Part Five: Air Density
Project OBSessed is now in to it’s fifth part of the build-up with a few basic bolts on already completed and over 300hp on chassis dyno it’s really starting to take shape. But since this truck was bought to be somewhat of a daily driver with plans of taking the family to the mountains camping in a fifth wheel camper and making horsepower isn’t the main goal. Making usable horsepower would be more a more sufficient way to describe our plans. Adding some custom tunes, a cold air intake, and a new 4” exhaust system really woke this big white school bus up, but after the first big towing trip it was apparent it was going to need more work to become what it needed to be. In order to keep up with the new trucks on the road, it’s still going to need some more horsepower, but the EGT’s towing with what we had proved that wasn’t possible unless we addressed some airflow issues.
As many of you Ford faithful’s already know, the 1994-1997 7.3L Power Stroke was never equipped with an intercooler, Ford just opted to go with a really large 1.15 a/r exhaust housing on the stock turbocharger to help combat high EGT’s, but even in a bone stock application that left something to be desired. That stock turbo is laggy with the 1.15 a/r and EGT’s are still tough to manage while towing long grades. A tighter exhaust housing could be installed to help with the lag, but that will just compound the EGT problems by increasing drive pressure and restricting exhaust flow. The only logical step would be cooling that intake charge and increasing the air density making its way into the cylinders. Que, Banks Power.
As one of the first companies to really start toying with turbochargers on diesels, Gale Banks was also one of the first to understand the importance of intercooling. While the turbocharger is used to compress the air and increasing its density for the engine, compressing it also heats the air, making it less efficient. An intercooler is used to remove that heat, but they need to do it without blocking airflow to your radiator, so you aren’t dealing with overheating. The Banks Technicooler kit for the 1994-1997 Power Stroke was developed to do all those things and allow you to use the power you already have, without worry of pegging a pyrometer gauge on every grade you try to tackle.
While the installation is rather labor intensive on these trucks, the Bank kit is very well engineered and will fit like a factory unit would’ve, had Ford been keen enough to install one on this OBS truck (Ford did finally smarten up and install them on the new Super Duty released in 1999). On the OBS, the factory core support will need to be modified and cut out to allow the new boost tubes to pass through to the intercooler that is mounted directly behind the grille where it will get the best airflow across the core. You can plan on this install, taking the better part of a weekend with the right tools, but rest assured, it’ll be worth your time.
While we were here installing the intercooler, we also opted to install a few add on pieces, like some billet plenum inserts from Riffraff Diesel and T-bolts clamps on the plenum boots, so we can be sure to torque them down tight for a boost leak free seal at the engine. The new powder coated boost tubes under the hood made everything else look bad, so we also installed some billet anodized caps for the engine oil fill, degas bottle, fuel filter housing, and radiator support bracket to dress it all up a bit.Results
First off, we’ll start here by stating these results were strong enough for us to suggest the intercooler installation being your first priority as a 94-97 7.3L owner. If you plan to do nothing else with your OBS Ford, plan on doing a Bank Intercooler kit, the drop in EGT’s and increase in usable powerband is that impressive. Before installing the intercooler kit, we made some data logs on our Edge Insight CTS2 monitor while towing a 10,400lb fifth wheel trailer over a long torturous 6% grade just outside of Salt Lake City, UT. This grade has been known to kill many of trucks in the hot summer months and maintaining the 65mph speed limit is tough on even brand new trucks while towing heavy. Forgetting about the speed limit and focusing on nothing but the EGT gauge that was almost impossible to keep under 1350-degrees, we ran the last two miles of the grade clear down in 2nd gear running just 37mph. Contemplating reaching for the hazards lights and asking my wife to jump out and help push, we finally crested the top with the engine oil and coolant about ready to boil itself out of the engine. We should also note, this was over Memorial Day weekend, when it was just 46-degrees outside and raining, it’d take a miracle to get through that mountain pass on a 97-degree July 4th weekend.
With that said, we did basically just that, with plans to camp in the same canyon near a great fishing hole the last weekend in June. We towed the same trailer over the same grade, with no changes made except the addition of the Banks intercooler kit, and the outside temp at 89-degrees and no rain. Conditions were worse, but the results were far better. With the charged air coming out of the turbo being cooled through the intercooler core, before entering the cylinder heads, we had so much more throttle to play with. This trip, we were able to pull 3rd gear the entire grade at 59mph at a much more manageable 1250-degrees. That was over 20mph increase in speed at 100-degree cooler temps, towing the same load over the same grade. The is still only making around 300-hp, but with the help of the intercooler we can actually use that horsepower, where non-intercooled, we had to really feather the throttle to keep EGT’s in check. By maintaining a more constant throttle input, RPM’s were easier to hold, which kept boost where it needed to be, and our engine oil and coolant temperatures were kept a little more under control as well.
While the intercooler does take some investment in both your time and money, if you plan to increase horsepower in that 7.3L Power Stroke and have any intentions of towing, it’s worth every penny and bead of sweat invested into the job. No, we can’t wait to get the 63mm turbocharger from KC Turbos and 205cc Hybrid injectors from Full Force Diesel installed and really start making some horsepower.DW