Eventually, we installed the...
Eventually, we installed the 9-inch crank pulley and a 2.57 blower pulley on the Autorotor along with the AccuFab throttle body and special air entry. The result was a whopping 522 horsepower and 600 lbs.-ft. of torque.
Thinking ahead, I decided to run a test before increasing the boost to find the limit of the Autorotor in the same manner as we did for the Eaton. Since the Autorotor flowed so much better (and produced more boost) than the Eaton M112 using the same pulley ratios, I decided to satisfy those skeptics out there who think they should have been run at identical boost levels.
To reduce the boost on the Autorotor, we installed a larger 3.5-inch blower pulley in place of the 3.0-inch. The reduction in blower speed relative to the engine resulted in less boost pressure. Running just 9.1 psi, the Autorotor produced 364 horsepower at the wheels. Even punishing the better blower by slowing down the Autorotor to a speed that produced a matching 9 psi, it still out-powered the M112. Credit the lower parasitic loss and better overall airflow ability of the Autorotor for the power gains. The difference in power between the two blowers at 9 psi was actually as much as 28 horsepower near 5300 rpm.
Next, we decided to run the boost up on the Autorotor to see how far we could go with the stock air intake assembly in place. You will remember that we produced 396 horsepower with the Eaton using the stock air intake (box, MAF and throttle body) assembly. The Eaton was equipped with a 9-inch crank pulley and 3.00-inch blower pulley, so we installed that same combination on the Autorotor. So equipped, the motor produced 15.8 psi and 449 hp at the wheels.
Since we had a number of different blower pulleys available for the Autorotor, we wanted to install a smaller 2.57-inch in place of the 3.0. Unlike the Eaton, the Autorotor was still responding to our demand for more boost. Before getting carried away on smaller blower pulleys, we decided to try removing some of the substantial inlet restriction. The factory inlet was now even more of a restriction at this elevated power level.
Eaton vs. Autorotor -- Charge...
Eaton vs. Autorotor -- Charge Temperature
One of the measures of efficiency is charge temperature. Compres-sing the air in any blower results in heat. Obviously we want as little heat as possible, as heat is a major cause of detonation. The ideal supercharger flows a substantial amount of air with minimal heat production. This graph illustrates the difference in charge temperature between the Eaton and Autorotor superchargers produced at 9 psi. Note that both temperature curves climb as boost increased during the run. More boost pressure equals a higher temperature. Note that the Eaton (upper line) increased at a much higher rate than the Autorotor. The Eaton peaked out at 207 while the temperature exiting the more efficient Autorotor only reached 165. The difference in charge temperature between the two superchargers was a full 42. Lucky for the Lightning owners, the intercooler used on the 5.4 is exceptional and the charge temperatures exiting the intercooler core were nearly identical.
Running the 9-inch crank pulley and the 2.75 blower pulley, we installed the Accufab throttle body and cone filter. The result was a dramatic increase in power, up to 511 horsepower at the wheels. Later (isolated) testing would show that the prototype throttle body from Accufab was worth 17-20 hp at the wheels at this power level.
The Autorotor was pumping out 20.6 psi of boost with a charge temperature out of the blower pegged at 307°. The intercooler dropped this 307° charge temperature to just 107°, for a total drop of 200°. This was one great intercooler. Our data logging had indicated that we were topping out the electronics on the 90mm mass air meter. The voltage had reached 5.0 volts, a sure sign that we were nearing the end in terms of safe power production.
Undaunted, we took one final step and installed a 2.57-inch blower pulley in place of the 2.75. We were rewarded with the best run of the week, a whopping 522 horsepower and (are you ready for this) 600 lbs.-ft. of torque. Not some flash converter reading but a steady reading hovering around 600 lbs.-ft. for quite some time. The peak boost registered 21.6 psi during the run and boy, were we all happy.
There are several things to remember about this adventure, not the least of which is that you can increase the maximum power of your supercharged Lightning by more than 100 horsepower by installing an Autorotor supercharger upgrade from Kenne Bell.
Here are a couple of other important points to consider. Running 21.6 psi and producing 522 hp and 600 lbs.-ft. on the last run, the charge temperature out of the blower reached 320°. After passing through the intercooler, the net result was just 106°. Your factory Lightning intercooler kicks some serious ass.
Ponder this for a moment. We made 522 hp through the stock cats, with the factory 90mm MAF and a few smaller blower pulleys left. Heck, Kenne Bell never even altered the tuning via the chip until after we returned it back to stock configuration.
Was there power left in the configuration at 21 psi? You bet. Kenne Bell was able to chip-tune an extra 25-30 hp from the motor in stock configuration. Just think what might be lurking at 21 psi.
How about we go back and tune it, ditch the stock exhaust manifolds and cats, install a larger MAF and even Extrude Hone the inlet manifold: I wouldn't be surprised if we manage to produce 600 hp at the wheels with an internally stock Lightning motor. If we did, it would make a heck of a story.
Intercooler Efficiency @ 522...
Intercooler Efficiency @ 522 HP
We have praised the efficiency of the (late-model) intercooler system employed on the Lightning and for good reason. Check out the results of this test. We all wanted to see just how much power was available from the Autorotor and since the air/fuel ratio (also data logged) was nice and safe (usually about 10.5:1) we decided to really get serious. The motor was equipped with what we dubbed (at nearly midnight) the "Ken Super Tube"(a large section of 4-inch aluminum tubing used to keep fan wash from upsetting the filter). The tubing was attached to the 90mm meter and the stock flexible section of tubing used to join the MAF to the throttle body. We used the AccuFab prototype throttle body and equipped the supercharger with a 2.57-inch blower pulley. We continued use of the 9 inch crank pulley from Johnny Lightning. So equipped, the motor ripped out 522 hp at the wheels and a whopping 600 lbs.-ft. of torque at the wheels--through the stock cats no less. What was real impressive was the fact that the charge temperature at 21.6 psi reached 320 exiting the blower but was reduced to a peak of just 106. The stock intercooler system running ambient water (no ice water tricks) pulled out over 200 of charge temperature. I guess Ford suspected Lightning owners might be subjecting their trucks to some abuse.
AccuFab Prototype Throttle...
AccuFab Prototype Throttle Body
Though not specifically part of the test on the supercharger upgrade, we experimented with the new prototype Lightning throttle body from the experts at AccuFab. Though the twin 57mm openings on the stock Lightning throttle body does an adequate job of flowing air to support even modified power levels, we picked up 17-20 horsepower with the new piece from AccuFab. The excessive vacuum present in the inlet system was a sure sign that the stock throttle body was restricting airflow. The AccuFab billet throttle bodies have never failed to impress us with their build quality and performance. This test indicates that AccuFab has hit another homer with its Lightning throttle body.
Kenne Bell Lightning Chip...
Kenne Bell Lightning Chip
With all their supercharger experience, it comes as no surprise that Kenne Bell was able to whip up a chip to improve the performance of our Lightning test truck. Tuning is the critical element when it comes to supercharging any motor. Too much spark advance or not enough fuel and things can go bang in a big way. MM&FF (East Coast division) has already demonstrated that chips can make a dramatic difference in power on a Lightning. Not surprisingly, Kenne Bell was able to draw from their forced induction experience and create a chip for the Lightning that improved peak power by 24 horsepower. The gains were nearly 30 horsepower out near redline. Kenne Bell plans to offer chips, Boost-a-Pumps and air intake systems along with their Autorotor blower upgrade for the Lightning enthusiast.
Every bit as impressive as...
Every bit as impressive as the power output of the supercharged 5.4 was the efficiency of the intercooler. Part of the credit goes to the large heat exchanger and circulation pump used by SVT on the Lightning.
Naturally we data logged the...
Naturally we data logged the watertemperature of the intercooler systemduring the runs. All we can say it that this is one efficient intercooler system.
After removing the Autorotor...
After removing the Autorotor andreinstalling the Eaton back to factory specs, Kenne Bell tried their hand at a custom chip. The results were impressive, as the new KB chip increased power by 27 hp.