At what point is intercooling practical? If the air discharged by the supercharger is too hot, the intercooler lowers the air temperature so the engine can accept that boost level without detonation. If the supercharged air is cool enough for 6 psi boost, then intercooling is not necessary. Intercooling is more practical with the less efficient Roots type superchargers at any boost level, as they heat the air more than a Twin Screw or Centrifugal. Therefore, intercooling with the Centrifugals and Twin Screws is not as critical as with the Roots type. However, for higher boost applications, a better case can certainly be made for intercooling. For us, it's a moot point, because Kenne Bell specializes in street applications that operate with 92 octane, factory throttle body, mass air meter, manifolds, heads and drivetrain. All these components have their air flow (HP) and power limitations. Keep in mind that those high boost/high horsepower levels demand larger inlet and exhaust and beefed up engine and transmission components to survive.
The '99 up Lightning? The Lightning has a reduced compression ratio of 8:1 vs. 9.5:1 for standard 5.4's. The lower 1.5 ratio will allow 3 psi more boost which equates to about 38HP. The lower compression loses 11HP giving a net gain of 27HP on the same octane. That is why all the turbocharged Buicks and Syclones and supercharged engines use 8:1 from the factory. The Lightning utilizes a Roots type. It has a higher air charge temperature than the Kenne Bell Twin Screw. An intercooler is used to cool down the charge temperature. With a 2.5 ratio, 5000 rpm is the maximum recommended (12,500) for the Roots type. The Kenne Bell is offered as a direct replacement and will produce up to 300% more boost. At the same 9.0 psi stock boost, the Kenne Bell uses 10-15 less HP, and enjoys a 23% lower charge temperature (33° to 55°) depending on boost level. The Kenne Bell is a direct bolt on replacement that raises the boost potential from 9 psi to up to 21 psi or 96HP! See "Lightning Dyno Tests."
Can I change cams or rocker arms? Chrysler products and early Fords are Speed Density. No way is it worth the expense and driveability problems of a cam - that no one can fix. Go with 1 ratio higher rockers. That's good for 10HP, which is all you'll get with a high lift cam with stock duration and overlap. Change the duration from stock and you alter vacuum which is what Speed Density uses to calculate fuel delivery. Mass air Mustangs are another story. Don't expect more than 20-25HP with "street" cams from the Mustang 2V, 3V or 4V. Those 60HP claims are B.S. A cam change for a stock pick up or SUV is not worth the expense and driveability problems.
How is it possible for a vehicle with a lower "peak" HP rating to out accelerate one with a higher "peak" rating? We see it all the time. The engine simply cannot accelerate from 0-60 or through the 1/4 mile without "seeing" or "visiting" the HP readings at 2500, 3000, 3500, 4000, 4500, 5000. For example, if the lower peak HP engine "sees" more HP at 2500, 3000, 3500, 4000 and 4500, but the higher peak HP engine "sees" more HP at only 5000 rpm. Which engine do you think will accelerate the vehicle quicker and be more fun to drive - unless of course, you are in possession of a supercharged "dream vehicle" that allows the rpm to jump to 5000 and remain there through all 3 or 4 gears. Not possible, is it? So that's what this is all about - whoever has the most boost (torque and HP) over the widest range - wins!
Are there any back to back tests? Here are two old but typical drag strip tests conducted by the magazines that you may find representative. Motor Trend (1994 Mustang 5.0) The exact same 4 speed 1994 Mustang that Motor Trend voted "Car of the Year" had 2.73 gears. It ran 90 at 15.0 in the 1/4. We installed our 7 psi supercharger on this same car with a larger mass air meter, ram air kit and chip and it ran 107 at 13.35 with street tires and went through the lights in 3rd gear! After installing slicks it ran 107 at 12.90. Super Ford (1993 Cobra 5.0) Super Ford Magazine asked if we were willing to do a back to back test on a '93 Mustang Cobra at LA County Raceway. We agreed. Editor Tom Wilson was in attendance for all runs. The stock Mustang made two near identical passes of 13.66/98.75 and 13.70/98.76. In 26 minutes - the car had been pre-prepped for the kit install - Ford guru Mark Sanchez, owner of AWE had the Kenne Bell 8 psi supercharger installed and ready to run. With no other changes to the engine or weather conditions, the Cobra charged to a 12.36/111.05 and a 12.31/110.80, an average of 1.35 seconds and 12.17 mph. Calculated HP for the 3450 lb car with driver is 255HP without supercharger and 365HP with the Kenne Bell Supercharger - a total gain of 110HP. When Tom Wilson, Editor of Super Ford asked if we'd change to a 5 psi pulley, we obliged. In 4 minutes the car was ready and responded with a 12.57/109.09 (345HP).
Should I buy a larger filter, throttle body, mass air meter, inlet manifold, headers, exhaust, catalytic converter etc? Find someone who has run an accurate test on a Dynojet. Remember, air flow is everything. What work's for one engine, vehicle, model, year or manufacturer may not work on another. At Kenne Bell we carefully and systematically analyze the inlet and exhaust systems of many vehicles. Any engine's performance can be improved IF there is a resistance to air flow in the inlet or exhaust tract. The fact: If there is no restriction, THERE CAN BE NO HP GAIN. If there is a restriction, removing or reducing the restriction will increase horsepower incrimentally.
