Why doesn’t my Magnum 5.9 sound good?

This is a subjective thing but I think most of us know a good sounding V8 when we hear one. My engine is an old Magnum 300 crate engine. Demon 650 carb, Mopar M2 dual plane intake, Doug’s headers, Jones Max Flow flow-through mufflers, no cross-over pipe.

Obviously I’ve got a pretty mild cam and low compression...but something just doesn’t sound right. The exhaust seems kinda flat...no crispness or rumble, even at WOT. I didn’t want the echoey/hollow sound from Flowmaster type mufflers and I thought the flow through mufflers would have been the key to getting some sharper/better sound...but did I just pick the wrong style muffler?

Or...could this be a symptom of something else? Maybe it’s a timing/tune issue? The motor pulls ok but it’s not even close to the stock 5.0 Coyote in my Mustang...which has more hp but less (advertised) torque and in a much heavier car.

Any input is welcome.

You have a broomstick for a cam. The 380hp version of that engine was essentially a cam and intake swap you might consider that.

https://www.hotrod.com/articles/mopp-0303-360-crate-engine-buildup/

that motor is not going to run ANYTHING like your coyote 5.0....as said you have a broom stick. up the compression and put a big cam in if you want some rumble that has power to back it up.

No need to up the compression. As I said, the 380hp version is nothing more than a production line truck 5.9 with a cam and single plane intake swap. the 300hp version is a dual plane intake swap only.

Read the link for tuning details and dyno info on the 380hp version.

The 300 Crate is near factory OEM.

Several owners over the years have posted that degreeing the cam, then advancing the cam a few degrees greatly improved the smoothness and sound of the Magnum 5.9 V8.

When you input the valve event degrees in the 1995 Ram FSM into the Engine Analyser 3.0 software by Performance Trends, it reports that the OEM cam is retarded 9 degrees.

I've had 2 5.9 trucks and my friends have also had a few. Every one of them sounded weird at idle like they had a burnt valve or something, especially with a non stock exhaust on them.

My Durango has a Cherry Bomb- Flowmaster copy installed by the PO. Sounds pretty good at idle but the drone at cruise and crackle when I let off is getting to me. I'm going to try the short-glasspack-for-a-resonator trick to quiet it down some. To me, it sounds like most any other stock vehicle with Flowmasters.


Tim

I just looked at the internal view of the Jones Max Flow. It's a knock-off of a Magnaflow, which is a knock-off of a Dynomax Ultra Flow Welded. None of those mufflers do ANY tuning at all - none. They are just straight-through resonators basically - similar to a glasspack, but oval. Plus they all have a smooth round perf core - the only way they get loud is when you are at WOT. They sound "flat." If you run the right aggressive mufflers that do some tuning, you'll get sound.

You could try Flowmasters but with cheap glass packs as resonators along side the fuel tank, same way the factory did.

Ok so like a powerstick then I guess ? Or what.

On a stock 1995 Ram 5.9 Magnum V8 the exhaust backpressure rises to 7.5 psi at full throttle and 4000 rpm. I measured at the EGR gas feed tube off the passenger side rear of the exhaust manifold. The truck was 4 years old at the time. It was possible the catalytic converter was already partially plugged.

The 1995 FSM says that when the exhaust backpressure reaches 3 psi the PCM software begins feeding EGR into the intake manifold to limit NOx emissions.

In model years 1992 to 1993 Magnum 5.2 V8s had larger outlet exhaust manifolds.
I cannot think of a reason why the Magnum exhaust manifolds would be made smaller for years 1994+ except to increase EGR flow using the same EGR valve.
For model years 1996+ the EGR system was eliminated as more efficient catalytic converters became available.
OEM camshaft specs changed in 1998.

Magnum V10 camshaft specs are different than V8.
The V10 camshaft valve event specs seem to be more “truck towing duty” and would produce more 1200 to 3200 torque if used in a V8, but limit high rpm horsepower.
The V10 idle seems smoother.

Mine do tune the exhaust. There are others that "tune" also - like Dynomax Super Turbos, Flowmasters, Cherry Bomb Vortex, Borla, etc.