#101-----Magnum V6 Truck Engine Performance Upgrades 03/01/2004

1/13/2008
David Hughes


The 3.9L V6 engines used in the 1992 and later Dodge trucks are of the same family and share many similarities with the 5.2L and 5.9L V8 engines, in both parts interchange and technology areas. Although the V6 is a cylinder short on each side, most parts, in some way, can be interchanged with the 1992 and later 5.2L Magnum truck engine. Also, the research and development that has been done on the V8's can be transferred over too, in most cases. I've got to be honest with you V6 guys.  I never thought this engine would be much of a performance market for us. This is why you see little or no mention of them on our web-site or in the catalog. This article and information is an attempt on our part to see if there really is a market. We have had some inquiries and helped some of you already build more power, so if you've got a V6 and need some more power, we will be waiting to hear from you. 

As you read through this article you will notice some of the words appear in orange. These are links to the product they are describing. Click on the orange colored words and it will open a new browser window where you can view the prioduct without losing your place in the tech article. When you are done looking at the product or you have added it to your cart simply close out the window and you can continue where you left off in the tech article.


Some of the most obvious examples of interchangeability are the rocker arms, lifters, pushrods, timing chains, pistons, rings, valves, valve springs, retainers and in a slightly modified version the cylinder heads, camshafts, intake manifolds, throttle bodies and cold air intakes. In other words just about everything to build horsepower. 

The combination of parts should be used in the same groups as the V8's and the same percentages of power increases should be expected. However some changes in the V6 component will yield a greater gain than it will in a V8. For example when we modify the stock throttle body for the V8 the percentage of flow increase is 15%, but for the V6 (p/n 5500) the improvement is 43%. This change would be like putting a 900CFM throttle body on a V8, in other words a very big change!  

 Our billet throttle bodies , which are really great looking in their glossy black powder coat finish and our logo engraved in them ) will all bolt directly on the V6 manifold just like the original. All of the sensors bolt-on too! If you do decide to install the Stage 3, note that the throttle plates will clear the intake throttle bore openings and run ok, but the bores in the manifold are about 3/8" smaller and they will defiantly restrict the air this unit could flow. Bore out the manifold if you want the full benefit of the billet throttle body. A note about throttle cable linkages, all of our billet throttle bodies use the later "type 3" throttle shaft and that type cable hook-up. If you are using the throttle body on an earlier truck you will need to get the later style cable, call, we can supply it. 

Moving on to the intake manifold itself, we have 2 modified versions. The Stage I (p/n 5516R) and Stage II (p/n 5517R). These intakes feature larger ports, shortened intake runner lengths, filled plenum volumes, and our popular billet plenum cover plate (p/n 7712). The Stage I works best for Rams or Dakotas with stock or small cams or doing some towing. The stage II is the higher performance unit and is recommended for Dakotas that are building for maximum horsepower. 

Both manifolds have the port sizes opened up to match the cylinder heads. This increases the air flow by removing the production manifold's restrictions. The plenum volume is reduced by filling in the voids and cavities inside the stock manifold. This smaller volume results in quicker throttle response. Another key modification is the shortening of the runner lengths. This change increases the cylinder filling capability at different rpm levels. The long stock runners produce more of their boost just off idle and up to about 2500 rpm. After that point they are a drawback in producing power. The stage I intake runner lengths help from about 2000 to 4000 rpm, just right for towing and/or mild "street work". The stage II runners are shorter yet and do their best work between 3000 to 5000 rpm. Both manifolds feature our 1/4" thick billet plenum cover kit (p/n 7712) installed. This plate stops the nasty habit the Magnum engines have of sucking in the gasket, or blowing it out if you have a forced induction set-up, and you know who you are! As a comparison, the runner lengths in the factory stock manifolds are 16" long. The runners in our Stage I are 13" long and the Stage II are 12" long. Which one you choose will depend, as usual, on vehicle weight, rear gear, cam, stall speed, the use of the vehicle, etc. 

There are no R/T cylinder heads for the V6 engines,( now if we cut the end off an R/T head and put a plate on it and used some epoxy I think it might work, I don't think the V6 guys wouldn't be interested...) but the ports and valve sizes are the same as the stock Magnum V8's. The V6 heads don't seem to crack as easily as the V8's either. Either Stage I p/n HSP1-MAGV6, which is priced at $710.00 or Stage II p/n HPS2-MAG V6, priced at $940.00 will have the potential of producing tremendous power increases on the 238c.i. V6. The prices are based on the customer sending in or returning good cores. Refer to the V8 Magnum section for a description of the modifications. Note the part numbers and prices are not yet shown on our web-page, only here. For those of you who want to do your own work, the valves, valve springs, retainers, locks, and seals are the same as the V8's. 

The rocker arms are the same stock 1.6:1 ratio as the V8's and we will sell you 12, as in p/n 1538-12 for your V6. We hope to have 1.7:1 rockers, later this winter, and they will fit the V8'too, just don't tell those guys yet. 

Camshafts, good news, good news, ALL of the V8 cams shown as regrinds HER9208, HER0814, HER1418 and HER1828 are available for the V6 engines. Any larger grinds require new cores and if the demand is there for the larger grinds we will get some new cores. The price is the same as the V8 cams and we refund your core charge just like the V8s, if you return a good core. The hydraulic lifters are the same p/n too, p/n 5006, order 12. 
 
Our V8 timing sets p/n 6442 and p/n 6440 along with the timing chain tensioner p/n 6450 will work on the V6s too. The two chain sets are the same quality, however, the p/n 6442 features the 7 keyway cam sprocket. You will find that the price difference more than makes up for the hassle you will encounter if the 3 keyway sprocket used in the p/n 6418 will not bring your cam into the correct position and you have to resort to the off-set keys. Been there, done that! 

The piston department is like the valves, all of the 5.2L V8 pistons will work. This includes the 5.2L Keith Black pistons. Remember when you increase the cam size (duration @ 0.050"), the cylinder pressure will decrease. So, if you are rebuilding and putting a larger cam in, look to increase the compression ratio at the same time. The KB pistons are slightly higher compression than the stock pistons. We can supply either, along with the rings. 

The connecting rods are much narrower on the big end than the stock 5.2L rod and will not interchange, without some machine work. The reason is that the V6 has individual rod journals which are off-set from one another to help the inherent V6 balancing problems. We are looking into supplying an "H" or "I" beam rod if the demand is there. The rod bearings are narrower as well!  

A stroker kit might be possible but it would only yield about 17ci and would probably cost in the neighborhood of $100.00 per cubic inch???  

We can also supply all of the gaskets so call if you need something.    

What will it take to give problems to V8's, glad you asked! 

Before you get started working on your engine please read our tech article: "What you need to know", and make sure you are ready to take the plunge! 
 
There is one modification you can make to almost any vehicle that will cost you nothing in-so-far as trade-offs and that is an up-graded ignition system.  Which ever system you get be sure to get some good performance plug wires, no O.E.M. stuff. Note if you have some suggestions on which ignitions you like, or don't like (and why) let us know, thanks.  

Next, like the V8's, start with the intake side of the engine, also like the V8's there is more bang for your buck modifying the intake side of the engine first, and a lot easier to do, especially if you're new at this business.

The throttle body is next. Here you need to make a decision about how far your modifications are going to go. If this is a get-all-you-can-for-little-work-as-possible, job, and you do not plan on going into the engine with a cam or heads, get one of our modified stock units, p/n 5500. This unit flows an amazing 43% more air than a stocker and comes with many tuning tips that will improve both power and mileage, if you keep your foot out of it.  

If you plan on going to headers which would be your next step (we don't carry any yet, we are out of room for big items) then you need one of our billet throttle bodies. Part number 5550 is our Stage I billet unit and we suggest it for the serious work. The throttle body will bolt-on just like the stocker and all the sensors will too, but throttle plates in this Stage I are 50mm and are about 0.400" larger than the bores in the V6 intake manifold. The plates will clear the intake manifold bores and it will run ok, but the small bores will act like NASCAR restrictor plates, until you get them opened up. Of course you will need to do this anyway to see the full benefit of all of the other modifications you are planning to do.  

The manifold is the next restriction in the quest for more power. We offer 2 modified stock (barrel type) intakes. Choose the one that fits your cam the best. The Stage I would work best the HER9204AL and HER0814AL cams, and the Stage II with the HER9204AL and HER0814AL HER1418AL and HER1828AL cams. Our V6 manifolds will be bored out for the 50mm throttle plates, or larger if you request it.  

With any of our cams, milling of the heads would be recommended to keep your cylinder pressure up, especially if you are not going to install new higher compression pistons. Stock cylinder pressure in your V6 is about 180 psi, and there is no reason to reduce it. We will give milling recommendations when you buy a cam. Actually I should say cam, springs, and retainers. The stock springs are the bee-hive type and use a very small retainer which will not fit our springs, and the stock springs will not work with any of our cams. The R/T trucks used a larger spring and retainer, so in that case you will only need our springs. The stock locks are fine if they are in good condition.  

The roller lifters can be re-used if they are in good condition, it is not mandatory to replace them like you must do with flat tappet cams. To check the rollers condition, roll it against the palm of your hand while applying pressure. Does it roll smoothly and quietly, and does it pump-up properly? If not our p/n is 5006.  

 Ok Perry and the rest of you V6ers, let's see how serious you are; let's build a "hammer" get "a-board" and you can nail a Ford!

Home