The plenums were designed...
The plenums were designed to accept dual 75mm throttle bodies from Accufab. The 5.0 throttle bodies look right at home on the mod motor.
Ignition mods included replacing the stock coil packs and plug wires with high-energy units from MSD. Voltage into (and spark energy out of) the coil packs was increased with a Kenne Bell Boost-a-Spark. The final element on the list of ignition upgrades was a set of Denso Iridium IT31 spark plugs (gapped down at 0.025). The precious metal plugs and shortened plug gap help eliminate misfires associated with boosted applications
As always, we ran the 5.0 stroker combination in naturally aspirated form to establish a baseline. Running the motor naturally aspirated allows us to verify the power gains offered by the twin-turbo kit. The turbo-ready 5.0 produced 462 hp and 446 lb-ft of torque running an air/fuel ratio of 13.0:1 and total timing of 29 degrees. Installation of the twin-turbo kit on the dyno required a number of modifications. After the installation, we had the twin-turbo motor up and running in no time with the FAST engine management system. Running vacuum/boost reference lines directly to the dual Tial waste gates resulted in a maximum boost pressure of 9.8 psi. We had a rising boost curve that peaked at 9.8 psi.
Naturally the motor was run with race fuel for safety, though this boost level was certainly achievable on pump gas. We dropped the total timing from 30 degrees to just 21 degrees, and the air/fuel mixture from 13.0:1 to 11.8:1. Once we had the air/fuel and timing dialed in, the twin-turbo motor produced an impressive 771 hp and 683 lb-ft of torque. Remember that all this horsepower and torque is coming from a motor displacing just 281 ci!
Before increasing the boost pressure, we dropped total ignition timing from 21 degrees to just 19 degrees. Running 16 psi of boost brought 937 hp and 829 lb-ft of torque. Stepping things up to 19.4 psi, and ignition timing down to 17 degrees, brought the peak numbers up to 1,006 hp and 872 lb-ft of torque. Now that's what we call a Power-Improved Two-Valve.
 The majority of the power...  The majority of the power for this turbo stroker came from HP Performance in Roswell, New Mexico. The twin-turbo kit features everything you need to add boost to your Two-Valve mod motor. Naturally the company offers single and twin kits for the original pushrod 5.0 Mustangs as well, not to mention kits for the Three- and Four-Valve modular combinations. |  The kit from HP Performance...  The kit from HP Performance was available with 57mm or 67mm turbos. We chose the smaller 57mm turbos for our 1,000hp Two-Valve. |  The HP turbo kit comes with...  The HP turbo kit comes with a front-mounted air-to-air intercooler, but we modified the top tank by welding on dual outlets to feed our twin-plenum intake manifold. |
 HP Performance recently redesigned...  HP Performance recently redesigned its exhaust manifolds to further improve performance. We used the older (shorter) manifolds in our test. |  Before adding the turbo kit,...  Before adding the turbo kit, we ran the 5.0-stroker in normally aspirated trim. Equipped with the new dual-plenum intake and breathing through Hooker Super Comp headers, the 10.0:1 5.0 produced 462 hp and 446 lb-ft of torque. Though we ran the motor at lower boost levels before putting the screws to it, the 5.0-stroker eventually produced 1,006 hp and 866 lb-ft of torque at 19.4 psi. |  The HP kit also features a...  The HP kit also features a pair of Tial waste gates to properly control the boost pressure. |