The past two decades have been a memorable timeline for all of the engine evolution and innovations. Many automakers took many risks and circumvented their way of producing, making, and engineering their power plants that fit society and their desired vehicle.
And one of the engines from the engine collective of the ’90s is the compact but adorned 4VZ-FE engine. Coming from the pockets of 2VZ-FE, it is a smaller version of that.
Join me as we tackle the luxurious 4VZ-FE engine’s design, architecture, power, applications, issues, reliability, tuning potential, and many more.
Let’s get right to it!
What are 4VZ-FE Engines?
Toyota 4VZ-FE is a naturally-aspirated, water-cooled, 2.5 Liter, V-type six-cylinder gasoline engine produced by the Japanese automaker Toyota Motor Corporation from 1992 until 1996. This V-type six-cylinder engine is designed to be mounted on front-wheel drive vehicles with its compact size and architecture. However, the primary objective of Toyota for the 4VZ-FE engine is to be the new 2.5 Liter and replace the older model 2VZ-FE. Unfortunately, 4VZ-FEs are only sold in Japan, and they are pretty hard to find in North America.
The 4VZ-FE comprises six cylinders arranged in a ‘V’ orientation at a bank angle of 60-degrees. This machine features a cast-iron cylinder block with a four-bearing crankshaft, two aluminum heads with two camshafts, and acts through a four-valve per cylinder – two for both intake and exhaust valves.
The 4VZ-FE, like the 2VZ-FE, is highly rated and heavily regarded as a luxury paired kind of engine with its quietness that is suitable for high-grade vehicles; crankshaft and cylinder block with high rigidities made these compliments possible. It is also integrated with a hydraulic mounting, crankshaft pulley with a dual-damper mode, and other advanced technologies from Toyota.
This engine is equipped with Toyota’s Idle Speed Control System (ISC), Electronic Spark Advance (ESA), and fuel is provided through an Electronic Fuel Injection System (EFI).
The engine was designed to achieve maximum fuel efficiency by, even with the same displacement as the 2VZ-FE, its optimal air-fuel ratio, ignition timing by Toyota Computer Controlled System (TCCS), compact pentroof-type combustion chambers, and other automotive technologies. High-performance and more significant torque was also attained.
Engine Specifications and Design:
- Production Run: 1992 – 1996
- Cylinder Block Material: Cast-iron
- Cylinder Head Material: Aluminum
- Configuration: V6
- Bore: 87.5 mm
- Stroke: 69.2 mm
- Valvetrain: DOHC with four valves per cylinder
- Displacement: 2.5 L (2496 cc)
- Compression Ratio: 9.0 to 9.6
- Weight: 425 lbs.
- Max HP: 173 HP at 6,000 RPM
- Max Torque: 169 lb-ft at 5,000 RPM
The 4VZ-FE engine has a cylinder bore of 87.5 mm, a slightly shorter stroke than the 2VZ-FE at 69.2 mm, and an expanded compression ratio from 9.0 to 9.6. The 4VZ-FE engine can produce a maximum power of 173 HP at 6,000 RPM and 169 lb-ft of maximum torque at 4,600 RPM.
The engine’s cylinder block is made from cast iron and has a six-cylinder bank arranged in a ‘V’ orientation at a bank angle of 60-degrees. Four bearings, made from copper and lead alloy, support the crankshaft inside the crankcase; and the crankshaft is also integrated with five counterweights for balance.
Oil holes are drilled and strategically placed at the crankshaft center for supplying oil onto the moving mechanical parts such as the pistons, connecting rods, and other internal components. The firing order of the engine is 1-2-3-4-5-6. The crankpin diameter is 48 mm, and the crankshaft main journal diameter is 64 mm.
The pistons of the 4VZ-FE are modeled from the 2VZ-FE as their pistons have the same material made from high-temperature resistant aluminum alloy. Built onto the piston heads is a depression clearance to prevent the pistons from interfering with the intake and exhaust valves. The piston pins are semi-floating, with pins secured to the connecting rods by pressure fitting, allowing the pins and pistons to float.
Each piston is provided with one oil control ring and two compression rings. The oil control ring is made from a combination of pure steel and stainless steel; the top compression ring is also made from steel, and the second compression ring is made from cast iron.
The piston ring outer diameter is deliberately made to become slightly larger than the pistons. The ring’s flexibility allows them to the hub of the cylinder walls when they are installed on the pistons.
The 4VZ-FE engine’s cylinder heads are lightweight which are made from aluminum alloy, and have a double-overhead camshaft design with four valves per cylinder – two for both intake and exhaust valves. It is integrated with advanced cross-flow type intake and exhaust layouts as well as pentroof type combustion chambers for better fuel combustion. The spark plugs are placed in the center of the combustion chamber and work like a down-pop ante-chamber for a more efficient burn without much waste.
Two mechanisms – belt and gear, drive the camshafts. The intake camshafts are operated via a single belt. A scissor gear on the intake camshaft is engaged with a gear on the exhaust camshaft that drives it. The camshaft journal is supported at four exhaust and five intake places between the front end of the cylinder head and the valve lifters.
The valve clearance adjustments are made through an external shim type system, where the valve adjusting shims are placed right above the valve lifters. This mechanism creates better leverage for maintenance since you don’t have to remove the camshafts, for that matter.
Some applications of the 4VZ-FE engine:
- 1992 – 1996 Toyota Camry Prominent
- 1993 – 1996 Toyota Windom VCV11
Engine Tuning, Upgrades, and Modifications
The engine potential of both 2VZ-FE and 4VZ-FE is almost identical. They also share the same architecture but the latter being slightly smaller, and they have a reputation for being solid and fast engines. With that, the mechanism and upgrade effects should stay the same; to add to that, 2VZ-FE has a lot of power and torque potential. But you can still increase its strength.
The first step in tuning the 4VZ-FE engine is to service it for port and polish; if you can do it yourself, better, but if not, give it to someone else, a specialist. Then after that, buy some performance parts such as 4-2-1 headers, cold air intake, and a 2.5-inch performance exhaust. Bolt and install all of these upgrades and configure the ECU; this can get you around 220HP at the crank. Add some performance cams with 262/262-degree lift, and gain an extra 15 HP.
You can extend the power production to a higher digit up to 250 HP by buying or swapping it with a more aggressive engine such as 1JZ or 2JZ of the same automaker. In some cases, you can buy a 1MZ supercharger kit and modify it to fit in the 4VZ-FE. Another option is to build a turbo kit using turbochargers used in Supras, make turbo manifolds, and custom every part.
When tuning the 2VZ-FE, avoid increasing the compression ratio, buying an intake manifold, lighter pistons, and other parts. It is costly, and the power gained is not parallel to the price.
Problems Surrounding 4VZ-FE Engine:
Toyota 4VZ-FE, like its predecessor 2VZ-FE, is a product of intricate design and engineering, a highly reliable and durable one. But even with an exceptional reputation of being strong, it still has some weaknesses and shortcomings, which are shared among all machines. Some troubles might arise and affect the engine’s performance and overall its overall mechanism. So we created a precautionary list for you to use as a not-so-formal guide on the risks accompanied in the 4VZ-FE engine.
The first and widespread problem of the 4VZ-FE is engine overheating. We’ve encountered this before in Toyota 2VZ and 3VZ, which is not new for most engines. This issue is caused by the lack of coolant supply flowing in the engine due to extreme heat. When you talk about engines and temperature, oil deprivation is detrimental and may result in severe damage to the machine, which affects the performance.
Check your coolant level, which can be seen on the engine bay or in the dashboard; if it is low, the problem is in the head gasket; there might be a leak. If the level is normal, check the cooling fan because these fans are rather frail. After inspecting and checking everything and none of those appeared to be the reason. Check the radiator cap, radiator condition, and thermostat; it might be there.
Engine knocking is also another issue that needs to be said because it’s annoying. These foreign acoustics sounds like a grave sign of your engine that it is almost game over already, but no, you can resolve this by adjusting the valve clearances, and if the sound goes away, then you’re good to go. If not, bring it to a specialist to check thoroughly.
The 4VZ-FE engine is old enough to add to the issues mentioned since it was produced more than a decade ago. Its emergence in production years ago is equivalent to its deteriorating internal components. And the common problem with an old machine is its excessive oil consumption due to loose components and regressing parts. There could have been an increase in the wear of the connecting rods, and sometimes cylinder head cracks occur.
Always use the recommended high-quality engine oil and avoid compromising for lubricants and fuels. Have the engine serviced regularly and constantly monitor the condition of the cooling system.
The 4VZ-FE engine being a smaller 2VZ-FE engine, is not a tiny piece that is sometimes underestimated in its size. But its compact build and technologically advanced attributes; quietness, comfort, and balance between aggressiveness and power. It earned a place on the podium of being worthy of being placed on high-grade and luxury vehicles.
It is more efficient and durable compared to its predecessor and also to its competitors. Its tuning potential is also topnotch as it can withstand upgrades even without changing its internals.
Though it has some issues and troubles that might prematurely occur or later in its useful life, this engine is special even with those problems. Many still look up to this engine as a satisfying engine that can last a lifetime. With proper engine care and maintenance, the 4VZ-FE will not be abused and sidelined.
Do not forget to use high-quality engine oil and take note of the necessary replacements to be made before the recommended mileage.
I hope that this simple discussion helped you understand the 4VZ-FE engine’s design, specifications, applications, issues, tuning potential, aftermarket support, reliability, and overall impact on the industry and community.