Mitsubishi 4G92: Everything You Need To Know

Mitsubishi introduced the 4G92 engine in late 1991 and appeared in the Japanese Spec Mirage RS and Super R. If we take a look at 4G92 and 4G93, they are basically the same, but with some minor differences.

4G92 engines belong to the Mitsubishi 4G9 family of engines which are inline-4 that use both single and double overhead camshaft heads. These series of machines were the first modern engines to integrate GDIs (Gasoline Direct Injection).

Today we will tackle one of the engines that belong to this family. That was considered one, if not the, of the most powerful 1.6 Liter naturally aspirated engine created by Mitsubishi. The 4G92 engine.

So, let’s get right to it.

Engine Specifications and Design

• Production Run: 1991 – 2005
• Cylinder Head Material: Aluminum
• Cylinder Block Material: Cast-iron
• Configuration: Inline-4
• Bore: 81 mm
• Stroke: 77.5 mm
• Valvetrain: SOHC and DOHC 4 valves per cylinder
• Displacement: 1.6 L
• Compression Ratio: 10.0 and 11.0
• Weight: 320 lbs.
• Max HP: 170 HP at 7,500 RPM
• Max Torque: 12 lb-ft at 7,000 RPM
• Redline at 7,800 MIVEC and 8,200 MIVEC RS

Mitsubishi 4G92 is an inline-4, 1.6 Liter petrol engine which is based on the 4G93 engine that debuted in the Japanese spec Mirage RS and Super R in DOHC form.

Under the hood, 4G92 engines, compared to the4G93s, has a lower cylinder block with a deck height of 188.75 mm; has a connecting rod length of 120 mm, piston compression height at 30mm, cylinder bore at 81 mm, and a new crankshaft with a 77.5 mm piston stroke.

4G92s have a single camshaft – SOHC, the fuel-efficient version, and two camshafts -DOHC heads with 16-valves. 4G92 engine is famous for its high-performance MIVEC-equipped DOHC version that replaced the initial DOHC released in 1993.

The SOHC version can produce 94 HP, and later on, Mitsubishi released a 113 HP 4G92 SOHC for the domestic Japanese market due to its higher cam. It has a 10.1 compression ratio, 190 cc fuel injector size, and a smaller throttle body size at 48 mm.

However, the DOHC variant is the most sought-after version of the 4G92s not only because of its power and intensity but the ripple it created for the 4G family engine. There are two variants for the DOHC version: the non-MIVEC and MIVEC equipped.

The non-MIVEC, which was run from 1991 – 1993, was the pioneer of the 4G92 series and can produce 147 hp at 7,000 RPM, 110 lb-ft of torque at 4,500 RPM, and 11.1 compression ratio, all of that in stock form.

It was a head-to-head matchup against the bad man from Honda, the B16A.

Concurrent to the early release of the 4G92 non-MIVEC was the MIVEC equipped DOHC, which was released in 1992. An angrier, nastier, and aggressive alter ego of the 4G92 DOHC.

It features a variable valve timing system that is essential for top-end RPM to provide more air into the engine. As we say, during high speeds, the MIVEC starts to kick in and are switched into larger cam profiles.

This engine peaked at 170 HP at 7,500 RPM, 12 lb-ft of torque at 7,000 RPM. It has larger fuel injectors with 275 cc and a 60 mm throttle body size.

There are three versions of this engine:

The 4G92 MIVEC Silvertop has a rev limiter at 7,800 RPM.

The 4G92 MIVEC MD, where the engine will function as an 8-valve system for lower RPM and lower fuel consumption. And the 4G92 MIVEC RS blacktop has a different intake manifold, valves, camshafts, lighter flywheel, a new exhaust system, and another ECU.

It saw an increase in power at 175 HP with a redline at 8,200 RPM.

Some Applications of the 4G92 engine:

• Mitsubishi Lancer
• Mitsubishi Mirage
• Mitsubishi Carisma
• Proton Wira
• Proton Satria

Engine Tuning, Modifications, and Upgrades

Please take note that we need MIVEC heads for upgrades for you not to waste some money and time. Outside MIVEC, it is hard to put some additional power for the stock non-MIVEC. So let us proceed.

The thing you must do is install a 4G92 MIVEC head with the intake system, ignition system, timing belt, fuel rail, water pump, 4G93 oil pump, a 4G93 oil, front crankshaft seal, MAP, sensor, IAT-sensor, and performance exhaust system.

So basically, this is a 4G93 in a 4G92 engine block with some minor differences. To add more power with that, you will need a cold air intake system, 4-1 header, ECU tuning, and of course, a performance exhaust system.

Throttle bodies should be replaced with 70 mm, buy H-Beam rods, replace a lighter flywheel, ARP rod bolts, 81 mm high compression pistons, and ACL rod bearings. These changes will enhance the engine’s reliability, especially in higher RPMs, increase the compression ratio to 13, at maximum.

Do some head porting and polish, and it is done.

Next is like the stroker kit for the 4G92. On this one, we need to use the 4G93 engine block and bore it out to 83 mm to increase the displacement. You also need to install 390 cc 4G93T fuel injectors, and that will give 200 HP at the crankshaft and 1.93 liters of displacement.

Turbo

It is recommended that we use the 4G93 block and cover it with a 4G92 MIVEC head for this to work. That increase in displacement is what we need to install the Evo TD05 turbocharger.

After that, we need to replace the pistons that can make a 9.1 compression ratio, make an oil feed and oil drain for the turbocharger.

We need to add in some performance parts like the turbo manifold, Evo oil cooler, Evo intercooler, intake piping, 4G93T throttle body, Evo, fuel pump, fuel rail, adjustable fuel pressure regulator, 630 cc fuel injectors, and a 2.5-inch exhaust system.

Install 4G93T pistons and connecting rods and oil squirters as well. These upgrades can give you 300 HP.

Problems Surrounding 4G92 Engines:

Engines are gone for good if we do not take care of it, the majority of all things, especially those with moving parts inside. Keeping an eye on minor problems can help prolong the service life of our engines.

Some issues might arise on 4G92 engines, but take this with a grain of salt, for this is not an official list but more of a precautionary heads-up.

The first is excessive oil consumption. This issue is highly detrimental to the engine as the oil plays a massive part in keeping the engine at the peak condition as possible. If you have less oil inside than what is recommended, most likely, the engine will prematurely break down and overheat or, worse, fail.

That’s why we have dipsticks right to keep the levels of the oil good. This issue is prevalent among old and deeply experienced engines, those who logged huge numbers into their odos.

We said that because old engines have some loose components like piston rings, and most of the time are left in the corner to collect dust due to infrequent use. You might need an overhaul for this kind of issue.

The second is the Engine knock. The cause of this sound might come from the hydraulic tappets, and usually in these components. You need to check if that is the problem. If yes, replace them.

The third is the rough idling or idle problem. This problem happens when you have an inconsistent fuel burn that can be caused by faulty spark plugs, spark plug wires, dirty fuel injectors, dirty throttle body, and clogged air filters.

This might also be due to a defective idle air control valve (IAC valve) and MAF-sensor. Check all of these components, and without a doubt, you can find it in one of those.

In addition to the concerns mentioned earlier, 4G92 uses a timing belt instead of the chain, so you must replace it periodically every 60,000 miles to keep it from breaking and protect the valves from bending. Also, 4G92 SOHC does not use hydraulic lifters.

That is why valve adjustment must be made every 30,000 miles. The clearances are 0.2 mm for the intake and 0.3 mm for the exhaust for the hot engine, 0.1 mm for intake, and 0.2 mm for the exhaust for cold engines.

Don’t forget to use high-quality engine oil and regular checking of the engine itself.

Summary

4G92 is for sure a good worth of money especially considering its longevity and reliability. Its level and challenged many competitors in its time. It can run more than 200,000 miles depending on how you take care of the engine but as long as you do not abuse it, this engine will most likely serve you a lifetime.

Though it has some minor issues, this is not detrimental and is outside the design itself and more of a sign of aging and external factors. Overall, an engine that can be used every day but can be aggressive when tuned.

So that’s it!

I hope that the things and information that we discussed today 4G92 engines will help you understand the engine even more. Its contribution to the automotive industry, society as a whole, and the innovations that it undertook to make it the engine we have today better and faster.

So if you are planning to buy one, I hope this will be a good guide to give you some ideas with 4G92s.