5.7 why 16 spark plugs

[Mopars & Missiles]

They want an arm and two legs for one of them trucks. And a left Gonad.

What's strange is when I was truck shopping back in 2015, there wasn't much difference between the price of a new Ram 2500 with the 6.4 hemi or the Ram 2500 with the Cummins 6.7.

I was looking for a new truck with towing capacity, and while the 6.4 Hemi would have done what I needed, the dealers wouldn't "deal" on the 6.4 Hemi's. They were only $500 less than the same truck with a 6.7 Cummins. I thought they were nuts, so I spent an extra $500 and now I have a 2015 Ram CTD in my garage. That Cummins has considerably MORE towing capacity than the 6.4 Hemi.

 

[Budnicks]

That was low Dave.

But is/was funny

 

[Budnicks]

You need a 2025 Ram with the new upgraded Cummins.

View attachment 1817822

Cummins Launches Next Generation 6.7L Turbo Diesel Pickup Engine System for 2025 Ram Heavy Duty Trucks

Yeah could always go diesel so no plugs needed or ever changed
well maybe glowplugs

 

[Nxcoupe]

The original gen 3 hemi used spark plug wires to fire the second plug on the exhaust stroke as others have mentioned. When the eagle hemi appeared with VCT, the need for waste spark went away. According to the FCA service information, both spark plugs on the eagle are fired at the same time. There is no delay. I researched this because I was really curious about it. This why these engines don't require a ton of wot total timing like the earlier hemis and other engines do. I am going to pull the calibration off of my 23 1320 and if I remember, I can post the timing tables here. So, there is no waste spark on the eagle hemis according to FCA.

 

[Krooser]

The second plug adds 3 hp according to the Gen3 experts... really!

I wanted to run a bone stock Gen3 in my dirt late model in a class that routinely allows $40,000 engines.

Nope... cant have two plugs per cylinder. The engine CAN run on one plug without issues with an MSD 6 ignition box and zero factory computers.

 

[1967coronet]

@Bob

@RJRENTON would know

That took longer than I thought it would.

 

[Triplegreen500]

That Cummins has considerably MORE towing capacity than the 6.4 Hemi.

Admittedly, the 6.4 gasser "can" tow as much as most people need - but it's like drum brakes on our classics. They do the job...but nothing in reserve in case its needed. And the delta from empty to towing 10k lbs for my Cummins is about 2mpg; a gasser, it's more like a 12-15mpg drop when you load it up.

The Cummins is MASSIVELY detuned for the pickups, which is why they last forever. Mine has nearly 300k on it and I still get 18mpg towing 10k lbs...and the truck doesn't even know its there. Boost runs a little higher...EGTs are a couple hundred hotter...I have to actually use first gear at stop signs...and that's about it.

The diesel carries a premium, sure...but you get every cent back at resale (if you ever sell it - but after living with one for a while, chances are it'll be the last truck you want to own). 2G Rams like mine run about $5k for a gasser right now; comparable trucks with the Cummins (especially with the stick shift) are 5 times that, regardless of miles. Fuel cost is about the same, dollars per mile, once you factor in the fuel economy savings, even with diesel as much as $1.25 more per gallon than regular. And, lower maintenance - no plugs, no wires, oil change every 5k, fuel filter every 10k, air filter when it gets dirty, and a valve lash adjustment every 24k. Woo. Hoo.

On my 300k 2001, I've done regular maintenance. The "extra" stuff? One belt tensioner and belt, around 225k. One water pump, around 235k (likely damaged by the belt tensioner locking up, and eating the wp bearing). A clutch at 250k. And the achilles' heel of the 24v, I replaced the electric fuel lift pump with a mechanical one at around 210k as a preventative measure. When the stock lift pump loses pressure, the high pressure injection pump starves, overheats, and locks up - to the tune of about $2400 in parts. If you get a second-gen with the 24v...change the pump, and install a fuel pressure gauge. Worth their weight in gold. Earlier 12v engines, and later engines, don't have this issue - but there are dozens of options to upgrade this setup (FASS, Glacier Diesel, etc).

While I love the new engine and its specs...you can't get a manual trans anymore. I'll stick with my six speed 2001.5 (rear disc brakes), and keep after the rust monster. Anyone in Maryland wanna tack on a set of cab corners and outer rockers for me? One thing I never learned how to do was weld.....

 

[j-c-c-62]

The extra plug fires during the power stroke to more fully burn the hydrocarbons. The second ignition allows additional power in the down stroke while lowering the need for restrictive catalyst plates in the converter.

This is the first I have heard the 5.7 dual plugs fire at different times.
Isn't that the basis of the popular simpler single plug MDS spark boxes?

 

[j-c-c-62]

The original gen 3 hemi used spark plug wires to fire the second plug on the exhaust stroke as others have mentioned. When the eagle hemi appeared with VCT, the need for waste spark went away. According to the FCA service information, both spark plugs on the eagle are fired at the same time. There is no delay. I researched this because I was really curious about it. This why these engines don't require a ton of wot total timing like the earlier hemis and other engines do. I am going to pull the calibration off of my 23 1320 and if I remember, I can post the timing tables here. So, there is no waste spark on the eagle hemis according to FCA.

You IMO have touched on the real answer first to the OP's question.
Spark reliability being unintended benefit, with the real reason being less timing. Fuel in best case scenario "burns" (rapidly), that burning takes time, and at high rpms that time is decreasing. Dual plugs effectively cuts in half the distance the burn has to cover, allowing for less timing and all the inherent downsides early timing leads to, like detonation and extra combustion chamber pressure as piston reaches TDC, wasting output energy vs having more combustion pressure available on the downstroke.

Dual Plug Gen 2 motors care squat about emissions

 

[F4R/T]

08 5.7 doesn’t use plug wires, it cop. Which is much better than the extra wires. The piston rings are also moved up high on the piston for emissions , that is why boosted guys have issues above about 8 psi and a tune is critical .. I’m a fan of the pre eagle engine, per Indy the eagles do flow more cfm but not much. The big changes were in compression, cam and induction. All are great engines my pref is the 6.1 nothing but straight up engine.