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2001 Chevrolet Silverado Duramax Diesel - Project Duramax

Posted in How To on September 8, 2006
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Some three years and 50,000 miles ago, we installed some performance improvements from BD Power on our '01 Chevrolet Duramax test truck (June '03). Nearly all the mileage this truck gets is towing. Going down the highway means 20,600 pounds-yep, a real load.

Just to refresh your memory, we had added the BD air-intake system and a complete exhaust system, which we later found on a dyno to make about 20 more rear-wheel horsepower. We also opted for the BD exhaust brake, in which an air cylinder controls a butterfly valve, which, when activated, virtually shuts off the exhaust from escaping, thus building backpressure. It works so well when towing that only on the steepest grades do we ever touch the truck's brake pedal, and that's very seldom.

To keep track of engine performance, we mounted up BD's excellent X Monitor gauge package to the window's A-pillar to give us exhaust gas temperature (EGT), turbo boost pressure, and exhaust backpressure readouts.

Diesels thrive on fuel delivery. The more fuel delivered at the proper time, the more power developed. The installation of the Amp Box from BD allowed us to program four different power levels by altering the injection delivery timing and opening duration. Keep in mind that diesels operate without a butterfly-type throttle, so engine speed and power are regulated by the amount of fuel delivered to the injectors, and with a turbocharger, airflow is augmented by how hard the turbo spins due to exhaust flow. So it all comes down to more fuel, more air, more power.

The biggest drawback is that the program was designed for those trucks with the more common Allison automatic transmission, not the six-speed manual that we have. We leave our Amp Box set at the third power level and closely monitor our EGT. To change the power level, we have to locate an Allison transmission-equipped truck, plug in our Amp Box, and follow the instructions. OK, it's only a 20-minute job, but it's still a pain to locate another truck.

Thanks to BD, where driving conditions allow, we can cruise at 75 mph. While we can now usually pull most grades in Sixth gear, we'll grab Fifth gear even if not needed, just to reduce the gear and clutch load.

The power gain is phenomenal! Forget about the slow lane on the hills. The only problem is that we have to monitor our exhaust temperature and usually have to back off on long grades to prevent turbo meltdown. But even at reduced throttle, we're towing faster than most people drive without trailers. If we had the Amp Box set on "1," as BD recommends when towing, then we most likely could keep our foot down, but naturally with less power.

As to the air filter and exhaust, there is a slight increase in engine intake and exhaust noise. BD claims the two let the turbo run cooler and enhance the power output provided by the Amp Box. While I can't directly prove it, I'd have to agree.The best fuel mileage has been 22 mpg without a load, and our pulling average is 12.3 mpg. Not bad considering the speed, weight, and wind resistance involved.

While these charts show the torque and horsepower produced by the Intimidator, the Juice/Attitude box will also produce similar gains.

The oil vapor from the K&N air filter bothered the mass airflow sensor and sent a trouble code, and the exhaust brake's backpressure exceeds a normal reading, causing a series of trouble codes to be stored. These lit up the "service engine soon" light. This totally mystified the service technician at our uncooperative Chevy dealer. We had them clear the codes and took our truck home running just fine. The "light" will periodically come on when using the exhaust brake but then will reset itself.

However, one day the light came on, stayed on, and fuel mileage dropped by 2 mpg, along with black smoke on start-up. Back to the dealer (with the Amp Box removed), where they refused to work on the truck unless we had a GM stock air filter (not even an auto-parts OEM-style replacement) as well as the GM-installed exhaust system. After reminding them that they would be in violation of the Magnuson-Moss Warranty Act, several "heated discussions," and many letters and phone conversations with GM's Customer Service (which was a total joke), we were getting nowhere. Then I contacted SEMA, as well as K&N. The right letters to the right people, and within the month, the service manager called to say that there was a "misunderstanding" and they would be glad to work on our truck.

Funny thing is the local GM truck dealer has no problem at all with the intake and exhaust modifications, but this Chevy dealership (who is also a GM performance dealership and even sells aftermarket air filters and exhaust for diesels) won't work with customers once the products are installed. Go figure! Other people tell me that they have no problems with their dealers.

In a word, yep! However, we would perhaps skip the air filter and 4-inch exhaust system due to the high cost and relatively low gain. Might just also make it easier down the line with any warranty problems-but then again, we would lose some horsepower and torque, and maybe have to back out of the throttle sooner to control EGT. The exhaust brake is a definite keeper, and the Amp Box is an almost unbelievably quick way to make fantastic gains in horsepower and torque. The X Monitor is a very useful tool to make sure you don't exceed certain parameters. The bottom line: wow! It sure beats pulling a load with a small-block gas engine. With the truck empty, it's Mustang-hunting time.

The Intimidator from BD Power is a handheld programmer that plugs into the diagnostic port under the dash.

While there's nothing wrong with the EZ Amp Box (made for BD Power by Edge Products), BD has a new Duramax offering called "the Intimidator," which is an alternative to the underhood-mounted EZ Amp Box that we had been using. The Intimidator instead plugs into the diagnostic port under the dash and reprograms the factory curves. First, the factory settings are stored so that they can be reinstalled in case the truck needs to go to the dealer for warranty work. Then, the Intimidator programs the fuel/timing curve to any of the four settings of horsepower/torque (55/110, 80/200, 100/205, or a whopping race-only 170/350). These are BD's actual average rear-wheel-dyno horsepower and torque figures.

The Intimidator also eliminates the rpm/speed limiter for more driveability, plus it reads any engine trouble codes and clears them if need be. Running taller tires? No problem: The Intimidator can reprogram the speedo to display actual road speed to compensate for just about any tire-diameter or gear-ratio change. It's simple to plug in the Intimidator, make whatever changes you want, unplug, and drive away.

One thing that we noticed right off (and for some reason hadn't experienced with the EZ Amp Box): the engine seemed to have more of a "rattle" sound than stock. This was likely due to timing changes, and we just didn't notice it with the EZ Amp Box. At the Number 1 setting, performance and pulling power seemed to almost equal the EZ Amp Box's Level 2 setting. Any setting above 1, and we had to keep an eye on EGT-on several occasions at a full-throttle pull, EGT exceeded our conservative preset maximum on the X Monitor gauge. It may seem a bit strange, but fuel mileage under a load seems to stay right in the same range, whether on the 1 or 2 setting or stock.

With the truck bed empty and free of its trailer weight, we just had to try the top level of performance. Damn, if it wasn't scary! Really impressive was the 65 mph to "much too fast on the truck tires" acceleration. And, yes, we went looking for a Mustang or Camaro to challenge, but perhaps fortunately for our DMV driving record, didn't find any takers. Fuel mileage sure did suck, though, with the lowest recorded figure of 15 mpg. If you want to play, you got to pay.

Edge Products offers its Duramax power-adders in two parts. First, Edge has the Juice, the underhood box that BD Power private-labels as the EZ Amp Box. However, the Juice version is modified to work in conjunction with Edge's Attitude in-cab controller (also available through BD Power or other Edge dealers).

Instead of using the bracket supplied by Edge, we glued and velcro'ed the Attitude to the dash just below the instruments because we were already using the BD Power X Monitor on our window pillar.

The dash-mounted Attitude offers you on-the-fly control of the black box's five power levels while driving, plus several other features. First and maybe foremost, the Attitude reads and displays EGT from a probe that goes into the exhaust manifold. (The "before turbo" location is a better indicator of true turbo temp than one installed in the downpipe.) Boost pressure is also displayed on the Attitude's LCD screen, as are the Juice power level selected, the true road speed when using a non-stock tire diameter, the engine temperature, the percentage of engine load, and the percentage of Allison transmission slippage.

The system also has a few powertrain safeguards. For starters, cold-start protection delays the Juice power levels from being used until the Duramax is at proper operating temperature. Speaking of temperature, Edge's EGT back-down allows you to set a maximum turbo temperature. When it's reached, the Juice/Attitude system cuts back on the fuel to prevent the temperature from climbing higher, and also chimes a warning sound. The system protects the automatic transmission too: the Attitude monitors and displays the percentage of slippage when the torque converter is locked, and reduces power if any slippage is detected. Subsequent power increases are limited during shifting to further control slippage.

And the Attitude's built-in 0-60 mph and 11/44-mile elapsed timer let you compare performance gains at the different power levels. That's a lot in such a small package.

Naturally, the Juice module with Attitude monitor/controller costs more than the Intimidator, but you get more features, most notably the ability to switch power levels on the fly. For those who already have a Juice (or Amp) Box, it can be factory retrofitted to work with the Attitude controller.

We made a long-distance trip with the truck unloaded with the Attitude at the Number 1 setting, hoping for some better fuel mileage, but it actually dropped nearly 2 mpg from the factory stock setting. This disturbed us a bit, and we are still not quite sure what caused the loss as nothing had changed other than our fuel source. We even consulted with the Edge engineers without a clear-cut answer. A number of times, we've found that the quality of fuel-both in Cetane rating and the percentage of paraffin wax-will have a pronounced effect on both fuel mileage and performance. More testing is in order as, according to Edge's engineers, mileage should have been better. When the truck was loaded (and the fuel came from a different source) and working like a truck should, with the Attitude at the Number 1 setting, fuel mileage stayed the same as it was in the stock setting, with an increase in performance. It's pretty simple to just punch up to a higher setting when we want more power on hills or in passing, but we are definitely keeping a eye on EGT at the higher setting. We save Number 5 for showing off with short bursts of power and unsuspecting Mustangs.

The Attitude box is what controls the "new" Juice box, plus a lot more. Note the extra plug for the Juice box, as well as the two small wires for the temperature probe.

The BD Intimidator is less money up front than Edge's Juice "black box" and Attitude controller/monitor. The Intimidator offers the ability to read and reset trouble codes. However, power-level changes require that the motor be shut off for reprogramming (not quite as convenient), and the Intimidator doesn't offer any powertrain monitoring or safeguards.

Although more expensive, the fuller-featured Juice With Attitude might actually be a better value since it saves the mounting hassle and approximate $350 cost of the aftermarket gauges it replaces if you don't already have them: pyrometer (EGT), turbo boost, transmission temperature, and oil temperature. This system also includes safeguards for cold-start protection, auto transmission slippage, EGT back-down, and boost control-potentially saving costly drivetrain repairs. "Push-button" power levels on demand is convenient, and the only Intimidator feature the Juice With Attitude lacks is the code-reader. However, the code reader and clearing ability is definitely a valuable asset as higher boost pressures, exhaust brake backpressure, and such will often set off an unnecessary trouble code.

The diesel motors-be it in a Chevy, Dodge, or Ford-seem to handle the extra power produced by these electronic wonders without any problem. Especially so if boosts are under 25 pounds and turbo EGTs-below 1,350 before turbo and 850 in the downpipe-as well as keeping rpm at factory redlines. However, only time will tell. Just keep in mind, there are only just so many horsepower-hours available in any motor.

Aluminum turbo housings start to melt down at 1,450 degrees Fahrenheit, so it stands to reason that the exhaust temperature should be kept below that number. Duh! Edge recommends 1,350 degrees as the maximum EGT.

But just where should we measure EGT? The easiest location is in the downpipe, past the turbo. It's simple to drill a hole and weld in a bung for the probe. In fact, BD Power preinstalls this bung in its aftermarket exhaust. But gases start to cool after they leave the turbo, so how hot is the turbo itself? We've always been told that there is up to 500 degrees in difference between before and after turbo temperatures, and we use a conservative 850-degree EGT as maximum read-out on our X Monitor. This also depends on how far down the exhaust pipe the probe is installed.

Edge's Attitude also reads EGT, and they recommend installing the probe in the Duramax's right exhaust manifold. This means drilling and tapping the cast iron. Kind of a scary thought at first. We did it with our engine running to blow out any metal chips.

What did we find? Cruising down the interstate with no turbo boost there was about 100 degrees difference, but this would change depending on throttle opening and the load put on the engine. While under 22+ pounds of boost at full throttle and full load, there was darn close to 500 degrees temperature difference. This puts it right at around 850 degrees at the down pipe. Safe enough.


Edge Products
Ogden, UT 84404

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