Dodge SRT Performance: SRT 392 Engine
A performance engine isn’t just a bigger engine, it is a big engine in which every little part has been carefully tuned and tweaked to maximize power and performance. Dodge has three performance engines, and two of them are available on the Charger and Challenger lineup. While the SRT Hellcat engine is the most powerful, the SRT 392 engine isn’t far behind and on the track, it smokes a lot of the competition.
The SRT 392 engine is a 6.4-liter HEMI V8 engine and it pushes out 485 horsepower and 475 lb-ft of torque. This engine is available on two Charger models and three Challenger models. When the Dodge Charger is equipped with this engine, it accelerates from 0-60 mph in 4.3 seconds, which is faster than the Chevy Camaro LT and the Ford Mustang.
What makes it so powerful? Let us tell you.
SRT 392 = 6.4L HEMI V8 powered by SRT
The displacement of the SRT 392 engine is 392 cubic inches, which can also be expressed as 6.4-liters. Though a lot of people think that liters refers to engine size, in reality, it is engine displacement, which affects the size of an engine, but is not the only thing that makes up the total size of an engine.
Engine displacement is the volume of the vehicle’s cylinders and/or the volume of air displaced by the action of the pistons. More volume inside a cylinder means there is more space for air, and more air makes bigger combustions, and bigger combustions create more power. In fact, the only thing that creates power is the size of the explosion in the cylinder, so the cylinder is where things get complicated, tuned and tweaked.
Alright, so now we are on to where the magic happens, the cylinders. The SRT 392 engine has eight cylinders and they all have HEMIs. All cylinders have a combustion chamber and HEMIs are a specific type of combustion chamber that is domed rather than flat. The domed shape has a couple benefits to increase engine performance, like more space for valves and a decrease in heat loss, so fuel burns more efficiently.
Bore and Stroke
The cylinders on this engine, like many performance engines, make this engine an oversquare engine, which means the cylinder bore (diameter of the cylinder) is bigger than the stroke, (length or distance traveled by piston from 0-180 degrees). There are a couple reasons oversquare engines are common in performance cars.
- The larger the bore, the more room for valves, which are what let air in and out of the cylinder.
- The shorter stroke distance means the piston speed is faster, so an engine can rev higher and faster.
The SRT 392 engine has a bore of 4.09 and a stroke of 3.72, which is a ratio of 1.09: 1. With the bore and stroke known, you can determine the engine displacement.
Engine displacement= pi/4 x bore x bore x stroke x no. of cylinders
392 cubic inches = pi/4 x 4.09 x 4.09 x 3.72 x 8
392 cubic inches = 6.4L
So now that we know that one advantage to oversquare engines is to allow more valves, we should focus on what valves do in cylinders. There are two types of valves, air intake valves (let air in) and exhaust valves (let burned air out). The more air that can enter increases the size of a combustion and the faster and more efficiently air exits the cylinder, the faster the new air can come in again.
Not only does the SRT 392 have two intake valves and two exhaust valves for each cylinder, but the valve design is tweaked to improve performance. The intake valves are hollow stem valves, which makes them lighter and therefore easier to move. The exhaust valves are filled with a sodium mixture, which dissipates heat faster.
Compression ratio is another factor that affects performance. Not only does more air lead to bigger explosions, but the tighter and more compact the space for air and gas is within the cylinder, creates bigger explosions. The SRT 392 has a compression ratio of 10.9:1, whereas the 3.6L engine has a compression ratio of 10.2:1. Since the compression ratio is fairly high, a higher octane gas is recommended. At a high compression ratio, lower octane gas can ignite before the spark plug ignites and this can cause serious engine problems. So higher octane fuel prevents this from happening.
Want to know what all of that power feels and sounds like?
Come down to Kendall Dodge Chrysler Jeep Ram. We have a large collection of SRT performance engines available.