Mitsubishi 4M41 3.2 Engine Specs, Problems, Reliability

Since 1999, the Japanese Mitsubishi Pajero SUV has been equipped with a 3.2-liter 4M41 turbocharged diesel engine, which has become a development of a similar design 2.8-liter 4M40, which we have already dismantled, and has a more modest volume.

The features of the 16-valve engine are aluminum cylinder head, timing chain with rollers and the absence of hydraulic lifters. Serial production of the engine was organized only in the version with direct injection and a turbine. Initially, the engine had a Zexel VRZ injection pump, which was replaced after modernization in 2006 with Common Rail fuel equipment created by Denso specialists.

The 4m41 engine is powered by diesel fuel. It is equipped with 4 cylinders and the same number of valves per cylinder. The block is protected by a new aluminum head. Fuel is supplied by a direct injection system.

The engine design is standard for two-camshaft designs. The intake valves are 33mm and the exhaust valves are 31mm. The valve stem thickness is 6.5 mm. The timing drive is a chain, but it is not as reliable as on a 4m40 (it starts to make noise closer to the 150,000th run).

The 4m41 is a turbocharged engine with an MHI blower installed. Compared to the predecessor 4m40, the designers managed to increase power (it reached 165 hp), torque in all ranges (351 Nm / 2000 rpm) and improve environmental performance. Of particular importance was the reduction in fuel consumption.

Read Also: 6G75 Mivec / GDi 3.8 Engine Specs, Problems, Reliability

4m41 Engine Specifications

ProductionKyoto engine plant
Engine brand4M4
Release years1999-present
Block materialcast iron
engine’s typediesel
Configurationin-line
Number of cylinders4
Valves per cylinder4
Piston stroke, mm105
Cylinder diameter, mm98.5
Compression ratio16.0

17.0

Engine volume, cc3200
Engine power, hp / rpm165/4000

175/3800


200/3800

Torque, Nm/rpm351/2000

382/2000


441/2000

Environmental regulations
TurbochargerMHI TF035HL
Engine weight, kg
Fuel consumption, l / 100 km (for Pajero 4)
– city
– highway
– mixed.

11.4

8.0
9.3
Oil consumption, g/1000 kmup to 1000
Engine oil5W-30
10W-30
10W-40
15W-40
How much oil is in the engine, l9.3
Oil change is carried out, km15000

(preferably 7500)

Operating temperature of the engine, hail.90
Engine resource, thousand km
– according to the plant
 – in practice



400+
Tuning, HP
— potential
— without loss of resource


200+

The engine was installedMitsubishi L200 / Triton
Mitsubishi Pajero
Mitsubishi Pajero Sport / Challenger

4M41 Engine Performance Summary

Here, we will investigate the characteristics of this engine by referring to the data of the 4M41 type turbo engine installed in Mitsubishi’s V98W type Pajero Long-Exceed 2010/09 model.

mitsubishi PAJERO 4M41 3.2 Engine
Mitsubishi’s V98W type Pajero Long-Exceed
Vehicle modelLDA-V98W type
Car name & gradePajero
Long-Exceed
Engine model4M41
typeIn-line 4-cylinder
Displacement3200cc
Inner diameter × stroke98.5mm×105.0mm
Bore stroke ratio1.07
Single cylinder volume800.1cc
Compression ratio16.0
Intake methodturbo
use fueldiesel
Maximum output190PS/3500rpm
Maximum torque45.0kgm/2000rpm

First of all, as a basic structure, the 4M41 type engine is a long stroke type engine with a bore (inner diameter) of 98.5 mm, a stroke (stroke) of 105.0 mm, and a bore stroke ratio of 1.07 (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 4M41 type turbo engine is the 3rd generation Pajero [V68W type | 2002/09] released from 1999/09 , and the newest model is 2006 /. It is the 4th generation Pajero [V98W type | 2010/09] released from 10, and all 6 models of NA cars are registered, 0 models, and turbo / SC cars are 6 models.

Evaluation from the viewpoint of transient characteristics and liter equivalent horsepower

Image of engine performance curve
4M41 engine performance curve diagram
Changes in horsepower125.6PS → 190PS
Transition of torque45.0kgm → 38.9kgm
Liter horsepower59.38PS/L
Liter torque14.1kgm/L

Pajero’s in-line 4-cylinder 3200cc, compression ratio 16.0, diesel-powered turbo engine, which is the reference vehicle this time, produces a maximum output of 190 horsepower at 3500 rpm and a maximum torque of 45.0 kgm at 3500 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 3500 rpm is 38.9kgm.

The horsepower per liter of displacement is 59.38PS / L and the torque is 14.1kgm / L, and the horsepower per cylinder (single cylinder volume 800.1cc) is 47.5PS and the torque is 11.2kgm.

When the 4M41 turbo engine is applied to a 10-step evaluation based on the deviation value aggregated from all turbo cars registered on this site, the evaluation is ” modest ” with a converted horsepower of [ 3 ] and a converted torque of [ 5 ]. It is categorized as ” engine of output “.

By the way, among the 4M41 type turbo / SC engine-equipped models, the highest output was 190PS / 45.0kgm of V98W type Pajero, and the smallest was 175PS / 39.0kgm of V78W type Pajero.

Displacement increase, compression ratio increase, bore stroke ratio change

Normal displacement and compression ratio
BoreStrokeDisplacementCompression ratioB/S ratio
98.5105.03200cc16.01.07
Displacement expansion by bore up
99.0105.03233cc16.21.06
99.53266cc16.31.06
100.03299cc16.51.05
100.53332cc16.61.04
101.03365cc16.81.04
101.53398cc16.91.03
Displacement expansion by increasing stroke
98.5106.03231cc16.21.08
107.03261cc16.31.09
108.03292cc16.41.10
109.03322cc16.61.11
110.03353cc16.71.12

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 98.5 mm to 101.5 mm in 0.5 mm increments and when the stroke is extended from the genuine 105.0 mm to 110.0 mm in 1 mm increments. And, the change of the compression ratio when it is assumed that the volume of the combustion chamber 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.

B / S ratio is an abbreviation for 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 4M41 type engine, the ratio changes from 1.07 to 1.03 when the bore is increased by +3.0mm from the genuine piston.

Increased displacement with engines with similar piston diameters

Since there are two engines with pistons that are close in size to the piston diameter of 98.5 mm of the 4M41 type engine, let’s calculate the displacement when the bore is raised by diversion of the piston as a sideshow.

Eg typePiston diameterDisplacement
Nissan
QD32 type
99.2mm
[+0.7mm]
3246cc
[+46cc]
Subaru
EJ25 type
99.5mm
[+1.0mm]
3266cc
[+66cc]

Engines with similar piston diameters include the QD32 type 3153cc 99.2mm mounted on the Nissan: RR50 type Terrano and the EJ25 type 2457cc 99.5mm mounted on the Subaru: BP9 type outback.

(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
2000rpm
Maximum output
3500rpm
105.0mm7.0m/s12.2m/s
Rotation speed / minuteper secondspeed
2000rpm7.0m/s25km / h
4000rpm14.0m/s50km/h
6000rpm21.0m/s76km/h
8000rpm28.0m/s101km/h
10000rpm35.0m/s126km/h

Next, let’s look at the average piston speed. The average piston speed at 3500 rpm, where an engine with a stroke of 105.0 mm produces maximum output, is 12.2 m / s , which is a piston speed that travels a distance of 12.2 meters per second (43.9 km / h at speed). It means that is moving up and down.

The average speed is 14.0 m / s when the rev limit is assumed to be 7.0 m / s at 2000 rpm where the maximum torque is generated, and 4000 rpm which is 500 rpm higher than 3500 rpm where the maximum output is generated.

For reference, I calculated the change in piston speed when a 4M41 engine with a stroke of 105.0 mm was rotated up to 10000 rpm. Looking at this, it seems that the speed increases by about 7.00 m / s every time 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 5710 rpm (whether it rotates or not). It seems to be preferred both mentally.

4m41 engine malfunctions

Problems faced by the owner of a car equipped with 4m41.

  1. After 150-200 thousand km run, the timing chain starts to make noise. This is a clear signal for the owner – it is necessary to carry out a replacement until it is torn.
  2. “Dies” injection pump. The sensitive high pressure pump does not recognize low-grade diesel fuel. Symptom of a non-working pump – the engine does not start or does not start, its power decreases. According to the manufacturer, the high-pressure fuel pump is capable of serving more than 300 thousand kilometers, but only on condition of high-quality fuel and competent service.
  3. The alternator belt is failing. Because of this, a whistle begins, penetrating into the interior of the car. Usually, belt tension saves for a while, but only replacement finally helps to solve the problem.
  4. The crankshaft pulley is falling apart. Approximately every 100 thousand kilometers it is necessary to check it.
  5. Valve adjustment should be carried out every 15 thousand kilometers. The gaps are as follows: at the inlet – 0.1 mm, and at the outlet – 0.15 mm. Cleaning the EGR valve is especially relevant – it does not recognize low-grade fuel, it quickly becomes polluted. Many owners act universally – they simply jam the USR.
  6. The injector fails. Nozzles are able to work without problems for more than 100-150 thousand km, but after that problems begin.
  7. The turbine declares itself every 250-300 thousand kilometers.

Conclusion

Since September 2006, the production of the 4M41 version with Common rail and with an IHI RHV5S turbine with variable geometry began.

Engineers finalized the intake channels, installed a new intake manifold with swirl valves, changed the shape of the combustion chamber, and improved the EGR system.

This raised the environmental class and added power, now its 175 hp. at 3800 rpm and a torque of 382 Nm at 2000 rpm.

In 2010, the 4M41 went with modified IHI RHV5S variable geometry turbines. Power increased to 200 hp. at 3800 rpm, and a torque of up to 441 Nm at 2000 rpm.

Since 2015, Mitsubishi has been replacing the 3.2-liter 4M41 diesels with the more compact 2.4-liter 4N15.

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