Magnum Engine Modifications
We have talked about doing this article for quite some time now and were finally forced into it by the December 2000 issue of Hot Rod Magazine and it's story Dogkota. Hot Rod Magazine has historically kicked Mopars every chance they got. As far as the story went it was factual and parallels our testing. The problem is that it left the reader and potential Dakota buyers believing that there is no hope of ever making any power with these engines. Nothing could be further from the truth. Many streetable Magnum powered trucks can be run in the 12's. That may be the reason the article went no further---the Mopar trucks might be faster than the red Camaros they love so much.
Starting with the Magnum powered vehicles, we will lay out Prescriptions for Performance-these will be arranged in the order of the most BANG for your BUCK$ and we will even suggest products we do not offer when they prove to do the job. We will start with the easy stuff and work into the serious stuff in later sequences.
These changes are not guaranteed or approved by anyone and we accept no liability for their use. They are for off-road use only. The doctor is IN.
Level 1
Fuel injected engines like cool air. The K&N® Gen II air intake system is a good system. Don't waste your money on the replacement filters--the cool air is what the engine wants. Actually, if you could get your filter (air intake) out of the engine compartment completely it would work even better. Change to synthetic engine, transmission and rear end lubricants.
1. Upgrade the ignition coil, cap and wires. Jacobs, Mallory, MSD, Moroso, Crane, etc
2. Use a 180 degree thermostat
3. Hughes Engines does offer a larger air filter element to use with the K&N Gen II system that is worth up to 8HP at the rear wheels over the K&N supplied filter. #11000, $59.95
This filter element is a direct replacement for the K&N® Gen II systems on 5.2L/5.9L V8 engines. 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
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. I don't suggest any changes here until many more intakes system changes are made. At this point they are loud, expensive, too much work and cost you power.
5. We also do not suggest an E.C.U. change at this time, a lot of money for little if any power. The above listed Mods should help you pick up 15-20 H.P. on a 5.2 and 20-25 H.P. on a 5.9 at the rear wheels and are what we call free HP. In other words, they won't cost you any mileage. Actually you will find mileage increases if you keep your foot out of it.
Since you will not be using the Mopar Performance ECU, the engine will still work well without having to use pump premium gas, good news for those of you that tow trailers.
Level 2
The next step in the performance ladder involves getting more air into the engine through the use of modified throttle bodies and intake manifolds. We offer 3 levels (so far) of both modified, OEM throttle bodies and new, billet aluminum throttle bodies. We also offer 2 levels of intake manifold modifications.
1. Modified Throttle Bodies
Our Stage I level throttle body flows 15% more air for the V8 and 43% more for the V6 and is the best choice for all V6 applications and 5.2L V8 engines that won't have camshaft or cylinder head modifications. The Stage II V8 flows 30% more air and is best for 5.2's that will receive internal mods such as cam and heads. The Stage II V8 Stage II TB is for all 5.9L V8's. (A Stage III is currently being researched). There are a lot of smoke and mirrors in regard to throttle bodies on the Internet. The bottom line is: How much more air do they flow than the stock TB? They are not carburetors! The color, shape and coatings can't be seen once the air duct is in place; only the airflow increases are going to show up---at the rear wheels.
2. Modified Barrel Intakes
There is also much confusion and misunderstanding about intake manifolds, especially the stock barrel type. The stock intake system has separate individual runners for each cylinder. It is a very nice high tech design. The fact that the runners are separate and equal in size and shape causes an effect called inertia supercharging or ram tuning. This effect causes the cylinder to be filled with a greater air/fuel mixture in certain R.P.M range increasing the power over what it would be with older conventional style manifold. This power increase occurs at in an R.P.M. range, which is dictated by the runner lengths.
There are also some drawbacks to the manifold as it comes from the factory. The runner lengths are very long and they provide the power increase at RPM's just above idle for quick throttle response and mileage. The runners are also quite small at the cylinder head interface area, and in need of a port match in a big way. The ports in the manifold are approximately 0.100" shorter and 0.100" narrower than the ports in the head, which severely limits the amount of air flow through the system.
In our modified intakes we open the cylinder head end of the port up to match the cylinder heads and eliminate this severe bottle neck. Next we shorten the individual runner lengths to move the inertia supercharging effect up into higher RPM ranges. Everything you do to increase power (except for stroking) moves the power band up, so we need the intake modified to work at a higher RPM too.
To give you some idea of lengths, the stock magnum intake has runners about 16" long. Our Stage I runner has about 14" long and our Stage II is 12". If the runners get much shorter you will get dips in your power band. The Mopar Performance Magnum M-1 intake is basically a carbureted intake with injector bosses and is designed for non-roller, flat tappet or roller cams with power bands from 5500 RPM and up. The runner length is barely 4.75" long -- much too short for hydraulic, roller cam power bands, which are generally below 6000 RPM. If you plan on only racing at the drag strip with lots of gears and stall--this is the manifold. If not, be careful or you'll lose your entire bottom end and mid-range torque. Our intakes also have the Plenum volume reduced for better throttle response. Our Stage II throttle body and Stage II intake are making 425/450 HP at the rear wheels with our HER1824AL cam and Stage II heads.
