The 5R55S transmission uses an internal overflow tank located in the bellhous-ing. At the request of Burcham, we got a Moroso overflow tank (PN 41221), which retails from JPC Racing for $99.95.
A drain valve is located at the bottom to unload the fluid, and it meets all NHRA requirements for overflow tanks. Moroso includes a billet mounting bracket. Bryant bolted it behind the front bumper and out of the way.
The combination is mild thanks to a FRPP supercharger, Steeda 10-rib conversion and heat-exchanger, and JPC custom tune (DiabloSport Trinity hand-held).
Bryant drills a Vi-inch hole in the bottom of the bellhousing in order to gain access to the torque converter. This is done so he can spin the converter (using a screw driver) and tighten all four bolts to the flexplate.
A second OEM transmission cooler was added inline with the original one to help cool the transmission for everyday use. It goes for S196.95 from JPC Racing.
We added Red Line Oil D4 automatic transmission fluid to the transmission. The fluid is full synthetic and designed to replace the Mercon V ATF that comes in the 5R55S. The biggest bragging rights to the Red Line Oil D4 fluid is that it protects the transmission's internals from high temperature, which is a huge concern in high-performance slush-boxes.
100 MARCH SOU WWW.MUBCLEMUSTANGFASTrORDS.COM
A high-stall converter allows the engine to flash to a higher rpm.J J
quicker than with the factory low-stall torque converter," said Winstead. He continued to dispel some other misconceptions with stall speed. "Many people think that a 3,500-stall torque converter means that the car will not move until the engine reaches 3,500 rpm. That isn't correct. The car will still begin moving just above an idle." When you jump on the loud pedal and go WOT, the converter will flash to the stall speed and get you rolling quicker—provided the proper stall speed was matched to your combination.
The dyno sheet for our test car shows some serious low-end grunt, as the torque is over 460 lb-ft at around 3,400 rpm and remains above that mark until about 5,000 rpm. We want to exploit the long torque curve to help the car get moving quickly.
The OEM torque converter stall speed ranges from 1,600 to 2,000 rpm—far too low for the torque curve of our test car. Ideally, a torque converter's stall speed should be within 200 rpm of peak torque. In our case, that number is a broad one thanks to the twin-screw's characteristics, and we settled on a 3,500-rpm stall speed. The general rule of thumb for torque converters in street cars is that anything over 3,800 rpm tends to be too loose, but it also comes down to personal preference. We settled on an off-the-shelf TCI 3,500-rpm stall speed unit (PN 456002). It retails for $995.95 from JPC Racing.
The most power our car made was 479 rwhp, but that was with 19 degrees of timing and 93 octane pump gas. That's what it made when we ran our best of 11.49 at 119 mph. After that test, we backed the timing down for everyday use. It was set at 16 degrees peak at 6,500 rpm (shift point). We wouldn't have to worry about getting some bad gas while tooling around town. The safer tune slowed the car down, and a month earlier it went 11.58 at 119.78 mph with the 4.10 gears. That was with peak timing of 16 degrees and Mickey Thompson ET-Street bias-ply tires.
Was this article helpful?