Exploring A New Idea [ Archive] - GasSavers.org - Helping You Save at the Pump

Single-shot injectors.

My 7.3 uses split-shot injectors. Two small squirts per injection event. Quiets the engine but imposes a degree of timing retard. Using single shotters from the earlier Powerstroke I get a more efficient combustion event.

My opinion is that a continuous injection throughout the power stroke is more benefitial than slamming the piston top, at or very near TDC, with the full fuel charge. The crank angle is such that the force produces little torque just past TDC, but the roughly 90 degree angle of the connecting rod to crank halfway through the stroke is able to produce more torque.
There has to be some fuel injected at TDC to take advantage of the compression heat and allow self-ignition, but withholding some of the fuel for injection (and using prior fuel's heat to ignite that late volume) until later in the down stroke when conversion from piston pressure produces less direct down load on the crank bearings and more torque from the nearer 90 degree angle can make more power on the same fuel with less noise and lower emissions, too.
The new common rail TDI from VW uses 7 separate injection 'pulses' per power stroke to keep quiet and to meet 50 state emissions requirements.

Single-shot injectors.

My 7.3 uses split-shot injectors. Two small squirts per injection event. Quiets the engine but imposes a degree of timing retard. Using single shotters from the earlier Powerstroke I get a more efficient combustion event.
Dave is this something that you're thinking about or trying?

My E350 is a '96 and has single shots. The new to me Excursion has the split shots.

but imposes a degree of timing retard.

Since you have a six speed, can't you take the plug off the EOT sensor and get timing advance? If that's what you were looking for.

I'm in negotiation to get it done.

A lot of guys I respect seem to think this is more efficient. The engine was designed for single-shots.

We'll see. Wouldn't be the first thing I've tried that didn't work. Free-flowing exhaust and warm air intake gained me squat.

Going to Nashville the 11th for single-shots.

Going to Nashville the 11th for single-shots.
Ok, who's doing the tuning? More info, more info!!!! $$$? (The scary stuff)

Swamp Donkey is doing the injectors. I'm a bit fuzzy about the tuning.

My guess is about a grand, but remember I need injectors antway. Its getting crotchety to start and I get a puff of black smoke on startup. My injectors (with 217,000 miles on them) are dribbling when cold.

Is the dribbling common with age?

:D

Or is it common to the split shots?

My understanding is that the check valve at the tip does wear out. It is cycled thousands of times a minute.

The single shots and Swamp's tuning got me my best single tank ever -28.2 MPG.

All INTERSTATE at the posted limit - mostly 70.

Circuit testing in progress.

Real interesting...

I'm watching.

First fillup on my normal circuit: 27.67 MPG.

That's up 0.4 MPG from split-shots.

Or less than 1.5% change on your 'normal' route from the old tips.
Keep reporting the most comparable results.
Do you have some data from a similar trip with the old tips to which you can relate the all interstate 28.2 in post #11?

Not to be pessimistic, but I just want to make sure I understand this correctly. You improvement came from replacing worn out injectors with new ones, changing to the single shot tips and having some "tuning" done?

From the info you have can you differenciate the difference between replacing worn out injectors and going to single shot?

You said part of the reason they went to the split shot was to quiet it down, do you hear a difference in engine noise now?

very interesting stuff... I am still trying to determine if I am glad I have the single shots or not.

Mr_C

A 100% Interstate run 315 miles, driving the posted limit both ways. One way splits, the other way single shots.

Split shots: 27.8 MPG
Single shots: 28.18 MPG

In my normal circuit (30% Interstate, 35% city/suburban, 35% rural roads)

Split shots 27.24 MPG (average of three tanks)
Single shots 27.65 MPG (one tank only so far)

"Highway" improvement: 1.35%
"Combined" improvement: 1.48%

Look at the graphs of MPG in various contributors garage entries. Notice how much inherent variation there is with no concious driving difference or vehicle adjustments. Your change of less than 1.5% is effectively no change.
If you have less noise, or lower smoke output, or other benefit that is more difficult to measure, that's great. But mileage improvement? Statistically unchanged.

True, but Dave's pretty consistent at home about using the same place for his fill ups. However, this might have been different. Dave will have to elaborate, and whether the effectiveness of the tune is correct? I don't know. More data is needed.

Considering what Dave does with his pick up compared to my Excursion, he's about 10MPG ahead of me, still. I'm taller, wider tires, geared shorter, different shape. I'm still pretty impressed with where he's at.

I never claimed this is necessarily a winner. I?m testing it out. I have tried many things that didn?t work or didn?t do much. Free-flowing intake and exhaust didn?t help a bit. A chip helped only 0.75 MPG. A 203 degree stat was good for 0.5 MPG. Synthetic oil goes a very long way between changes but didn?t help MPG. An air dam and side skirts got me 0.6 MPG.

But actually in the MPG game there aren?t too many real silver bullets. I got 3 MPG improvement from my gearing and a total of 3 MPG from my bed cover but other wise all the improvements have been 1 MPG or under. If you are looking for a single silver bullet, you might be on a fool?s errand, but cumulatively I get pretty good performance.

I got these injectors in exchange for some thorough testing so my testing season is completely eaten up for this summer. The weather will turn in about six weeks and my MPG will roll off. I look to peak out at about 27.75 MPG this summer, and that will set the bar for more stuff next summer.

Dave, have you considered the idea that there might be carbon in the combustion chamber too? On the last legs of my bus, I looked for an additive to attempt to clean things up. Have tried a couple of things, but I have no specific results without physically taking things apart.

Might skew your results, per se. But, on the topic of experimenting...

When the old injectors were pulled, there was no visible carbon on the tips.

Answered. Thanks! You use additives regularly or just as it comes out of the pump?

About two months in, Dave, what's the next step? What are your thoughts?

I will be posting on test results shortly.

After 3,000 miles of testing my conclusion is:

They help, but not much. About 0.5 MPG improvement on a 26 MPG truck.

I'd recommend them if it is new for freshening up your injectors. MPG driving befuddles most tuners but I did work out a couple of decent ones.

Tell your tuner: More timing advance, less fuel, more ICP.

Tell your tuner: More timing advance, less fuel, more ICP.
Ok, so can you fool your manual transmission EOT and ICP a little more to work better?

I know the EOT on an automatic is linked to some things on the trans shift strategy, but I might not be completely correct.

Interesting thread. 26mpg is pretty dang good for an F350!

Isn't there a CPS that can get you a little advanced timing?
Who did the tuning?

This winter I'm hopping up the F250 with 190hp (single-shot) injectors, a D66 turbo and a TW chip. I want to get an economy setting on the chip. Allegedly, TW can set it up based on your configuration. I know my injectors are worn pretty good (245k miles). I need the power for towing, but want the economy when I'm not. I'm already using an Edge Evolution programmer, and can still get good FE on Stock or Extreme settings - it's all in the foot.

Swamp Donkey did my programming and the injectors. He did six different tunes. Three were undrivable.

Three were usable.
One was a fangs-out MPG tune. One was a lesser MPG tune. One was a regular permance tune with s shallower fuel ramp.

The fangs out tune was best but the perfomance (smoke screen) tune was second but I had to drive it entirely differently.With the MPG tune I upshift at 1200 RPM. Do that with the performance tune resulted in black smoke. Not good. But if I upshifted at 1700 RPM, no smoke and nice low EGTs.

The difference in the MPG tune and the performance tune was 0.3 MPG.