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Monday, June 15, 2009

Heath Diesel 6.5L Land Speed Racing Truck at Bonneville

September 2008, Bill Heath raced the Heath Diesel Team’s 6.5L GM Diesel pickup at Bonneville. maxxTORQUEfeatured the vehicle in our Summer 2008 issue before the event. Now, here is a look at the Bonneville performance and what’s inside that makes this truck – that could pass for a daily driver – fast...
Heath Diesel Power’s 6.5L GM Turbodiesel Land Speed Racing truck ran a solid 153 MPH on its first trip to the Bonneville Salt Flats – that felt pretty darn good. Knowing that she has more speed in her yet – that’s even better. Here’s a look at our experience at Bonneville and the details of the build that got us there...

When we first schemed to build the 6.5 land speed racing truck, we saw it as an opportunity for the Heath Diesel gang to have some fun and to give each member a chance to exercise, and maybe expand, his automotive skills. Someone suggested that if we could manage to go fast enough, it would be a great way to champion the 6.5 diesel engine for customers and fans around the world. From that moment on, our project took on a new and vastly more important meaning. We were now more focused and determined to do our best for 6.5ers everywhere – and maybe even give them some bragging rights.
Early on, we decided that our racer should be a full-sized truck with a near-stock 6.5 engine. Of course we realized that we could run faster if we used the smaller S-10 truck; however, GM never offered the 6.5 in the S-10, so such a vehicle would not accurately represent the trucks our customers drive. While modifications would be necessary to get the needed power, we endeavored to keep these modifications to a minimum and, in every way possible, retain original equipment components.
Heath Diesel 6.5L Land Speed Racing Truck at Bonneville
To our knowledge, no one before us has entered a 6.5 at Bonneville and, while we were excited about giving it a go, we were a little concerned about being able to reach a decent speed. Understandably, when working with an untested combination, there is no way to know for sure how it will perform until you give it a try – but we sure did not want to embarrass ourselves. Our calculations suggested we ought to hit 138 MPH; we would certainly have been happy with that. However, we could not know for sure if the truck would even reach 120 MPH. Those with experience on the salt will tell you: do all the calculations you want, but you will never really know until you turn it loose across the flats. You learn, make changes and try again. But then, isn’t that the fun of it?
With no obstacles on it to bump into, the gleaming white and seemingly endless expanse of the Bonneville Salt Flats is a super neat place to go fast, there is just no doubt about it. However, one cannot ignore its 4400-foot elevation and 95-to-105°F race-day temperatures. These two conditions combine to drive the density altitude up toward 11,000 feet on some days, plenty high enough to hinder the production of power. Not knowing for sure what to expect from our combo – and most especially how it might react to the high density altitude – all we could do is take our best shot and see what would happen.

On the Highway

The racer is a very civilized vehicle. It starts and runs just like any other 6.5. It rides well and is quiet and smooth on the road. With its tilt-power steering, power windows, cruise control, stereo and cup holders, it’s a fine cruiser.
We have taken it on some longer journeys to settle the engine before going to the Salt Flats and found our racer to be a very good highway traveler. At 70 MPH, the truck runs in third gear at around 2,200 RPM where it usually gets better than 30 MPG.
As for acceleration performance, the truck moves away from a stop quite well in normal driving even though it is still a naturally aspirated engine under this low-RPM, low-load condition. The turbos do not really begin to contribute much before 2,000 RPM. You can run around town without any exhaust smoke and more than keep up with traffic, no problem. When you get into the throttle a little further, however, and with the tachometer swinging through 2,500 RPM on its way up the scale, the engine starts to make very good power. By about 3,000 RPM, it is coming alive and pulls strongly from there to our 4,600 RPM limit.
From a stop, if the go pedal is suddenly pushed to the floor, the 5200-pound truck moves out fairly briskly. Then, while still in first gear and as the engine gets up into its happy zone (3,000-plus RPM), the power comes on well enough to squall the tires. However, because the transmission gear-ratio spread is wide, the first-to-second gear change results in a shift recovery RPM that is below this happy zone; so there is a lull in the rate of acceleration until the engine can recover into that 3,000-plus RPM zone once again. The second-to-third shift is a better one as the gear spacing is a bit closer, so the shift recovery RPM is higher and the engine is not pulled quite so far below its power zone. The difference in ratios between third and fourth gears is even less, so the shift recovery RPM on this shift is much better and the engine can continue a good strong pull as it moves into fourth gear. Keeping in mind that the Land Speed Racing Truck was never intended to be a drag racer, the net result is this: the truck’s acceleration is only OK up to about 50 MPH. Because each successive gear change results in more favorable shift recovery RPM, it pulls harder and harder as speed builds. By 80 MPH, it is accelerating quite well. It tops out at 90 MPH in second and reaches 133 MPH in third at which point the third-to-fourth gear shift occurs. On this final upshift, the shift recovery is 3300 RPM which is close to the bottom of the power range and still good enough to pull on out and continue to accelerate well on up to top speed. As you might well imagine, our full-sized truck is up against a pretty tough aerodynamic load at 133 MPH so having a good shift recovery RPM going into fourth is critical to be able to continue the acceleration on up to top speed.

On the Salt

The Bonneville experience is totally unique. I know of nothing which can compare. Everything about being here is so rewarding; however, the real excitement happens when the starting line official has given his signal that the course is yours. That is when all the efforts pay off and when we get to see just how fast our racer will run.
For a thirty years, I have stationed myself at the starting line to watch others take off across the salt, thinking all the time that someday, somehow, I would know this thrill. That thrill was finally realized in September, 2008, when the Heath Diesel team rolled our entry toward the starting line to make its first pass. I had long envied those who made their dash across the salt flats in hot pursuit of the dream: and now, I was about to join their ranks – I can barely contain myself! Being here is great, being here to drive on the salt – well that is the best! As we wait our turn, slowly inching our way closer to the starting line, my team helps me into the driver safety gear and secure me into our racer. At long last, we are getting closer to knowing the thrill of running flat out on the Bonneville Salt Flats!
During our time in the staging lane, I have started the engine a number of times to help keep some temperature in it prior to blasting off. While we would much prefer having the engine oil, coolant and automatic transmission temps up to a normal level, we simply cannot achieve these under the circumstances. Still, I want all the temperature I can muster, so I try to have things as warmed up as much as possible.


Ready, Set, Go! The Heath Diesel Power Team preps at the start line; receives some last minute “don’t forget you’re a salt virgin” cautioning from the start official, Monte, and then, the moment for which Bill Heath has waited 30 years – the signal to go.
When we are finally on the starting line, Monte, our starting line official, comes over to have a little chat with me prior to signaling the send off. Monte explains that he likes rookies to take it slow and easy until they develop a feel for the racer and the salt – no heroics please. He explains that the race surface, under the best of circumstances, offers about half the traction of pavement. He said that when an experienced driver takes off, he applies all the power the tires will hold on to in order to be at full throttle fairly early in the run. However, since I am a salt virgin Monte says I should move out slowly and easily, gradually applying power. He points out that there will be other runs and that these early efforts ought to be gentle in order to avoid a spin-out. Monte looked me right in the eye and said, “cool it dude”. He is a big rascal, so I listened. Then he leaned into the truck to check the fire control safety pin and to cinch-down my belts. He told me that it is important the belts be tight and he proceeded to give them a firm tug. Good grief – I thought my eyes were going to pop out! I could feel bones breaking and I couldn’t breathe! Then he told me to have fun and reminded me that he would see me on the next round. I was already dreading the next belt-tightening encounter.

Our First Mistake

From the outset, we had wanted to keep our truck as original as possible, so we opted to retain the factory shift lever. Mistake! Now that Monte had me so solidly belted down, I could barely reach that factory lever with my finger tips, arm fully extended. I could see that it was not going to be easy to affect precise control over gear changes so, at the last second, I decided to not try to change gears manually. Instead, I clicked the lever down to “OD” and figured I would let the computer do the upshifts when it wanted. Certainly, this would affect our performance as we had set the full throttle upshift points to make automatic changes at less than perfect RPM levels. I knew this would result in low RPM upshifts and that they would be lower still if I did not have enough throttle pressure as the result of trying to avoid wheel spin. I reasoned that even if it shifted way too soon to second and then third, I would still be able to run flat out in third and have a good third-to-fourth upshift.
I had the engine running for the last five minutes while waiting for the send off. The time was at hand: Monte receives the course-clear signal to his head set, turns to me and gives me the visor-down signal and then, in a most dramatic fashion, spins on his heals as he swings that big arm through an arc waving me off, down the track: a fabulous send off! After all these years, I was enjoying the thrill – I have finally gotten my signal to head down course and it was more spectacular than I had imagined. I have anticipated this moment for years and rehearsed in my head every step I would take, so I felt quite cool and calm. I was ready and on my game.

Pass Number One

Things did not work out so well on that first pass. I was pre-occupied just drinking in the experience of my first Bonneville run: the transmission was in third gear before I had gotten far, so I was forced to get into the throttle to try to keep it there in pursuit of a higher top speed. As it turned out, I did not get into the throttle soon enough to prevent an early third-to-fourth shift. As a result, engine RPM was pulled down below the happy zone. So here I was, climbing through 110 MPH in top gear at only 2700 RPM – way below where the engine would like to be. It would have been another mistake to try to downshift so late in the game. I just pushed the throttle to the floor and held on. The engine eventually climbed out of the hole I had dug for it and began to get stronger as the RPM moved beyond the 3,000 mark. Despite this trouble, the pass was smooth and straight – and boy, was it fun! As I passed the three-mile marker, I gently rolled out of the throttle and coasted down beyond the four-mile point, to the turn out and then moved over to the return road where I was met by my chase crew. I was quite surprised to learn from them that I had reached 141 MPH – not bad considering the trouble I had encountered. I called Todd back at the shop with the news about the shifter. Now that I was over my demand for a stock shifter, we would move a proper ratcheting shift control and get down to business.
Inside the 6.5 LSR, Bill Heath is all buckled up and ready to run his first pass at Bonneville in September 2008.
I learned some things on that first pass and decided that on the next one I would get further into the throttle earlier in the run. I wanted the upshifts to occur at higher speeds. Clearly, shift recovery RPM was critical to a higher top speed, something I knew we would not be able to achieve under the first-run configuration.

Pass Number Two

On the second pass, things worked better. Still, the first-to-second and second-to-third upshifts occurred much too early but this time I got the pedal down far enough to cause the third-to-fourth upshift at around 100 MPH. This helped the shift recovery RPM going into fourth and the engine was farther up the RPM scale where it could pull harder. This time the truck ran through at 145 MPH. I was getting more comfortable with the feel of the racer and liked it very much.

Pass Number Three

By the third run, everything – myself included – was working better. I got into the throttle deeper and sooner which caused higher speeds in each gear before the automatic upshift – the engine responded favorably. I had the throttle into the carpet while the transmission was still in third gear and the truck was pulling quite well when I was surprised with a too-early upshift to fourth at only 110 MPH and 3,700 RPM. I had missed the mark when we created the unique power program: I had it telling the engine to do full throttle third-to-fourth upshifts much too early. This early upshift resulted in a shift recovery of only 2,775 RPM. Now, the truck faced a long hard climb on out to top speed. Having it get into second and third early did not pose the same issue as this early shift into fourth. At the lower vehicle speeds, the engine did not have to deal with the much greater aerodynamic load of the higher speeds, so it can more easily continue to accelerate, even if the RPM was low.
Even though things were – once again – not perfect, we still managed a solid 149 MPH and we were all thrilled. When we realized that we had come close to the magical 150 MPH mark on that third pass and I could see that we could do better by managing the transmission upshift points, we knew that there was still more speed to be discovered in our racer.
We talked it over and decided to manually control only the third-to-fourth gear change on the next outing. While I wanted to avoid any potential issues in moving the shift lever at arms length, I felt comfortable enough by now to hold third on up to the RPM that we needed and to make that shift to fourth myself when ready.

Pass Number Four

I took off very much like the previous pass, letting the transmission move into second and then third on its own; but this time I had the throttle fully into the carpet by about 90 MPH and I held third gear until 4,500 RPM and 133 MPH. As a result of this later third-to-fourth upshift, shift recovery was 3,350 RPM – the engine really appreciated the help. When I got up to about 3,700 RPM in overdrive (148 MPH) and as I closed in on the two-mile marker, the rear end of the truck began to dance or skate around like it wanted to spin the tires and I think that was probably what was happening. Certainly, this had my attention; however, being slow-witted, I kept the pedal buried as I concentrated on keeping it straight down the chute. Clearly, sudden moves would have been ill advised. Later that day, long time salt racer Bill York, from the Burkland streamliner team, told me that having the rear skip around like that was a normal sort of thing and that we needed to add ballast over the rear axle. He figured 250 to 300 pounds ought to solve the problem and that it would buy us some margin until some higher speed might require more.
Even though the truck was slipping around some, I continued my pursuit of higher speed over that next mile. As I closed in on the three-mile marker and the final timing point, I was getting to be a little less anxious about the rear end dancing around. I took time to scan the gauges and take a look in the rear view mirror. Wow! What a sight greeted me there: the view to the rear was totally obscured by a white-out of salt spray-very cool, indeed. After going past the three-mile marker, I eased back out of the throttle and began to slow down. I had the stereo cranked up loud enough that I could here the announcer broadcast my speed. I was totally thrilled when I heard him broadcast 153 mph!! Just past the four-mile marker I pushed on the brakes and made the gentle swing off course and over to the return road.
Rolling to a stop on the return road, I was comforted by the familiar sound of my trusty 6.5 as it chuckled away at idle RPM. As I sat there waiting for the turbos to cool, it struck me that, while this had been a big deal to me, the engine sounded no differently than it would after a trip to the corner grocery: just another day for this as-close-to-stock-as-possible 6.5 I guess. When my chase crew came driving up, I could see that they were really jazzed up – that was definitely worth the price of admission. It occurred to me then that this had been the coolest automotive event I had participated in – ever! No getting around it now: I was solidly hooked.
As it turned out, we would not have another chance on the salt that day, the last day of the event. If I had known time would run out, I would have driven our racer differently, in spite of the hard to use shift lever and I would have held each gear to maximum RPM. I am convinced, based on what we learned here that we could have run faster. However, we may have had trouble getting any more speed without the ballast Mr. York suggested; so maybe it is just as well we stopped when we did. We are plenty happy with the result and know we can do better. Based on all we have learned, we are confident in making 160 MPH or better next time out. Our buddy, Pat McSwain, and his Duramax currently hold the 166 MPH record in our class. We may never be able to break Pat’s record, but our little ol’ 6.5 will be knocking on the door. Hello Pat-anyone home?

Building the Vehicle

An important milestone in this project was starting with the right truck: that meant a C-1500 extended cab, short box diesel, if we could find one. If we had to, we could retrofit a gas pickup but that would not be quite the same because we wanted a real diesel truck. We were thrilled to find exactly the truck we wanted, a one-owner vehicle not far from our shop. Mr. Kent Pearson of Othello, Washington had purchased it new and then logged more than 288,000 miles on his trusty Chevy before we drove it away.
The conspicuous twin turbos – visible at far left and right of the engine – are one of the few design modifications for the near-stock 6.5L Land Speed Racer.
The 6.5L Suburban featured in the Winter 2007 and Spring 2008 issues tows the land speed racer en route to its first runs at Bonneville last September.
A view of the engine block from above showing the cylinder head intake ports. 
A look at the engine block from the driver’s side shows the exhaust ports.
Our goal was – and continues to be – to go as fast as possible with a near-stock 6.5 and, so long as the engine’s original components checked out OK, we would reuse them: including the block, connecting rods, cylinder heads, and camshaft/valve train. In keeping with the stock engine theme, we fitted it with standard compression ratio Mahle replacement pistons. In its final form, the racer’s basic block assembly is very much the same as the one that powers the Suburban used to tow the racer to and from the salt flats. Certainly, the racer’s engine would be carefully machined, assembled and balanced; everything would be engineered to perfection, but still, it would be close to stock in every possible way.

The Block

In order to prepare them for heavy work, we do a number of upgrades to our 6.5 engine blocks and the racer would be no exception. After the block is thoroughly cleaned and inspected for cracking or other flaws, we sandblast the coolant passages to remove all traces of rust and scale from these cavities. Then, we install the main caps and special main cap studs (more on these later) and torque them in place. We also install both cylinder heads with used head gaskets and the ARP studs. The studs are torqued to finish specifications. Then, after everything is cinched down, we spend time ringing the block. We use a 16 ounce ball-peen hammer to bang on virtually every surface of the block except the machined ones. This procedure is intended to help relax the casting in order to reduce the chance of cracking. We usually spend three to five minutes ringing the block in this fashion. Admittedly, a certain feel is necessary to do a proper ringing and, as you might have guessed, experienced ringers are few and far between.
Next, we remove the heads in preparation for filling the coolant passages with a concrete-like material that solidifies around the cylinders. This process of filling the coolant passages improves rigidity of the block assembly to make it better able to deal with the forces generated during periods of higher output. We fill these passages with a product known as Hard-Blok. There are several manufacturers of block filler and while we have tried them all, we prefer the Hard-Blok brand. Filling the block in this way virtually eliminates flexing of cylinder walls to promote a superior piston-ring to cylinder-wall seal. The filled block is far more stable – thermally and dimensionally – so cylinder walls, crankshaft mainline and cylinder-head deck-surfaces suffer less stress and distortion.
With the block mounted onto an engine stand, we install all expansion plugs. Then we position the block to level one head gasket deck surface. We apply a piece of tape over each water pump port, covering the lower two-thirds of these openings.
Next, we mix the Hard-Blok exactly as recommended and use a funnel to pour the mixture into the coolant passages through the holes in the deck surface, filling these passages to within about 0.625 inches of the upper deck structure. We use a dowel rod to work the mixture into all nooks and crannies. We leave a 0.625-inch space between the upper surface of our concrete and the under-surface of the deck structure of the block casting to facilitate distribution of coolant from the block into the cylinder heads.
Immediately upon filling the passages, we install a head gasket and cylinder head, fastening it in place with the ARP studs and nuts. The studs are brought to full torque in sequence. Just as was the case with the main caps and studs. This step also helps to load the block with the stresses it will see when assembled. The Hard-Blok is allowed to cure with the block loaded in this manner. After the Hard-Blok is cured just enough to not flow when we rotate the block, we position it and level the other deck and repeat the process on that side.
Now, we remove the tape from the water pump ports and shape a passageway in the yet uncured Hard-Blok in each port to facilitate the flow of coolant. When done, we allow this trussed-up block to cure by putting it outside and exposed to the elements for fifty to sixty days so it can continue to cure and season before machine work begins. After the curing is complete, our rocked block is trundled off to expert automotive machinist, Rich Eims, owner of Joe’s Grinding in Yakima, Washington. Rich makes sure that all critical dimensions are brought to factory specifications in preparation for our build-up.
It is critically important that the crankshaft mainline be straight and its housing bores be round. The housing bores are machined to the smaller end of the dimension range for maximum crush or grip on the bearing shell. A part of the mainline machining process is making certain that the main cap register surfaces are perfectly square with one another – in both planes. These will sometime require machining; however, we find this to be an important factor in the life of a high output engine, so if it needs work, it gets done.
The later style, piston cooling-nozzle blocks are usually pretty crooked and tend to crack easily, so we avoid them altogether. No need to mess around with one of them when there are plenty of the older units available.

Main Caps, Studs And Torque

We use special 12 millimeter ARP studs and nuts in all 20 main cap positions. These are brought to torque in steps and in sequence. The inner studs are ultimately torqued to 95 pound-feet and the outer studs to 85 pound-feet. We take the torque up in small, ten-pound steps working the sequence beginning on number three main and complete them in this order: three, two, four, one and five. On the first pull, the inner ten studs are brought to 25 pound-feet. Then we do the outer studs to 25 pound-feet in that same cap sequence. Next, we go over all the studs – first the inners and then the outers – adding ten pound-feet each round until we reach 85 pound-feet on all. Once there, we do a final pull on the inner ten in sequence, adding an additional ten pound-feet to reach our 95 pound-feet total.

The Crankshaft

This engine features one of the new Scat 9000-series crankshafts. We have used a good many of these in the engines we build for company use. Scat uses superior material as well as advanced manufacturing processes to create a crank that is more durable in high stress applications. We think this is an especially good insurance policy in a higher output engine like this one and a very good idea for any rebuild.
Our Scat crank rides in King brand bearings. We believe that the King bearings are superior to the more conventional three-layer type. The King features two-layers; a precision built steel back with a 0.014-inch thick alloy overlay. This configuration delivers excellent durability in higher stress operations along with a superior ability to imbed foreign particles, thereby protecting the crank. We try to have 0.0018 to 0.0022-inch oil clearance on both rod and main journals with these King bearings. GM built these engines with select-fit bearings for the purpose of correcting for the crooked mainline and inconsistent housing bores. When the mainline is made to be straight and the housing bores round, any brand of regular replacement bearings fit and work well.

The Rods

The factory connecting rods were checked for cracks and flaws before being subjected to a trip through our oven. We feel that cooking the rods helps to relax the grain structure and reduce the possibility of failure. We strip them of their bushings and bolts before they spend 10 or so hours in our 430 to 450°F oven. They are brought back down to room temperature in 100°F steps over about six hours. When these are done to a turn, Rich installs new GM bushings and bolts and re-sizes the big ends to the small side of the housing bore specification range for a good tight grip on the bearing shells. Rich locates the pin bushing final bore center as needed to help equalize all piston deck heights.

The Cylinder Walls And Pistons

We like a very smooth finish on the cylinder walls. Rich hones the cylinders using 600-grit stones. We use a piston to wall clearance of 0.0054 to 0.0058 inches with the rocked block and coated Mahle pistons.
The Mahle pistons we used in this engine feature a 0.010-inch reduced compression height to help offset block deck-surface cuts. We send our pistons to Performance Coatings of Auburn, Washington for their Tri-Coat process. They apply a thermal barrier coat to the piston crown that extends down to the top ring grove, an anti-scuff coating to the skirts below the ring package and an oil shedding coat to the underside of the piston. We think this Tri-Coat process plays an important role in reducing the piston’s thermal experience for improved dimensional stability. We used the rings Mahle supplied with these 0.020-inch oversized pistons.
For compression ratio, we factor in the added thickness of the thermal barrier coating on the piston tops and combustion chamber surface of the cylinder head. When all is said and done, we set the piston deck height in this engine an average of 0.0035 inches out of the hole. At 22:1, the net compression ratio in our racer is a tad higher than GM specification.

Oil Pump, Oil Pan And Oil Cooler

We run an out-of-the-box 98-00 GM high volume oil pump. This pump, with the factory oil pickup screen, provides 30 to 35 pounds of oil pressure at idle and 55 to 60 pounds of oil pressure at 2,000 RPM in our older, non piston-cooled engine. We think it is best to run the pressure a little higher in our racer because of the 4,600 RPM it experiences.
The oil pan is the original pan and no mods are made to it. Likewise, the oil cooler is the one that came on the truck. The oil cooler lines have been replaced with new GM service parts for this truck.
As I related earlier, we run the engine while waiting our turn in the staging lanes to keep as much temperature in the oil as possible before the run begins. However, because we are forced to initiate our trips across the salt with less oil temperature than we like, we run full synthetic diesel oil because we think the stuff gets around better than the mineral type and so is better suited to our application.

Camshaft, Drive, Related Components

This engine’s factory-issued cam, lifters, pushrods, rocker arms, rocker shafts and cam sprockets were all in good, serviceable condition, so they were reinstalled. We did splurge on a new GM timing chain, but that was a waste: the original was still well within service specifications. We should have spent the money on pizza. The valve springs were replaced with new GM replacements; more on this later. We also replace the nylon buttons that locate the rocker arms to their shafts.

Cylinder Heads

In terms of their ability to fill the cylinder and the quality of the swirl they generate in the process, the 6.5’s intake port design is a very good one. The exhaust port in these heads is also a pretty decent design. This cylinder head design was originally created for the 6.2 engine, which debuted in 1982 as a naturally-aspirated diesel. GM engineers were challenged to produce maximum fuel efficiency with the 6.2 and the design of the cylinder head played a key role in getting that done.
Because these are an inherently good design and in keeping with our goal of doing the most with the least, we opted to limit our racer’s cylinder head modifications to some basic upgrades. For the first race outing we chose to leave the port runners alone and to confine our work to fitting the larger valves. We decided to install valves originally used in the heavy-duty J model 6.2 offered in 1982. These 1982 J valves measure 1.96 and 1.66 inches compared to the smaller 1.81/1.53-inch 6.5 valves. 
The assembled rotating assembly viewed from the bottom.
The cylinder heads showing coated combustion chambers and valves. 
The assembled engine, ready to be installed into the land speed racer.
Todd Hughes, the build’s supervisor, assembles components to the engine.
The head castings were machined to accept these larger valves, using angles that duplicate those used in the original 6.2 heads. Purposely, we confined our machine work to only what was needed to achieve the various approach, seating and departure angles. We performed no hand-blending of these cuts into the parent valve bowl or runner shapes. We wanted to minimize modifications until we had established a baseline performance. We believe that the potential exists for greater performance levels through additional, yet basic, valve bowl and port runner modifications and we plan to administer these in calculated and logical progressions. The next step will be a hand-blending of the valve machine cuts into the parent shape of the valve bowl and we plan to have that completed before the 2009 Speed Week event.
Our cylinder head combustion surface features a thermal barrier coating. The diameter of this coated area is just smaller than the head gasket bore in order to allow the gasket a smooth sealing surface. Because these engines have sufficiently thick head and block deck structures, they are more than stable enough to provide good head gasket loading, so we do not perform any deck O-ring/lock groove modifications.
While the original heads on our one-owner truck were in fine shape we decided to find a set that had none of the cracking common to these engines because we wanted our valve seats to be cut into crack-free material. We elected to cut the seats directly into the head casting and not to use hardened seat inserts because they would necessitate machine cuts much deeper into the parent iron that could threaten the integrity of the casting. A call to Jamie Avant solved the problem.
Jamie’s Diesel Depot had a set of crack-free castings and agreed to perform the machine work necessary to install the larger valves for us. We subscribe to the factory recommended valve and pre-chamber insert protrusion values and these heads were no exception to that. The only drawback to this particular head/valve package is that the valve seats must be cut into the casting outside the area of induction hardening; this will affect long term durability as the valve seats wear and recess. The modification is fine for the land speed racing truck; however, it would not provide a long enough service life for a daily-use application.
We set our heads up with valve stem to guide clearance on the tight side of GM specifications at 0.0010 (intake) and 0.0012 (exhaust) inches. We use the factory valve stem seals and O-rings. We also use the factory oil shields, spring retainers and keepers. We use new GM springs, shimmed to an installed height of 1.72 inches, which provides an increased seat force on the valve to help reduce bouncing of valves on the seats. This is exactly how we do all our company engine cylinder heads.

Head Gaskets and Studs

We always use the ARP heads studs because we believe that they provide a much more uniform clamping force compared to the course-thread factory bolts. We think that it is more than sufficient to use the studs in conjunction with Fel-Pro head gaskets in the majority of applications. In the land speed racing motor, we use the Cometic MLS gasket. We believe that the Cometic design is a lot friendlier to the block and head castings while providing superior strength of seal. We are convinced that, by virtue of design, the Cometic product is much more likely to endure in higher stress applications such as this one.
With the Cometic gaskets, we torque the ARP studs to 95 pound feet. We use the ARP-supplied moly lube on the threads and pull them in sequence and in steps starting with 25 pound feet, going up in 10 pound feet increments all the way up to 95 pound feet. We go through the sequence three to four times per step to help settle the gasket. When fully torqued and after the gaskets have settled for 48 hours, we go over the sequence at 95 pound feet a few more times.

Fuel System

We outfitted our engine with a stone-stock DS-4 5521 Stanadyne injection pump and a set of our high output fuel injectors. The truck uses its stock (and original) fuel tank. While our heavy duty fuel lift pump and the standard fuel plumbing are fully capable of supporting the engine up to 3,700 RPM, we elected to use an AirDog fuel supply pump and filter system in order to assure adequate supply at the higher RPM this engine would see. This particular AirDog was built with a seven PSI maximum delivery pressure. We also installed one of Tim Outland’s Feed-The-Beast fuel injection-pump inlet-fittings.
For the B/DT class in which we ran, only event-supplied diesel is used: no additives of any kind are allowed. Water injection is allowed as long as there are no additives such as methanol. This is a diesel and water deal – period.

Electronic Engine Control

Engine control in the 1994 to 2000 6.5 C-K truck is by way of a cab mounted computer box. The computer in the race truck used a unique Max-E-Tork program, specifically designed for the Bonneville event. This program is based on our regular production GL4 series program, modified from its standard format to provide the type of control we needed in the racer. Specifically, we reworked the fuel and start of injection timing schedules to stretch them out across a wider range of engine operation. In the regular GL4 program, these schedules are designed to control the engine up to a maximum of 3,700 RPM with peak torque occurring at 2,300 RPM and peak power occurring at 3,500 RPM. The racer’s program was reconfigured to allow control up to a 4,600 RPM limit. Peak torque and power values in the race program occur at 3,100 and 4,500 RPM respectively. The racer uses our regular production PMD Isolator system.

Cooling System

We use a standard issue 1995 GM water pump, the low volume unit it was supplied with when new. We use the original issue water pump because it requires about ten less horsepower to operate at RPM levels over 3,500. We run without a cooling fan or shroud – the truck runs cool in every driving situation we have encountered – and use a standard, original equipment radiator and Delco 192° thermostat (# 12559338). The truck is outfitted with standard hoses and coolant reservoir. We run distilled water in blend with Redline water wetter, which serves as a conditioner for the water to help prevent corrosion.

Headers and Turbochargers

The purpose of the headers and twin turbos is to help our engine breathe better at high RPM. We spin the engine up to a 4,600 RPM redline, which means a substantially greater flow of air through it than a stocker. Freeing up the exhaust side is critical to producing power in the 3,100 to 4,500 RPM range our engine experiences. Our unique system is designed to produce 22 PSI when operating at Bonneville on a typical race day. The headers were built for us by John Raney of Yakima. John built these using heavy-wall, drawn over mandrel (DOM) 1.625-inch (OD) mandrel-bent tube.
The extra thick header flanges that we used provide a sturdy base and allow blending of the exhaust port to the header tube. The tubes culminate in a simple four to one collector which mounts the turbo via six-inch mount flanges. The Raney headers were coated by Performance Coatings to help them retain exhaust heat and to reduce rejection of heat into the under hood space. The turbos were custom designed for our application by renowned turbo engineer, John Todd, of B-D Power in Canada. Mr. Todd really nailed them: these custom units could not have been more appropriately suited to our needs.

Exhaust System

We wanted our racer to deliver a quiet and refined exhaust note, so we had it outfitted with a single exhaust and big muffler. Eddie at Stan’s Headers in Auburn, Washington custom-crafted the beautiful, one-off exhaust system on our racer. He brought the two three-inch mandrel-bent turbo down-pipes together over on the passenger side, blending them into a single four-inch system which features a big, quiet four-inch straight-through muffler. The four-inch mandrel-bent tailpipe exits the truck behind the passenger side rear wheel. We are very happy with the system Eddie built for our racer – it could not be better. We wrapped the two down-pipes to keep heat out of the engine compartment. These two down-pipes feature ball-socket fittings at their lower ends to facilitate service. Nice system.

Intake Manifold

We run a stone stock L-65 F-engine lower intake manifold. The specially crafted plumbing which connects the turbos to the intake was built for us by Martin Fabricators in Yakima. Martin used heavy-wall seamless aluminum tubing to craft the unique manifold. Martin included features that allow mounting of the factory MAP and temp sensors. It all fit together perfectly – thanks, Martin.

Water-Mist Injection

The diesel-truck (DT) class we run in allows water-mist intercooling. Our racer’s system features full electronic control over the injection process. The Heath water-mist injection system on the racer is adjusted to begin administering the highly atomized spray at six PSI boost. It increases to 100 percent delivery rate when boost pressure reaches 16 PSI. A misting nozzle is installed in each of the two intake tubes. The delivery curve and injection rate are tailored to this unique application and would be far too aggressive for a normal highway truck.
Why water-mist instead of an air to air-intercooler? Simple: water-mist injection is much more compact and provides superior performance. The process dramatically reduces intake charge temperature and the water participates in the high temperature combustion process to create a super-heated steam resulting in an increased expansion ratio. That means stronger push on the pistons and over a longer portion of piston travel. That means more power, and all without the restriction to intake airflow inherent to the air to air type system. Water mist is win-win.

Transmission and Drivetrain

We chose to replace our racer’s original 290,000 mile 4L80E with a brandy dandy new one rather than to take chances. We installed one of PML’s deep, cast aluminum oil pans, but other than that, the transmission is stock and filled with Dexron 3 and a dose of Lubegard.
We could not be comfortable running the original driveshaft so we had a new one made for the truck using heavy wall DOM tubing as well as heavy duty weld yokes and Spicer race joints. The whole shebang was balanced to be smooth for safe operation at high driveshaft RPM.
Because we needed to be able to swap final gear ratios, we opted for a nine-inch Ford setup. We learned from Benny Avant that the rear axle assembly from a 1976 Lincoln is exactly the correct width and even came equipped with the five-on-five wheel lug pattern featured on a half-ton two wheel drive GM truck. With little more than the addition of spring perches to fit our springs, this thing fit perfectly.
The Ford nine inch is designed with a good deal of pinion offset and that is supposed to eat some power as compared to more modern differentials with lesser offset but it works well and affords a good deal of latitude with regard to final drive ratios. While brakes are not all that important in this application, the Lincoln rear is factory equipped with discs – neat.
We have been running and will continue to run a synthetic 75 weight gear lube, unless or until something better comes along.

Wheels And Tires

When we get to the salt, we bolt on the special wheels and tires built for us by Nate Jones Tire in Signal Hill, CA. The wheels are goofy looking, five-inch bead-to-bead, heavy duty steel units made especially for our application. The tires are Goodyear land speed racing models that meet our needs in terms of both carrying capacity and speed rating. The wheels and tires are assembled by Nate Jones who balanced them to perfection. They are capable of way more speed than we will ever give them, however, we feel that a little overkill in this department is a good thing. For street driving, we use the standard-issue pickup rims with speed-rated tires-nothing fancy here.

Creature Comforts

We have made every effort to keep our racer as original and complete as possible while making it race worthy and safe. In order to meet SCTA (Southern California Timing Association) rules and regulations, the truck was outfitted with a heavy duty roll cage and driver cocoon, built into the truck by Yakima’s John Raney. Additional necessary driver protection includes a window net, arm restraints, fire suppression system, etc. John was able to design these safety systems around the existing, factory interior. The racer retains its factory dash, door panels, extended cab side panels, headliner, carpeting and interior lights. The interior of the racer is complete and original. We even retained the power windows, tilt-power steering, cruise control, cup holders, rear-view mirror and factory stereo.

The Team

We are blessed to have such a great group of people working together in support of this effort. The year-long project to build the truck required contributions by people with a wide range of talents. While I focused my efforts on building the power plant, Heath Diesel’s Todd Hughes supervised the build of the truck. Todd’s penchant for perfection assured no corners were cut, that every nut & bolt were the proper type and that they were accurately torqued and that every wire and hose was expertly routed.
We appreciate his commitment to quality work and feel that it shows in the performance as well as the presentation of our racer.
The crew that supports the racer on its excursions is comprised of these hearty and dedicated souls:
  • Curt Huffman, Seattle, WA
  • Carl Everett, Wapato, WA
  • Jamie Avant, Sandersville, GA
  • Dr. Bob Henrichsen, Auburn, CA
  • Benny Avant, Sandersville, GA
  • Joe Heath, Ellensburg, WA
  • Rod Riddle, Ellensburg, WA
  • Dr. Tod Henrichsen, San Clemente, CA 
  • Kent and Barbara Pearson, Othello, WA 
This project has been a most rewarding one. We want you to know that your interest and support is deeply appreciated by us all. We encourage your participation and look forward to seeing on the salt!

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