What makes Bill Heath's land speed race truck so interesting is it's based on a real production truck. It's a common '95 Chevy 1/2-ton, extended cab, short box, two-wheeldrive diesel, with a 4L80E automatic transmission. This particular truck served its original owner for 290,000 miles before it fell into the waiting hands of the 6.5L gurus at Heath Diesel. After a concentrated, year-long build, the truck debuted at the September World of Speed event on the Bonneville Salt Flats.
The World's Fastest 6.5L Diesel
The Heath Diesel land speed racer streaked to a solid 153mph pass across the salt in Bonneville, Utah, thrilling team members and supporters worldwide. Driver Bill Heath is confident the truck could have gone faster if he had driven a bit more aggressively-this was only his fourth pass across that great white expanse, and he was still getting a feel for the truck. In any case, 153 mph for a full-size Chevy pickup powered by a stock-block 6.5L is nothing to be ashamed of. Interested gearheads everywhere want to know how such a feat is possible-after all, isn't the 6.5L a slug?
Making it Possible
In today's world of common-rail injection systems, fourvalve heads, and crazy power levels, the indirect-injection 6.5L is often left standing in the shadows, but not on this sunny day on the salt. The guys at Heath Diesel are quick to point out that, while this engine may never be able to drag the world away, with the right modifications it can be reliable, fuel efficient, and able to produce sufficient power. The Heath team made the decision early on that its racer must be as close to stock as possible, and this included using the factory issued engine. In order to achieve its power goals, the team needed to make sure the engine would stay together.
Block and Internals
The Heath guys believe firmly in filling the coolant passages within 5/8 inch of the deck surface with hydraulic cement. Filling these passages strengthens the block, and decreases bore flex while tying the cylinders more securely to the main bearing caps. Heath Diesel allows 45 days for the process prior to any machine work, and claims that this process does not result in a negative affect on cooling. In fact, all Heath engines, even those used in heavy towing, are treated to this same process. The block was then machined, and with the exception of the crankshaft, was fitted with stock internals.
The stock 6.5L block was paired with twin S200 turbochargers from BD Diesel and water-mist
Here is the Chevy nearly ready for paint.
GM Sandlewood was applied by Brian Maybee's McIntosh Auto Body in Ellensburg, Washington.
The crankshaft is one of Scat's high-quality 9000 series units that the Heath team trusts more than a high-mileage stocker. The connecting rods were carefully checked for any flaws, heat-treated, fitted with new GM bolts and bushings, then brought to factory dimensions. The cylinder walls were sized to Heath's specs to provide a piston-to-cylinder wall clearance of .0057 inch with a super-fine wall finish. The pistons are Mahle standard compression height replacement units treated to Performance Coating's Tri-Coat process. They were set to factory specs (.006 inch out of the hole). This, combined with a .045-inch Cometic multilayer steel gasket, delivered a stock compression ratio of 21.3:1.
Heads and Valvetrain
The factory issued 6.5L heads on this engine were outfitted with larger valves, as used in the '82 6.2L J-code engine. Other than machine work necessary to fit the valves, the heads are bone-stock-no port or runner work of any kind. Valve stem clearance is on the tight side of GM's spec range at .001 inches on the intakes and .0012 inches on the exhausts. The entire valvetrain, including the sprockets and chain, camshaft, followers, pushrods, rockers, springs, retainers, and seals are stock. The intake manifold is a stock, unaltered unit from the L65 heavy-duty 6.5L engine.
The fuel injection pump is an out-of-the-box stock Stanadyne DS-4 5521. The injectors are Heath's own high-output units. The fuel lift pump is a special version of the AirDog, with delivery pressure reduced to 7 psi. The computer programming is Heath's GL4 series with a higher rpm limit. The GL4 is supplied to customers with a 3,700rpm limit. The program used in the Bonneville racer is altered to rev to a limit of 4,150 rpm.
Turbos and Water Injection
The only areas of the engine that were radically modified are the custom tube-type headers and turbochargers. The headers were fabricated from .125-inch wall DOM tubing and coated by Performance Coatings. The turbos were engineered by John Todd of BD Diesel Performance, and are based on non-wastegated Garrett turbo models. The truck was outfitted with Heath's computer-controlled Water-Mist injection system for intercooling. The truck is restricted by class regulations to diesel and water. No nitrous, propane, or methanol are allowed.
At 153 mph the engine is at 3,900 rpm, and feels as though it could stay there all day. The truck runs along with a coolant temp of 190 degrees, and the exhaust gas temperature stays at 1,150 degrees. The boost pressure is at 22 psi, and the intake air temp is at 130 degrees. The transmission in the racer is the factory 4L80E that came in this truck. The rear axle, however, has been updated to allow quick and easy axle ratio changes. Heath used a Ford 9-inch from a Lincoln Mark IV. The Mark IV axle happened to fit this two-wheel-drive truck perfectly, as it is the exact same width as the Chevy, and the lug bolt pattern matches the truck's original design. The axle ratio used on the 153mph pass was a 2.75. The final overall ratio when in Overdrive is 2.06. The racer rides on Goodyear land speed race tires fitted to wheels specially fabricated for this particular application by Nate Jones Tire in Signal Hill, California.
In the interest of safety, the racer is outfitted with a rollcage and driver cocoon built to Southern California Timing Association (SCTA) specs by John Ramey of Yakima, Washington. The Heath racer features a near-complete factory interior, with factory dash, headliner, door panels, cab surround panels, and carpet. The truck retains functional wipers, lights, power windows, cruise control, stereo, and tilt wheel. McIntosh Auto Body in Ellensburg, Washington, suggested the GM Sandlewood color, telling Heath that this would help enhance the sleek appearance of the truck, and we agree. The Heath team has driven its racer some 2,000 miles on the highway, and reports that it will deliver more than 30 mpg if held to the speed limit. Freeway driving is done in Third Gear because of the 2.06:1 final ratio in Overdrive.