Any time you come across a family run, small business in the midst of its fourth-generation of success, you get the feeling they're doing something right. That company is South Bend Clutch in Mishawaka, Indiana.inline_mediumwraptextrightSouth Bend Clutch26741575/tech/dodge/0912dp_2002_dodge_ram_3500_upgrade0912dp_01+2002_dodge_ram_3500_upgrade+south_bend_clutch.jpgTrue

Welcome to Top Tech Questions. Oftentimes, readers contact us with questions about articles, or to praise us on what a good job we are doing. But our favorite form of reader communication is tech questions. Our Top Tech section is a place where you ask what's on your mind, and we answer it. Got a trouble code? Wondering how to get your engine to make more power?

Here is a simple question: How much can your vehicle tow? There are two ways to get this answer-experiment and risk vehicle failure, or you can look it up. When towing goes wrong, it's not a pretty sight. So unless you're conducting controlled experiments on your own private highway, Diesel Power says it's better to ask someone-but who? The first authority one thinks of is the truck manufacturer, but since they all have their own testing procedures, it makes it difficult to compare them. For one thing, the vehicle specifications are extremely complicated because there are so many different configurations of pickup trucks. Not to mention they are using weight ratings as a selling point. This might have you wishing there were some impartial organization dedicated to creating standardized recommended testing procedures. Guess what. There is and it's called the Society of Automotive Engineers (SAE) International.inline_mediumwraptextrightTowing26710771/tech/0911dp_society_of_automotive_engineers_international0911dp_01+society_of_automotive_engineers_international+towing.jpgTrue

In the aftermath of Diesel Power Challenge 2009 we decided to once again showcase the event's most successful trucks. The only difference this time is that we'll explain what got them there. With the help of Industrial Injection, TS Performance, Amsoil, Nitto Tire, and 4Wheel Parts, we've prescribed what it will take to steal next year's show.

Thanks to the diesel aftermarket, many aspects of our trucks can be improved tenfold to help us tow easier. We can simply plug in a programmer, bolt on an air intake, and install an exhaust system-which all improve acceleration performance. But what about the other side of the coin: braking?inline_mediumwraptextrightChevy Silverado Truck26709721/tech/chevy/0911dp_banks_speedbrake0911dp_01+banks_speedBrake+chevy_silverado_truck.jpgTrue

Isn't the diesel aftermarket a great thing? If we want added performance, there's something for us. If we want to spice up our truck's look, there's something else for us. And occasionally, there's something that does both.inline_mediumwraptextrightDiesel Engine26497609/tech/ford/0911dp_cfm_plus_intake_manifold_installation0911dp_01+cfm_plus_intake_manifold_installation+diesel_engine.jpgTrue

From the time the Environmental Protection Agency proposed that ultra-low sulfur diesel (ULSD) be run in all on-highway diesel vehicles to when it was fully implemented in late 2006, there has been much debate about this new fuel's effect on older diesel engines. Specifically, the fear that ULSD has a lower lubricity and cetane rating, which could affect pre-2007 diesel engines and fuel systems.inline_mediumwraptextrightUltra Low Sulfur Diesel Fuel26513938/tech/ford/0911dp_fuel_additive_test0911dp_01+fuel_additive_test+ultra_low_sulfur_diesel_fuel.jpgTrue

Up until now, all of our modifications have had ulterior motives. Any fuel mileage increases were a welcome side effect of the products installed, but not the only reason for their being chosen. However, our primary purpose in bolting a Fitch Fuel Catalyst from Advanced Power Systems International to our 6.7L Cummins was to see if the company's claims of increased fuel economy would really pan out. We tested this product for more miles than any of our other modifications in this series and discovered some interesting results.inline_mediumwraptextrightPre Production Kit26513119/tech/dodge/0911dp_fitch_fuel_catalyst0911dp_01+fitch_fuel_catalyst+pre_production_kit.jpgTrue

When diesel owners in the Midwest seek the best performance money can buy, they come to a place where some very serious horsepower is made-Scheid Diesel. It's a business that, oftentimes, is directly linked to the most successful sled pull and drag race vehicles in diesel performance, not to mention some of the hottest running street trucks around. With this kind of reputation, and with our Midwest bureau being located so close to Scheid Diesel's Effingham, Illinois, location, we knew which shop would be turning up our '02 Dodge dualie. After all, some of the most powerful trucks in the country leave Scheid's shops on a daily basis.

Our '08 diesel-powered Jeep Grand Cherokee has racked up more than 40,000 miles since we picked it up in Detroit back in 2007 ("Detroit To L.A. In Three Days," Feb. '08). Since that time we've use the truck to test four sets of tires, develop a new shock package with Bilstein, test MBRP's DPF-back exhaust, and prototype a new air intake with S&B Filters. For the last three months, we've been collecting fuel economy data with a TS Performance MP-8 Luxury Edition computer module on the Jeep-and the results have been impressive.

Your diesel engine injector nozzles are responsible for delivering the proper amount of fuel to each cylinder bore for the load and horsepower demand. Over the course of the life of the engine, the number of injection events can reach the billions, and possibly trillions. In addition, the injector nozzles are subjected to an extremely abusive environment-more than any other part of the engine. The nozzles live in the diesel engine's combustion chamber and are exposed to temperature peaks of more than 1,800 degrees, while the internal pressure may exceed 30,000 psi.

The Sacred Seven
1. A typical gasoline engine has a throttle plate. This unfortunate feature restricts its cylinders from completely filling up with air, except at wide-open throttle. This creates a vacuum in the intake manifold and pumping losses for the engine. A diesel, on the other hand, allows its cylinders to take full breaths of air during every intake stroke and instead relies on increasing the amount of fuel to create torque. The average gasoline engine spends 16 to 40 percent of its total power on overcoming its own air intake restriction (throttle). The word "throttle" is exciting for some reason. Perhaps with more knowledge, its meaning will change to what it represents-a wheezy and inefficient way to control power.

Now we're getting somewhere! We broke the 400hp barrier, and not by a little either. When the dyno stopped smoking, we'd hit 449 hp, and 842 lb-ft of torque. While that might not seem like a lot, it now means our 5,000-pound truck has the same power-to-weight ratio as an 8,000-pound truck with 715 hp-so the truck feels pretty quick. In our August '09 "Rust Bucket Recession" article, we made an all-too-familiar 330hp at the wheels after adding bigger injectors. And that was with nitrous. We talked to a few different people and they agreed the truck was starving for air and timing. We also thought our exhaust drive pressure was holding us back. For our next trip to the dyno, we installed an external wastegate, turned our fuel screw another 1/2 turn, and heated our nitrous bottle up (so the bottle pressure was 950 psi, as opposed to 650 psi on our last dyno run). When the truck was on the dyno, the first thing we found out was that drive pressure alone would not open our Tial external wastgate properly. Smoke came out, but not enough to make a big difference in drive pressure, as our boost hit 56 psi-the highest number yet. In order to get the wastegate to open all the way, we'll neeed to apply boost to the top and bottom of the diaphragm in order to push the internal spring all the way up. The second thing we learned was what a difference a little more fuel and a lot more nitrous makes! Our fuel-only horsepower jumped up to 302 rear-wheel horsepower, and when we hit the button it climbed to 449 rear-wheel horsepower-not bad for a truck that still has a stock downpipe, stock head bolts, a stock headgasket, and a stock turbo with a High Tech Turbo compressor upgrade.

Every diesel truck on the road today has a differential and ring and pinion gear set in the rear axle. Four-wheel-drive trucks add a second set of gears and another differential to the front axle to transmit engine torque to all four wheels. Yet differential modification and repair is one of the most feared and least understood aspects of diesel trucks.

Our '87 Ford F-250 is called Project 300. Its name comes from the dollar amount we forked over to get the keys. Once we had them, we soon found out they were unneeded, since the steering column was broken. Currently, this truck has many tricks and procedures in order to get it started, which makes for the best security system available. Since we bought the truck, we've added glow plugs, various hoses, a seat cover, pedal bushings, a firewall reinforcement, an ATS turbo kit, body mounts, an exhaust system, a fuel pump, V-drive belts, a fuel return line kit, a front corner lamp, a front filler, and batteries. This project not only involves adding stuff, it includes removing things as well. For example, at least 50 pounds of grease, rotten carpeting, a dangling headliner, deteriorated firewall and hood insulation, a leaking fuel water separator, and a spare tire holder. This real-world project highlights the problems and triumphs you'll likely face if you buy a $300 diesel.

Welcome to Top Tech Questions. Oftentimes, readers contact us with questions about articles, or to praise us on what a good job we are doing. But our favorite form of reader communication is tech questions. Our Top Tech section is a place where you ask what's on your mind, and we answer it. Got a trouble code? Wondering how to get your engine to make more power?

The most important upgrade a tow vehicle needs is more fuel capacity. After all, fuel mileage can be cut in half, depending on how much weight you're towing. Whether you're towing heavy, or refueling equipment or a friend's truck, you don't want to go back into town to top off your factory tank, so having extra fuel on board is a necessity. This brings us to our '97 Power Stroke towing rig buildup. Although the truck already had two fuel tanks that when combined, could hold approximately 35 gallons of diesel, we wanted to double the amount of fuel onboard. In addition, we also wanted to have enough room for all of our tools.

This segment of our Power Stroke power recipes consists of ways to safely upgrade the 6.0L mill. Like our 7.3L power recipes offered in last month's issue, we've compiled some bang-for-the-buck-type power recipes to help your 6.0L make horsepower gains-without sacrificing longevity or reliability. Also coinciding with last month's suggestions, our power-adders don't include the cost of labor you might have to pay should you prefer a shop perform the modifications (with the exception of head studs). Stay tuned for 6.4L Power Stroke power recipes next month, followed by Cummins and Duramax suggestions in future issues.

The last time around, we added a larger, slightly heavier wheel and tire combo and lost a little more than 1 mpg. Granted, with the 6.7L's whacked-out emissions system that dumps raw fuel into the engine on the exhaust stroke to burn the soot from the DPF, who's to say what the real mileage numbers could be? But despite the capricious and fuel-wasting antics of our vehicle's active regenerations, our test data is what it is.

Our newest round of modifications is where we're really going to give 'er hell. We stepped up to 6x0.016 injectors from New Era diesel, added a Carter electric lift pump, and fiddled with the throttle linkage to ensure full travel. The result? The horsepower on our '89 Dodge actually went down, from 339 rear-wheel horsepower, to 332. Granted the day was hotter and our nitrous pressure was lower, but still, we were looking for more like 400 hp, and instead we didn't even make it to the mid 300s.

From '94-1/2 to '96, all 7.3L Power Stroke engines came equipped with single-shot HEUI injectors. When fired, the single-shot injectors would deliver all of their fuel in a single shot--hence the name. The '97 7.3L Power Stoke trucks sold in California received a new injector design that used a split-shot system for lowering emissions. The split-shot injectors work by dividing the fuel delivery into two parts in order to make the engines run cleaner. By the time the '99 Super Dutys came out, all 7.3L engines were built with split-shot injectors.

Welcome to Top Tech Questions. Oftentimes, readers contact us with questions about articles, or to praise us on what a good job we are doing. But our favorite form of reader communication is tech questions. So we're introducing our Top Tech section, a place where you ask what's on your mind, and we answer it. Got a trouble code? Wondering how to get your engine to make more power?

Project 300 is Diesel Power's budget buildup. In two stages we were able to buy a diesel truck and get it running for $1,203. For this third stage we added a turbo. Ford Motor Company made this same decision back in 1994 when it offered ATS-turbocharged 7.3L International diesel pickups and vans. ATS claimed its turbo could double the vehicle's power to the rear wheels and increase fuel economy. Today's ATS kit is based on the original design. However, the turbo was changed from a Garrett to an Aurora 2000, which is said to have a stronger cartridge and a more advanced housing and wheel design. Another change is with the 3-inch exhaust system that is designed to drop exhaust gas temperatures 200 degrees and add 30 hp compared to the stock system.