Written by Bill Heath Monday, 02 November 2009 17:13

Heath Diesel 6.5 Land Speed Racer at Bonneville 2009

Bill Heath flashes the victory sign at a Bonneville 2009 event We appreciate your interest and support! We will continue in our efforts to maximize the near-stock engine and fuel system package until we are satisfied we have achieved all it can deliver. Then we will move on to phase two in our quest to push the truck to 190 MPH.

Because we wanted to make some upgrades to our racer’s ’08 engine and because time was rapidly running out for getting it done in time to attend the August '09 Speed Week event, we opted to reduce the stress on ourselves and cancel out of all three 2009 Salt Flat events.

In a last minute decision, some of the guys and I decided to attend the August Speed Week event as spectators. That did it! Before we knew it, those go-fast flames had been rekindled. On the way home, we brainstormed about building an interim engine for the September and October 2009 events. Time was tight so this engine would not be able to use the planned-on upgrades for the race engine. Instead, it would be a more conventional build up of a standard engine: much more similar to we find in our everyday drivers. Then I learned that our engine machinist, Rich Eims of Joe’s Grinding in Yakima, was on vacation and would not be able to complete necessary machining operations in time to support our schedule.

Heath Diesel 6.5L LSR Revived

As we were scooting along across the wide open spaces between Bonneville and Ellensburg, the phone rang and I found myself talking to Jamie and Benny Avant of The Diesel Depot in Georgia. They too had been thinking about a way to get us onto the Salt for the upcoming events. They agreed that an interim engine was the way to go. When I explained the dead end we had come to in our efforts to get things together in the few weeks remaining, they surprised me with an offer to supply an engine out of their engine building facility in Georgia. I quickly called Todd Hughes back at the office to discuss how we might work this out in the 19 days left before the first of these events. I then called the Avants to advise them of our acceptance of their generous offer.

After a discussion, we decided that The Diesel Depot would supply a later model 6.2 with the one-piece rear main seal. We chose a 599 casting made in December 1991. The crankshaft is one of Scat’s fine replacement units fitted with King bearings set to a 0.002-inch clearance on both rods and mains. The engine uses the Heath Diesel Main Stud Kit and the block is line honed. We would resize the rods to factory specifications at both big and little ends. The wrist pin-to-rod bushing clearance, especially important for our application, would be set within the factory range of 0.0003 to 0.0004 inches. The wrist pin-to-piston bore clearance is established by Mahle at 0.0004 inches. These wrist pin clearances are critical for our application in order to keep the engine alive at the high power levels that our diesel engine would experience. The pistons would be regular Mahle 6.2L replacement units with a 0.010-inch reduced compression height to allow room for decking the block. We wanted to have the pistons up, out of the cylinder bores 0.006 inches and that is exactly how it all ended up. The pistons were treated to The Diesel Depot’s ceramic thermal barrier coatings and fitted to the cylinder walls at 0.0055-inch skirt clearance per our request. We wanted the compression ratio to be close to the factory stock 21.3:1. This engine worked out to 22.5:1. All of these details are pretty much standard Diesel Depot production techniques: just a simple and straightforward engine with a piston-to-wall clearance that is revised to suit our unique, land speed racing application.

Per the plan, The Diesel Depot would ship the engine in short block form and we would install the cylinder heads from last year’s race truck using standard FelPro gaskets and the ARP cylinder head studs. Those cylinder heads were also built at Diesel Depot. Per our specs, they are standard 6.5 diesel castings that have been machined to accept 1982 J code 6.2L intake and exhaust valves in place of the standard 6.5 units. These are larger than 6.5 valves at 1.96 and 1.63 inches respectively. The 6.5 valves measure 1.81 and 1.53 inches. Other than the machine work necessary to fit the valves, these heads are as cast without port work of any kind. The exhaust port runner passages are thermal barrier coated.