5.9L Magnum Improve performance while fixing manifold?

[svdsinner]

I've got a 5.9L Magnum that I've purchased the Aluminum manifold plate for. The engine currently has scattered misfires on various cylinders (most commonly 5 and 1) and the cat and O2 sensors have just been replaced. I'm also replacing the water pump and timing chain when I install the plate.

The truck's main purpose is to tow a gooseneck 13,000# horse trailer (13,000lbs, meaning 19,000GVW when fully loaded) and struggles up big grades. (On huge hills, I have hit grades where the truck can't get past 10-15mph in first gear, but the old girl does get up them without having to shift the transfer case into granny gears.)

If I wanted to add some towing performance without breaking the bank, and I'm already going to have the plenium off the engine, what would you guys recommend? (Obviously solving the vacuum leak from the plenium issue is going to help alot) Let's say I don't want to add more than $500-1000 to the job for performance improvements, and only if they make sense. (IOW, pulling grunt from 2200-4000 rpm is all I care about. Not interested in racing or showing off.) I won't be offended if it turns out that the answers is that there isn't much I can do without spending way more than that.

Roller lifters?
Better muffler?
Something else?

 

[kyle watson]

help the engine breath in and breath out. if the intake manifold is off and apart- cut the air journels flush. replace the factory cat with a high flow along with the muffler. if you want to spend money, put Harland sharp 1.7 ratio rockers on the head. and don't forget the chain tensioner for the timing cogs. it helps clean up the idle. that might put you a grand in the hole.

 

[pacofortacos]

Chances are your heads are shot if they are original. If they are, do not go with EQ heads, the ports are larger than stock and will kill low rpm torque.

Don't cut the intake runners more than a 1/2" and then only at an angle, much more will hurt torque.

Stay with the stock timing chain setup, but you can replace the chain and add a tensioner that is on the V6 motor. If you go double roller, advancing the chain 4 deg. will help low rpm power and it will pull hard but run out of power at about 3500 rpms.

The 1.7 roller rockers help at all rpm levels. You already have roller lifters.

IF the motor doesn't ping at all, using Jeep 4.0 spark plugs will give more torque on the bottom end.

The next thing would be gears depending on what gears you have now.

That is a big load for a 5.9 gas motor.

 

[EvilSpirit]

The truck's main purpose is to tow a gooseneck 13,000# horse trailer (13,000lbs, meaning 19,000GVW when fully loaded) and struggles up big grades. (On huge hills, I have hit grades where the truck can't get past 10-15mph in first gear, but the old girl does get up them without having to shift the transfer case into granny gears.)


Something else?

 

[EvilSpirit]

I hate to be the bearer of bad news, but the real answer is "something else" - another truck more suited for the load you are trying to pull. You don't mention what truck you have, but 13K is waaaay more than even a 3500 series with a 5.9 was designed to pull. You are firmly in diesel territory here. Even though you may be slightly down on power from the intake leak, even fixing it and adding mild upgrades will IMO still leave it underpowered for the loads you want to pull, especially if you need to do this on a regular basis.

I could go through a laundry list of engine mods and why they will or won't work, but that really would just be typing practice -especially with a limited budget - and that is assuming the truck is up to the task.

 

[bulrid8]

Just a tuner alone will wake these engines up. They are severely detuned from the factory. Gears would be the next best bet.

Sent from my SM-G955U using Tapatalk

 

[dapepper9]

Do not cut the runners. That **** is an old myth that has been dyno proven to reduce power. Only after an entire day of dyno tuning does is make 8-10 more after its already peak. Peak didn't change it just doesn't curve down as quickly. Lost tq almost everywhere

 

[dapepper9]

To be pulling thur right you're pulling you need a larger truck. A 1500 is only rated at a max of 7500lbs. V8 2500s and 3500s aren't much higher. Hell even a 2500 diesel is only rated at like 12000lbs. You need a newer bigger diesel

 

[pacofortacos]

I agree cutting the runners on the stock manifold kills torque, however, by removing the stock belly pan and replacing with an aluminum pan you now really restrict the runner.
The runner to flat plate clearance is almost nil. The stock plate drops down about 1/4-3/8".

In this instance, an angled 1/2" cut will help unshroud the runner.

I also agree, that is way too big of a load.

He must have a manual trans though, I can't see the auto surviving

Manual trans with 4.56 or steeper gears might pull it, probably shouldn't, but might.

 

[dapepper9]

Aluminum plate doesn't get any closer to the runner than the steel pan. Bolts to the bottom on the outside. Doesn't go INTO the plenum. Also, plate material isn't the cause for the gasket going bad

It's not the ability to pull it that is a problem, it's the steering braking and suspension that becomes an issue

 

[pacofortacos]

The plate does get closer to the runner vs. the stock steel plate.
Just look at the stock plate, it goes into the lifter valley vs. flat and straight across like the alum. plate.
I just threw one away the other day. Stock plate is not flat like the alum. plate.

I used to run 2 stacked stock plates with insulation between them, this fixed the bolt length issue as well as kept the intake a bit cooler.

If he has a 3500, is the steering, brakes , suspension, etc. any different between a diesel and a gas motor of the same model year ???

 

[dapepper9]

The plate does get closer to the runner vs. the stock steel plate.
Just look at the stock plate, it goes into the lifter valley vs. flat and straight across like the alum. plate.
I just threw one away the other day. Stock plate is not flat like the alum. plate.

I used to run 2 stacked stock plates with insulation between them, this fixed the bolt length issue as well as kept the intake a bit cooler.

If he has a 3500, is the steering, brakes , suspension, etc. any different between a diesel and a gas motor of the same model year ???

Less than an 1/8". You're not impeding flow AT ALL. There's absolutely nothing to gain from shortening the runners. Only losses

 

[pacofortacos]

Well I guess you measured the pan recess and did flow bench testing, so I stand corrected.
Unless you didn't and it is just your opinion.

 

[dapepper9]

Problem with cutting runners is it doesn't open up the flow capability (flow benches have been done) and decreases port velocity. There's no meat to open them up and even cutting 2 inches off they're still like 12" long. It all adds up to a tq loss. FRP lost 32wtq and only after a full day of dyno tuning did they match the same peak as his canned keg tune.

Honestly a throttle body spacer does more for you and unless they're used for nitrous they're a paper weight

 

[pacofortacos]

I agree with all of that, but if you look at how close the runner is to the belly pan that little bit starts to become a factor.
That is why I said just a bit and at an angle, so when you are done, you are basically just removing a little on the inside end of the runner. It helps unshroud the runner just a bit and make the 90 deg turn into the runner just a little easier.

Personally, I like the stacking of 2 stock pans w/insulation between them as a better alternative to the aluminum pan. More rigid gasket mounting surface as well as takes care of the shallow bolt hole issue.

It is also the reason why I don't like to go to the EQ heads on a heavy 4X4 truck, the ports are too big and lazy at normal operating rpms.

I also like the stock timing gears as on my 2001 I would swear they advance the cam about 2 degree.
Doesn't seem like much, but vs. a Mopar double roller I prefer the stock.
On the Mopar double roller (this is all with a stock 01 cam), the difference in performance between 0 deg, +4 deg, -4 deg is amazing. So the slight advancing on the stock chain is the sweet spot IMO using a stock 01 5.9 cam - which is a bigger cam than most people think.

It is a small cam but not as small as most places publish, it has about the same lift on the intake and exhaust as the 5.2 cam with a little more duration - most places/people say it has much less lift than the 5.2.
When I measured my cam, that was not true and I was the original owner of the truck.

 

[dapepper9]

There's nothing to be gained with that clearancing though. EQ heads are still good even with a stock intake because stock heads are done by 4000rpm and you can stretch the rpm hand of the keg a tad on the 4000+ range due to higher head flow. They're not at all lazy and in fact drive pretty much exactly as smooth as stock. But with vastly more potential.

Stock chain has slight cam retard from wear, not advance. The crank spins a few degrees further before the chain tightens the slack and turns the cam

 

[pacofortacos]

EQ heads were a torque loss on my setup, maybe with a bunch of mods they work but on a stock motor they were a power loss, esp. when towing and 3.55 gears. Definitely no gain on top either.
Truck ran better with stock heads with 4 sunken exhaust valve seats that missed at idle.

All chains have a retard from stretch, the stock gears are advanced.

It is all in the way the motor is setup. My 01 ran very well the way it was setup.

Please don't try to tell me next that a 180 thermostat is a performance gain over stock. Or that autolite plugs 3923's are the hot ticket - because neither are true. They can cover a poor tune or pinging problem, but neither are a performance gain.

 

[dapepper9]

With stock intake and exhaust sure that may be the case. Especially without tuning to account for it. Tune will behave exactly as ive stated.

Stock gears are not advanced.

180 stat just keeps the motor cooler. Cooler temps do have a power difference vs stock when if it's negligible on an engine dyno but the big thing is a cooler motor is less prone to pre-ignition. Cooler plugs also are less prone to hotspots and as such pre- ignition.

If you stick around you'll see im not the people you're used to dealing with. I know my stuff pretty dang well and that's not being cocky, that's being real

It's not like all this stuff hasn't been done thousands of times over. Stuff is well documented and pretty figured out

 

[pacofortacos]

Yep and I am a newbie who doesn't know anything or so you think.

You seem to play with the modified stuff, I fine tune mostly stock stuff- with tweaks.

I was able to adjust my timing from -5 deg. to + 9 deg from stock using the crank sensor.
Played with fuel sync in the - 10 to +10 range for different performance gains, hint - 9 helps higher rpm and +9 gives a low rpm boost, +6 is about the ideal everyday setting.

Not saying you don't know anything, just saying you don't know everything and that there is more than one way to skin a cat.

Mopar has for years played around with cam timing via the gears on various motors. When I compared the 01 stock gear to a Mopar double roller, the stock was advanced. So either one of my gear sets were cut incorrectly or the stock was cut advanced. In theory, if you set the motor at TDC and both sets are 0 deg advance, you should be able to install either set without moving the cam or crank. In my case on my 01 this was not the case, I had to advance the cam to install the stock gear.

So if you ever get a chance, see if this is true on your sets.

Have a pleasant evening.

 

[dapepper9]

Never claimed you were a newbie. I will be straight up and say you're playing with things that have little to no impact in the real world and are no more than old tricks from before custom tuning was available. End result is marginal if anything, often called diminishing returns

I fail to see how fuel sync retard can help at all. Particularly when any tuner will tell you to advance it with notifications. Aftermarket cams that peak in the 6k rpm area for example, are quite often advanced to the +12 area in order to provide fuel quick enough to adequately make the ratio needed. Too slow and intake valve will close before all the fuel gets into the cylinder.

My stock chain vs my double roller, if anything the double roller had a degree or two of advance. It lined up perfectly left stock gear slightly off, on the retarding side