Volume 3 Issue 1 - Diesel Articles

Bill Heath plans to return to Bonneville in 2010 with his 6.5L GM Diesel Racer. Some things just keep getting better with age.

The Heath Diesel land speed race team has raised its sites for the 2010 Bonneville Salt Flats events, hoping to top 160 MPH this season. Team 6265 has its goals set on wringing every last bit of speed from the current, nearly-stock engine configuration: this year’s effort represents a further refinement on the package but we still consider it Phase One. When we feel that we have gotten all we can from the truck in its current form, then we will move to Phase Two, which will include some changes in the fuel injection system. For now though, efforts are focused on making the best showing they can with the truck as it is.

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Ol' Dad (Bill Heath) posing with starting-line official at Bonneville in 2009.

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With only a few months left before the August event, the 6265 team is wasting no time preparing a new 6.2 engine for the 6265 racer. While the changes planned are small ones, the team is confident these improvements will produce enough additional power to meet its 160 MPH goal.

From the beginning, this rather ambitious project has been focused on one very important goal: to champion the truck and its diesel engine for all of its enthusiastic fans worldwide. The team feels the pressure to make a good showing, so a decent performance and meeting our goals is pretty darned important. During the early stages of the project the team calculated a projected speed based on frontal area, coefficient of drag and engine output eventually setting its’ sights on 130 MPH. It was reasoned that getting to 130 MPH in a full sized pickup would be a respectable accomplishment in any camp. The fact is, you just don’t see very many full-size, street legal trucks that will do 130, even down at sea level let alone at Bonneville’s 4,300-foot elevation.

One can only imagine our jubilation when, on its first official run across the salt, the team was rewarded with a very nice 141 MPH pass! And this was the average speed over the final mile. The actual top speed at the end of the 3-mile pass was 145 according to GPS! By the end of that event 6265 racer had managed to achieve a best average of 153 MPH with 157.5 as it max GPS-recorded speed at the three-mile marker. Yes, we were happy!

The 6265 racer is registered in DT class (diesel truck) which is a class that allows a wide range of performance upgrades with limits on engine displacement and fuel. And if water injection is used, only pure water is allowed. Chemical enhancements, such as methanol, propane and nitrous oxide are strictly prohibited. Team 6265 would appreciate ruling in this class that segregates trucks according to fuel system type. The more modern common rail equipped engines should compete with one another and distributor type injection pump trucks would compete with others in their own, separate class. At this point in time, however, this distinction is not made, so the 6265 truck must compete against all comers, even those with common rail, in spite of the vast differences in potential.

The limit on power imposed by the 6.5’s comparatively fuel-stingy Stanadyne DS-4 injection pump is a very real one and the team knew its only hope was to squeeze every last bit of power it could from what fuel is delivered. Toward that end, it would have to focus on doing everything possible to maximize diesel combustion efficiency.

The team has often referred to the racers engine as being ‘near-stock’. Near-stock in this case means using as many of the factory engine components as possible; however, in the interest of longevity, a few aftermarket upgrades are used. One is the crankshaft. Heath uses the excellent, cast steel replacement 6.5 crankshaft built by Scat Enterprises. This crank features the stock stroke length, so it has no affect on power output; however, in consideration of the engine’s relatively high power output and 5,000-RPM engine speed limit, the Scat crank is considered to be low cost insurance. The 6265 racer runs a higher-than-stock static compression ratio at 22.5:1. In addition, we force feed it with 31 PSI boost. This equates to fairly significant peak cylinder pressures and a great deal of both momentary / dynamic loading on the rotating assembly and its main-bearing support system. We are convinced of the superiority of the SCAT 6.5 crankshaft and likely would not attempt this feat with a factory unit. Even though the factory crankshafts just do not wear out, they can sometimes fail due to internal flaws. We find solid value in the improved material and manufacturing method used by SCAT in building this replacement crank.

Other upgrades include ...

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