Michael Niss out of Wisconsin has been searching for 11 miles-per-gallon for the past three years, and we are committed to helping him get there. When I met Michael for the first time, he had a 386 Pete with a PACCAR engine pulling a flatbed trailer with a roll tarp. At the time, I could not help him with that engine, however I did have several ideas about aerodynamics pertaining to the trailer. We also talked about driving with the turbo boost gauge and the Kevin Rutherford scan gauge. Michael changed his driving habits and started to work on the trailer aerodynamics. The end result was a two miles-per-gallon improvement.
Michael’s next move was to sell the Peterbilt and purchase a Kenworth T660 with a DD4 Detroit engine so he could install our performance parts. Unfortunately, the factory reman Detroit engine was the PK series, and the white smoke and raw fuel smell was terrible. The Detroit distributors always had the same diagnosis for Michael – it’s within specs. I talked about this problematic engine last month, and if I keep talking about it, maybe Detroit will do a recall or figure out the problem (like we had to do).
We now have the cure for the PK and GK series DD4 Detroits, and that fix requires a piston change. The white smoke is gone, and so is that raw fuel smell that permeates your clothes and your lungs. So, along with the piston change, we also installed a large variable geometry turbocharger. Our engineering department has wanted to do this for the past two years, and Michael’s truck, searching for 11 mpg, was the perfect truck to experiment with. Please keep in mind that the DD4 Series 60 Detroit engine did not come with a variable geometry turbocharger.
Those of you who know me and have been reading my articles for the past few years know that I’m against the variable geometry turbo because of the failure rate of the variable vanes in the turbine housing. However, all of the VG turbocharger-equipped engines came on EGR engines starting in 2003. As we all know (or should know), EGR engines eat their own soot and that soot is what plays havoc with the variable vanes in the turbine housing of the turbocharger. Since the DD4 Detroit does not have EGR, there is no soot coming from the burned exhaust and going back into the intake manifold, so the amount of soot accumulating on the vanes is minimal – because of this, we feel that the problem has been eliminated. Time will tell – Michael is on his second load since we changed the pistons and installed the VG turbo.
On the dyno, our engineers had to write new programs to allow Michael’s ECM to talk with the new VG turbo we installed, and we have some awesome news to report. The 12.7-liter engine usually has a peak torque of 1400 RPM, but that has been lowered to 1200 RPM, which is similar to a 3406 or C-15 Cat engine. On the dyno, this Detroit produced 1800 foot-lbs. of torque and 600 horsepower to the ground. That is 705 horsepower at the flywheel, and we cut it back on fuel to get to the 705 hp.
His first load leaving Pittsburgh going to Minnesota was 78,000 pounds gross, and the fuel mileage he got was 8.6 mpg, which was up from 6.8 to 7.5 on average before the changes were made. So, even if we take his higher average of 7.5 to the new mileage of 8.6, the increase is already 1.1 mpg for only two changes to the engine (pistons and turbo). On the level, cruising at 65 mph, the engine only required 2 to 3 pounds of turbo boost, and on most of the rolling hills, it was at about 10 pounds of boost. Since we balanced the pistons and connecting rods, the engine ran smooth and quiet. According to Michael, the engine just hums along!
Exhaust gas temperatures, with the thermocouple in the exhaust manifold, are now running at about 750 degrees on the level and max out at 1200 degrees on a hard pull. Those of you running with the thermocouple in the exhaust pipe, after the turbo, will run about 300 degrees cooler.
Next on the schedule for this truck is to change the gears from 3:55 ratio to 2:64 so the transmission can run in 11th gear instead of 13th, which should gain him another .5 (half) mpg. Being that Michael does run in the higher elevations, we are going to program his ECM to have two variable geometry programs – one for sea level and up to 5,000 feet elevation, and the other will be for above 5,000 feet. There will be a switch inside the cab so he can change the program according to his location.
Michael Niss’ truck and trailer is on an ongoing quest to achieve 11 miles-per-gallon. We are already working on the next item to increase his fuel mileage, which will entail making this rig part hybrid. We may need investors for this next step, so if anybody out there with a large company would like to work with us, we could use some financial backing.
Driving for efficiency is not a new subject for us, however every day I speak to owner operators about fuel mileage and many of them can’t tell me about their boost gauge – or don’t even have one. You can’t drive efficiently without this $68.00 gauge. Many of you have ex-fleet trucks and they don’t have boost or exhaust gas temperature gauges. They are not hard to install – you can do it in your driveway in about five hours and, if you pay attention to them, your driving habits will change and your mpg will increase.
To get decent fuel mileage, you must keep the turbo boost to a minimum on the level terrain and use the power only on the hills. The level (or almost level) terrain is where fuel mileage is obtained. Never use excessive power to buck a head or side wind. When it’s windy, drop down half a gear and slow down about 4 to 6 mph. If you have a 10-speed transmission you will have to run in 9th gear and slow about 6 to 8 mph. I always hear the story “the load has got to go and I don’t have time to go slower.” Well, if that is the case, you will always have the fuel mileage you currently have, because driving habits are between 33% to 50% of the equation.
Until next month, keep your truck clean and well-maintained. It’s much more economical to properly maintain it than to neglect it and just wait for it to wear out. If you have any comments or questions, I can be reached at Pittsburgh Power in Saxonburg, PA at (724) 360-4080.
