merc 2.5 injectors

[HStream1]

Blake points!! Whats not known about these Bosch 0 280 150 036 Injectors is at what point within the RPM threshold is the duty cycle exceeded? Most if not all Injector Manufactures say is dont exceed 85% of the injectors duty cycle yet 90% can be achieved before the Injector begins to "float"? The other thing that needs to be taken into account for instance What happens say if a ECU is set at 100% fuel percentage vs being set at 105% fuel percentage? Most all my Drag engines require 105/106% fuel or they tend to run a bit lean and show high EGT's. I wish i had the capabilities and video photography know how to video and slow down whats happening with these injectors through out the RPM ranges of a Drag engine that starts out at 2000 RPM at the green and can spin 11K at the 800 ft mark. Granted when mercury developed the 260/S3000 for race purposes they never dreamed these engines would be turning north of 10K. And Gosh knows the Mercedes 450 SL that these Bosch injectors were used in saw nowhere near those RPM's. Yet mercury chose them and their Drag ECU's A48, A63, A6, A13 all had 11500 rev limits??? I had to come back for a edit. The other thing thats out of the norm for most all Fuel Injected systems if the mercury ECU driver fires Two injectors simultaneously , 1 & 2, 3 & 4, 5 & 6 which we cant duplicate on our machines. How does that come into play with the over all Duty cycle vs firing each injector individually???

Another thing that noone is talking about here is the injector reaction time. Bud, I know you've seen this before. Run some injectors up to 10,000+ rpm, and watch them start to cut out. They literally can't move fast enough.

[InjectorService]

So Bud,
If I am following you correctly, the injectors fire 2 times per revolution. 1 time per revolution is on every 2 stroke, and because 1&2, 3&4, 5&6 are batch fired, at 11,000RPM the injectors would be firing 22,000 times per minute, or 367 times per second.

Or did I miss what you were saying there?

On another note, I'm going to see if I can find some time to run a few tests on some 2.5 hose feeds and see if I can get some limits on their capabilities. Maybe run them side by side with my "new" injector, see what happens.

Some more natable points. The Bosch 0 280 150 036 injector that the Merc racing motor uses, were not only "early" fuel injectors, they are actually THE EARLIEST injector that was used in production vehicles. The D-Jetronic injection system dates back to the early 1960s. Anything before that was either not mass produced, or considered a failiure. Why Mercury 30 years later chose to use that exact same injector in their race motors is beyond me.

EDIT: Also going way back in the thread, I can 95% garuntee that those Rock Auto replacement injectors are trash. Been there seen it too many times. They are "OEM replacement" "Flow matched", maybe Ill order some to make a point. All you need to do is hold it in your hand and you know. Those cheap knockoff injectors are so light they probably float.

EDIT 2: I've got to get back to work but I'm not quite done talking yet. Bud I'm just spitballing here, but I would suggest your need for the extra 5% fuel on the top end, would be because the injector just can't react that fast and you need to add the extra 5% on the table to compensate. Also you guys are running pretty rich oil mixtures, the effect of the oil ratio should lower EGTs. Chances are your even leaner than 5%

Blake

[InjectorService]

IDC is not directly interlinked with engine RPM, as there are a number of factors that influence fuel delivery through the injector. Since the injectors job is simply to deliver the precise amount of fuel that is needed for a specific engine at a specific RPM, and since you can use a number of methodologies to increase fuel delivery thorough a given injector at high rpm, a F1 V8 injector might not actually have to pulse any faster than an injector in a 2.5 at 10,000rpm.
For example, one of the biggest factors in fuel delivery through any given injector is fuel pressure, so if you can increase fuel pressure dramatically as the engines rpm increases, you won’t need to pulse the injector as much as you would have to if the fuel injector is static. The converse of that is where the injector tip is seeing an increase in atmospheric pressure (boost) as rpms increase: if your fuel pressure remains static, then you will need to pulse the injector much more than if you would if you have a boost-referenced fuel pressure regulator, which increases fuel pressure in lockstep with boost.
BTW: the fuel pressure regulators on our mercury 2.5 EFIs uses this method in reverse, by utilizing engine vacuum to pull against the diaphragm in the fuel pressure regulator to reduce fuel pressure at idle, which helps to reduce the amount of fuel flowing through the injectors at idle.

You have some good points here, but I think you missed the mark a little. While there are methods for increasing fuel delivery at any given RPM, such as larger injectors, higher fuell pressure, or multiple injectors per cylinder, the injectors STILL need to fire 1 time per revolution on a 2 stroke, or 1 time per 2 revolutions on a 4 stroke. The pulse width doesn't affect that at all. Still the same injectons per revolution.

[PanRonnie]

a fast rule of thumb is at 6000 rpm a single crank rotation is 10 Miliseconds , at 10000 rpm it is 6 Miliseconds
now the dutycycle limit or deadtime is also dependant on voltage
a trick some megasquirters use is to run 16 volts, this way you can charge ignition coils faster and reduce injector times but blue smoke is never far away
as STV mentioned you can increase pressure to increase flow but this is squaered
roughly double the fuel pressure gives 50% more flow
nearly all injectors can take up to 70 psi without problems , what will become a problem is the the Amp draw of your fuel pump
since the 16 Amp system is not easily upgradable this can be problematic
the old and still probably the best method is injector staging
a set of injectors from idle to midrange and from midrange to top
you could do this even with the mercury ecu
both injectors are wired into your 12 to 14 volt but only one of the negative injector sides is connected to the ecu through a relay
the idle injectors obviously the smaller ones

the Megasquirt V3 mainboard drivers can handle 4 injectors of 2.5 ohm
with 2 channels you can handle 8 injectors
as you see in the picture you can adjust everything of the mainboard injection drivers
so if your handy with a soldering iron you can put one togehter for $ 445 ,-
https://www.diyautotune.com/product/...assembled-kit/

The last time i used the Ultimate for testing, it has software selectable peak and hold either 4 Amp peak 1 Amp hold or 8 Amp peak 2 Amp hold so one injector driver can be used for 2 injectors
i used the latter

[HStream1]

You didnt follow me. The mercury ECU fires Two Injectors at the same time in relation to the firing order (1 2, 3 4, 5 6) Meaning 1&2 fire at the same time, 2 & 3 Fire at the same time & 5 & 6 fire at the same time. Meaning in a rotation cycle the ECU only pulses the injectors 3 times dual vs 6 times individual.

So Bud,
If I am following you correctly, the injectors fire 2 times per revolution. 1 time per revolution is on every 2 stroke, and because 1&2, 3&4, 5&6 are batch fired, at 11,000RPM the injectors would be firing 22,000 times per minute, or 367 times per second.

Or did I miss what you were saying there?

On another note, I'm going to see if I can find some time to run a few tests on some 2.5 hose feeds and see if I can get some limits on their capabilities. Maybe run them side by side with my "new" injector, see what happens.

Some more natable points. The Bosch 0 280 150 036 injector that the Merc racing motor uses, were not only "early" fuel injectors, they are actually THE EARLIEST injector that was used in production vehicles. The D-Jetronic injection system dates back to the early 1960s. Anything before that was either not mass produced, or considered a failiure. Why Mercury 30 years later chose to use that exact same injector in their race motors is beyond me.

EDIT: Also going way back in the thread, I can 95% garuntee that those Rock Auto replacement injectors are trash. Been there seen it too many times. They are "OEM replacement" "Flow matched", maybe Ill order some to make a point. All you need to do is hold it in your hand and you know. Those cheap knockoff injectors are so light they probably float.

EDIT 2: I've got to get back to work but I'm not quite done talking yet. Bud I'm just spitballing here, but I would suggest your need for the extra 5% fuel on the top end, would be because the injector just can't react that fast and you need to add the extra 5% on the table to compensate. Also you guys are running pretty rich oil mixtures, the effect of the oil ratio should lower EGTs. Chances are your even leaner than 5%

Blake

[PanRonnie]

Maybe this will help

[HStream1]

On the 0 280 150 036 Bosch Injectors ive tested they seem to hit a wall at 65 to 67 psi. After that there is no flow increase. No matter what pressure is applied you can't shoot but so much liquid through a fixed size hole. The Bosch 984 which alot of Racers use has the following spec's. 12 Volts, Max Power 10 Amps; Operating Pressure: 72.5 PSI (5 Bar); Minimum Flow @ Outlet: 43.4 GPH. So in theory the pump should draw less amps at 56 psi than 72.5 psi.

a fast rule of thumb is at 6000 rpm a single crank rotation is 10 Miliseconds , at 10000 rpm it is 6 Miliseconds
now the dutycycle limit or deadtime is also dependant on voltage
a trick some megasquirters use is to run 16 volts, this way you can charge ignition coils faster and reduce injector times but blue smoke is never far away
as STV mentioned you can increase pressure to increase flow but this is squaered
roughly double the fuel pressure gives 50% more flow
nearly all injectors can take up to 70 psi without problems , what will become a problem is the the Amp draw of your fuel pump
since the 16 Amp system is not easily upgradable this can be problematic
the old and still probably the best method is injector staging
a set of injectors from idle to midrange and from midrange to top
you could do this even with the mercury ecu
both injectors are wired into your 12 to 14 volt but only one of the negative injector sides is connected to the ecu through a relay
the idle injectors obviously the smaller ones

the Megasquirt V3 mainboard drivers can handle 4 injectors of 2.5 ohm
with 2 channels you can handle 8 injectors
as you see in the picture you can adjust everything of the mainboard injection drivers
so if your handy with a soldering iron you can put one togehter for $ 445 ,-
https://www.diyautotune.com/product/...assembled-kit/

The last time i used the Ultimate for testing, it has software selectable peak and hold either 4 Amp peak 1 Amp hold or 8 Amp peak 2 Amp hold so one injector driver can be used for 2 injectors
i used the latter

[PanRonnie]

A side by side between the hose and the pink tip might be an idea
Possible the pink tip can handle pressure increase better at comparable flow

[HStream1]

Ive tested the Bosch top feed against the keihn pink tip and YES the Keihn flows more at the same pressures 39 psi thru 62 psi.!!.

A side by side between the hose and the pink tip might be an idea
Possible the pink tip can handle pressure increase better at comparable flow

[InjectorService]

That patent has a lot of good info in it.

[Onetime]

Excellent thread here! Lots of great information. Thanks guys for posting it.

Many years ago I tested the aftermarket replacements compared to true Bosch on the dyno and concluded I would never run them in a Mercury Outboard again. Was on a 260 and tested back to back. Power went down and EGT’s went up on the aftermarket injectors. Obviously lean. I stopped the test quickly and Bosch only ever since.

[Capt.Insane-o]

Not to go sideways, but another issue that can/happens is the injector seals and or grommets harden over time and transfer engine harmonics to the injector. In the case of the first motor it was an f1 that developed issues above 10,5, and at the end 10,3 when with a previous set up it would go past the fabled 11k mark. It was a three fold issue as the seals and grommets had hardened up and along the way the studs for the injectors were swapped out with shorter ones with incorrect spacers so that the injectors were physically crammed into the front half. I got the motor to go through the electronics and looking at the injector hold downs being tweaked went against my ocd and was corrected.

Anyway TLDR, the electronics went from my motor to this one. It ran as advertised. The old electronics went back on and ran as advertised, the above being the only variable.

[CI STV]

You have some good points here, but I think you missed the mark a little. While there are methods for increasing fuel delivery at any given RPM, such as larger injectors, higher fuell pressure, or multiple injectors per cylinder, the injectors STILL need to fire 1 time per revolution on a 2 stroke, or 1 time per 2 revolutions on a 4 stroke. The pulse width doesn't affect that at all. Still the same injectons per revolution.

Point taken, but I was specifically referring to IDC not being necessarily linked to rpm. You are correct that with the typical injector setup (especially with “sequential” fuel injection), the injector is fired once at some precisely predetermined point during the intake stroke, which would mean once per revolution on a 2 stroke and 1 per two revolutions in a four stroke. I know from tuning my own vehicles with HP Tuners that injection timing is critical to achieve proper burn of the air/fuel mixture and there’s tons of discussion on the HPT forums about injector timing/logic that’s way above my pay grade or comprehension, to be honest.
However I had ASSumed (without thinking it through properly) that with the batch fired crankcase-injected system in the 2.5s, all the injector needs to do is inject the precise amount of fuel needed to mix with the air that’s ingested when the reeds open (sort of like GM’s TBI of old, with a carb type central-injector system)?
But, by reading the patent document that PanRonnie posted, I can see that the logic used by mercury is in fact more sophisticated than I thought, albeit overall ingeniously simple. And, thinking logically, that means the reeds on each cylinder open once per revolution on these motors, so simple logic would then dictate that the injector needs to “fire” each time that event happens to maintain the correct AFR in the crankcase.
So, insofar as all of that is relevant to the discussion of what injector is a worthy replacement for the old tried and trusted Bosch hose-feed injector, it’s good to read (and learn from) the experience of you gentlemen who have actually tested these things, so that we don’t go and run off to buy a replacement that is cheaper and apparently “better” and more readily available than the Mercury listed replacement. The last thing I would want to do is install (or convince anyone else to install) a junk injector that fails at high rpm.
It really is mind boggling that an old-tech injector invented in the 60s can keep an 11,000 rpm capable 2-stroke fueled properly.
I’m also very glad to hear that you’re working on replacement injectors yourself, and if they run as good as they look, then I’ll gladly order a set from you when they’re ready.

[CI STV]

Ive tested the Bosch top feed against the keihn pink tip and YES the Keihn flows more at the same pressures 39 psi thru 62 psi.!!.

Pardon my ignorance, but what is this “pink tip” injector that I keep hearing about? Is that a direct replacement for the Bosch 0 280 150 036?

[PanRonnie]

It is what mercury used on the 2.5 liter laser intake system
If you can turn them into hose end injectors or make a new fuel rail you would have a good replacement for the bosch injector
You are going to have a hart attack if you ask for dealer list price