NM: What would a new 4th generation Dodge Hemi engine be like? Something that keeps the soul of the 3rd generation, but less complex parts, more fuel efficient, similar sound, etc. Who are some companies they could learn from? JLR? Mercedes? BMW? Volvo? Conceptualize a 4th generation Hemi engine for Dodge/Chrysler/Jeep/Ram
The 4th Generation Hemi: Evolution with Soul
Let me conceptualize what a truly modern Hemi could look like while preserving what makes these engines legendary.
Core Philosophy: "Simplified Brutality"
The 3rd gen Hemi's complexity (VVT, MDS, dual spark plugs, etc.) was born from EPA regulations. A 4th gen should be intelligently simplified while being cleaner and more efficient.
Engine Architecture
Displacement Options:
Mercedes-AMG (M156/M159 engines):
Breathing:
This is non-negotiable. The burble, the lope, the muscle car rumble:
Simplified = Bulletproof:
Hellephant Successor (Supercharged 6.4L):
Would Stellantis actually do this? Probably not. They're committed to electrification and turbo inline-6 engines. But if they wanted to give the Hemi one more generation that honored its heritage while meeting 2025+ requirements, this would be the recipe: Mercedes-level engineering execution, BMW-inspired efficiency technology, and pure Mopar attitude.
The 4th gen Hemi would be the V8 engine that proves internal combustion still has a place in the modern world - not through gimmicks, but through intelligent evolution.
NM: There's been some recent backpedaling of full speed EV development while they're more carefully developing solid state technology. Lithium Ion EVs seem to be getting dropped. SRT division has been reformed, and Durango is all Hemi right now, so my question is to ask how HEMI could be continued meeting future regulations, and improved over the very old current one.
Stellantis SRT division reformed 2024 2025
10 results
future emissions regulations 2026 2027 2028 EPA CAFE V8
10 results
Excellent context! You're absolutely right - Stellantis has revived the SRT division under Tim Kuniskis to unify high-performance efforts across Dodge, Ram, Jeep, and Chrysler MotorTrendMotorTrend, and the 2026 Ram 1500 can now be ordered with the 5.7-liter Hemi V-8 SRT is Back, but is It Enough to Rev Stellantis Into the Near Future?. This changes everything. Let me give you a realistic roadmap for how the Hemi can survive and thrive through the regulatory gauntlet.
The Regulatory Reality
The EPA's new standards phase in from 2027-2032, targeting a 56% reduction in greenhouse gas emissions compared to 2026 model year standards Federal RegisterCar and Driver. This doesn't kill V8s - it just means they need to be dramatically more efficient or offset by EVs in the fleet average.
The 4th Gen Hemi: A Realistic Engineering Path
Phase 1: 2026-2028 - "Hemi Refined"
Immediate improvements to the current architecture
What they can do NOW without massive investment:
More substantial changes, new engine variant
The "e-Hemi" - Full Hybrid V8
Learn from: Ford PowerBoost (3.5L hybrid), Toyota iForce Max (3.5L hybrid V6)
If V8s still exist, this is how
Advanced Technologies:
This is how Stellantis actually keeps Hemis alive:
The regulations don't ban V8s - they just require fleet-wide averages. Stellantis can:
The Sound Preservation
Non-negotiable: Keep the muscle car sound
Mercedes (M256 inline-6 hybrid):
Why Stellantis WILL do this:
The Hemi absolutely CAN meet future regulations through:
With SRT back and Tim Kuniskis leading the charge MotorTrendMotorTrend, they have someone who actually understands that the Hemi isn't just an engine - it's the soul of these brands. The technology exists. The customer demand exists. The business case exists.
The 4th gen Hemi isn't a fantasy - it's a necessity if Stellantis wants to remain relevant in the American market.
The 4th Generation Hemi: Evolution with Soul
Let me conceptualize what a truly modern Hemi could look like while preserving what makes these engines legendary.
Core Philosophy: "Simplified Brutality"
The 3rd gen Hemi's complexity (VVT, MDS, dual spark plugs, etc.) was born from EPA regulations. A 4th gen should be intelligently simplified while being cleaner and more efficient.
Engine Architecture
Displacement Options:
- 5.7L V8 (base) - 420 hp / 420 lb-ft
- 6.4L V8 (performance) - 525 hp / 510 lb-ft
- Both naturally aspirated, maintaining that linear power delivery
- True Hemispherical Chambers - Keep the heritage, but optimize chamber geometry with modern CFD modeling for better combustion efficiency
- Single Spark Plug Per Cylinder - Modern combustion chamber design and direct injection eliminate the need for dual plugs. Simpler, lighter, more reliable.
- Advanced Direct Injection - High-pressure (2,900+ psi) system with intelligent spray patterns. Think Mercedes M156/M159 execution but Dodge-engineered.
- Cylinder Deactivation Done Right - Variable displacement (4-cyl mode for cruising), but using BMW's Valvetronic-style variable valve lift instead of complex lifter deactivation. Seamless, reliable, no MDS tick.
- Forged Internals as Standard - Forged pistons and rods in all variants. Built to last 300k+ miles and handle power modifications.
Mercedes-AMG (M156/M159 engines):
- Naturally aspirated V8 excellence
- Simplicity and reliability (no turbos, no cylinder deactivation in early versions)
- Glorious exhaust note through smart engineering
- Their dry-sump systems for performance variants
- Valvetronic variable valve lift technology
- Individual throttle bodies for response
- Rev-happy designs that remain durable
- What NOT to do: avoid complex wet-belt timing systems
- What TO do: modular architecture for cost efficiency
- Yes, the competition, but they nailed simple, powerful, reliable
- Flat-plane crank acoustic engineering (for sound tuning insights)
- Port and direct injection combo
- Dry-sump oiling systems
- Thermal management excellence
- Building engines that reward high RPM use
Breathing:
- Port and direct injection (like Toyota's D4-S)
- Long-tube headers as factory equipment (performance models)
- Active exhaust valves (but mechanically actuated, not vacuum)
- Twin 4-barrel throttle body design (homage to heritage, modern execution)
- Pushrod OHV (maintains packaging, character, and simplicity)
- Roller followers throughout
- Advanced cam profiles with variable valve timing on exhaust only
- 6,800 RPM redline (7,200 on performance variants)
- Deep-skirt cast iron block with aluminum structural pan
- Aluminum heads with integrated exhaust manifolds (thermal efficiency)
- Cross-bolted main caps
- Deck plate honed for perfect bore geometry
- Plasma-sprayed cylinder walls (reduced friction, lighter block)
- Variable displacement oil pump
- Intelligent thermal management (split cooling, electric water pump)
- Stop-start system that doesn't feel agricultural
This is non-negotiable. The burble, the lope, the muscle car rumble:
- Unequal-length headers maintain classic V8 sound character
- Active exhaust with mechanical flapper valves
- Tuned intake resonators
- Strategic firing order optimization (keep the traditional Mopar sound)
- No fake symposer nonsense - purely mechanical acoustics
- 5.7L: 18/27 mpg (city/highway) - ~25% improvement over current
- 6.4L: 16/25 mpg - competitive with GM's 6.2L L87
- Lower friction design
- Better combustion efficiency
- Optimized cylinder deactivation
- 10-speed automatic transmission pairing
- Aerodynamic improvements vehicle-side
Simplified = Bulletproof:
- No more lifter failures (better oiling, simpler design)
- Single cam per bank (two total)
- Timing chain in front (accessible, durable)
- Conventional coil-on-plug ignition
- Cast aluminum valve covers (no plastic junk)
- 10,000 mile oil changes
- 150,000 mile "lifetime" fluids (realistically serviceable)
- Easy maintenance access - DIY-friendly
Hellephant Successor (Supercharged 6.4L):
- 850+ hp with 2.7L IHI supercharger
- Maintains street manners and reliability
- Forged rotating assembly handles boost
- High-output 6.4L tuned for low-end torque
- 500 hp / 550 lb-ft
- Desert-runner durability
- Keeps the soul: Pushrod V8, natural aspiration, traditional muscle car character
- Reduces complexity: Fewer failure points than 3rd gen
- Improves efficiency: 20-25% better MPG while maintaining power
- Costs less to build: Simpler manufacturing, fewer parts
- Easier to modify: Enthusiast-friendly like the old days
- Globally viable: Meets modern emissions while staying V8
Would Stellantis actually do this? Probably not. They're committed to electrification and turbo inline-6 engines. But if they wanted to give the Hemi one more generation that honored its heritage while meeting 2025+ requirements, this would be the recipe: Mercedes-level engineering execution, BMW-inspired efficiency technology, and pure Mopar attitude.
The 4th gen Hemi would be the V8 engine that proves internal combustion still has a place in the modern world - not through gimmicks, but through intelligent evolution.
NM: There's been some recent backpedaling of full speed EV development while they're more carefully developing solid state technology. Lithium Ion EVs seem to be getting dropped. SRT division has been reformed, and Durango is all Hemi right now, so my question is to ask how HEMI could be continued meeting future regulations, and improved over the very old current one.
Stellantis SRT division reformed 2024 2025
10 results
future emissions regulations 2026 2027 2028 EPA CAFE V8
10 results
Excellent context! You're absolutely right - Stellantis has revived the SRT division under Tim Kuniskis to unify high-performance efforts across Dodge, Ram, Jeep, and Chrysler MotorTrendMotorTrend, and the 2026 Ram 1500 can now be ordered with the 5.7-liter Hemi V-8 SRT is Back, but is It Enough to Rev Stellantis Into the Near Future?. This changes everything. Let me give you a realistic roadmap for how the Hemi can survive and thrive through the regulatory gauntlet.
The Regulatory Reality
The EPA's new standards phase in from 2027-2032, targeting a 56% reduction in greenhouse gas emissions compared to 2026 model year standards Federal RegisterCar and Driver. This doesn't kill V8s - it just means they need to be dramatically more efficient or offset by EVs in the fleet average.
The 4th Gen Hemi: A Realistic Engineering Path
Phase 1: 2026-2028 - "Hemi Refined"
Immediate improvements to the current architecture
What they can do NOW without massive investment:
- 48V Mild Hybrid System(Learn from: Ram's existing eTorque, Mercedes M256)
- Belt-driven starter/generator (10-15 kW)
- Small lithium battery pack
- Instant torque fill, smooth stop-start
- Electric A/C and water pump
- Gains: 2-3 MPG improvement, 10-15% emissions reduction
- Advanced Thermal Management
- Split cooling (block vs. heads can run different temps)
- Electric coolant control valves
- Faster engine warm-up = lower cold-start emissions
- Gains: 5-8% emissions reduction in real-world driving
- Improved Cylinder Deactivation
- Current MDS is clunky and has reliability issues
- Copy GM's Dynamic Fuel Management (can run 1-2-3-4 cylinders as needed)
- Better NVH isolation
- Gains: 8-10% fuel economy in mixed driving
- Port + Direct Injection(like Toyota D4-S)
- Direct injection for power/efficiency
- Port injection for low-speed cleanliness, prevents carbon buildup
- Already proven technology
- Gains: 5-7% efficiency, cleaner emissions
- Modern 10-Speed Transmission
- ZF 8HP is good, but a 10-speed keeps engine in optimal RPM range
- Gains: 3-5% highway economy
- Current: ~15/22 MPG (city/highway)
- With these changes: 19/28 MPG
- Emissions: ~30% reduction
More substantial changes, new engine variant
The "e-Hemi" - Full Hybrid V8
Learn from: Ford PowerBoost (3.5L hybrid), Toyota iForce Max (3.5L hybrid V6)
- Dedicated Hybrid Transmission
- Integrated electric motor (100+ kW / 134+ hp)
- Small battery pack (1.5-2.0 kWh)
- Electric-only launch and low-speed driving
- Engine can shut off completely at stops and in traffic
- Atkinson Cycle Capability
- Variable valve timing allows pseudo-Atkinson cycle
- Better thermal efficiency at cruise
- Combined with electric motor for low-end torque
- Smaller Displacement Option: 5.0L V8
- Still Hemi architecture
- Undersquare design (bigger bore, shorter stroke)
- High compression ratio (12.5:1+)
- With hybrid: 420+ hp combined, 500+ lb-ft
- Full hybrid 5.0L Hemi: 22/29 MPG (truck application)
- Full hybrid 5.7L Hemi: 20/27 MPG (performance application)
- Emissions: ~50% reduction vs. current
If V8s still exist, this is how
Advanced Technologies:
- Miller Cycle + Supercharging(Learn from: Volvo's old supercharged 4-cylinders)
- Low-pressure supercharger for cylinder filling
- Extreme Atkinson/Miller cycle
- Electric supercharger (no parasitic loss)
- Combined with full hybrid system
- Water/Methanol Injection(BMW M4 GTS)
- Allows higher compression + boost
- Cleaner combustion
- Lower emissions
- 48V Active Suspension Mounts
- Completely cancel cylinder deactivation transitions
- Run 2-4-6-8 cylinder modes seamlessly
This is how Stellantis actually keeps Hemis alive:
The regulations don't ban V8s - they just require fleet-wide averages. Stellantis can:
- Sell PHEVs with Inline-6 Hurricane (Wrangler 4xe already doing this)
- Offer full EVs (like the electric Ram coming)
- Use those credits to offset Hemi sales
The Sound Preservation
Non-negotiable: Keep the muscle car sound
- No equal-length headers (that makes it sound like a Ferrari)
- Keep traditional firing order
- Active exhaust systems (already have this)
- No fake noise - purists will riot
- Let the hybrid system be silent so the V8 drama stands out more
Mercedes (M256 inline-6 hybrid):
- Integration of 48V system
- Smooth power delivery with electric assist
- Premium feel despite complexity
- 48V architecture done right
- Seamless start-stop
- Don't copy: complex cooling systems that fail
- Packaging hybrid components in trucks/SUVs
- Don't copy: Land Rover reliability issues
- THIS IS THE BLUEPRINT
- Proven hybrid V6 that tows, performs, and returns 20+ MPG
- Reliable, simple, effective
- Scale this concept to V8
- Onboard power generation (Pro Power)
- Hybrid tuned for truck duty cycles
- Proves customers want hybrid performance trucks
- Historical lesson: forced induction + efficiency tech
- Don't copy: abandoning what made them special
Why Stellantis WILL do this:
- Profit margins - V8s command price premiums ($3,000-$8,000 over base)
- Brand identity - Dodge/Ram without V8s lost their soul (they learned this)
- Competition - GM still sells 6.2L V8s, Ford still offers V8s
- Customer demand - Ram sales plummeted without V8 option
- Technology exists - Nothing here is science fiction
- Mild hybrid system: +$800-$1,200 per vehicle
- Full hybrid: +$3,000-$4,000 per vehicle
- Customers will pay it for V8 capability
- 2026 MY: Current Hemi with mild hybrid (48V eTorque improvement)
- 2027 MY: Refined Hemi with DI + port injection, better MDS
- 2028 MY: Optional full hybrid Hemi in Ram 1500
- 2029 MY: Full hybrid becomes standard on 5.7L
- 2030 MY: New-design "Gen 4" Hemi debuts (cleaner sheet design)
- 2032+: Hemi continues as premium option alongside inline-6 and electric
The Hemi absolutely CAN meet future regulations through:
- Mild hybridization (quick, cheap, effective - 20-25% cleaner)
- Full hybridization (like Ford/Toyota - 40-50% cleaner)
- Modern efficiency tech (DI, better MDS, thermal management)
- Fleet averaging with EVs and PHEVs
With SRT back and Tim Kuniskis leading the charge MotorTrendMotorTrend, they have someone who actually understands that the Hemi isn't just an engine - it's the soul of these brands. The technology exists. The customer demand exists. The business case exists.
The 4th gen Hemi isn't a fantasy - it's a necessity if Stellantis wants to remain relevant in the American market.
