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Big Dave 07-24-2008 03:31 PM

Exploring A New Idea
 
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.

Lug_Nut 07-25-2008 04:28 AM

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.

GasSavers_SD26 07-25-2008 04:40 AM

Quote:

Originally Posted by Big Dave (Post 112481)
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.

GasSavers_SD26 07-25-2008 04:42 AM

Quote:

Originally Posted by Big Dave (Post 112481)
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.

Big Dave 07-27-2008 06:15 PM

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.

Big Dave 08-01-2008 05:07 PM

Going to Nashville the 11th for single-shots.

GasSavers_SD26 08-01-2008 05:17 PM

Quote:

Originally Posted by Big Dave (Post 113598)
Going to Nashville the 11th for single-shots.

Ok, who's doing the tuning? More info, more info!!!! $$$? (The scary stuff)

Big Dave 08-02-2008 11:57 AM

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.

GasSavers_SD26 08-02-2008 01:55 PM

Is the dribbling common with age?

:D

Or is it common to the split shots?

Big Dave 08-02-2008 06:12 PM

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


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