6.1 hemi vs 6.4 hemi (Big Performance Difference)

Are you in the market for a 6.1 or 6.4 Hemi powered vehicle? Are you interested in the pros and cons of each and what potential problems you can expect from each? Are you concerned about the maximum reliable mileage you can expect from either? Well then this article is for just you!

The maximum mileage you can expect from a 6.4 Hemi is anything from 250 000 miles and more. The Hemi 6.1 Engine is a reliable, well-built engine that can deliver high mileage in excess of 250 000 miles, with regular services and maintenance.

If you’re looking at purchasing a used 6.1 or 6.4 Hemi with decent mileage on it, what are some of the potential snags you could expect? What is the performance difference between the two? Are these engines reliable enough to purchase used with high mileage, and what do Hemi owners have to say about their reliability and maintenance?

All these questions and more will be covered in this article.

6.1 vs 6.4 hemi (TECHNICAL SPECS)

Engine:Chrysler 6.4L Hemi V-8
Configuration/Type:90° pushrod V-8
Applications:• 2014 – current Ram 2500/3500 pickups
• 2014 – current Ram 3500/4500/5500 cab and chassis trucks
Displacement:392 CID, 6.4 liters
Firing Order:1 – 8 – 4 – 3 – 6 – 5 – 7 – 2
Bore:4.090 in (103.9 mm)
Stroke:3.72 in (94.6 mm)
Compression Ratio:10.0 : 1
Engine Block Material:Cast iron
Cylinder Head Material:Cast aluminum, hemispherical combustion chambers
Aspiration:Naturally aspirated
Ignition:8 individual ignition coils mounted near spark plugs.
16 individual spark plugs, 2 per cylinder.
Valvetrain:2 valves per cylinder, cam-in-block (pushrod V-8) variable valve timing (VVT), hydraulic roller lifters
Fuel Injection:Sequential multi port fuel injection
Fuel Requirements:Regular 87 octane fuel adequate, minimum 89 octane recommended
Engine Oil Capacity:7 qts w/ filter change
Engine Oil Spec:Full synthetic SAE 0W-40 meeting Chrysler MS-12633
Oil Change Interval:Replace engine oil and filter every 8,000 miles or 12 months under normal conditions
Replace engine oil and filter every 4,000 miles under severe duty conditions
Peak Horsepower:Ram 2500/3500 pickup410 HP @ 5,600 RPM
Ram 3500/4500/5500 cab and chassis367 – 370 HP @ 4,600 RPM
Peak Torque:429 lb-ft @ 4,000 RPM (pickup and chassis cab models)
Maximum Engine Speed:66RFE automatic (<= 10,000 GVWR)5,800 RPM
Aisin automatic (> 10,000 GVWR)4,660 RPM
Engine:Chrysler 6.1L Hemi V-8
Configuration/Type:90° pushrod V-8
Applications:2005–2010 Chrysler 300C SRT-82006–2008 Dodge Magnum SRT-82006–2010 Dodge Charger SRT-82006–2010 Jeep Grand Cherokee SRT-82008–2010 Dodge Challenger SRT-8
Displacement:6059 cm3 or 369.7 cu-in
Firing Order:
Bore x Stroke :103 mm × 90.9 mm (4.055 in × 3.579 in) 
Compression Ratio:10
Engine Block Material:A forged crankshaft, lighter pistons and strengthened connecting rods aid durability
Cylinder Head Material:A cast aluminium intake manifold is tuned for high-rpm power and does not include variable-length technology. Chrysler‘s Multi-Displacement System is not used on the 6.1.
Aspiration:N/A
Valvetrain:16 Valves
Fuel Injection:Indirect Injection.
Peak Horsepower: 425 bhp (317 kW; 431 PS) at 6,200 rpm
420 lb⋅ft (569 N⋅m) of torque at 4,800 rpm
Peak Torque:569 Nm or 419 lb.ft @ 4800 rpm

6.4 hemi (PROS & CONS)

The 6.4 Hemi has more HP than the 6.1, in the region of about 50hp extra. It also has a better cylinder head flow and larger displacement when you compare the two. The 6.4 has variable cam and variable intake manifold, making it a more sophisticated engine to the 6.1. All the added engineering and technology built into the 6.4 means it reaches the higher power quicker in the rev range and can maintain it for longer, which it particularly noticeable when you are at full throttle.

The lifters on the 6.4 that are designed to accommodate the MDS system are a known failing point. This can be a deal breaker for some if they intend on modifying the 6.4 at a later stage. The 6.4 is more expensive option both to purchase as well as for future modifications.

Hemi 6.1 VS 6.4 Drag race (Charger SRT8 vs Scatpack 392)

Hemi 6.4 Owners Feedback

Mine is 2011, the one with 322,000 is a 2012, and the 276,000 is a 2013. We also have a 2009 with the 4.7L that has been a shop plow truck for the past 3 years that is at 397,000. All these trucks get driven by 3+ different people per day, and get absolutely ragged on.

https://www.ramforumz.com/threads/how-long-does-the-hemi-last.200097/

This is by far the best Ram truck I’ve owned. Even after 127k miles, close to 100k miles towing the truck still feels/rides like a new one. I can’t say the same about the previous generations I’ve owned. I can see myself owning this truck beyond 250k easily.

https://www.ramforumz.com/threads/how-long-does-the-hemi-last.200097/

Potential 6.4 Issues (Ram Trucks)

  • Gas engine struggles with towing up steep hills
  • Poor gas mileage while towing
  • High transmission temps climbing steep hills/towing

In an attempt to protect the Hemi engine, when towing a heavy load up a steep incline for extended periods, the engine will govern you to 35mph to prevent over-revving.

Many owners have complained about sluggish performance and poor gas mileage when towing heavy loads with the Ram, only returning as low as 6MPG. This is weird since the 6.4 torque curve is about 1000rpm lower than the 5.7 which means it gains power earlier in the rev range allowing you more control and power when towing. 

  • MDS solenoid fail.
    Many earlier model owners reported this issue, resulting in the engine running rough.
  • Wrist Pin Issue
    Early 6.4 V8’s suffered from the Wrist Pin Issue. This was evident on the 2014 models where the engine would emit a loud ticking or knocking sound after it sat overnight. The cold-start would give off a loud knocking noise after an overnight cold soak. Certain engines built in 2014 where built with the incorrect piston wrist pins, resulting in a 30 minute long audible knocking noise.

Although the service bulletin only covers the 2014 year model, does not mean Dodge is not liable to replace your engine if your model is not within the date range and showing the wrist pin ticking/knocking symptoms on cold start.

  • Vibrations from the engine. (Possibly caused by the MDS Solenoid failing and rough running)

6-Speed Transmission
Dramatic Downshift from 2nd Gear to 1st Gear when hauling or towing heavy loads up steep hills.

6.1 hemi (PROS & CONS)

The 6.1 Hemi is a fairly basic engine since it doesn’t have variable intake nor does it have variable cam timing, so pretty old-school in a sense. Its boasts a pretty traditional FI intake with no fancy “electrickery” to make big power. That means its quite easy to modify the old-school way. Because of the head and throttle design, it also has a really responsive throttle.

Owners Feedback (Hemi 6.1)

run a Dodge Challenger SRT 8 as a daily which is basically the same car just different body and it will tick all the boxes, great in traffic, around town and on a run, bit thirsty around town circa 13-15 mpg but 20mpg on a steady run, what it will give you is lots of smiles as 425bhp in a daily is fun, I do around 20k a year in mine and had it nearly 3 years, all ive done is filters and oil engine wise and usual tyres brakes ect but im very happy, they do go through ball joints and bushes though. But pound for pound you cant beat them and most likely you will sell it for what you pay for it as they kinda stay where they are value wise once they’ve done their initial drop.

https://www.pistonheads.com/gassing/topic.asp?t=1561383

I pushing 150k on my charger, so I can tell you the reasons I wouldn’t buy my car now. The front suspension is worn and noisy, I’ve replaced everything in there at least once before, it just doesn’t last. The real issue, that I may not be able to get over, is rust. I have bubble over the windshield, at the seam between the rear bumper and quarter panel, a little around the gas fill door, and an actual hole in the floor board. I feel like the hole is from salty snow feet getting that **** in the driver’s foot well, then rotting from the inside out. I’ve done a lot of work on my car, and still really like it. It’s fast, loud, big enough to haul the whole family around, and I still think the 1st gen chargers look the best. Check the underside for rust, check the trans fluid for color and smell, and do a leak down test if you can. I would think that if all that checks out, and you are getting a good vibe from the seller,….do it.

https://www.lxforums.com/board/the-srt-8-6-1l-and-6-4l-v8-/403155-mileage-6-1-a.html

198K kms on mine now and I’d still buy one with high mileage if I needed to. Front suspensions are a known issue across the entire Lx platform, not just SRT’s. Engine is strong and as long as it’s been looked after, not too much to worry about. Definitely check every knook for rust, especially on each side of cats. I’ve heard of frame rails rusting though at that location if car spends a lot of time idling – not sure why or how that works. Keep in mind that car is 11 years old so chances of it being totally rust free are slim, unless you are in a favorable climate. If the engine is quiet, it shifts well up and down, oil pressure is good at idle (24-27 PSI when engine warm at idle), no dash lights triggered, the ride is good at time of purchase, minimal rust and it passes whatever safety exam is required, and if the price is attractive, I’d go for it. Check if airbag recalls have been done and ask for all maintenance receipts. Good hunting!

https://www.lxforums.com/board/the-srt-8-6-1l-and-6-4l-v8-/403155-mileage-6-1-a.html

Hemi 6.1 Known Issues

Some of the known issues of the 6.1 Hemi include

  • Lifter roller fail – Cam lobe failure (MDS more prone on 5.7 Hemi but also reported on certain 6.1 and 6.4)
  • Lifter bearing seizes up and the roller wouldn’t roll causing a loud ticking noise
  • No Misfire codes, no running or performance problems, No Check engine lights
  • Can fail From as low as 60-80k miles
  • Is regarded as a “Know issue”
  • DIY Fix – fit hellcat lifter and delete the MDS
  • Front Suspension bushes, ball joints and struts premature wear.

Resources

https://www.ramforumz.com/threads/how-long-does-the-hemi-last.200097/

https://www.ramforum.com/threads/how-many-miles-on-you-6-4-hemi.100126/page-3

Bluetooth OBDII Scanner and clear CHECK ENGINE error

High Performance Aluminum Fuel Rail

Jade C.

4-Wheel drives and off-road driving techniques has been my passion for over 20 years. Here we strive to provide the most accurate, up-to-date, information about the functionality, common faults and latest technology built into most 4 Wheel Drives.

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