Toyota 1KR-VE, 1KR-VET Engine Specs, Problems, Reliability

The 1KR series engines were put into production in 2004. They were equipped with compact cars of Toyota Motor Corporation and its subsidiaries.

The development was carried out by Toyota engineers, production was carried out at the Kurume plant, owned by Daihatsu Motor Corporation.

In 2016, another engine upgrade took place, and a modification called 1KR-VE appeared. The engine was intended for small cars Toyota Agya, Daihatsu Sigra, Ayla, Perodua Bezza, which were supplied to the countries of Southeast Asia.

When upgrading the engine, Toyota engineers focused on weight and size indicators, efficiency, but not at the expense of driving performance.

Read Also: EJ-VE 1.0L Engine Specifications And Performance Summary

Engine design 1KR-VE

The engine is a three-cylinder power unit, in which all overall parts and assemblies are made of light aluminum alloy. Among them:

  • cylinder block;
  • cylinder head;
  • oil pan.

Pistons, oil scraper and compression rings are treated with a special heat-resistant material that reduces the coefficient of friction.

The piston stroke significantly exceeds the cylinder diameter, which is why “long-stroke” connecting rods were needed. The compression ratio of the engine has been increased to 11.5:1, cars with this power unit consume A-95 gasoline.

To prevent overheating, a thermostat is installed, which opens early enough, at a temperature of 78-82ºC, depending on the configuration. A lightweight crankshaft is used, equipped with a minimum number of counterweights.

There are 12 valves in the cylinder head, 4 for each cylinder. The timing drive is carried out by a chain equipped with a hydraulic tensioner and damper.

The VVT-i system is installed on the intake camshaft, which allows you to change the valve timing at the intake by turning the camshaft around its axis at a given angle.

A variable-length intake manifold is used, which improves the filling of cylinders at low and medium speeds. There are no hydraulic valve clearance compensators.

Such design solutions made it possible to create a light, compact engine with a power of 67 – 71 hp. at 6,000 rpm, and the torque was 91 – 94 Nm at 3600 – 4800 rpm. 1KR-VE engine are currently installed on cars.

Engine 1KR-VET

At the end of 2016, the 1KR-VET version appeared. The main difference is the presence of turbocharging. Installing the turbine required reducing the compression ratio to 9.5:1.

This engine has no other fundamental differences from the 1KR-VE version. Power increased to 98 hp at 6,000 rpm and torque was 140 Nm at 4,000 rpm. The internal combustion engine is currently installed on Toyota Raize, Toyota Roomy, Toyota Tank cars.

1KR-VET Engine Problems And Reliability

These internal combustion engines are modern power plants of complex design. A prerequisite for the normal operation of these engines is the timely replacement of oil and regular maintenance carried out within the time limits established by the technical regulations.

The engine are sensitive to oil quality and require the use of lubricants of at least 0W30-5W30, SL/GF-3 class.

Among the shortcomings of these internal combustion engines, the following are noted:

  1. low resource before overhaul, rarely exceeding 200,000 km;
  2. pump leakage after 50,000 km;
  3. chain stretching after 100,000 km;
  4. at the slightest deviation of the composition of the air-fuel mixture from the stoichiometric – increased vibration, up to unpleasant shaking of the car.
  5. disposability, i.e. unsuitable for major repairs.

The advantages of these engine include high specific power in the turbo version, efficiency, high torque at medium engine speeds.

1KR-VET Specifications

Here, we will investigate the characteristics of this engine by referring to the data of the 1KR-VET type turbo engine installed in Toyota’s M900A type Roomy Custom GT 2016/11 model.

toyota ROOMY 1KR-VET
Toyota’s M900A type Roomy
Vehicle modelDBA-M900A type
Car name & gradeRoomy
Custom GT
Engine model1KR-VET
typeIn-line 3-cylinder
Displacement996cc
Inner diameter x stroke71.0 mm x 83.9 mm
Bore stroke ratio1.18
Single cylinder volume332.2cc
Compression ratio9.5
Intake methodturbo
Fuel usedRegular gasoline
Maximum output98PS / 6000rpm
Maximum torque14.3kgm / 2400-4000rpm

First of all, as a basic structure, the 1KR engine is a long stroke engine with a bore (inner diameter) of 71.0 mm, a stroke (stroke) of 83.9 mm, and a bore stroke ratio of 1.18 (the stroke amount is larger than the piston diameter).

When the displacement and the number of cylinders are the same, the engine has better torque characteristics in the low rpm range than the short stroke type and is easy to handle, but in the high rpm range, the filling efficiency deteriorates and the sliding resistance increases. There is a concern that the output will drop.

Moreover, when the number of revolutions is the same, the average piston speed tends to be higher than that of the short stroke type, so the load on the engine tends to be heavier.

Among the models registered on this site, the oldest model equipped with the 1KR-VET type turbo engine is the first Roomy [M900A type | 2016/11] released from November 2016 , and the newest model is 2019. It is the first Rise [A210A type | 2021/11] released from 11/11 , and all 9 models of NA cars are registered, 0 models, and turbo / SC cars are 9 models.

Evaluation from the viewpoint of transient characteristics and liter equivalent horsepower

Image of engine performance curve
1KR engine performance curve diagram
Changes in horsepower47.9PS → 98PS
Transition of torque14.3kgm → 11.7kgm
Liter horsepower98.39PS / L
Liter torque14.4kgm / L

Roomy’s in-line 3-cylinder 996cc, compression ratio 9.5 and regular gasoline turbo engine, which is the reference vehicle this time, produces a maximum output of 98 horsepower at 6000 rpm and a maximum torque of 14.3 kgm at 6000 rpm.

If you know the horsepower and the number of revolutions, you can know the torque, and if you know the torque and the number of revolutions, you can know the horsepower. The torque at 6000 rpm is 11.7kgm.

The horsepower per liter of displacement is 98.39PS / L and the torque is 14.4kgm / L, and the horsepower per cylinder (single cylinder volume 332.2cc) is 32.7PS and the torque is 4.8kgm.

When the 1KR turbo engine is applied to a 10-step evaluation based on deviation values ​​aggregated from all turbo cars registered on this site, the evaluation is ” standard ” with a converted horsepower of [ 6 ] and a converted torque of [ 5 ]. It is categorized as ” engine with high output (upper middle) “.

Displacement increase, compression ratio increase, bore stroke ratio change

Normal displacement and compression ratio
BoreStrokeDisplacementCompression ratioB / S ratio
71.083.9996cc9.51.18
Displacement expansion by bore up
71.583.91011cc9.61.17
72.01025cc9.71.17
72.51039cc9.81.16
73.01053cc10.01.15
73.51068cc10.1.1.14
74.01082cc10.21.13
Displacement expansion by increasing stroke
71.084.91008cc9.61.20
85.91020cc9.71.21
86.91032cc9.81.22
87.91044cc9.91.24
88.91056cc10.01.25

There are three factors that determine the engine displacement: the number of cylinders, the bore diameter, and the stroke amount. By increasing or decreasing these, engines with various displacements are created.

Here, regardless of whether it is actually possible, the displacement when the piston diameter is expanded from the genuine 71.0 mm to 74.0 mm in 0.5 mm increments and when the stroke is extended from the genuine 83.9 mm to 88.9 mm in 1 mm increments. And, the change of the compression ratio when it is assumed that the combustion chamber volume does not change is listed.

* It is easy to say stroke up, but if you want to make a long stroke, you need a crankshaft and a compatible connecting rod, and if you can not divert it, you have to make it in one-off, so it is expensive anyway. It is a menu that requires considerable preparedness to put out.

Regarding the compression ratio, in most cases, the uneven capacity of the top surface of the piston changes as the diameter of the piston increases, so the compression ratio values ​​in the list do not match, but the displacement. Please enjoy the atmosphere that the compression ratio will naturally increase as you increase the size.

The B / S ratio is an abbreviation for the bore stroke ratio, and as the bore diameter is widened, the characteristics of the long stroke type, square type, or short stroke type are approached. In the case of 1KR type engine, the ratio changes from 1.18 to 1.13 when the bore is increased by +3.0mm from the genuine piston.

Increased displacement with engines with similar piston diameters

Since there are 12 engines with pistons that are close in size to the piston diameter of 71.0 mm of the 1KR type engine, let’s calculate the displacement when the bore is raised by diversion of the piston as a sideshow.

Eg modelPiston diameterDisplacement
Toyota
K3 type
72.0mm
[+ 1.0mm]
1025cc
[+ 29cc]
Daihatsu
KJ type
72.0mm
[+ 1.0mm]
1025cc
[+ 29cc]
Toyota
1NR type
72.5mm
[+ 1.5mm]
1039cc
[+ 43cc]
Honda
L15B type
73.0mm
[+ 2.0mm]
1053cc
[+ 57cc]
Honda
L15C type
73.0mm
[+ 2.0mm]
1053cc
[+ 57cc]
Honda
LEA type
73.0mm
[+ 2.0mm]
1053cc
[+ 57cc]

Engines with similar piston diameters are Toyota: K3 type 1297cc 72.0mm mounted on J102E type cami, Daihatsu: KJ type 936cc 72.0mm mounted on M312S type boon, Toyota: 1NR mounted on NSP140 type spade 72.5mm of type 1329cc, Honda: 73.0mm of L15B type 1496cc mounted on RW1 type CR-V, Honda: 73.0mm of L15C type 1496cc mounted on FK7 type Civic, Honda: mounted on ZF2 type CR-Z LEA type 1496cc 73.0mm etc. is applicable.

(Although the number of people who find pleasure in such a quest has decreased) No matter how close the diameter is, there are factors such as the diameter of the piston pin, the height of the piston, and the convenience of valve recess, so if possible, the same manufacturer, If possible, if you choose the same fuel and the same intake method, and if possible, the one with a similar displacement, the possibility of genuine diversion may increase.

Average piston speed

strokeMaximum torque
2400rpm
Maximum output
6000 rpm
83.9mm6.7m / s16.8m / s
Rotation speed / minuteper secondSpeed
2000rpm5.6m / s20km / h
4000rpm11.2m / s40km / h
6000rpm16.8m / s60km / h
8000rpm22.4m / s81km / h
10000rpm28.0m / s101km / h

Next, let’s look at the average piston speed. An engine with a stroke of 83.9 mm produces a maximum output, and the average piston speed at 6000 rpm is 16.8 m / s , which is a piston speed that travels a distance of 16.8 meters per second (60.5 km / h at speed). It means that is moving up and down.

The average speed is 18.2 m / s at 2400 rpm, which generates the maximum torque, and 18.2 m / s when 6500 rpm, which is 500 rpm higher than the 6000 rpm where the maximum output is generated, is assumed to be the rev limit.

For reference, I calculated the change in piston speed when a 1KR engine with a stroke of 83.9 mm is rotated up to 10000 rpm. Looking at this, it seems that the speed increases by approximately 5.60 m / s as the number of revolutions increases by 2000 revolutions.

Considering only 20.0 m / s, which is a guideline for general engines assuming mass production, it is mechanical to set the upper limit of high rpm to about 7150 rpm (whether it rotates or not). It seems to be preferred both mentally.

Conclusion

The table shows some technical characteristics of the 1KR-VE and 1KR-VET.

Engine1KR-VE1KR-VET
Working volume, cm³996996
Power, hp at rpm67-71/600098 / 6000
Torque, N m at rpm91–94 /3600–480011.5/4000
Compression ratio11.5:19.5:1
Supply systemDistributed injectionDistributed injection
Number of valves per cylinderfourfour
The presence of turbochargingNoYes
Approximate resource, thousand km200200

Toyota 1KR-VE, 1KR-VET engines are not widely used outside of Asia. But in the countries of Southeast Asia, where they were intended, cars with these internal combustion engines are in steady demand due to low fuel consumption and traditional Toyota reliability.

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