BUILDING-UP MAGNUM TRUCK ENGINES (1993-2003)
3.9L V6 as well as the 5.2L and 5.9L V8’s
Modifying magnum truck engines is a major part of our business. To obtain more information on any part number listed in this article, please visit our website at www.hughesengines.com. We cover everything from our plenum repair kits (P/N HUG 7720R for V8 and P/N HUG 7725 for V6) to “streetable” 550+ HP beasts.
To get started, you need to make a decision about power. What do you want and what do you need? An engine has 2 types of power that we usually talk about, torque and horsepower.
Torque is what increases your pulling or towing capability. You could stroke an otherwise stock engine and improve its torque 20%-30% without doing anything else, and it would be in the same RPM range or slightly lower. Torque is pulling power, good for cruising and street performance. Torque for the most part is a product of displacement.
Horsepower is most important at the track, and you may even trade off some torque to get more horsepower at a higher RPM. Horsepower is a product of airflow resulting from parts that allow more airflow through the engine.
However, there is a lot of room for co-mingling of parts. As an engine’s displacement increases, all the parts that control airflow (such as the carburetor, throttle body, cam, heads, exhaust, etc.) will act smaller. This is because part sizes are based on the ability to flow air, C.F.M., so when the displacement increases, the air flow control parts act smaller. This means you can increase the size of air flow components and positively affect both torque and horsepower.
Now here is where the co-mingling of parts comes in. For example, if you stroke a 360 (5.9L) magnum engine to 408 (6.7L) cubic inches, you could put in a bigger cam and increase the torque and horsepower and not lose anything. There is a common misconception that anything bigger than the smallest cam, heads, etc., are automatically race engine parts. Nothing could be further from the truth. As the engine increases in displacement, all the stock parts that control air flow act smaller because they were designed for the smaller original engine, like DUH! So when you increase the displacement, you should increase the size of those components. Chief among them is the camshaft, then the intake manifold, heads, throttle body, headers and exhaust system, pretty much in this order. These upgrades will increase torque and horsepower at the same time.
As you upgrade the air flow capacities of components, at a certain point, the horsepower increase will grow faster than the torque, and you are entering the high performance area. The same situation exists for all the other airflow controlling parts. The displacement will determine whether a component is a torque or horsepower part. For example, a hot street cam in a 5.2 would be an RV, towing or high torque cam in a 408 c.i. engine.
Now that you know all of that, we will try to suggest the best bang-for-your-buck modification in an order intended to give you the most productive improvements.
In our opinion, the greatest restriction to making more power in stock magnum engines is the camshaft. It is not little, it is teeny weeny. The chart below compares the stock (5.2/5.9 - they are the same) cam to our smallest 5.2 torque cam.
CAMSHAFT COMPARISONS
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STOCK CAM
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VS.
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OUR SMALLEST HIGH TORQUE
CAM (P/N HUGHER9703AL)
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DIFFERENCE
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Intake valve lift w/ 1.6 rocker
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.411”
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vs
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.507”
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.096” MORE LIFT
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Exhaust valve lift w/ 1.6 rocker
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.430”
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vs
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.517”
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.045” MORE LIFT
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Intake Dur @ .050” lift
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182°
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vs
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197°
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15° MORE
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Exhaust Dur @ .050” lift
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194°
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vs
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203°
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9° MORE
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This chart is not meant to show how big our cam is, but rather how tiny the stock cam is when compared to our smallest torque cam.
Using our SER9703AL cam in a 5.2 engine a customer reports an improvement of 23HP and 35 lb/ft of torque @ 2,000 rpm at the rear wheels. Using our SER0814AL cam in a 5.9 engine a customer reported 48 lb/ft of torque @ 3,500 rpm and a 31HP gain @ 4,700 rpm at the rear wheels. These changes are with a cam, lifter, timing chain and springs only.
Due to the low lift and small valve springs used with the stock cam, there is not an aftermarket cam available that will work with the stock springs, and that is a good thing. Our drop-in spring (P/N HUG 1110) is used with our retainer (P/N HUG 1278) and our locks (P/N HUG 1307). As long as your original lifters are in good condition they can be re-used as well. New lifters are available as stock replacement (P/N HUG 5006) or high performance (P/N HUG 5007). These springs and retainers can be installed on heads without removing them from the engine, no machine work required. Our tool (P/N PFM66784) will allow you to change springs with the heads on the engine. When you change the cam, you will probably need a timing chain (P/N HUG 6440). This is a good start, and it is a double roller. Look at the tensioner (P/N CLO9-5387) for a more accurate timing and extended chain life. We suggest our P/N HUGHER9703AL-114° as a first step cam for 5.2 V8 engines or 3.9 V6 engines. Use P/N HUGHER0814AL-114° as a first step cam in 5.9 V8 engines. Either of these cams alone will increase low end torque considerably. We are talking in the neighborhood of 12-18 lb/ft of increased torque and it will continue to pull hard above 3000 rpm where the stock cam flattens out. No other modifications besides springs & retainer kit (part #1199) such as computer changes or tuners, will be required to use these cams. Need even more power? Check our cam list or give us a call.
The problem with changing the cam is that it’s a lot of work, but worth it in the end. However, due to the fact that a camshaft change is a major mechanical undertaking, and human nature being what it is, we’ll suggest easy stuff to do first. They may not have the rewards of the cam change, but they do help.Fuel injected engines like cool air. The K&N cold air intake systems are a good system. Don’t waste your money on just a replacement air filter—the cool air is what the engine wants. Check our induction section for your application. The oversize air filter that we sell (P/N HUG11000-- mentioned later on) is a good idea when combined with a cold air kit. Actually, if you could get your filter (air intake) out of the engine compartment completely, it would work even better.
LEVEL 1
1. Upgrade the ignition coil, cap and wires. OEM ignition systems are borderline at best, and our tune-up kits have proven to be a worthwhile improvement. (P/N ACLTST10, ACLTST11, ACLTST24 & HUG22056).
2. Use a 180° thermostat. The cooler thermostat helps reduce the intake air temp and helps increase power like the cold air system. Works best in high ambient temperatures. (P/N HYT 1026).
3. Air Filter. Hughes Engines does offer a larger air filter element to use with the K&N cold air intake systems on 5.2L/5.9L V8 engines that has shown to improve horsepower. This includes 1997-2001 Dodge Dakotas, the 1998-2001 Dodge Durango and 1994-2001 full-size Dodge Ram trucks. Note: Some minor trimming of the Gen II heat shield may be necessary on the Dakota and Durango applications. (P/N 11000).
14” overall length
12” length filter element
6.00” to 5.25” tapered OD
4.00” ID inlet.
4. Exhaust systems. The stock exhaust and cat-back systems are not too bad. But, I want to mention some things to take a look at. The exhaust system might not need headers, yet! But some of the exhaust system downstream of the exhaust manifold can caus restriction. Look at the Y pipe. The outlet end should be larger than the two inlet pipes. Here, along with tailpipes, bigger is better. OEM Dodge catalytic converters (in good condition) are not a big restriction. They flow almost as much as an aftermarket cat.
5. Lubricants. Change to synthetic engine, transmission and rear end lubricants.
At this level we do not suggest an E.C.U. tuner change —a lot of money for little power increase. The above listed mods should help you pick up 10-15 H.P. on a 5.2 and 15-20 H.P. on a 5.9 at the rear wheels—what we call free H.P. In other words, they won’t cost you any mileage. Actually, you will find mileage increases if you keep your foot out of it. If you do not use a performance “chip”, the engine will still work well without having to use pump premium gas (which is required with chips)--good news for those of you that tow trailers.
LEVEL 2
1. Modified throttle bodies. The next step in the performance ladder involves allowing more air into the engine through the use of high flow throttle bodies. We suggest one of our modified OEM throttle bodies. There is a lot of hype about throttle body bore sizes, and we all know bigger is better—Ah, but not true with throttle bore size. What you are really looking for is air flow. Your engine does not care, and neither do you, what the throttle bore size is. What you and your engine do care about is how much air the throttle body can flow. For example, our 50mm “BIG GULP” throttle body will out flow all the 52 mm throttle bodies on the market. Our “BIG GULP” (P/N HUG 5504) flows over 1000 CFM. These are modified OEM throttle bodies so you know everything will bolt up and fit correctly. And the price is right.
For those who don’t need maximum power but still want improved performance, we have our line of Stage 1 modified stock throttle bodies for those applications. They are more mild and for those applications that are not after every last ounce of power (P/N HUG 5501).
2. Intake manifolds. You only need to know one name—our “FI-Air Gap”. This manifold does everything better than any other manifold on the market (P/N HUG 5409), and they are always in stock. Check out the installation video on our website too!
3. Camshafts. (Here he goes, talking about camshafts again). When you remove and replace the intake manifold, you are nearly halfway to installing the camshaft. If you are even thinking about a cam, you are going to save yourself a lot of time, doing the same job over again when you put the cam in later, so why not do it now and be done with it?
LEVEL 3
This level will involve more work, some dedicated tools and greater mechanical skill. Generally, tuners such as SCT (P/N SCT3200, A & B) with 2 custom tunes are required at this level.
1. Camshaft. At last, we can put in the camshaft. At this point, you may just install one of our smallest cams (P/N HUGHER9703AL-114 for 5.2 or HUGHER0814AL-114 for your 5.9) for a big torque boost in your stock engine, or you may build a high performance or a stroker needing a lot bigger or even a custom cam. The bottom line is that the cam installation procedure is the same. With some of the larger cams, you may need double springs and the heads will need to be machined to accept them.
We have a special line of cams for applications using an SCT tuner. These cams have tighter lobe separation angles (L.S.A.). The tighter L.S.A. will cause the engine to produce even more power and torque, and have more aggressive idle. But it also lowers the vacuum enough to confuse the E.C.U., therefore, the SCT tuner is necessary to re-program the E.C.U. to operate properly with this lower vacuum. These are listed as tuner cams.
2. Lifters. Hydraulic roller lifters can be re-used if they are in good condition. In other words, if the roller rolls smooth and the lifter pumps up. However, we see lifters with over about 50K miles as noisier (tick-tick-tick) than new lifters on the same cam. We have 2 types of lifters. P/N HUG 5006 are stock replacement style,and our high performance version, P/N HUG 5007. These act more like a solid lifter, produce more power and have a mechanical sound.
3. Heads. One of the first things you will learn, from reading this or the hard way, is that OEM magnum heads are cracked—or at least 95% of them are. This problem is so common that at least 4 aftermarket manufacturers supply now cast iron heads for them. We work with 3 of these manufacturers, so we can supply new heads for everything from a budget rebuild to a ported racing version with oversized valves. Edelbrock has a very nice aluminum head that we can CNC port to outflow any other head. Stock rocker arms can be used on all iron replacements heads but we suggest that you upgrade to either our stainless steel or aluminum rockers for more accurate ratios and improved performance.
Cylinder head air flow is most important from about .100” lift up to about 90% of maximum lift. The reason is because the valve is in that area twice—once when the valve opens and once when it closes. The valve is at maximum lift for a very short time, making the mid-lift air flow much more important for making power. Our cams are specifically designed to give you the most lift possible at this critical area.
4. Strokers. Now, we get to strokers. A stoker kit will increase torque considerably—50% to 70% depending on what other options are included. A common internet tale made in regards to strokers is that they are only for racing. Nothing could be further from the truth. Stroker engines increase the displacement, which automatically increases the torque. With no other change to the engine but stroking, the torque will increase considerably and the horsepower very little. Horsepower increase comes with breathing modification (such as intake, heads, cam, exhaust, etc) improvements. So stoker engines can be made for torque or all out horsepower, you choose and we’ll help you build it.
5. Headers. Now it is time for the headers. We show several types. We suggest stainless steel as they live longer. Make sure your exhaust system is larger too, to compliment the better flowing headers.
Pick up the phone and give us a call with what you need in power and use of your truck and let us help you make it happen.
An important fact to remember is that we have excellent tech help – the best in the industry – so if you do-it-yourself and have a question, help is only a phone call or email away.
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