate high boost and because a centrifugal blower simply cannot produce much boost a low engine speeds. In addition, as the boost goes up, the intake air heats up. This occurs no matter what method is used to cool the intake air - it's simply a property of gasses that they heat up when compressed, and the more compression, the more heat. 

A large nitrous system becomes difficult to control when running street tires and, of course, it is only available when there is nitrous in the tank and the system is activated. The "shock" that occurs when a large system is activated may break parts as well as cause wheel spin. The plumbing for a port system can also be a problem on a street car with all of the other systems that compete for under hood space. 

A moderate sized supercharger and a nitrous system in the 100-200hp range complement each other in a way that addresses all of these issues. The smaller supercharger is easier to package and, of course, the power from it is always on tap.  Since excessive boost pressures are not necessary, excessive heating of the air charge does not occur. The 100-200hp nitrous system can be activated at relatively low rpm to compensate for low boost, and the "shock" from this relatively small shot is not as likely to cause wheel spin or break parts. A simple one or two nozzle or a plate system is all that is needed to supply the needed amount of nitrous. Additionally, due the high heat of vaporization of nitrous, when the nitrous is activated it significantly cools the intake charge. 

Kennedy's approach to dual power adders 

Keys to any safe high power motor include proper parts selection and professional assembly. These factors are well understood by all high performance enthusiasts. What is not so common knowledge is the vital importance of tuning. Proper tuning not only maximizes the horsepower from your expensive parts but helps ensure safe, reliable operation. Unlike times past, tuning in the modern era of electronic fuel injection, high boost superchargers, and nitrous systems is no longer a backyard operation for the "shade tree mechanic". It takes knowledge, experience, and the proper equipment, and at Kennedy's we have the expertise and tools needed to do the job right! We tune using the Dynojet  248C chassis dyno. Our CDS data logging software allows us to measure your air:fuel ratio, blower and fuel pressure, torque and horsepower and exhaust gas temperature (EGT). Using our extensive knowledge of electronic engine management systems we can take this data and optimize your combination, ensuring a safe air:fuel ratio and an appropriate timing curve. We have extensive experience in creating different programs to optimize performance both with and without the nitrous activated. Of course, we also can tune your carbureted setup if you haven't yet adopted fuel injection technology.

Engine controls

 A key issue in making a dual power adder setup work is how to control spark and fuel. The requirements differ in non-boosted, boosted, and boosted plus nitrous modes. There are two primary methods for managing these different scenarios. The first involves using a reprogrammed OEM stock computer along with add-on systems. Add-ons may include such devices as window switches,  timing retard controls, nitrous controllers, the Electromotive TEC3 ECM, ignition and fuel enhancements, low impedance injector drivers and others. This method can be made to work and work well. One project we are particularly proud of is the dual power adder Camaro Z-28 we built and tuned for a local owner. We utilized our expertise in tuning the LT1/LS1 PCM along with add-ons to make this awesome street/strip combo produce over 700 rear wheel horsepower with full emissions equipment and a very mild cam. 

While an OEM engine control system can be made to work (and work well) with dual power adders, the ultimate setup involves an aftermarket ECU. The best unit for this purpose is the Electromotive TEC3. Features of this unit include 

• Crank Triggered Multiple Coil Direct Fire Ignition which has the Most Accuracy and Delivers the Longest Spark Duration on the market.

• Powerful WinTEC Software Includes ‘Tuning Wizard’
  for fast Start-ups

• On-Board Data Acquisition records vital Engine and
  Chassis information

• Activate Nitrous, Turbo Boost, VTEC, Shift Light,
  Cooling Fans and more with four General Purpose Outputs

• Eight Injector Outputs allow full sequential and staged injection on most setups

• New Dual RPM Limiters with ‘Triple Smooth’
  Technology for the Softest Rev Limit

Electromotive TEC3 prices start as low as $1,650 with installation available for as low $595.99 with tuning and wiring extra. Using this system and our fully instrumented Dynojet we can tune your super high performance combo to provide unparalleled power and reliability. 

Camshaft selection 

At Kennedy's we have found that any power adder car has cam requirements that are quite different from what a normally aspirated setup requires. When dual power adders are selected the cam choice becomes even more specific. We have performed extensive testing of cams on our Dynojet 248c chassis dyno and can supply you with the cam you need for "the performance you want and the reliability you deserve". A custom grind from Kennedy's is a little more expensive than an "off the shelf" grind or a generic "custom", but what you are paying for is our expertise. Our current price for a custom roller cam is $349.95. Please call us to discuss your cam needs. Further cam information may be seen here.