Introduction
The 426 HEMI is one of Chrysler’s most identifiable engines and has the reputation for power and performance. Currently, there is frivolous discussions on the internet on whether or not it is possible to create 426 HEMI from 318 blocks. In this blog post, we will look into the possibility of this conversion, potential problems and what changes would be needed for it.
Uderstanding the 426 HEMI
The HEMI Design
The 426 HEMI engine which came into production in the 1960s contains a hemisphere-shaped combustion chamber which charges the carburetor with a better air fuel mixture, and will produce more power. This design makes it unique from traditional wedge-shaped combustion chambers of most engines, including the 318.
Specifications of the 426 HEMI
Below we take an inside look at the engine specifications of the 426 HEMI which makes it ideal to be used in the Modified American cars.
Bore and Stroke: The 426 HEMI has a bore of 4.25 in and stroke of 3.76 in.
Power Output: In its stock form it can churn out in excess of 425 horsepower.
Engine Block: HEMI block is thicker and it’s more heavy duty in nature to take higher amounts of power than what you have in a engine 318 block.
The 318 Block Overview
Block of 318: Specifications
The 318 engine is a small block V8, make and model of engines that have been in circulation for some time now. Here are some key specifications:
Bore and Stroke: The 318 has a bore of 3.91=”” and a stroke of 3.31 inches.
Power Output: They produce about 150 to 200 horsepower, but this varies with the configuration and given modification.
Usage: The 318 block is used standard in numerous Chrysler automobiles and generally, the motor offers reliability and decent power output.
Limitations of the 318 Block
While the 318 block is a capable engine, it has limitations compared to the 426 HEMI:
Lower Power Capacity: The brilliant 318 cannot add up the power levels such as the HEMI.
Different Design: Least from what was observed from the internal part of the 318 and its overall design it cannot be subjected to HEMI conversion.
Problems of Turning 426 HEMI from 318 Block
Fundamental Design Differences
The first major issue here in changing a 318 block to accommodate a 426 HEMI is that the two engines are mainly dissimilar. The 318 block cannot just be adapted to the HEMI by installation of a hemispherical combustion chamber and specific cylinder head as basic designs are entirely different.
Required Modifications
To build a 426 HEMI from a 318 block, you would need to consider the following modifications:
1. Custom Cylinder Heads: To make or purchase certain cylinder heads that would mimic the HEMI design would most definitely be required.
2. Bore and Stroke Adjustments: In essence the 318 block may have to be bored out radically as well as the stroke which will suit the HEMI specifications.
3. Pistons and Connecting Rods: New bore and stroke will require aftermarket pistons and connecting rods to be used in the engine block.
Cost and Complexity
It’s not impossible to build a 426 HEMI from a 318 block, but it becomes quite costly because the job demands lots of custom parts and a lot of machine work. The time, money and effort needed in the process will be slightly longer and it will also prove to be cumbersome since the obtaining of the labor and materials need may be quite elaborate as compared to the ready made HEMI engine on the market.
Alternatives to Consider
Purchasing a HEMI Engine
However, given some of the obstacles and expense required to switch over a 318 block to a 426 HEMI, many performance lovers choose to acquire HEMI engine instead. This provides the following advantages:
Reliability: Factory built HEMI engine will have been designed for a specific power output and have undergone the proficiency tests.
Power and Performance: This way you will get the levels of power you want without all the headaches associated with a custom build.
Remington Performance Upgrades for the 318 Block
For those who want to have a lot to do with the 318 block, there are changes that may be done to improve on the power in the block without having to implement HEMI conversion. Some options include:
Aftermarket Intake Manifold: Different intakes can be selected; performance intake can be upgraded to increase airflow, thus leading to a higher horsepower.
High-Performance Camshaft: A better camshaft can actually fine-tune the balance of the hardware of the engine itself.
Headers and Exhaust: The exhaust system can be tweaked up to improve power rating as well as loudness.
Conclusion
It is, of course, possible to build a 426 HEMI from a 318 block, but doing so turns the process from a decently complex pastime into something feasible only for a relatively limited number of enthusiasts. There are certain design differences which are hard coded into the system and no amount of tweaking will allow this project to be accomplished efficiently. Those people who are looking for the power from Hemi, it is cheaper to find a complete engine or bring the attention to the improvements for the 318 block.
All in all, if you are dedicated HEMI car owner or just want to upgrade your current system, there are numerous opportunity to find something that will be suitable for your car and your performance expectations.
