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Monday, March 15, 2010

Heath Diesel 6.5 Land Speed Racer at Bonneville 2009

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.We use new factory valve springs on our heads along with factory retainers, oil shields, oil seals and keepers. We shim the valve springs to increase seat force from the factory recommendation of 83 pounds to 100 pounds in order to affect better valve control at higher engine speeds. We have learned that the factory valve train, with the springs set to 100 pounds closing force, is stable to 5,100 RPM. We subjected the springs to an overnight stint in the bench vise, squeezed to coil bind in order to help settle and normalize them for the duty they will see.
The Diesel Depot builds its engines using new, high quality camshaft drive sprockets and chain and that is how this engine arrived. We are perfectly content with high mileage used cam drive components chosing these over new in engines we build, but since this new stuff is already in place in this engine, it will be fine. The factory spec on these parts sets out chain side play of 0.500 inches with new parts. It lists the wear service limit at 0.800 inches. Most engines we have seen, even those with 250-300,000 miles on them have chains which are still well within spec range.
In keeping with our theme of factory stock equipment in our racer’s engine, and to the surprise of many, we use factory camshaft, cam followers, pushrods, rocker arms and valve-train-related pieces. This includes factory valve stem seals, springs, oil shields, retainers and keepers.
The Diesel Depot 6.2 engine arrived on a Thursday. We wasted no time in getting it put together and into the truck: it was installed and running the next day. Because I wanted to settle the cylinders, I drove the truck about 600 miles on Interstate 90 back and forth between Ellensburg and Spokane. This freeway driving helps to settle in the cylinder walls to produce a good seal with minimum friction.

Important Changes from Last Year

In last year’s engine, we ran the standard oil pump which seemed to work fine in the range of RPM to which we subjected the engine. In an application such as ours, we must take into consideration the capacity of the oil pan, oil pump flow rate, oil flow into the upper part of the engine as well as the return-flow of oil to the oil pan. In the case of last year’s engine, all these factors were in a good enough balance to provide adequate lube system function. At least, it maintained oil pressure and the bearings all looked great.
this year, we had plans of trying a couple of different rear axle ratios, both higher and lower than last year’s 2.75:1. If we were to run the lower axle ratio and buzz the engine higher, there were concerns about how the high volume oiling system might respond to this higher RPM. With the lower axle ratio, we could be running the engine to around 4,800 RPM and for extended periods. This is fully twice the RPM these engines normally experience and since the oil pump is a positive displacement type, RPM has everything to do with how much oil is pulled out of the pan and forced to the upper regions of the engine. In spite of our success with the smaller oil pump last year, we decided to experiment with the high-volume pump this time around which proved to be a real learning experience. The high volume pump I refer to is the one found on engines produced with piston cooling nozzles (’97 and newer). This high-volume pump is popular on remanufactured engines, those built for normal pickup truck use and, in that application, it works well. In our application, though, because of the high RPM we operate at, we were concerened about
  • the volume of oil this pump would move at higher RPM operation, 
  • how much oil would gather in the valve covers and 
  • how long the supply of oil in the pan would last without running low enough to suck in air.
It is a widely understood fact that a big pump will put a lot of oil upstairs, unless there is some restriction to oil flowing through the pushrods to the rocker arms. Regretfully, I chose to use the big pump without any changes to affect a restriction of top end flow. I fretted about this all the way to Bonneville. I knew better and somehow, most likely the time crunch, allowed myself to proceed. Todd and his guys had created a big, bright low-oil-pressure warning light set to illuminate at 60 PSI decreasing pressure. Fittingly, they were calling this an ‘idiot’ light. The idea was that this would alert me to any oil starvation issue in time to save the engine. Looking back with 20/20 vision, I cannot believe I risked the outing on such an experiment, when the old low volume pump setup had worked so well.

Making the Pass

As you will recall, the World of Speed event in 2008 was our first time out with the truck and it was my first time driving on the Salt. Event officials harped on the importance of salt virgins like me taking it easy on the first laps, to avoid the temptation of being a hero. I responded to that stern advice, driving the truck in a very conservative fashion. This year however, would be a different story. I had decided to pour the coal to it, to feed in all the power the tires could hold on the salty surface. I had learned enough about how the truck feels to be confident in it and I also learned that, in reality, there is a limit to how many times we would get to make a pass each day. I planned not to waste a single opportunity.
6:15 AM – On the roll toward staging lanes. We love the unmatched beauty of this strange and interesting place. 
In the staging lanes at World Finals getting ready for our first pass; 58ยบ and sunny. 
8:00 AM – Drivers’ meeting on the opening day of World Finals. 
What a lovely sight to behold! The black lines are 120 feet apart but seem very close to one another at speed.
The 6265 racer can make a bit of smoke if crowded much before the turbos are stirred up. Runs clean and clear down track.
When Team 6265 finally got its turn to go, I went into the throttle fairly aggressively. The diesel engine sounded good and came on strongly as I squeezed the pedal down to something like 75% power. As I left the starting line behind, the tires were on the ragged edge of spinning and the truck quickly accelerated up to the 4,500 RPM shift point. I shifted into second gear before I pushed the throttle to the mat. With a split-second to take my eyes off things ahead, I scanned the gauges. The boost pressure gauge was climbing in sync with the tachometer, reaching 30 PSI when the engine reached 4,500 RPM. I shifted to third gear at 90 MPH. With the shift accomplished and the engine settled down and pulling in third gear, the boost pressure was again on its way back up to 30 PSI. The pyrometers are both showing about 1300°F and the intake air temp is 130°F. When the tachometer had again climbed to 4,500 RPM, I moved the lever to fourth gear. The boost recovered to 22 PSI and again began the climb back to 30 PSI.
The engine felt good and the truck accelerated well as it climbed through 155 MPH. Then, just when things were feeling so good and as I was approaching the 1-3/4 mile marker, I detected a pronounced surge in power.
Please understand, I had waited a long time for this so was not going to give up and back out of the throttle until I was danged sure I had a problem. Then, I scanned the gauges to find that they were beginning to do goofy things. The pyrometers were climbing and the boost had hit 35 PSI when smoke began to pour into the cab around me. Any uncertainty I had up to that point vanished. Without doubt, the time had come to get out of the power! I got on the brakes hard in order to slow down enough to turn off track. 5,600 pounds of Chevy diesel does not stop on a dime. When I had slowed to about 50 MPH, I began my turn out. Clear of the track and while rolling across to the return road, I was busy getting all the safety gear undone. If this dude was on fire I needed to get out quickly. As I rolled to a stop, I realized that the engine was still running and that it did not sound so good. But it was running and it still had oil pressure.
About this time, one of the fire-rescue crews skidded to a stop near me. They were concerned about fire and safety, pointing out a big cloud of smoke hanging over the course back around the two-mile marker. Back in the pit area, we began a basic forensic study and found that the crankcase depression regulator (CDR) hose was full of oil. We determined that the CDR system had pulled in some oil which had apparently gotten pretty deep in the valve cover. This fed a slug of oil to one turbo which then blew it into the engine resulting in hydrostatic lock and bent connecting rods. Our day was done. Certainly, we now had a wounded engine to deal with and even though we were not able to achieve our goals, we were still a happy bunch; we appreciated this experience and were happy to be here on the Salt with kindred souls.

The Heath Diesel Bonneville Team

Our On-The-Salt team this year is comprised of these dedicated folks:
  • Ted Rich of Mt Vernon, WA
  • Curt Huffman of Seattle, WA
  • Paul Weddle of Salt Lake City, UT
  • Joe Heath of Ellensburg, WA
  • Cody Jackson of Ellensburg, WA
  • Jamie Avant of Sandersville, GA
  • Kent and Barb Pearson of Othello, WA
We appreciate them one and all. Without them we simply would not be able to do this thing we love to do. Thanks to all!
Sacrifices to the gods of speed at Bonneville World Finals 2009. 

6 AM on the Salt Flats, checking the truck out before we push down to the staging lanes for our first pass.
World Finals team members Curt Huffman, “Yer ol’ Dad”, Paul Weddle and Jamie Avant, enjoying the experience together. 
6265's Engine bay... Plans include upgraded intake air system for next season.

Heath Diesel Post Mortem

Once we were back home, we removed the engine and dismantled it for inspection. Four connecting rods were very crooked and a lot shorter than they should have been. The ingested oil, which is not compressible, had been trapped between the piston and head; the result was rods that had been smushed about 0.25 inches. Todd dubbed the engine The Python in honor of its crooked connecting rods. We were impressed that the engine had not broken in two and that it would still start and run. In fact we drove it onto its trailer to come home and drove it into the shop when we got here. I feel badly to my team and the 6.5L diesel community that the opportunity was, in large part, wasted. I should have predicted and avoided the outcome, but pursued it to its smoky end. Our plans for this engine are to fit it with new pistons and a set of straight rods. We also plan to change back to our original program with stock, low-volume oil pump. In the interest of assuring better control of oil, we will engineer a change to restrict oiling to the upper engine.
From the outset, our primary goal for the 6265 racer has been to achieve the highest speed we can with its near-stock engine. We will continue to work this package through 2010 or until we are satisfied that the combination has been optimized for maximum 6.5 diesel performance. Then and only then, we will move into phase two. We feel that the current engine configuration is good for still more power, that the limiting factor today is with the current DS-4 injection pump. We will be looking at a variety of ways to add power and will make sure you are there with us through this phase of the project.
We also plan to change from the current automatic trans to one of the new Tremec TKO 600 5-speed gear boxes. It will handle the torque well and it has a far more favorable set of gear ratios: most important is the split between fourth and fifth. We want to keep the shift recovery RPM well enough up into the power band. The .82 overdrive fifth gear in the TKO 600 box will do very well for us. Unfortunately, this upgrade will have to wait untill we can con our comptroller (Mr. Meanie) out of the $3,500 we need to make the change!
Rest assured, we will continue to pursue our goals with the 6265 racer and we will do everything within our power to make the 6.5L diesel community proud. We want to encourage you to consider doing a 6.2/6.5 diesel project vehicle for land speed racing. I cannot imagine a more rewarding endeavor and we would surely enjoy seeing you on the Salt. Till we meet again, the Heath Diesel 6265 team remains respectfully yours.

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