Photo 3/9 | Unlimited Diesel Fuel Injector | Since we ventured past Unlimited Diesel’s Stage 3 238/80 7.3L injector (known in the industry as the standard hybrid), what are referred to as “fuel-side modifications” became necessary. In order to convert our 238/80s into Stage 4 300/200s, fuel plates were added within each injector body, the stock 16mm intensifier piston was cut down to increase stroke, and 200-percent-over nozzles were installed. While the seven-hole nozzle design remains, each hole measures 0.0120 inches in diameter, making them 7x12s in injector-speak. Comparatively, stock 7.3L nozzles measure 7x6, so it’s a substantial change. Like the Stage 3 238/80s, the Stage 4 300/200s are still hybrids, which means only one high-pressure oil pump (albeit an aftermarket unit) is necessary to supply them the oil they need.
Photo 4/9 | Checking Head Studs | With the injectors pulled, Flynn’s gained access to each ARP head stud, so we decided to make sure each nut was still tight. This was a good insurance measure to perform with more boost on the way. After two years, all studs were holding strong at 125 ft-lb.
Photo 5/9 | Larger Injector Nozzle | The major benefit of running such a large nozzle is its quicker injection rate. This means much less timing and pulse width (injector on-time) are needed at any given engine speed and injection control pressure (ICP) level. For example, with the Stage 3 238/80 injectors we were running, it took 3.5 milliseconds of pulse width to empty the injector. Now, it takes nearly an entire millisecond less to do the same thing, and at approximately the same engine rpm and ICP level. To sum it up, the Stage 4 300/200 injectors allow us to inject a larger fuel volume in a shorter timeframe, and the engine sees less cylinder pressure (due to less timing advance) and lower in-cylinder heat (due to lower pulse width).
Photo 6/9 | Transmission Pan | Before sending even more horsepower through our John Wood Automotive Street Performance E4OD, Flynn’s serviced the transmission. As expected, very little clutch material was found when we dropped the pan, indicating the 19,000-mile automatic was just getting broken in.
Photo 7/9 | Pouring In Transmission Fluid | Due to the added fluid capacity of our Mag-Hytec deep pan, 15 quarts of Motorcraft Mercon V ATF was required to top off the transmission. The transmission filter was replaced as well (PN YC3Z-7A098-BA).
Photo 8/9 | Ts Performance Six Position Chip | Considerable tweaking was done to our TS Performance six-position chip, which was programmed by Matt Robinson at Gearhead Automotive Performance. One of the changes was slightly firmer transmission shifts to ensure the built E4OD lives trouble-free. Also, the Overdrive shift was extended out farther in the rpm range to avoid any turbo surge once a larger turbo is in the mix. Robinson also lowered our cruising pulse width in order to keep things clean out the tailpipe while running down the highway.
Photo 9/9 | Racing Time Slip | Eager to see what the truck could do with the 300/200s, we hit the local eighth-mile dragstrip before heading to the dyno. To shed weight, we pulled the tailgate, bedliner, all of our tools, and showed up low on fuel, which put us just under 7,100 pounds. With a hard, boosted launch, we were able to nab a 1.77- second 60-foot time on our way to an 8.26-second pass at 81 mph. Our elapsed time converts to a high 12-second quarter-mile and, according to the horsepower calculator, we’re making between 510 and 530 rwhp with the S366. In the coming months, we’ll see what kind of horsepower we make on the dyno, and how much more power we make with a 68mm S400.