Toyota 1UR: Everything You Need To Know

The entire Aluminum build of the 1UR Engine was introduced first in the Middle East in 2006 and relaunched in 2010 in other markets to replace the 2UZ-FE by powering the luxury sedan heavyweights Lexus LS 460 and Lexus LS 460 L that displaces 4.6 L. In addition, the newly developed 1URs are produced to replace the prior 2UZ-FE Engine offered in Toyota’s pickups and trucks (Tundra, Land Cruiser, and Sequoia).

1UR Engine is a notable member of the UR engine family.

So let’s dig deeper into the 1UR engines; their engine design, power output, abilities, potential, and overall performance.

Engine Specifications and Design:

  • Production Run: 2006 – Present
  • Cylinder Head Material: Aluminum
  • Cylinder Block Material: Die-cast Aluminum
  • Configuration: V8
  • Bore: 94 mm
  • Stroke: 83 mm
  • Valvetrain: 32-Valve Dual Overhead Camshaft
  • Displacement: 4.6 L (4,608 cc)
  • Compression Ratio: 10.2
  • Weight: 489 lbs.
  • Max HP: 385 HP at 6,400 RPM
  • Max Torque: 369 lb-ft at 4,100 RPM

The Toyota 1UR is a 4.60 L V8, water-cooled naturally aspirated internal combustion gasoline engine which made its way under the hood in 2006. It has two versions, 1UR-FE and 1UR-FSE, but unlike the latter, 1UR-FE has no direct injection while 1UR-FSE has.

This Engine has a lot to offer, but some of its notable features are integrating the L-type sequential fuel injection system (SFI). Direct Ignition System (DIS) by having individual coils in each Iridium-tipped spark plugs; Electronic Throttle Control System – Intelligent (ETCS-i), and Acoustic Control Induction System (ACIS), which Toyota used in other engines such as the GR family. It is also equipped with Toyota’s Dual VVT-i Variable Valve Timing Technology in both intake and exhaust camshafts. In addition to that, the 1UR-FE uses a water-cooled exhaust gas recirculation system (EGR) to minimize emissions and an air injection system installed in the catalytic converters for faster warm-up.

The 1UR-FE Engine has the same 90-degree bank angle in a V-arranged die cast-Aluminum alloy block. It has a bore of 94 mm, a stroke of 83 mm, and a 21 mm cylinder bank offset, equating to a 4.0 L capacity. Around the bore, walls are cast spiny type cast-iron liners that were sketched. The casting externals form a large, asymmetrical surface; these edges allow better adhesion between the Aluminum block and liners, which reduces the bores’ heat deformation and improved heat dissipation.

To add to that, 1UR-FE engines have plastic spacers in the water jackets to control the coolant flow, which are essential in regulating the temperature of the cylinder walls. To go with that, Toyota created a coolant pathway to link the in-between of the left and right cylinder banks to enable the smooth flow of water between the cylinder banks to each cylinder bank’s cylinder head and water jackets.

There is also a minor improvement of airflow at the bottom of the cylinders; this is due to air passage holes on the bulkheads of the cylinder block. In addition, the reciprocal movement of the dynamic pistons reduces the back pressure it created while also reducing pump losses.

The 1UR-FE has a forged steel crankshaft supported with five prominent bearing journals and six balance weights. The crankshaft bearings are made of Aluminum, while the bearing lining surface is strengthened to improve wear and seizure resistance by coating it with a resin. To secure the main journals, the crankshaft bearing caps have four plastic region tightening bolts which were tightened laterally to increase the reliability; it also has different bolt sizes for the inner and outer sides of the caps.

As we mentioned earlier, the 1UR-FE has only six balance weights, two units shy of its predecessor, the UZ engines; due to that, 1UR-FE engines have lesser smoothness of its operation. However, noise and vibrations caused by this are reduced by the automakers themselves as they put a torsional rubber damper in the 1UR crankshaft pulley.

Its connecting rods are forged steel with resin-coated Aluminum bearings and, same with the crankshaft, has plastic region tightening bolts. Knock pins are used at the mating edges of the bearing caps to minimize movements and shifting of the bearing caps during assembly.

To go with that, 1UR-FE pistons are made of high-temperature-resistant Aluminum that was cooled by four oil jets in the cylinder block. Piston skirts are resin-coated to reduce friction, while the top compression and oil ring have a PVD (Physical Vapor Deposition) coating. Piston pins are full-floating type.

The 1UR-FE cylinder heads are made from Aluminum and were mounted on a three-layer steel-laminate type cylinder head gasket. Toyota used shims about the bores of each gasket for better sealing and durability; the gasket surface is coated with heat-resistant fluoro rubber.

The cylinder covers are magnesium-made and have a better ventilation design. In addition, fresh air was drawn from the left and right cylinder head covers, which dramatically improves the airflow and increases engine oil resistance to deterioration. The cylinder heads also include an oil delivery tube for an added lubrication to the sliding parts of the valve rocker arms.

It has dual overhead cast-iron alloy camshafts with four valves per cylinder (two for both intake and exhaust). It used primary timing chains to drive the intake camshafts which exhaust camshafts were driven by a secondary timing chain which is also driven by the intake camshaft.

1UR-FSE

1UR- FSE is identical to the 1UR-FE Engine. The apparent difference between the two is the direct injection which the 1UR-FE is lacking, as well as hollow camshafts to reduce the weight of the 1UR-FSE. To add to that, 1UR-FSE engines undergo a thorough review that includes an x-ray inspection and a CT scan to ensure minimal deformation after the die-casting process.

1UR Engine Applications:

For 1UR-FSE

  • 2006 – 2017 Lexus LS 460 and LS 460 L
  • 2008 – 2011 Lexus GS 460
  • 2009 – 2013 Toyota Crown Majesta

For 1UR-FE

  • 2006 – 2017 Lexus LS 460 and LS 460 L (Middle East)
  • 2005 – 2011 Lexus GS 460 (Middle East)
  • 2009 – Present Lexus GX 460
  • 2012 – Present Toyota Land Cruiser (China, Japan, Australia, and the Middle East)
  • 2009 – 2012 Toyota Sequoia
  • 2009 – 2019 Toyota Tundra

Engine Upgrades, Tuning, and Modifications:

We can consider 1UR-FSE Engine is a modified version of the 1UR-FE, which are tuned very well already. The version has a D-4S injection system that featured one injector in the combustion chamber and one on the intake port for each cylinder, increasing the compression ratio of 11.8.

However, you can still tune the 1UR-FSE and buy a tuning chip, and this can give you around 30-40 HP, which is quite impossible to do on a stock ECU.

A few aftermarket companies make performance parts capable of improving the engine performance but are still under the skeptic umbrella. That aftermarket item is the VVT-i Quantum Solenoids. These solenoids are only applicable on the exhaust side solenoids because the 1UR Engine as the VVT system uses electronic motor-driven intake side VVT-i controls and the much more familiar oil control valve solenoids. These Quantum Solenoids claim 25 HP upgrade and 22 lb-ft improvements on the chart.

Problems Surrounding 1UR Engines:

1UR engines are not immune to having issues and problems, and some issues may prematurely arise and terrorize the Engine. However, these are some precautionary heads-ups to understand some issues in the 1UR Engine.

First is the water pump leak. Water pump leaks can be either due to a dry-running system or adding a contaminated, worn coolant in the system. This component is highly subjected to wear just like others. So if you experience a coolant leak in front of the car or have a low coolant level, the water pump might be the problem.

Next is oil consumption. 1UR Engine is not the only one who suffers in this issue; other car manufacturers too. When there is too much room and clearance between the guides and the valve stems, the Engine has no choice but to take in more oil down the guides and into the cylinder. This is an adverse effect of broken, worn, or poorly installed guide seals, leading to excessive oil consumption.

Now, this is a design problem; this 4.6 L engine has issues regarding the hydraulic timing chain tensioner. As a result, it does not take its role as it tends to lose the timing chain that causes the Engine to skip time or, eventually, fail. This is mainly due to a lack of proper maintenance and periodic checking.

And engine knocking problems. This is mainly due to a failing piston, and knocking happens when the piston is being forced up and down the cylinder. As 1UR engine gain more speed, pistons go through a cold clearance which contributes since 1UR have huge wall clearance.

Summary

1UR engines are reliable and innovative at the same time. Both versions are identical with each other, only contrasting in the absence of direct injection in the 1UR-FE. It powered Lexus luxury cars and continuously representing the 4.6 flags for an incredible run. Though it has some minor problems like leaks and water pumps, and design flaws, this does not hamper the extensive hard work and effort that they put into this Engine.

I hope that this simple guide can help you understand the 1UR’s engine design, power output, torque, innovations, details, and overall impact on the automotive industry and community a lot better.

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