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Mods for Coyote Mods, Part 4 - Coyote From Hell
Testing a Hellion Turbo Kit on a Ford Racing 5.0L Coyote motor.
Sized properly for the street and chassis dyno, the 38mm wastegate proved a tad on the small size to control boost on the engine dyno. The loads experienced on an engine dyno are never duplicated on the street or track (or chassis dyno), and this places additional strain on the wastegate. When we revisit the turbo system, we'll test a larger wastegate or double up on the 38mm units to ensure proper boost control.
Turbosmart also supplied a manual boost controller, but it went unused during this test session (we had all the boost we could use).
Once the exhaust tubing was in place, on went the turbo, drain-pump assembly, and air-to-air intercooler. The intercooler featured a provision for the factory MAF. The location of the MAF combined with the position of the Turbosmart BOV (before the MAF) allowed the BOV to vent to atmosphere rather than recirculate the air back through the intact tract. A few sections of tubing, silicone bends, and couplers later, and the Coyote from Hell was starting to take shape.
One change we made prior to installation of the turbo kit was to replace the factory throttle body with a larger unit from Accufab Racing. It is a direct bolt-on, and we wanted to eliminate any inlet restrictions. Look for a test of the throttle body when we upgrade to ported cylinder heads and a Boss intake. The only thing left was to replace the factory injectors with a set of 75-pounders then beg Ken Christley from Kenne Bell to come over and tune the sucker using our SCT software. Tuning is critical on any motor, but can be extremely complicated on the Coyote motor. (There are no less than 32 different timing tables!) A huge thanks goes to Jim and Ken from Kenne Bell for their help with this project.
We started slow with limited timing and a rich fuel mixture and tuned our way right into serious power numbers. The engine produced a rising boost curve that started at over 8 psi (despite our 7 psi spring) and finalized at just over 14 psi. Given our tuning ability (actually Ken's), the rising boost curve was not a problem. What really limited power production on our killer Coyote was valve float. No amount of tuning (cam or ignition timing) could overcome the loss of valve control above 6,000 rpm. This presented a problem since the 5.0L made peak power (in normally aspirated trim) at 6,600 rpm and revved safely to over 7,000 rpm.
Since we did not experience valve float when the engine was normally aspirated or with the Kenne Bell blower, the culprit must be exhaust valve spring pressure. The motor got terribly unhappy when attempting to run above 6,000 rpm. The good news is that (despite the valvespring handicap) the rising boost curve allowed us to produce amazing power numbers anyway.
After tuning with the Hellion single turbo kit, the Coyote produced peak numbers of 844 hp and 780 lb-ft of torque. The boost curve started at 8.6 psi at 3,500 rpm, rising to 14.2 psi at 6,000 rpm. The peak power number of 844 hp came at just 5,800 rpm, at which point the motor started becoming unhappy due to the valve-spring issue.
Simple math lets us know that running 10 psi on our 515hp 5.0L (10/14.7 + 1 (1.68) x 515 hp) should equate to over 850 hp, so we suspect that the turbo system had considerably more to offer. Considering the elevated static compression ratio, we took the liberty of testing our motor with 114-octane Rocket Brand race fuel. Even if we backed the boost down to 7 psi and drop the ignition timing for pump gas, you are still talking about a 700hp 5.0L!
We can't wait to run the system once we modify the internals, add the ported heads with the necessary valve spring upgrade, and install a larger wastegate. Next time out, look for ported heads, a Boss intake and possibly even wilder cams to maximize the normally aspirated combination.
Ford Racing 5.0L Coyote-NA vs. Hellion Turbo (8.6-14.2psi)
Even in normally aspirated trim, the 5.0L Coyote was an impressive performer. How do you argue with a 5.0L motor that produces over 500 hp and an equally amazing 450 lb-ft of torque? Only after you see the power numbers put down by the turbo motor do those start to look a little anemic. Despite valvespring pressure limiting the available engine speed, the Hellion turbo system improved the power output of the 5.0L Coyote by over 300 hp! Running a rising boost curve that started at 8.6 psi and ended at 14.2 psi, the turbo 5.0L produced peak numbers of 844 hp and 780 lb-ft of torque. Without valvespring issues, these power numbers would have come at something near 10 psi of boost.