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360 Swan Song

Posted in Vehicle Reviews on December 8, 2004 Comment (0)
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With the new 5.7L Hemi engine on the horizon packing 345 hp and 365 lb-ft, the original 8-year-old 360ci Chrysler small-block is looking a little lacking with 245 hp and 335 lb-ft. Don't get us wrong, these are great truck engines that make power low in the rpm range where you can feel and use it. It's just that we know our readers are never satisfied with the power they have. But we also realize that many of you are afraid to tear into an engine that is still covered by a factory warranty. So with both these things in mind we set out to see if real power gains could be squeezed out of a 360 V-8 by bolting stuff on and plugging stuff in without breaking any smog laws or removing the engine's valve covers. Here's what we found out.

Open Element Air Cleaner
With the new throttle body in place, Turbo City installed its dual-inlet air tubes with twin 5x5-inch K&N air filters. We like the way this setup looks and sounds at wide-open-throttle, but we don't really dig the fact that the intake now draws heated air from the engine compartment. Turbo City recognized our concerns and explained that even though the hot air entering the engine is not as dense as what the factory cold-air intake provided, the added volume of air now available to the engine would more than make up the difference. We suppose it might, but Turbo City agrees that more performance gains are likely if you added ductwork in the engine bay to direct cooler air from the grille to the new filters.
Price: $196.40

Throttle Body Modifications
Our 360's first stop was Turbo City in Anaheim, California, to have its throttle body bored and blended to flow more air. You can see the difference for yourself when you compare the stock unit on the left with the reworked piece on the right. If you were air, which one would you rather flow through? Both throttle bores were increased to just over 2 inches in diameter, the shrouding around each bore has been shaved off, and the throttle shaft was milled down to improve airflow into the engine. The best part is the modified piece bolted in place just like the stocker, but for our tests we used a 3/8-inch throttle-body spacer for $49.25.
Price: $229 plus a $200 core charge

Tying It All Together
To help the factory computer compensate for the increased airflow on our 360, Turbo City developed a manifold absolute pressure (MAP) adjuster. This module plugs in series between the Dodge's MAP sensor and the engine's computer to alter the MAP output voltage in order to make the engine run richer. To install it you must splice the supplied weather-pack connectors into the factory wiring harness, and connect the extra white wire to a 12-volt positive source that is energized with the ignition key in the "On" position. Mount the MAP adjuster so that you can reach the test port and POT screw. Turbo City zip-tied ours to the throttle body.
Price: $94.45

Feeding More Fuel
The face of the MAP adjuster has a test port and POT screw that allows you to effectively enrich or lean the fuel mixture in the engine across its entire operating range. Using a voltmeter, Turbo City read the baseline voltage the MAP sensor put out with the key in the "On" position, and then plugged in its MAP adjuster and added 0.2 volts to the baseline MAP voltage. Don't try to make adjustments without a voltmeter, as a small turn of the POT can make a huge difference in fuel supply. Performance and economy can suffer if not adjusted properly. You can experiment with various settings to suit your engine's needs, and even bypass the system completely by plugging the two connectors into each other.

The Sound of Performance
Ask anyone why he put an after-cat exhaust on his truck and he'll tell you "to get more power," "to sound meaner," or "to get better fuel economy." We're no different from any of you so we ordered a T-304 stainless steel system from Borla to breathe some life into our Dodge. Now when we fire the engine we're rewarded with that smooth performance exhaust sound from the dual mandrel-bent tubes and unique Intercooled Tips. Now the engine doesn't feel like it's working as hard. We did notice a 1-2 mpg improvement, and the aggressive Borla sound was worth the price of admission. With its Million Mile warranty this system should outlast the rest of the truck.
Price: $665

Exhaust Hanger (Up)
Just like you, we end up doing a lot of the work on our own rigs to save money. Most of the time we'd rather pour time into a project than cash. We began questioning this philosophy after spending a couple of hours lying on our backs under this '01 Dodge Ram trying to remove the factory exhaust. The original clamps pinch the exhaust so well that we had to remove the factory system with a cut-off wheel and a sledgehammer. Expect the same on your Dodge too. Installing the Borla system was far easier in comparison but required us to relocate the rearmost factory hanger back 6 inches. Luckily there was a hole in the frame for us to bolt to (arrow), but our customization required us to get new rubber hangers to keep the tailpipe from hitting the sheetmetal where the exhaust exited.
Price: $12

Finishing Touches
The final phase of our installation was also the easiest. We had JET send us its Stage 2 performance module (PN 90002S) to see if we could eke out a little more power from our 360. The JET module plugs into the factory computer and accepts the factory computer connector. This module is designed to work with mildly modified engines like ours but requires the use of 91 octane fuel. If you want to run 87 octane just unplug the module, slip it into its static-proof bag, and store it in the glovebox.
Price: $319.95

So How Much Power Did We Make?
Measuring power increases on our computer-controlled Dodge with an automatic transmission proved difficult but informative. After each modification was made to our 360, we ran the truck on a chassis dyno, but the numbers recorded didn't show us the power increase we thought we were feeling under real-world driving conditions. We hoped the factory Dodge ECM just needed time to adjust so we put more than 1,000 miles on the engine and re-dynoed the truck with much better results. Horsepower at the rear wheels was up 7 points to 200 hp, and torque rose 27 points to 301 lb-ft, and that was the lowest rpm we could measure when the torque curve was on a downward trend. The modifications definitely make the 360 rev quicker when we're on the throttle, and it's now possible to pull grades in Overdrive with 3.55 gears and 32-inch tires--something that used to require a downshift into Third.


Oxnard, CA 93033
JET Performance Products
Huntington Beach , CA
Turbo City
Orange, CA


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