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HIGH FLOW FUEL INJECTORS In order to permit the fuel flow necessary for the 350-Horsepower Kit to work, the stock Power Stroke injectors must be modified for extra fuel flow. Hypermax performs the necessary modification on your injectors for $820, and provides fast one-day turnaround of the parts. An exchange program for your stock injectors is also in the works. The modification only affects fuel flow at wide-open throttle, so fuel economy and emissions at partial-throttle positions are not affected. These Hypermax-modified injectors have received CARB approval. (Use of the modified injectors requires installation of the intercooler, or else the increased fuel flow could result in excessive exhaust temperatures.) Power Stroke-powered trucks built for sale in California are already equipped with high-flow fuel injectors. These special California-edition injectors feature two-stage fuel injection - quite a bit different than those in the 49-state models. EXHAUST TEMPERATURE READINGSThe exhaust temperature readings listed in this evaluation may seem excessive during certain wide-open-throttle driving conditions. Hypermax installs an exhaust pyrometer very close to the engine, between the exhaust manifold and the turbocharger, which is the hottest possible point to measure the exhaust, short of inserting the pyrometer probe directly into a combustion chamber. Some aftermarket parts manufacturers choose to measure the exhaust temperature after the turbocharger, in a convenient position downstream of the turbo's exhaust port. A lot of heat is lost through the turbocharger, so there is a marked difference in exhaust temperature (cooler) if the probe is installed even a short distance down the exhaust pipe. DYNAMOMETER RESULTSThe test truck was a 1997 Ford F-250 with the 3.55:1 axle ratio., E40D transmission and four-wheel drive. To determine the truck's rear-wheel horsepower and torque figures in stock and modified form, we took the truck to Hesse Automotive, a shop that specializes in light-truck diesel performance tune-ups and testing (2049 270 Street, Calamus, Iowa 52729; 319-847-6155). Proprieter Dick Hesse started by inspecting the stock engine tune-up specifications and performance figures to make sure the buck was operating at peak efficiency. This gave us a reliable starting point for measuring the Hypermax component performance changes. Next, Hesse put the Ford through its paces on his chassis dynamometer and recorded the stock figures; the test was repeated after all of the Hypermax parts had been installed. In both cases, the torque converter was manually locked up to avoid slippage and the resultant power losses. Peak horsepower improved 66 percent with the bext gain recorded at 118 percent. Torque went from 409 lb-ft at 1,800 rpm to 774 lb-ft. Hesse pointed out that these numbers are not SAE-corrected to sea-level horsepower and torque figures. In his opinion, and that of Jerry Lagod, this avoids having the figures look too inflated, and the fact that Hesse's shop is less than 800 feet above sea level and the tests were run back-to-back the same day means the corrected figures wouldn't be that much different. |