Increase Yanmar 4JH4HTE RPM: How To Guide

Hello everyone, I'm new here and would like to introduce myself briefly:

My name is Maurice and I come from the western part of the country, which was originally a major coronavirus hotspot (I have been spared so far ).
I have a particular interest in Mercedes OM 60x engines. I've already significantly increased the power of several OM605 engines in W202 C-Class models, and currently drive a W124 with an OM606 turbo engine producing over 400 horsepower, so I definitely have some knowledge about diesel engines.

I thought .

My other hobby is watersports. We have a Beneteau Antares 6 boat with a Yanmar 4JH4HTE engine (2 liters, 16 valves, 110 horsepower, and 280 Nm of torque).

What bothers me a lot is that it downshifts at only 3200 RPM under load (while the engine easily revs above 4000 RPM in idle). At this speed, the boat doesn't accelerate properly. I also believe that a 16-valve diesel should be able to reach 4000 RPM or even slightly more. Therefore, here's my crucial question:

How do I set the engine speed to approximately 4000 RPM?

It features a mechanically driven injection pump from Bosch, specifically the VE type.

What I have already tried:
Max out the power, but no success.
"The anti-clockwise adjustment screw on the throttle was moved from 1 o'clock to 3 o'clock (the engine now has noticeably more power, but still doesn't misfire, and the maximum RPM remains stubbornly at 3200)."

My understanding of inline pumps is quite good, but unfortunately, I don't understand distributor pumps very well.

What I've read now suggests that the spring attached to the regulator is so weak that it causes the engine to shut off precisely at 3200 RPM, and consequently, the fuel injection amount is reduced.

Is the only way for me to increase the RPMs to replace this spring with a slightly stiffer one, or am I missing something?


Thank you in advance to anyone who takes the time to help me with my problem.

Hi there,
Perhaps the pump is simply unable to draw in any more diesel fuel.
The attempt with the adjusting screw was correct. Are the valve timings correct? And since the engine is likely turbocharged, is the boost pressure enrichment working properly?
hg
Herbert.

Hello Herbert,

Thank you very much for your prompt reply!

The engine only has a low number of operating hours, 640, and no one has ever touched the pump before me. I think everything seems to be in order here (I removed all the seals myself, and all the yellow markings were intact).

According to the specifications, the motor is set to a maximum speed of 3200 RPM, and it easily reaches that speed.

The boost enrichment feature works well; you can clearly feel how a significantly different amount of fuel is injected and burned starting around 2000 RPM.

Could it be that I touched the adjustment screw too gently? That I need to turn it a full rotation inward, and not even a quarter of a rotation?

With the quarter turn, the idle speed also changed, but it remained constant (I've often read that it increases when you adjust the fuel screw, and that the idle needs to be readjusted on the side facing the engine block with a screw afterwards; this was not the case for me).

Hello.

Do you happen to have the complete part number for the pump? From that, it's possible to identify the internal components.

Car engines have a different regulator (idle speed/maximum RPM regulator).

Marine, industrial, and utility vehicle engines have a universal speed control system that maintains the engine speed set by the throttle lever/pedal and cuts off power at the maximum speed.
Often, the governor springs/flyweights are designed in a way that limits the maximum RPM achievable, or the displacement piston is calibrated for a specific flow rate. Therefore, I suspect that under full load, the pump simply reaches its maximum volumetric output.

If you install a boost pressure gauge, you should be able to see a drop in pressure as the amount [of something] decreases.

Regards, Mpire.

Hello Mpire,

The following is written on the pump:

Sh81
129672-51950
104742-7570

I've read about "end-of-speed controllers" and "all-speed controllers" in various explanations, but I haven't understood them. So, are these two different types of variable speed pumps?

What type of regulator is installed in a Cummins VE pump? They seem to replace the control spring there to increase the engine speed.

Is this an option for me? Or would it be better to look for a car with a naturally aspirated engine instead of a turbocharged diesel?

Hello...

This part number doesn't work for me. You say it's a Bosch pump, so it should have a 10-digit Bosch part number.
This always starts with a single zero.

Okay, 0 XXX XXX XXX.

"Please take a picture of the pump's nameplate, and if possible, also of the entire pump. The 'VE' type has been around since the 1960s, and there are more than five different series."

The type of pump and controller used always depends on the specific application of the motor.
A conversion to a car fuel pump would likely yield even worse results, as it doesn't provide consistent regulation and performs poorly in rough seas.
If the load is fluctuating (e.g., due to repeated tightening or loosening of a screw), you will lose control of the system.
The fuel pumps for car engines are often tuned to different turbochargers than the same engine would be in a [different vehicle/application].
Utility vehicle / truck / construction machine / emergency generator / or combined heat and power (CHP) unit.
For each of these applications, a different speed range/rated speed and a different torque range are required.

Unfortunately, I don't have any information about Cummins pumps.

Regards, Mpire.

Hi, thank you very much.

That was the only number I found directly. I'm attaching some photos.

I found the following part number listed online as a Bosch part.

9460615093

And then there's this number related to the pump.

NP-VE4/12F1600RNP2595

Source:

https://www.stokkingdiesel.com/parts/detail/40086

Hello,

The function of the different types of Bosch fuel injection pumps is actually well described in literature. Perhaps there is similar information available for your Cummins fuel injection pump?

I just searched for "Cummins injection pump book," and of course, there are many results; hopefully, something useful will be among them.

Best regards, Rainer.

Thank you very much.

Unfortunately, I don't have a Cummins; I only have a small Yanmar 2L 16V engine in my boat, and everything else is running on older, indirect injection turbo diesel engines.

I had inquired about the Cummins pump because Mpire provided me with information about a universal speed controller and an end-speed controller. Until now, I was not aware that there is a distinction between these two types of controllers.
Then it occurred to me that, for example, Cummins 6BT engines also have a very low RPM, and in those cases, a spring on the governor is replaced to increase the RPM. Then I wondered if I could do something similar on my pump .

Okay, I misread that; the number above refers to the pump, and it appears to be a Bosch VE type.

NP-VE4/12F1600RNP2595

Distributor injection pump, 4 cylinders, plunger diameter 12 mm for a pump speed of 1600 rpm and right-hand rotation (resulting in a 3200 rpm engine).

ISBN 3-528-03873-X, page 152 and following might be helpful for you.

What about the boost pressure enrichment? According to the image, it seems you have a full-load setting that is dependent on boost pressure.

See page 181 in the book I mentioned.

Have you already searched for "AAZ Tuning" on the web? It might work in a similar way.

OM606 wrote:

Hi, thank you very much. That was the only number I found directly. I'm attaching some photos. I found the following part number listed online as a Bosch part. 9460615093 And then there's this number related to the pump. NP-VE4/12F1600RNP2595

Hi there,
Well, there we have the right number .

Okay, let's break it down:
VE4 = Distributor injection pump for a 4-cylinder engine.
12 = 12mm feed piston.
F = Spring-loaded.
1600 = Pump's rated speed of 1600 RPM multiplied by 2 -> 3200 RPM motor.
R = functioning correctly.
NP2595 = Auslieferungsstand/Änderungsindex f. Engine manufacturers.

In short: Speed governors up to 3200 RPM are spring-controlled, meaning you need a stronger connecting spring between the throttle lever and the governor lever on the pump to increase the maximum speed.

Regards, Mpire.

@dieselschrauber
I have noted down the ISBN for Christmas .

I Googled "AAZ tuning," and a lot of information came up about a tuning control cone.
It's hard to believe that such a simple measure can achieve such an increase in performance.
The only problem I see with increasing performance is that the turbocharger doesn't have a wastegate.


@Mpire

Would this be suitable, for example?

https://www.ebay.com/itm/284449366664?hash=item423a80e288:g:JGsAAOSwf1xhPig9

I found a Bosch part number, 1 464 650 354, for a corresponding governor spring with a speed of 4200 rpm.

Hello...


Unfortunately, I can't tell you if this feather will fit.
What worries me more is the increase of 1000 RPM .
"I would check beforehand to see if the motor is designed for those RPMs."
Flywheel, belt drive, valve drive, etc.
The mechanical regulation (diameter of the wastegate) of the turbo is also designed for a specific flow rate. If the engine fails and you're at sea, it will definitely be "exciting" .

...just my thoughts.

Despite everything, good luck .

Regards, Mpire.

Hi, this engine has been around for a while. It used to run at 3800 RPM, but it was reduced to 3200 RPM for environmental reasons. So, I don't need to make it spin at 4200 RPM; it's questionable whether it would even handle that, but with a 2-liter 16v engine, I'm not too worried about that. As I said, the turbocharger is, in my opinion, not pressure-regulated, but it's very large, so full boost doesn't kick in until around 2000 RPM.

"Yes, I would really like to know if the spring fits. I can't quite imagine that the RAM VE pump is different from one used in a 4-cylinder construction machine or my boat engine/construction equipment engine."

Does the propeller's pitch match the boat's load curve?
And what about the engine's torque curve?
At what engine speed does the motor achieve its maximum torque?
What is the highest performance achieved?
Does it operate at a higher speed than the maximum power output?
The noise is only getting louder...

A boat builder should be able to modify it.

Best regards, gnash.