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[drmiller100]

An article for the archives perhaps? I tried to make it fairly generic, yet contain good info.
It seems like a lot of the posts are repetitive here, and if we had a FAQ it might help someone shy.
Btw, I do need some specifics and editing, like the trans temp stuff.
Thoughts????

I can’t be the only one…..

Doug Miller
McCall Idaho
November 13, 2005

I am the proud owner of a 7.3 Super Duty Powerstroke diesel truck. I wanted more power and mileage without destroying anything. It took me forever to learn all the terms, caveats, warnings, and issues regarding the options for my truck. In this article I will describe the initial performance options a new owner might consider.

The good stuff

Diesel engines horsepower is governed by the amount of fuel they can burn. The more diesel fuel the engine can burn, the more power it will make. However, the more fuel you push into the motor, the more heat the engine will produce.

The fuel is delivered to the engine via injectors. These injectors are computer controlled. Telling the injectors to inject more fuel is as simple as changing the computer programming. There are a number of “tuners” out there which reprogram the computer to add more fuel to the engine. In addition, you can get a “chip” which plugs into the main computer, or PCM, which can more drastically change the logic used by the computer.

The tuners have the advantage of requiring no modifications of any kind to the truck. Simply plug the tuner, or programmer, into the service port of the truck, answer some questions, wait 5-10 minutes, and your truck now has a new set of brains. The disadvantage of the tuners is a limited amount of changes possible, and the requirement of the 10 minutes each time you wish to change the truck’s tune.

The chips require the removal of the PCM, cleaning of a board, and installation of a chip. The first time takes under an hour for even the most novice of owners, and once the chip is installed it is done. Chips have the option of a remote switch to change between “programs” which can be changed as you drive around town. Six position programmers are common, and most chip manufacturers can custom tune a solution for your specific needs.

How much difference can a tuner or chip make? Your Powerstroke probably will have around 220 horsepower at the rear wheels. Another 100 horsepower at the rear wheels is entirely achievable with a tuner or chip.

In addition, better drivability should be expected with a good tuner or chip. Turbo lag, or pause, or laziness when pulling out into traffic will be eliminated making the truck more fun to drive. The tuner or chip will change the shifting characteristics of the automatic transmission, making shifts firmer, more consistent, and probably increasing transmission expected life.

Tuners and chips change the timing of the injection pulse. This means your truck may make more smoke, but will probably get better mileage. On my truck I get consistently 20 percent better mileage with a hot programmer vs stock.

Heat
Heat is the enemy of the engine and transmission. If you throw more fuel at the engine, you will get more horsepower, but you will also get more heat in the engine, and probably in the transmission. If you get either too hot, you will destroy the unit, and warrantee will not cover the costs.

The engine will be hurt by excessive exhaust heat temperatures. A pyrometer, or Exhaust Gas Temperature Gauge (EGT) will measure the temperature of the exhaust gasses. It is generally agreed running the exhaust temps over 1250 degrees between the head and the turbo is running in the danger zone. The engine might live, but then again your exhaust valves might melt, pistons come apart, or heads warp. Ford programmed the computer such that in stock form the EGT’s will never exceed 1250 degrees. Change the programming, and all bets are off. Therefore, an EGT gauge is mandatory for ANY aftermarket changes in how much power the engine makes.

There are four effective methods of lowering EGT’s. The most effective is watching the EGT’s of your truck, and backing out of the throttle a little on a big hill. Letting off the throttle tells the computer to pump less fuel in, which lowers the EGTs. Letting that Chevy pass you up the hill isn’t a great feeling, so there are other options.

Another method to lower EGT’s is to install a higher flow intake system. The more cool air that enters the engine, the cooler the engine will run. The stock intake system is not very good. It is restrictive, and not always very good at filtering dirt. As a demonstration, remove the air filter from your truck. The air enters the bottom of the box, flows through the filter, and exits the top into the round tube. Many of the 1999-2002 trucks will have dust past the filter on the sides of the top of the air box. This is a function of the air box design that will not be solved by the change to a K&N style filter. The Ford AIS, Tymar, and …….. are all proven options.

The third method to lower EGT’s is to utilize a higher flow exhaust system. The less restriction in the exhaust system, the lower the EGT’s. From the turbocharger at the top back of the engine, a single tube runs down beside the bellhousing. This is called the downpipe. Stock this is about a 3 inch pipe. From there the exhaust goes into a catalytic converter on some trucks, and then into a muffler. The muffler is very restrictive. Aftermarket exhaust options include a high flow muffler, cat removal device, complete system, and aftermarket large diameter downpipe. Some systems are stainless steel like the factory system, and others are made of a less expensive steel.

The fourth method of lowering EGT’s is adjusting the computer. The hotter the tune, the more EGT’s. However, some of the gurus seem to be able to get big horsepower with relatively lower increases in EGT’s. Shop around.

As you add significant amounts of fuel you will reach a point where you have more fuel then air. At this point a larger turbocharger might be in order.

The automatic transmission will be hurt by excessive transmission fluid temperatures. Operating temperatures under 200 are great and anything over 230 will likely cause permanent damage. is the danger zone. In order to monitor the temperatures of your transmission, you need an accurate transmission gauge. For those with 2002 and later Super Duties, the stock gauge is worthless.

Ford wants 3500 dollars to rebuild your transmission, so the gauge is a cheap investment. For an absolute fact there are a LOT of people who have burned their automatic transmission up behind a bone stock Powerstroke diesel, let alone an engine putting out extra power. Even if you decide to leave your truck otherwise stock, a transmission temperature gauge is still a GREAT idea.

Fixes for excessive heat include backing out of the throttle, shifting down earlier, computer programming changes, valve bodies, and rebuilds from reputable shops, and aftermarket larger coolers. In my opinion, the automatic transmission is a weak link for the Powerstroke solution. A big name tuner or chip will have a recommended solution to make their chips work with the automatic transmission. As an example, adjusting the shift points and firmness via computer is adequate for towing almost anything up to about 80 horsepower if you watch your temperatures.

For the 6 speed, or handshaker crowd, the stock clutch is good for anything I have described above. The stock puck will sometimes come apart even on stock vehicles. I have personally used a Luk clutch with great results. The South Bend Clutch folks have a great solution as well. Both of these solutions are far superior to the stock clutch, even for a stock tuned engine.

Boost
Boost generally describes the pressurized air compressed by the turbocharger, and cooled by the intercooler. If you increase the fuel, you will increase the exhaust gasses, which will spin the turbocharger faster, which will compress more intake air, which will increase the boost. The stock programming is good for about 17 pounds of boost, while the hotter programs can run up over 30 PSI. There is a boost monitor for the computer called the MAP. If this device detects over 27 psi, it will defuel the engine, and throw a code, causing your Service Engine light to come on. There are devices to fool the MAP available, but they are not recommended with the stock turbocharger. The stock turbo was designed with an upper limit of 25 psi, and anything over that amount will lead to premature turbocharger failure.

Do you need a boost gauge? Not really, but they are pretty cool to watch.

Finally, if you throw too much fuel at your engine without adequate air flow, you can cause turbo surge. This is a really cool sound your engine will make almost like air is being compressed and released repeatedly. Typically this will show the worst under 2000 rpm at WOT while towing. Surge is really bad for your engine. It will destroy the turbocharger. Fixes include better flowing intake, exhaust, and changes to the turbocharger itself. For reference, look up Wicked Wheel, Intake housing, and surge.

More power, better mileage, just be careful……

This short article was written to describe basic changes which can be made to your Powerstroke engine to increase horsepower and mileage. Further, I described the gauges you need to monitor your engine and transmission to increase longevity, whether you decide to modify it or not.