Back in the 1990s, Mitsubishi had a lot of awesome performance cars on the market, namely the Evo, Eclipse, and Galant. The cars kicked some serious ass when they were new and even today, they are a great platform to build off of. The engine under the hood has become legendary in the world of high-performance 4-cylinders, and today I’m going to tell you everything you need to know about the 4G63.
The 4G63 follows the same basic formula of many high-performance 4-cylinder engines. It has two liters of displacement, dual overhead camshafts, a turbo bolted to it, and a bunch of boost. Although it follows the same basic formula of many engines before and after it, it’s what’s inside that makes the 4G63 special. For this particular article, we are going to be talking about the 4G63T, not the naturally aspirated 4G63.
The 4G63 is part of Mitsubishi’s Sirius engine family, which followed the naming scheme they used at the time. The 4 is for the number of cylinders, the G is for gasoline, the 6 refers to the engine family, the 3 refers to the engine itself, and the t stands turbocharged.
This is a group of engines that started all the way back in 1976 and continued in production up to 2013. The naturally aspirated version of this engine was used in a ton of different applications and was available in both single overhead cam and dual overhead cam variants.
The 4G63T Variant
Like I said earlier, the specific version we are talking about is the 4G63T. This version featured an 85mm bore, 88mm stroke, dual overhead cams, a cast-iron block, and a cast-aluminum cylinder head. From the start of its life, the 4G63T was designed as a race engine, and the first 4G63T in the US came about from Mitsubishi’s participation in rally racing.
The first cars in the US to use this engine were the 1st generation DSMs, which includes the Mitsubishi Eclipse, Eagle Talon, and Plymouth Laser. The 4G63T engine found in the 1G DSMs isn’t particularly powerful by today’s standards at just 195hp, but back 1989 when it was new that was a pretty impressive power figure.
In 1992 the US 4G63T was revised to match the Japanese market EVO, which featured different piston oil squirters, and a lighter rotating assembly. In 1995 the 2nd gen DSMs hit the scene and with them came a revised 4G63T which now output 210 horsepower.
Continuing their rally racing development, the 4G63T was eventually used in the Lancer (Sold as the Mirage in the US) after Mitsubishi dropped the Galant VR4 in 1993. Over the years and different generations of the Evo, the 4G63T was revised and output more and more power.
What Makes it Special
What makes this engine special is the architect inside and the materials Mitsubishi used for some of the components. To put it very simply, the bottom end of the 4G63T is known for being insanely tough and withstanding pretty insane power numbers.
Starting with the block, it uses basic and low-tech design, however, it’s constructed from a very strong cast-iron and features a lot of material in all the right places. The block itself is unbreakable.
The earliest 1G DSM engines are known as 6-bolt engines, because of their 6-bolts holding the flywheel to the crankshaft. The 6-bolt engines use massive and thick connecting rods, very wide and beefy rod and main caps, an insanely low 7.8:1 compression ratio, and a forged steel nitrided crankshaft.
The pistons are cast, but with a very strong design and had low and wide rings for extra strength. As mentioned earlier, there are piston oil squirters in this engine which spray the bottom of the piston dome to help reduce heat. To help reduce harmonic vibrations, two balancer shafts were used. The 1st and second, and 4th and 5th main caps are paired together, which makes the bottom end insanely strong.
6-Bolt vs 7-Bolt
The stock components on these 6-bolt engines were insanely strong, but also very heavy and each following version of the 4G63T used lighter rotating assemblies to improve efficiency. The engine was designed specifically for high-boost levels, and when it’s outside of boost, it’s underpowered and lethargic.
After the 6-bolt engine came the 7-bolt engine, which features a lot of notable differences. The first big difference is the big jump in compression ratio, with the 7-bolt at 8.5:1, which helped improve off-boost power output greatly.
The piston rings were redesigned and sealed better, the rod and main bearings were narrowed to decrease friction, and lighter rods decreased rotational mass. The main bearings changed from multiple paired caps to one large casting, which theoretically makes the bottom end quite a bit stronger.
There were some other minor changes from the 6-bolt to the 7-bolt, but the ultimate result was a more efficient engine, but also a slightly weaker engine. No discussion of the 4G63 is complete without talking about crankwalk, which is a problem the 7-bolt engines have become known for.
Early 7-bolt engines have gained a reputation for excessive thrust bearing wear, which over time allows the crankshaft to walk back and forth in the block. Eventually, this problem will destroy the crank position sensor and shut the engine off. The reasons for crank walk have been debated since the issue was first reported, but the problem has been somewhat blown out of proportion.
The design of the cylinder head is one of the keys to making big power, and Mitsubishi did a pretty good job with all versions of the 4G63’s head. The earlier 1G intake ports are huge and it’s often argued that the 1G head is better than the 2G head because of the port size, but looks can be deceiving.
While the 2G head does have smaller ports, they had a straighter design and provide better air velocity. In pretty much all applications other than massive turbo race cars, the 2G is better, because the increased air velocity helps improve low and midrange power. The last version of the 4G63T head, used on the Evo 9, used ports similar to the ports on the 2G head, but with the addition of MIVEC which allows the intake camshaft timing to be changed.
If you want to make big power on any 4G63, the stock turbocharger is typically a limiting factor. Throughout the years of the 4G63T, Mitsubishi used a few different turbochargers, but most of them cant push more than 5psi past stock. For a decently powerful street car, however, the stock turbos can provide enough power and provide decent throttle response as well.
One of the most common upgrades is the TD05H-16G turbo, which was used on some overseas Evo models and provides enough flow for upwards of 300whp in a DSM. If you want even more power, the MHI 20G turbo is a good solution, however, throttle response starts to suffer with a turbo that large.
To wrap this all up, just remember that the 4G63T was initially designed as an engine for race use with Mitsubishi’s rally racing ventures, and it features an insanely strong design. Unlike other 4-cylinder engines that rev high and produce very little torque, the 4G63T doesn’t rev all that high and produces a lot of low-end and midrange torque.
It has a massive amount of potential with aftermarket components, and producing over 400hp is fairly easy. At the peak of drag racing, you’ll find 4G63T engines producing upwards 100psi of boost and making huge power numbers.