How much horsepower does a Slant 6 engine have?
In stock form, the Chrysler Slant-6's horsepower typically ranges from about 145 to 170 horsepower, with some late-1980s variants approaching around 180 hp. Exact figures depend on year, carburetion vs fuel injection, and emission controls.
What is the Slant-6?
The Slant-6, built around a 225 cubic inch inline-six, earned its name from the engine block's distinctive 30-degree slant. It powered a wide range of Chrysler, Dodge, and Plymouth cars and trucks from the mid-1960s through the 1980s and beyond, known for torque and robustness as a workhorse in daily driving and fleet-duty applications.
Horsepower: a broad overview
Because the Slant-6 was produced for many model years with varying fuel systems and emissions requirements, horsepower is not fixed. Here is a snapshot of the typical ranges you might encounter on stock engines across the lineage.
Key performance drivers
- Carbureted two‑barrel vs. four‑barrel carburetion can add tens of horsepower.
- Compression ratio and ignition timing influence peak power and efficiency.
- Exhaust and intake tuning, including OEM exhaust manifolds and headers, affect breathing and horsepower.
- Emission-control hardware (smog equipment) can reduce peak power in later years.
- Fuel injection variants in the late 1980s and early 1990s pushed power slightly higher than early carbureted versions.
Because of these variables, exact numbers vary by year, market, and configuration. For a precise figure, consult a factory specification sheet for the exact model year and engine code.
Horsepower ranges by era (broad guide)
Here's a broad guide to typical stock horsepower figures for the 225 Slant-6 across its main eras and configurations. Note that these are general ranges and individual engines may differ due to wear, tuning, and regional specs.
- 1965–early 1970s: typically about 145–165 horsepower depending on carb setup and compression.
- Late 1970s–early 1980s: emissions controls and mild tuning often yielded roughly 150–170 horsepower.
- Late 1980s–early 1990s: introduction of more advanced fuel delivery could push figures toward 165–180 horsepower in some applications.
- Special or high‑output factory variants (rare): roughly up to around 180 horsepower.
In practice, the actual horsepower for a specific Slant-6 will depend on the exact year, configuration, and condition of the engine. For a precise figure, check the original brochure or factory service manual for your vehicle.
Common configurations that affect horsepower
Below is a concise guide to the main design factors that typically determine how much horsepower a Slant-6 can produce, including what to look for when evaluating a used engine.
- Fuel delivery: carbureted vs. fuel injection and the size of the carb or injector hardware.
- Compression ratio: higher compression generally increases peak power, up to engine-safe limits for the fuel used.
- Exhaust and intake: cam timing, intake manifold, headers, and exhaust backpressure influence breathing and power output.
- Emission controls: catalytic converters and EGR can reduce peak horsepower in late‑era engines.
- Camshaft and ignition timing: aggressive cam profiles and properly advanced timing can raise power, particularly at higher rpm.
Understanding these factors helps explain why two Slant-6 engines can have noticeably different horsepower numbers even within the same displacement.
How to verify horsepower for a specific Slant-6
To confirm the exact horsepower of a particular engine, use official sources such as the vehicle’s build sheet, original owner’s manual, factory service manuals, or Chrysler/Mopar catalog data. Enthusiast databases and reputable restoration guides can also provide year‑specific specs for common applications.
Summary
The Slant-6’s horsepower is not a single fixed figure; it spans a range that reflects its long production life and multiple configurations. Most stock 225 cubic inch Slant-6 engines deliver roughly 145–170 horsepower, with late‑era EFI variants sometimes approaching 180 hp. If you need the precise number for a given vehicle, consult the original factory documentation or a trusted reference for that exact year and engine code.
Are Slant 6 engines reliable?
It Was Exceedingly Reliable
One of the hallmarks of the Slant-Six's reliability was its use of something called a deep-skirt design, which means its crankshaft is mounted above the oil pan rails, leading to better structural durability and integrity.
Why did Dodge make a Slant 6?
The Chrysler Slant Six offered a tilted take on the inline six-cylinder motor that at the time, only Mercedes Benz had mastered aforehand. For Chrysler, this design provided the perfect solution to a time-sensitive issue, with the Slant Six ending up being produced on a global scale.
How much horsepower does a 1966 225 Slant Six have?
around 145 horsepower
Displacing 225 cubic inches (3.7 liters), the Slant Six produced around 145 horsepower in its early years, with plenty of low-end torque that made it ideal for daily driving.
How much horsepower can a Slant 6 make?
This package, called "Super Six" by the marketing division, brought rated horsepower from 100 to 110 hp (101 to 112 PS; 75 to 82 kW) and torque from 170 to 180 lb⋅ft (230 to 244 N⋅m), while improving throttle response and driveability while maintaining compliance with emission laws.
