Someone school me on injector effeciency

[Mims]

Why is it when all else stays constant or even stock, changing out injectors for slightly larger ones (i.e. +25 - +125hp) thus decreasing overall pulse width in nearly all map areas to achieve equal power output, can lead to better fuel mileage with proper tuning? The amount fuel need to be injected for the burn at any certain point should theoretically be equal between stock vs over-sized, the over-sized just open for a shorter period to match that quantity, but in the end isn't it the same exact amount being injected? Sorry if it's a dumb question

 

[p-Bar]

I could never understand also how this is too.

 

[jjdiesel]

Better fuel burn due to improved spray angles from new injectors? Just a thought.

 

[dieselshadow]

Timing has a bit to play in this. A quicker duration injection averages a bit more advanced than a longer duration injection if all else stays the same.

 

[AH64ID]

Shorter duration of injection leads to a quicker burn, and slightly higher cylinder pressure for the same amount of fuel.

The atomization of the fuel is also different and likely more efficient on a slightly larger injector but as you get above +100hp the low fuel volume atomization can decrease.

 

[Prairie Dog]

That's easy, it just doesn't - at least not in my experience with my DDP 50's (Which were new and slurry honed) and contrary to what they claim, they wont pass emissions either.
It does run smoother and more quiet than ever but if anything, FE has dripped slightly.

 

[cerberusiam]

Why is it when all else stays constant or even stock, changing out injectors for slightly larger ones (i.e. +25 - +125hp) thus decreasing overall pulse width in nearly all map areas to achieve equal power output, can lead to better fuel mileage with proper tuning?

That statement is a direct contradiction of itself. You cannot have "all else stays constant or even stock" and "better fuel mileage with proper tuning" for an equal comparison. Stock size injectors can achieve better efficiency with proper tuning and\or fixing the built in emissions problems on the later engines. On the flip side an injector that injects fuel faster in a better pattern and better atomized will increase the engine efficiency, and, no the amount of fuel injected is not the same if efficiency increases. The reason are as stated above; increased timing, shorter injection time leading to a quicker burn, better atomization, and higher cylinder pressures. The CR systems are dynamically adjusting fueling rates based on the actual engine output as measured by vehicle performance, if it takes less fuel to go 70 mpg with one injector over another then the ECM will inject less fuel as it manages the fuel curves.

There are a myriad of factors that contribute to observed efficiency (aka mpg), there is no one answer WHY certain injectors will show better results than others.

Now the discussion has to move off the title because it does not address the why. Injector efficiency is the ability of a SETof injectors to consistently deliver the same amount of fuel as demanded every time over a range of rpms and times. It is just one, albeit a very important, component of the real discussion which is "Injection Event Efficiency". That discussion will tell you why a set of DDP 50's and BMS 50's are crap compared to a set of BBI .5's or stock Bosch marine injectors, even they are about the same HP uprate.

 

[Prairie Dog]

Well LOL, at least my new set of DDP's run smoother and more quiet than the truck ever has in it's life.
So I'm good with this level of "crap".

Scott

 

[cerberusiam]

Well LOL, at least my new set of DDP's run smoother and more quiet than the truck ever has in it's life.

But, by your own admission they won't pass emissions testing and economy looks to be suffering. An injector that only checks 1 of the three important boxes will be well down the list when there are choices will in fact check all 3 boxes. Smoother and quieter on an 8 hole 143 degree nozzle is not that hard to achieve with just a little care, doing the same thing on a 5 hole 124-126 degree pattern is more than a little bit harder let alone meet emissions and increase efficiency. That is where the standard offerings of many suppliers tend to fail repeatedly.

Don't get me wrong here, if that is ALL you are looking for and it suits your needs then it is the old adage where one mans trash is another's treasure. Realistically, how many would buy this injector if the KNEW ahead of time time they would smoke more and get worse fuel economy even though you got a little more power? In this day and age that is a no-brainer answer.

Your response to the OP, based on your experience with the injectors you purchased, is a larger injector does not give efficiency gains. My experience shows a larger injector can be smoother, quieter, deliver better fuel economy, and still pass emissions, all things being equal and unequal with tuning. Tuning is like bacon, it makes everything better.

I submit you bought the wrong injector. The fact is if you had bought a different injector your experience would have been different, which is my whole point. There are a myriad of factors that determine a positive outcome, one aspect won't tell the story.

 

[Prairie Dog]

Perhaps, in retrospect I seem to remember something about marine something or other but I don't remember for sure.
I would never buy anything from DDP again because I caught them in several lies that were used just to sell me on stuff.
In all fairness, at the time DDP was the cats meow on this forum and thats one of the big reasons I went with them. Now they've left town and I've got a wierd, one of a kind batch of injectors that if I ever have a problem with, I probably will either have to replace all of them or at least the tips because he kept altering these things in a fruitless effort to pass emissions. Fortunately they've stopped testing here.
DDP has left me high and dry. What a disgusting experience.

So now these sticks are crap and something else is king of the pile - for now.
I would strongly suggest to anyone that's in the market and wants the best fuel efficiency and least amount of headaches to get a set of NEW STOCK injectors. Get your extra power elsewhere and skip all this flavor of the month krap.

 

[cerberusiam]

Depends on what you want to do an can afford to spend. A set of the marine injectors, which should pass emissions, in your truck are about $360 per. Usually cheaper than the stock injectors for your truck whihc you should be bale to source for around $400-420. Remans will be at the $360 mark but hate to even suggest that considering the experiences I and others have had with them.

If the bodies you have are new with just nozzles I would not hesitate to send them to BBI and have new nozzles installed and the injector setup correctly. Will require another set of injectors unless the truck can be down for several weeks. Either way you end up investing $$ to fix a purchase that should not require it.