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.

This engine bay of this old truck was in rough shape when we first purchased the truck, the maintenance had been kept up on, but it was in serious need of a degreasing and a pressure wash. But to help dress things up a bit, the complete anodized billet hardware kit from Riffraff Diesel was a must have. The matching red fuel filter cap, oil fill cap, degas bottle cap and the heater hose bracket will really clean up that engine bay.

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.

This fuel filter really should’ve been checked and replaced when the truck was first bought, but to our surprise it wasn’t in too rough of shape. Like everything else on the truck, we found the previous owner was religious about keeping up on his scheduled maintenance and fluid changes.
While the fuel filter that was in it was probably okay to keep running, we opted to replace it anyway with a brand new Ford filter that was an option with the billet fuel cap. The billet cap is a direct replacement to the factory plastic cap and not only looks better, but the machined nut on top, and optional tool from Riffraff will ensure you’ll never have to deal with another rounded off or cracked stock lid ever again.
The heater hose bracket was super simple to swap out, with just one bolt holding it down. The factory bracket was still functioning but showed some surface rust and wear and tear. The new billet holder is much sturdier as well.

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.

That billet degas cap ties it all together under the hood but made it apparent we needed to source a new coolant reservoir. The original tank is rather yellowed and dirty inside, when it comes time to replace the thermostat and radiator, you may find that we install brand new tank while we’re at it.
Since the 1994-1997 7.3L Power Stroke was never intercooled from the factory, you’re really limited to how much power you can use when towing. The factory turbo works okay for stock fueling, but in a tuned truck, you’ll soon find that EGT’s run hot and you’ll be limited to how much throttle you’ll be able to use safely. Consider the complete intercooler kit from Banks Power your next ‘must have’ mod.

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.

Besides the intercooler itself, one of the key pieces to the Banks system is this unique Twin Ram intake manifold that offers smooth airflow passages for the cooled charged air to enter the cylinder heads. The Twin Ram installs directly on top of the engine and is strapped into place ensuring you’ll have no issues with it leaking or blowing out of the heads under heavy load.
To start the install, you’ve obviously got to make room behind that grille for the new cooler. Removing the factory headlights, grille shell, support piece and bumper will give you the required access to the core support area.

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.

Since our truck has the automatic transmission, the factory transmission cooler will need to be relocated. But don’t worry hear, Banks is prepared for that and included new mounting brackets in a location that won’t require you to chance transmission lines. Meaning it’ll be a mess free relocation.
The most daunting part of this job is knowing you’ll have to cut up the core support area to make somewhere for the soon to be installed charge air boost tubes to pass through to the intercooler. But again, Banks engineers are on top of things and supply these super user friendly templates to show you exactly where you’ll need to mark and cut.
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.

Using the templates as a reference, we were able to draw out some rough cut lines with a permanent marker. Obviously, you’ll want to make sure to tuck the transmission lines out of the way and be sure you’re not going to cut into anything you don’t want to behind your cut lines in the core support.
We found that a couple of sharp blades and the battery powered Sawzall was the easiest option for us to use to get these areas cut out. While a small die grinder or even a Dremel style tool could be used, the Sawzall was quick and easy. The edges were cleaned up a bit and some paint was applied once we knew we had the right clearance around the intercooler inlet/outlet.

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.

The intercooler kit came with all the brackets and hardware you’d need, and these brackets will be the lower mounts for the new intercooler. Some supplied rubber grommets are installed on the lower mount posts of the intercooler and inserted into those oval holes so the intercooler will have some adjustment side to side for the proper fit.
With the lower mount posts sitting in their brackets, the supplied upper mounts are loosely installed, and the new core can be centered where it needs to be to ensure the inlet and outlets have the right clearance around the core support. Make sure there will be room to get the charge air silicone boots and clamps on. At this point, you can see how much fresh air will be passing through that core to cool down your charge temps.

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

When reassembling the front end of the truck, the only other real modifications required is some trimming to the grille support. The plastic will need to be trimmed some to make clearance around the cast end tanks of the intercooler.
With the intercooler mounted, it’s time to move on to installing the Twin Ram intake manifold and the boost tubes to run from the compressor outlet to the intercooler inlet and from the intercooler outlet to the engine. The factory intake manifold will be removed and tossed in the garbage where it belongs.
Before installing the Twin Ram intake, checkout these little 2” billet machined rings from Riffraff diesel that can be inserted into to the factory intake plenums to eliminate the plenum from distorting or crushing and creating boost leaks.
The billet machined sleeve can just be slid right down inside the plenum inlet and the machined groove around the upper edge can be bottomed out, so you know it’s in place. Obviously, if you’re plenums are distorted at all, you’ll need to take care to get these inserted and get that plenum back into the original round shape. But once installed, we can torque those boots and clamps down much tighter for a leak free seal.
The factory tin plenums aren’t known for being the strongest pieces. While you wouldn’t think the factory worm gear clamps could be tightened enough to warp that plenum, you can see this one has already been deformed a bit at some point. Since we’ll be upgrading to a better high torque t-clamp, we wanted to be sure the plenums would seal without issue, so the billet plenum insert is an easy remedy.
The Twin Ram intake can then be installed into the plenum boots and the t-bolts clamps torqued down. The new turbo outlet elbow is also installed and loosely clamped into place. Banks includes a new O-ring to seal these two mating flanges, and you’ll also notice the 1/8” NPT bung Banks includes on the elbow for an easy boost reference port. It will need to be plugged off if not used for a boost gauge.
While the boost tubes came powder coated in red from Banks, we opted to have a local shop reshoot them in a milder textured black that we think makes it all look a little more factory under the hood. Obviously, that’s a personal preference thing, but you can see how good these pipes fit with plenty of clearance around all the other engine pieces.

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