Everything you need to know about the legendary Slant Six and Hemi Six engines
The Chrysler Valiant isn’t just remembered for its stylish body lines and versatile body styles — it’s also celebrated for its engine lineup, particularly the straight-six engines that powered generations of Valiants from the 1960s to the late 1970s.
These engines weren’t just workhorses; they became legends in Australian motoring for their durability, torque, and performance potential. Here’s a complete guide to the Slant Six and Hemi Six engines, their history, strengths, weaknesses, and fun facts.
1. The Slant Six: Chrysler’s Original Straight-Six
Development and Specs
- Introduced in Australia in the early 1960s
- Inline six-cylinder configuration, tilted slightly to the right (“slant”)
- Displacement: 225 cubic inches (CI)
- Used primarily in early Valiant sedan and wagon models
Famous For
- Reliability and longevity – Known to go well over 300,000 km with proper maintenance
- Smooth and torquey – Perfect for everyday driving and light towing
- Fuel efficiency – More economical than V8s of the era
Strengths
- Extremely durable and easy to maintain
- Compact design allowed better engine bay packaging
- Lightweight, helping handling and fuel economy
Weaknesses
- Modest power output compared to later Hemi Six or V8s
- Limited performance potential without extensive modifications
Fun Facts
- The slant allowed lower bonnet lines, contributing to the Valiant’s sleek design
- Became a favourite for fleet buyers due to low running costs and reliability
2. The Hemi Six: Performance Redefined
Development and Specs
- Introduced in 1969, initially as a 245 CI and later in 215 and 265 CI variants
- Featured a hemispherical combustion chamber (hence “Hemi”)
- Designed specifically for Australian conditions and performance applications
Famous For
- High torque at low RPMs – Made the Valiant feel lively even in heavier models
- Performance potential – Easily modified for street or racing, especially the 265 Hemi Six
- Dominated Australian motorsport, including Touring Cars and drag racing
Strengths
- Smooth and responsive for daily driving
- Lightweight compared to V8s, helping handling in coupes like the Charger
- Excellent aftermarket support for tuning and modifications
Weaknesses
- Required better cooling in hot conditions or when highly tuned
- Higher-performance versions could be more temperamental than the Slant Six
- More complex than the Slant, so slightly higher maintenance
Fun Facts
- The Hemi Six powered the legendary VH Valiant Pacer, the Charger E38, and E49
- Some 265 Hemi Six engines with triple Weber carbs could outperform small-block V8s in stock form
- Still celebrated today for its distinctive exhaust note and tunability
3. Comparing Slant Six vs Hemi Six
| Feature | Slant Six | Hemi Six |
|---|---|---|
| Power | Moderate | High |
| Torque | Good | Excellent |
| Durability | Excellent | Very Good (depends on tuning) |
| Performance Potential | Low | High |
| Fuel Economy | Very Good | Good |
| Best Use | Everyday driving, fleets | Sporty models, performance builds |
Summary: The Slant Six is the ultimate reliable workhorse, while the Hemi Six is the engine for enthusiasts who want a balance of street performance and durability.
4. Why These Engines Are Still Loved Today
- Simple and robust design – Parts are easy to source and maintain
- Versatility – Suitable for sedans, wagons, utes, and performance coupes
- Performance heritage – Hemi Six versions still dominate classic racing events and Valiant shows
- Collector appeal – Many enthusiasts seek original Hemi Six models, particularly Pacer and Charger variants
5. Fun Facts for Enthusiasts
- Some Hemi Six-powered Valiants could do 0–100 km/h in under 8 seconds in stock form
- Slant Six engines powered thousands of Australian taxis and fleet cars thanks to their reliability
- The 265 Hemi Six became the backbone of Australian muscle six-cylinder performance, influencing tuner culture to this day
Final Thoughts
The Chrysler Valiant straight-six engines — both the Slant Six and Hemi Six — are true legends of Australian motoring. They proved that six cylinders could be reliable, torquey, and thrilling long before V8 muscle cars dominated the streets.