merc 2.5 injectors

[HStream1]

Absolutely NOT!!! If what you say is true that would place all 6 Injectors flooding the Crankcase constantly. That would be a disaster. The Firing cylinder would Hydraulic and and start breaking ****. If youve ever seen injectors tested on a Machine they cycle all the way through the RPM range. My machines have a Pulse threshold up to 9900 RPM's and you can hear them pulsing. My problem with the lesser priced injectors wouldnt be in the lower RPM ranges. But Id be worried about anything over 7K. My Drag engines constantly see North of 10500 or 175 RPM per Sec. If a injector fails at those RPMs its Disaster. Ive got some videos of Injectors testing but S&F wont let me down load them. I have to do them via HuluYouTube (Long)YouTube (Short)VimeoDailymotionMetacafe. And Im not wasting time trying to figure that one out.

I would think if they flow at high rpm in a test they would work but again, not testing on my motor! At high rpm the injector is not cycling anymore, it is basically open and flowing the whole time.

[CI STV]

There is no magical RPM where all fuel injectors stay open. That depends on the flow capacity of the injector and the duty cycle it sees in any application.
Injectors don’t know what rpm the engine is turning. They simply “widen their pulse” (length of time injector opens) based on what the ECU driver tells them to do, which is based on the data programmed into the ECU, in order to deliver the precise amount of fuel that that data dictates.
Every injector will reach 100% duty cycle at some point, since they all have a fixed delivery rate. Whether that is 650cc/min or 2000cc/min depends on the injector design. The key is sizing the injector for each application so that it never sees 100% duty cycle (IDC) at max rpm/fuel delivery.
So, as mentioned before, once a set of replacement injectors of similar design, impedance, etc. flow the same as the originals, then the engine won’t know the difference.
What is far more important, as PanRonnie is pointing out, is that in any application, ALL of the injectors flow as close to identical as possible, otherwise you’ll end up with different cylinders seeing different fuel delivery, and that can lead to catastrophic engine failure, if one or two runs significantly leaner than the others.
That is why it’s so important flow match a set of injectors.
BTW: the SMP Intermotor injectors offer that, as well as stainless internals and they’re made in the USA. That’s much more than the OEM mercury/Bosch units offer. I’ve never seen a set of mercury injectors for sale from any parts vendors that were labeled as flow matched or balanced. It could very well be that many a Merc 2.5 EFI engine was fried over the years because it had one bad/weak/dirty/slower flowing injector in it. We’ve probably all had one of those, “how come that cylinder stuck a piston/broke a ring land/seized in the bore, etc, etc.” kinda experiences, haven’t we?
So, maybe we’re placing too much reliance on “branding” and adherence to labels, rather than empirical data, which, coincidentally, is the logic that injectors operate on…

[rjdubiel]

Sounds good CI STV and HStream1. I was just stating what a well know injector cleaner told me when we were talking about possibilities of why my 280 lost #4 a few months ago (he flowed my injectors the week before my race where #4 let go). He double checked my injectors for free after and they were all the same as when he flowed them the first time. I agree with both of you after reading your posts and I may have not completely understood the injector cleaner I was talking to about possible issues. And maybe he gave me the dumbed down version!

[HStream1]

All Injectors are nothing but a solenoid and a pintle encased in a body that opens and closes based on pulse signals from the ECU Driver.. The Thing that scares me about the aftermarket injectors is how well built is the solenoid compared to say Bosch, Keihn, Denso etc? The Pintle spring also comes into play. If its of a high quality spring steel or border line in quality? If the spring fatigues the injector will flow erratically. If the Solenoid windings are substandard it cant handle the Higher pulse rates (I.E. RPM's).

So, maybe we’re placing too much reliance on “branding” and adherence to labels, rather than empirical data, which, coincidentally, is the logic that injectors operate on…

[PanRonnie]

Sounds good CI STV and HStream1. I was just stating what a well know injector cleaner told me when we were talking about possibilities of why my 280 lost #4 a few months ago (he flowed my injectors the week before my race where #4 let go). He double checked my injectors for free after and they were all the same as when he flowed them the first time. I agree with both of you after reading your posts and I may have not completely understood the injector cleaner I was talking to about possible issues. And maybe he gave me the dumbed down version!

i will give it go to try and explain it
in the woodward picture you see the current trace of your mercury 280 computer
you see that little dip in the second blue square!
that is where the injector neelde is fully open and seated
your injector is nothing more than a tap which you try to turn open and close as fast as possible
the moment your injector needle is lifting fuel is starting to come out but as with your tap very little until it is fully open now you would be in your injector static range
the same situation occurs when you turn off the injector , needle needs time to close again by spring force and maybe a little fuel pressure
it will still inject fuel until completley closed which you can see in the second picture takes almost a milisecond for that injector
those particular times opening and closing times your injector is not flowing to specification
if you where to run at a 100% duty cycle your injector needle would not have the time to close again , this would happen before you have a 100% pulse signal
a general rule is to stay under or close to 80% but this is with car or motorbike racing where you go around a track and go up and down in rpm giving the injector some breathing space
in boat racing you can have times where you can stay on power for long streches
imagine and injector running at 80% for an hour or even longer
you choose your injector to match your application have enough spare time at the top but still somewhat good idle quality,s and a proper resolution at midrange
your fuel injector pulse widht will follow the torque curve of your engine not the Horsepower curve
now mercury already did their best to match those injectors
so don,t be stupid like me when i installed a set of fiveO injectors in my mercury having complete faith in the flow sheet they provided
if you have a DDT you should be able to do a pulse test with your mercury ecu
just test them yourself and see what you come up with

BTW in the second picture you also see the voltage going up to more than 20 volts
that is the flyback voltage as the injector is turned off it acts as a mini ignition coil the collapsing field wants to go somewhere this flyback voltage will actually keep the injector open longer
the 849849 ecu's have a resistor peak and hold system but the brucato unit as the woodward ecu does this by Pulse With Modulation
during those very short off times a thousendt of a milisecond, voltage is brought in at the negative side of the injector clamping somewhat that voltage peak that you see
so the same injector would behave differently on a 849849 ecu or a brucato/mercury unit
ok i think i deserve a coffee now

[CI STV]

All Injectors are nothing but a solenoid and a pintle encased in a body that opens and closes based on pulse signals from the ECU Driver.. The Thing that scares me about the aftermarket injectors is how well built is the solenoid compared to say Bosch, Keihn, Denso etc? The Pintle spring also comes into play. If its of a high quality spring steel or border line in quality? If the spring fatigues the injector will flow erratically. If the Solenoid windings are substandard it cant handle the Higher pulse rates (I.E. RPM's).

Those are very valid points. Those three name brands have manufactured OEM injectors for many models, for many years, so no doubt they have certain standards they have to meet and have an established track record.
Again, I'm not promoting the use of a cheaply made injectors here, just trying to figure out if there's a viable alternative to paying $250 per injector for some early 1970's technology (that's when those Bosch "hose-style" injectors were designed). But I have to say that the write up on the SMP injector sounds promising. Don't know how anyone could verify (without testing them) that they're all they promise to be, but they do say that they have precision-wound coils, stainless internals, including the spring (which is something that ID does now with their "X" series injectors), etc. etc., and that they are tested through 1 million cycles. And, again, they're flow matched.
I've found from racing autos and boats over the years that generally many aftermarket manufacturers that actually do a better job at building quality parts than their factory OEM counterparts.

[PanRonnie]

Pride and a piston where seriously hurt in the making of this video
Pride was hurt more!!!!!

[InjectorService]

If anyone wants to send me some injectors to experiment on, Ill be happy to test. I've actually been working on a replacement injector set for these hose feeds, but haven't had the time to pursue it much further. They are sitting here, I just need to veryfy flow throught the RPM range and duty cycle. Then I'd like to get them in the hands of someone with a dyno.

[InjectorService]

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.

[Capt.Insane-o]

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.

That was going to be a next question, who around can duty cycle injectors at 10k for 30 seconds?

[HStream1]

Maybe we need to get our hands on some F! engine injectors and find out how and why they can sustain pulsing at 19k.

https://youtu.be/9kX8asluuNg?t=60

[ChrisCarsonMarine]

Bud,remember their 19K is only firing the injector every other rotation...9500 on a 2 stroke would be equal injector service,Chris

[PanRonnie]

Tunerstudio in combination with a megasquirt MS3 V3 board you can do whatever you want
with the option for Pulse width modulation you can adjust the period of full power ( peak period) and adjust not only the modulation frequency but also the percentage power is applied

so injector opening 1.5 to 2 miliseconds then a frequency of 55 Usec with a 30% on time meaning 30% of 55 Usec power is applied this is all adjustable

[CI STV]

Maybe we need to get our hands on some F! engine injectors and find out how and why they can sustain pulsing at 19k.

https://youtu.be/9kX8asluuNg?t=60

I suppose they simply use a big enough injector that can deliver the volume of fuel they need at that rpm. They must still pulse pretty rapidly at max fuel delivery, given the immensely broad rpm range and the use of a single injector. The magical thing is probably controlling fuel delivery so that the injector can deliver a small enough amount of fuel for the engines to idle without flooding.
Before the advent of injectors like the Moran/Atomizer injectors, many engine builders like Duttweiler used a secondary set of injectors for big power turbo setups. There have been giant strides in injector technology in recent years, which is one of the points I was trying to make. Just by looking at what Paul Yaw/ID has achieved with the Bosch style injector, where you can now use a 2000+cc/min in a street car, you easily can see that.
I would love to know what they use for springs in those older F1 V8 injectors though. I know they had to use nitrogen filled “buckets” as valve springs, since there is no spring wire that can cycle the valves fast enough in a four stroke V8 turning 19,000+ rpm.
To me, just looking at one of those F1 V8s, the real beauty of those engines was the simplicity of their design:

[CI STV]

IDC is not necessarily 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.