On a big truck like this,...
On a big truck like this, tires are a worry. The sidewall of the tire can contact a plate on the end of the rollers and smoke out the dyno room, not to mention leaving a groove down the side of your tire. We were lucky, ours smoked a little on the first pull, but that was all. The groove was gone after a day of driving.
Our first pulls on the dyno netted us 186 hp (Stock), 223 hp (Tow), and 244 hp (Race) while torque came in at 352 lb-ft (Stock), 410 lb-ft (Tow), and 454 lb-ft (Race). If these numbers seem low to those used to seeing big horsepower from programmers, remember this was a prototype programmer; somewhere along the line, the boost on the turbo was turned way down when the truck was lent to somebody else (OK, us). Even with our 30-plus-psi-capable turbo, we were only at 19 psi on the gauge, even in Race mode. With our numbers baselined, we dumped a 5-gallon can of B99 in to see what would happen next. Since biodiesel has a distinctive burnt popcorn smell, we had Kennedy stand over by the exhaust while we made a pull to make sure the engine was running in Bio mode. To be safe, we had the programmer in Race mode to make sure we had enough fuel to be smelled and also because it's really funny seeing someone trying to smell something while being engulfed by a cloud of black smoke!
When the smoke cleared and we were sure we were running biodiesel, we made three more runs in Stock, Tow, and Race, which netted us figures of 199 hp, 223 hp, and 244 hp. Torque seemed to improve slightly at 385 lb-ft, 420 lb-ft, and 459 lb-ft. After seeing the first run of 199 hp come up, we were actually expecting biodiesel to make a lot more power. After the other pulls (Tow and Race) were almost exactly the same as #2 Diesel, we looked at the original Stock run on #2 to see what was up. The big dip at the beginning of the dyno graph showed that our turbo was still spooling up on that pull, while all the other runs on #2 and biodiesel showed a smooth power curve. Comparing the Tow/Race pulls on #2 with those on biodiesel showed almost no difference in power, while biodiesel seemed to have a slight edge in torque.
 We dumped in a 5-gallon can...  We dumped in a 5-gallon can of biodiesel after our pulls on #2 Diesel to see if there would be a difference. We ran the tank almost dry, then put in the B99 to get an accurate reading. |  We dumped in a 5-gallon can...  We dumped in a 5-gallon can of biodiesel after our pulls on #2 Diesel to see if there would be a difference. We ran the tank almost dry, then put in the B99 to get an accurate reading. |  After our dyno pulls, we checked...  After our dyno pulls, we checked the fuel filter for any signs of contaminants. Luckily for us, the fuel filters on the 7.3L are on the top of the engine and only take a few minutes to check. |