Mitsubishi 4G63 vs 4G64: Which One is Better?

While Mitsubishi has completely fallen off the performance car market in the US since the disconnection of the Evo, back in the 1990s they had a ton of really great little performance cars like Evo, Eclipse, and Galant.

The engine which powered those cars is the 4G63 which we’ve done a video on in the past.

Since that video has released a lot of you guys have asked for a video comparing the 4G63 vs the 4G64. After all, they’re from the same engine family and have some differences, but have a lot of similarities. 

The Basic Info

Before we dive in too far, we should cover some of the really basic stuff first. As may or may not know, both the 4G63 and 4G64 are part of Mitsubishi’s Sirius engine family, which followed the naming scheme they used at the time.

The Sirius engine family started back in 1976 and it’s still in production today.

It’s important to note that many of the cars of the vehicles currently use some engine from the Sirius are not from Mitsubishi. Mitsubishi stills rely on the Sirius family, but it’s mostly being used by Chinese auto manufacturers such as Great Wall Motors.

The 4G63 specifically, started back in 1980 and is still being used by a handful of Chinese companies today. The 4G64, on the other hand, started in 1983 and is also still being used in China.

In case you were curious, the naming convention includes 4 is for the number of cylinders, the G is for gasoline, the 6 refers to the engine family, the final number refers to the engine itself, and if it’s a turbocharged engine it will have T at the end of its nice, such as 4G63T.

I would list off the different applications that use the 4G63 and 4G64, however, that list would incredibly long and boring, so instead I’ll put it down in the description for those of you who are interested.

The 4G63

With the basic stuff out of the way, let’s look a little bit more in-depth at these engines.

Starting with the 4G63, we’ve got a 2.0l displacement with an 85mm bore and 88mm stroke, some DOHC and some SOHC engines, a really strong cast-iron block, some variants feature Mitsubishi’s MIVEC variable valve timing system, and some of them are turbocharged.

The earliest 1st gen DSM engines are known as 6-bolt engines, because of their 6-bolts holding the flywheel to the crankshaft. Later 4G63 engines are known as 7-bolt engines.

It’s important to note that there are a significant amount of differences between 6-bolt and 7-bolt 4G63s, but most of the differences revolve around rotating assembly.

The 4G64

Looking at the 4G64, the biggest and most obvious difference is the displacement. Everyone calls it a 2.4L, but technically it has 2351cc of displacement but we just round up to 2.4 liters.

The increase in displacement was mostly achieved through increasing the stroke to 100mm, but the bore was also increased to 86.5mm which is just slightly bigger than the 4G63’s bore.

Aside from the increased displacement, the blocks of the 4G63 and the 4G64 are incredibly similar including the fact that there a 6-bolt and 7-bolt variant of the 4G64.

The differences between the 6-bolt and 7-bolt 4G64 are mostly found in the rotating assembly. Another important distinction between both engines is that the 4G64 has 6mm higher deck height.

Earlier 6-bolt had a heavy and inefficient rotating assembly which ultimately decreases total efficiency, so Mitsubishi’s used a lighter rotating assembly in the later 7-bolt engines.

What’s interesting, is that these engines are so incredibly similar that you can interchange a lot of the parts to give yourself a unique engine.

What mean by this, is that you can 4G63 block and use a 4G64 crank with stock 150mm connecting rods and an offset pin piston to build a 2.3L stroker motor.

You can do the opposite and put a 4G63 crank inside a 4G64 block to create a 2.1-liter destroked engine. It’s important to note that if you’re swapping around cranks, it needs to come from the same generation engine.

Cylinder Heads

Both engines came with either a single overhead cam or dual overhead cam cylinder head. For the most part, the heads on both engines are incredibly similar and mostly interchangeable.

You can even fit a 7-bolt head to a 6-bolt or the other way around, with some minor work. Not too surprisingly, the DOHC heads provide much better flow and overall a lot more performance compared to the SOHC heads.

Engine Internals

Internally, both engines are similar, but the connecting rods, pistons, and crank are different between both engines. On the 4G64 you’re going to find higher compression ratio pistons which can quickly become a problem if you’re looking to run a lot of boost. For forced induction applications, it’s best to run low compression ratio pistons.

Really, the N/A 4G63 and 4G64 are similar with the biggest difference coming down to the displacement. If you were to look at the 4G63T, the differences are more significant since it’s heavily beefed up for forced induction.

Realistically, the 4G63T was designed as a race engine for use with Mitsubishi’s rally racing ventures and it’s arguably one of the best turbocharged four-cylinder engines ever produced.

Which One is Better?

If you were to look at this from a high level and answer the question of which one is better, the 4G63 or 4G64, it depends on the specifics. If you’re looking at N/A engines, the extra of the 4G64 is great for low-end torque and drivability, but if you’re looking at forced induction engines, 4G63T is the answer.

If you’re talking about modified engines and which one is better to build for your street car, it’s pretty common to see a 4G64 with a 4G63T head and turbo setup, because buying a 4G64 engine is quite a bit cheaper than buying a full 4G63T engine.

At the same time, a 4G63T head is pretty expensive, so some people just resort to building a DOHC 4G64 with a turbo strapped to it.