High Performance Diesel Engines

Bruce Mallinson
June 2016

A new revelation has just taken place at Pittsburgh Power this past week. Michael Niss out of Wisconsin has been searching for 11 miles per gallon for the past 3 years. When I meet 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 Pete 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 spec. 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 too. We now have the cure for the PK and GK DD4 Detroits and that requires a piston change. The white smoke is gone and so is the raw fuel smell that will permeate 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 2 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 years know that I’m against the variable geometry turbocharger 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 the 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 going back into the intake manifold so the amount of soot accumulating on the variable vanes is minimal so we feel the problem has been eliminated. Time will tell and Michael is on his second load since we changed the pistons and installed the variable geometry turbo.

On the dyno, our engineers had to write new programs to allow the ECM to talk with the VG turbocharger, and we have some awesome news to report. The 12.7 liter engine usually has a peak torque of 1400 RPM, and now that has been lowered to 1200 RPM, much similar to a 3406 or C-15 Caterpillar 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 was 8.6 mpg, which was up from 6.8 to 7.5 on average. So even if we take his high average of 7.5 to the new mileage of 8.6 the increase was 1.1 mpg for only 2 changes to the engine. On the level cruising at 65 miles per hour, the engine only required 2 to 3 pounds of turbo boost and on most of the rolling hills about 10 pounds of boost.

The pistons and connecting rods are balanced and the engine ran along smooth and quiet, according to Michael the engine just hums along! Exhaust gas temperatures with the thermocouple in the exhaust manifold runs about 750 degrees on the level and will max out at 1200 degrees on a hard pull. Those of you running with the thermocouple in the exhaust pipe, after the turbo would 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 us another ½ mpg. Being Michael does run in the higher elevation, we are going to program the 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 in the instrument panel that will allow either program to be operative.

Michael Niss’s truck and trailer will be an ongoing quest for 11 miles per gallon, and we are working on the next item to increase the fuel mileage and that will entail making this rig part hybrid. We may need investors for the next step, so if anybody with a large company would like to work with us, we could use some financial backing.

Driving for efficiency, this 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 5 hours, and if you pay attention to them your driving habits will change. 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 almost level terrain is where fuel mileage is obtained, and never uses excessive power to buck a head or side wind. When it’s windy drop down ½ gear and slow down about 4 to 6 miles per hour. If you have a 10-speed transmission you will have to run in 9th gear and slow about 6 to 8 miles per hour. I always hear the story the load has got to go and I don’t time to go slower. Well if that is the case, you will always have the fuel mileage you currently have, driving habits are between 33 to 50 percent of the fuel mileage.

Until next month, keep your truck clean and well maintained, it’s much more economical to maintain it as opposed to waiting for it to wear out.

Written by; Bruce Mallinson, Pittsburgh Power Inc.

3600 S. Noah Dr.

Saxonburg, PA 16056.

Phone 724-360-4080