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If you are looking to replace your stock rockers ...
High Performance Diesel Market Includes Growing Number of Parts
It seems as though the demand for diesel power is growing among consumers for automotive passenger cars and trucks. In addition, diesel power is making its way to classic cars and restoration projects. But what if you wanted more than just stock?
By Bob McDonald
In many cases, the diesel engine is taking over the hot rod world. Instead of a small block or big block Chevy in the classic cruiser, people are looking at the Duramax diesel. The same goes for the Ford engines being replaced by the Powerstroke and the Dodge being substituted with the Cummins. The desire is for more power, of course, but the craze is mostly for the torque.
With the expansion ratio of the diesel engine, more work can be done with the same amount of fuel. We can cruise in our classic heavy cars with higher gear ratios and use accessories such as air conditioning and still get 20 miles to the gallon. In addition, we can pull out on the road with this massive torque monster under the hood and shred the snot out of the tires. Not only is this appealing, but think about the eyecandy it produces at car shows!
Finding great diesel opportunities seems simple, however, when compared with finding performance diesel aftermarket parts. There are manufacturers who do supply bolt-ons such as cold-air intakes, exhausts and programmers that work well, but the true gearhead is actually looking for more. Has the demand for more power from a diesel engine actually changed the thinking of the companies that are producing high performance parts?
I’ve been repairing diesel engines for years, and over that time I have come across some interesting parts that are available to those who want to get more from the internals of their diesels. One thing that you have to keep in mind is that most of the high performance parts being produced for diesel engines most likely will not be found in the inventory supply of a parts warehouse. These specialty products may need to be sourced through the Internet or a diesel-oriented magazine.
In many cases these parts are intended for serious applications such as sled pulling competitions or drag racing, but they can still can be applied to the daily driver. Keep in mind, however, that these pieces can be pricey because of the workmanship and material used to produce them. Remember diesel parts have to be tough and heavy for the cylinder pressures these engines crank out.
While the list of diesel aftermarket parts manufacturers is still fairly small, new things are developed regularly. I’ll talk about some of the areas in the engine I’ve had good luck finding parts in the aftermarket to solve fairly common problems.
If you look at the stock rockers of a 6.0L Powerstroke diesel, you can understand the need for more improvement. The stock rockers are a roller configuration, but this roller is actually a ball that sits underneath the rocker arm itself. The stock rocker arms are held in place by plastic clips that hold the rocker to the rocker stand. While this may work fine for stock applications it will not hold up under increasing engine rpm. When producing more power at higher rpm with better valve springs more valve spring pressures are encountered so the rocker ball would never hold up.
I have found replacement roller rocker arms in adjustable and non-adjustable sets. If you are looking to replace your stock rockers on the factory hydraulic roller cam you would use the non-adjustable version; if you are a serious competitor and wish to have solid-roller lifters custom made, then the adjustable ones are for you. But keep in mind that these rocker arms run around $3,000 a set.
If building a high performance diesel engine is your thing, then I am sure you need it properly oiled. Stock diesel engines are very dependent on a great oiling system when it comes to high performance, the demand increases even more. Because diesel engines not only have heavy internal parts that require heat removal and lubrication from the oil pump they also rely on piston oilers.
These oilers are placed in the main webbing of the block and feed from an oil galley. The oilers spray small streams of oil to the underside of the pistons, cooling them and removing as much as 200 degrees F or more from the piston. This is very crucial to a diesel that is turbocharged because piston heat can be so extreme. If anything happens to the oiling system the pistons are toast. One way to play it safe is to install a great oil pump.
One thing you want when building a high performance diesel engine is for it to stay together. These engines cost a lot of money to put together and to see one come apart will bring a tear to your eye. To give some insurance to your project, whether it is stock or modified, use quality fasteners. The fastener needed may be a stud or bolt depending on application, but a wide variety of fasteners is available for the main, rod and head bolts for your diesel. The great thing is that these fasteners will be around for along time with repeated number of uses.
In the piston department, a wide variety of pistons for mid-size diesel applications are becoming more readily available. Replacement pistons now exceed OE requirements of various manufacturers, or if your need is for custom pistons then they can be produced as well in various types of forging material in any size and shape imaginable. Piston and ring packages with the option of coated piston skirts are available.
Sealing a diesel engine is very important and I’ve had great luck finding the gaskets I need for stock replacement applications. A complete line of gaskets for mid-size diesel engine applications work fine in most high performance applications.
In some specialty situations, I’ve had to get head gaskets custom made especially with major oversize bores that are not common. I’ve been able to find the 7.3L Powerstroke, 5.9L and 6.7L Cummins as well as and 6.6L Duramax head gaskets in sizes ranging from .027˝ to .140˝ thick depending on the application. Unfortunately, the 6.0L Powerstroke engine was offered with a 18mm or 20mm dowel. Because of the dowel variations, most gasket manufacturers don’t offer them. The 6.0L Powerstroke head gasket is not very common other than through Ford.
Most crankshafts in diesel applications are forged and, personally, I have never seen a cast crank in the mid-size diesel market. But the connecting rods on the other hand are typically powdered metal. If I recall, the connecting rods in the 7.3L Powerstroke were forged until the 1999 model year when they went to powdered metal. Forged rods are available in the aftermarket for the Powerstroke, Cummins and Duramax diesel engines.
Don’t overlook the importance of tuning your high performance diesel engines. On a gasoline engine, one of the easiest things to do to help in tuning the engine is to use a wide band oxygen sensor. But what do you do with diesels? I have asked this question to various people and it seems that no one knows. Well, an air fuel ratio meter for diesel engines also exists, and is basically a wide band O2 for diesel engines.
In using the wide band O2 sensor you can tell where the air fuel ratio is in relation to what kind of power is being made. You may find that the engine is making great power at a certain rpm, but running on the lean side. By adding a little more fuel you discover that the engine is producing more power. The process keeps going until you find exactly what the engine wants without hurting anything.
This way when tuning your diesel you can discover what your engine may want. This is also useful when installing aftermarket programmers to monitor air fuel ratios and the effects of your vehicle performance.
As diesel performance gets more and more common there will undoubtedly be much more in the way of aftermarket performance parts. It feels like it’s the beginning of the hot rod generation all over again and, frankly, it’s pretty exciting!
Harland Sharp Custom Speed Parts, Melling, ARP, Mahle, Fel-Pro, Cometic, Carillo, FAST