6.5L Diesel Land Speed Racer: Beginnings

Diesel Articles

65L-diesel-land-speed-racer-371x184

In 1978, Bill Heath envisioned himself racing at Bonneville. That vision remained out of reach until last Year. Now, he plans to race there this Summer – in a 6.5L GM Diesel of course...

   

LLY Overheating: The GM Solution and Beyond

Diesel Articles

duramax-lly-overheating-canadian-rockiesFaced with runaway overheating and a thermal feedback loop in his LLY Duramax, Joel Paynton finds the GM LBZ cold-air intake upgrade a measurable improvement. But with one additional LBZ part, omitted in the GM service bulletin, he finds his LLY running significantly cooler – with more power.

   

Lube Notes: Petroleum Oil Production and Oil vs Synthetic

Lubrication

Lube NotesComparing Synthetic Oil vs Conventional Oil

If you read the first two installments of Lube Notes, you have probably come to realize that I am gradually equipping you to evaluate lubricating products including a comparison between synthetic oil vs conventional oil. I am convinced that understanding some basic principles of lubrication can free us from believing everything that we read or hear. In this issue, I will briefly explain how petroleum oils are refined, introduce synthetic base oils and explain motor oil’s classification system used to assign quality levels to finished base stocks.

Petroleum Oil

Oil refinery products from a 42 gallon barrel - click to enlarge

Crude oil, truly today’s black gold, comes from nature as a dirty blend of hydrocarbons and contaminants of every kind. The job of the refinery (see figures one (page 17) and two (page 18)) is to clean this mixture and then crack it into various fractions for specific use. Crude oil typically comes with inorganic salt crystals and water mixed into the oil. It is necessary to remove this salt and water. This removal is accomplished by adding even more water and then allowing the crude mixture to settle. The oil is then heated by a large furnace until it becomes part semi-fluid and part vapor. This mixture then proceeds to the atmospheric tower, the heart of the refinery. The semi-fluids become asphalt and other derivatives while the vapors condense at various levels in the tower depending upon molecular weight. The portion of the vapor with lower molecular weight separates immediately, including kerosene and diesel. While diesel is derived from the first stage of the refining process, today’s ultra low sulfur diesel requires an extra step to remove sulfur (this step seems to be an excuse to raise the price). Vapors with higher molecular weight must go through an additional process to further crack – or separate – the oil into a greater variety of components or fractions as they are called. Lubricating oils – the fractions with which we are particularly concerned – are made from these latter, heavier fractions of the crude remaining after the gas oils have been removed. (Of note, recently refineries have developed methods to effectively use the heavier lubricating oil fractions for making gasoline. This competition for the portion of crude oil that previously was only usable for lubricating oils is one of the reasons for the rapid rise in the cost of petroleum lubricating oils.)

Crude oils from different regions of the world can be different with some being naphthenic and paraffinic. The paraffinic are much better feed stock for lubricating oils. Naphthenic oils contain no wax and are superior in cold flow applications. All crude oils contain roughly the same mix of hydrogen and carbon: 83 to 87 percent carbon and 11 to 14 percent hydrogen. Oxygen, nitrogen and sulfur round out the elements, with various metallic compounds also trapped in the oil. When dealing with lubrication qualities, it is important to consider the variation of molecular structure – from one molecule to the next – within the same sample of crude. Paraffinic molecules come in various carbon and hydrogen combinations to be sure, but to grasp the near-infinite molecular arrangements, consider a typical oil molecule of 25 carbon and 52 hydrogen atoms: this compound can occur naturally in any of 37,000,000 different molecular arrangements.

   

Oil Investors Drive Up Diesel and Gasoline Prices

Opinion

fuel-nooseSaudi Arabia, ExxonMobil, Warren Buffett: if you are an oil producer, retailer or investor, you have to be pleased with the recent jump in oil prices. It is, as Iago says, money in your pocket. More money for every barrel that you produce, sell and resell (at, of course, an even higher price). But you’re none of the above, you’re you, and each time you have to fill up that oversized tank with low-sulfer diesel, it feels that the noose closes a little more tightly.
   

Should I Use an Intercooler in My 6.5L Diesel?

6.2/6.5 Issues and Answers

I think I need to put an intercooler on my ’95 6.5. What is the best one to buy or how do I determine the best size for this truck?

A factory stock 6.5 runs a boost pressure low enough to not require intercooling so no meaningful benefit would be gained with an air to air system.
When performance modifications are made that increase boost pressure, intercooling can help to recapture power otherwise lost to the decrease in volumetric efficiency that increase boost causes.
Air to air systems for these trucks do not employ a properly sized grill mounted heat exchanger. Instead, they use a too small unit mounted between the frame rails. The tubing used to route air from the turbo and back to the engine is sized to fit the available space. These two design factors; small heat exchanger and restrictive tubes result in poor intake airflow.
Yes, these systems can lower intake air temp, but they also impose a considerable restriction to intake airflow, offsetting a good portion of any gain.
The type intercooling we like best for the 6.5 is water injection. There is a new water injection intercooling system available that employs solid-state control over multi stage function to provide fuel economy gains in addition to towing performance improvements. And it can be used as a stand alone upgrade with stock level boost pressures.
This system very effectively cools the intake charge and does so without imposing a restriction to intake airflow.

   

Improving Fuel Economy in a 6.5L Diesel

6.2/6.5 Issues and Answers

Like everyone else I know these days, I am looking for improved fuel economy from my turbo diesel GMC. It is a 1995 2500 4X4 6.5. My truck has the 3.73 axle and it is the automatic transmission. My baby is stone stock, except for big wheels and tires. In the driving I do, it gets 15 mpg overall, but I remember that it did better when new. I would be happy with 17 and happier with more. Any ideas?

   

6.5 L Diesel Fuel Injection Pump Fails the 2000 RPM Test

6.2/6.5 Issues and Answers

Recently, our truck began to take spells of stalling and we were told our fuel injection pump had failed. In an effort to get this done as cost effectively as possible, we bought the unit and did the installation at home. When we got it started, we took it to our local GMC dealer who set the TDC. The replacement unit came from a rebuilder who we understood to be a reputable one, but now we are not so sure about our choice. The engine is hard to start and smokes like heck until it gets pretty well warmed up. We read about and tried your 2000 RPM test (not until after the new pump was put in) we find we cannot put the tachometer on 2000. It either runs way above or falls below. In addition, it sometimes winds up to 4000 RPM when you touch the throttle. We have to turn the key off to stop it. The rebuilder says the pump his company supplied could not be the problem and that we have a bad computer. Please help. We have parked our truck until we can fix this problem.

A factory stock 6.5 runs a boost pressure low enough to not require intercooling so no meaningful benefit would be gained with an air to air system.
When performance modifications are made that increase boost pressure, intercooling can help to recapture power otherwise lost to the decrease in volumetric efficiency that increase boost causes.
Air to air systems for these trucks do not employ a properly sized grill mounted heat exchanger. Instead, they use a too small unit mounted between the frame rails. The tubing used to route air from the turbo and back to the engine is sized to fit the available space. These two design factors; small heat exchanger and restrictive tubes result in poor intake airflow.
Yes, these systems can lower intake air temp, but they also impose a considerable restriction to intake airflow, offsetting a good portion of any gain.
The type intercooling we like best for the 6.5 is water injection. There is a new water injection intercooling system available that employs solid-state control over multi stage function to provide fuel economy gains in addition to towing performance improvements. And it can be used as a stand alone upgrade with stock level boost pressures.
This system very effectively cools the intake charge and does so without imposing a restriction to intake airflow.

   

Increasing Power in the 6.5L Diesel

6.2/6.5 Issues and Answers

My 1993 dually is a very sharp truck. I have got only 127,000 miles on it; it is not modified in any way yet and I want to try for some more power. I think the place to start is with a big turbo and big injectors. I can get the marine injectors OK but need to know what turbocharger is best.

   

6.5L Fuel Economy Took a Dive

6.2/6.5 Issues and Answers

I still own the 98 Chevy 6.5 I bought new and I plan to keep it. The problem is, my fuel mileage has taken a sudden dive. I had been averaging 17 mpg overall and now it is down to 12.5 under the same exact driving conditions. I have changed the fuel filter, but found no improvement. The dealer charged me $148 to tell me he can find nothing wrong. Can you offer any ideas or solutions?

A factory stock 6.5 runs a boost pressure low enough to not require intercooling so no meaningful benefit would be gained with an air to air system.
When performance modifications are made that increase boost pressure, intercooling can help to recapture power otherwise lost to the decrease in volumetric efficiency that increase boost causes.
Air to air systems for these trucks do not employ a properly sized grill mounted heat exchanger. Instead, they use a too small unit mounted between the frame rails. The tubing used to route air from the turbo and back to the engine is sized to fit the available space. These two design factors; small heat exchanger and restrictive tubes result in poor intake airflow.
Yes, these systems can lower intake air temp, but they also impose a considerable restriction to intake airflow, offsetting a good portion of any gain.
The type intercooling we like best for the 6.5 is water injection. There is a new water injection intercooling system available that employs solid-state control over multi stage function to provide fuel economy gains in addition to towing performance improvements. And it can be used as a stand alone upgrade with stock level boost pressures.
This system very effectively cools the intake charge and does so without imposing a restriction to intake airflow.

   

Why No 4.10 GM Rear End on Duramax/Allison

Duramax Issues and Answers

Why does GM only offer the 3.73 geared rear end behind the Allison. I would love to have the 4.10 instead.
   

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