Pondering what if's retro a franken commonrail to 6.5

[schiker]

I wonder if you could make a retro kit to common rail a 6.5 diesel.

What is the expensive part of injectors the nozzle ? IF the solenoid and open close mechanism could be made less expensive maybe you could do a distribution block and run a sort of 2 stage system to the dumb mechanical injectors.

Say reduce the common rail injector pump to the range of pressure a DS IP outputs then electronically mimic the DS IP output with the first stage solenoid switches.

Would the mechanical injectors care if the fuel pressure rise was faster? Would it increase performance with a more crisp spray start? The actual injection pressure wouldn't have to change drastically would it? Is the bleed off pressure the problem so the mechanical injector closes?

 

[schiker]

Maybe plumb a de-rated pressure common rail pump into the DS IP somehow into the plunger area and let one solenoid driven injector type switch mimic the plunger fuel delivery. Let the normal fuel solenoid do its thing dump remaining fuel pressure and Just maybe the rest of the system wouldn't really be the wiser. Just have to time the common rail switch to the cam ring somehow ???

 

[schiker]

OR do more modern diesel injector pumps not have the fuel delivery either? Just higher pressure and better atomization?

 

[ak diesel driver]

My limited understanding of CR pumps is that the IP is a constant high pressure and the injectors are electronically controlled.

 

[Will L.]

How do you time the injection event that way?

 

[THEFERMANATOR]

Common rail injectors by design need to run at fairly high pressures in order for them just function. You need in the 3000 psi range just to get them to really function at idle speeds. The ds4 design is about as good as you can get for an idi design. Without going to direct injection, there wouldn't be much advantage to changing the injection system other than adding more fuel.

 

[schiker]

Just pondering. I see retro fuel injection kits for gasoline and just wondering.

That was what I was thinking of adding more fuel. Maybe faster more adjustable timing than stepper motor. And or consistent pressure on the dumb injectors across the injection event.

That is my limited understanding too about constant pressure injector control injection.

Maybe could key off the optic sensor or something similar added geared off crank. Plumb the common rail pump into DS IP somehow and let everything down stream stay the same just not have the cam ring and plungers.

It would have to be solenoid that could switch as fast as the metering solenoid. It would be 8 times faster than a common rail injector wouldn't it. But they do some pretty fast switching with pilot and 3 spurts so maybe not but 2x as fast????

Don't know if our Fuel metering solenoid and injectors could withstand an instant on injection pulse or it needs the cam ring ramp up pressure. OR if the switching could dampen the instant on/off with something like a tapered seat ????

 

[Will L.]

I don't want to stop anyone from playing Frankenstein builder, it's fun to play and real advancements can come from it. But understand how big the fight is before you throw the first punch.

You can't compare the efi in gas systems because you can start pumping fuel into the cylinder from the time the time the exhaust valve closes up until the ignition event which is the spark plug firing. Thats nitromethane process- on the edge of hydrostatic lockup. But you have a spark plug to control when the burn starts.

Diesel starts at compression ignition point, so you don't have the control. That's why it's timed with the fuel getting sprayed into the cylinder after the compression ignition point is already achieved, you have to time the ignition. You can't run constant pressure to a "dumb injector". It will never open to let fuel in.

Volumetric Effencicy in TD engines are roughly figured at 3:1. But if you are running a big turbo or two, maybe higher compression, improved flow, etc you can push to 4:1. That means at peak your 400 psi you generate can be at 1,600 psi. so your opening pressure of the injector has to be above that to work at all. 6.5 probably peak in the 3.5:1 area.

If you run your pop tester in a pressurized chamber, you'll see your true injection pattern, much different than on the bench in open atmosphere. Keep that in mind when determining your numbers.

Sounds like you basically are looking for a larger IP. The electronics added to this base design IP was never intended as an improvement. It generates less power, not more. It it less fuel efficient, not more. The only reason the ds4 was created was to meet the obd2 regulations that said fuel volume and timing events must be able to be monitored by computer. Not better, just monitored. Keep in mind the Honda carburetor the rest of the world got to use on gas engines that had more power, efficiency, 1/2 less pollution. They fought to use it here and was shut down because there was no ability to monitor it by the gubmint kompuerz.

Any changes you make to the system would be shot down by emissions standards anyways, so just switch to a big db2. You can go to twin IP set up. Gm in its place and the ford in front for the reverse rotation. The Ford needs to feed the factory injectors because it can push more fuel, and the GM IP pushes it's fuel through the smaller tipped stream injector that spray through the glow plug holes.

Really with the fuel you can run a fully built db2 and use of propane as supplement fuel and nitrous so you can burn it all in time before the exhaust valve gets too far open. Just start with a very stoutly reinforced bottom end.


Here is another option. The old fords HEUI don't get all there pressure from the ip, the engine uses a secondary oil pump to amplify the pressure in the injector. If you switch to those injectors, run a common rail fuel pump to bring them the diesel set at a pressure below pop pressure, then use the ds4 or db2 to pump oil to the injectors oil inlet, timed so the oil increased pressure causes the injection event when you need it, Maybe.

How much more fuel can the HEUI injectors move in the same amount of time? Engine oil aerates way worse than diesel fuel so that will mess with the IP contoroling the timing. Another can of worms.

You can come up with a system to do it, Infact many ways to do it- 8 linear fuel pump instead of 1 rotory and feed cps signal to control timing of them.

Look into some of the IP used in big rigs, you'll find a couple that are adaptable.

My question is -Why? There are pump builders that can get more out of a db2 than an 7.5 or 8 liter engine can swallow. The $ you spend doing it is easier spent on known technology to get enough power to blow up any 6.5 including the p400.

Heavily built db2 will still last 200,000 miles.

 

[Big T]

I don't want to stop anyone from playing Frankenstein builder, it's fun to play and real advancements can come from it. But understand how big the fight is before you throw the first punch.

You can't compare the efi in gas systems because you can start pumping fuel into the cylinder from the time the time the exhaust valve closes up until the ignition event which is the spark plug firing. Thats nitromethane process- on the edge of hydrostatic lockup. But you have a spark plug to control when the burn starts.

Diesel starts at compression ignition point, so you don't have the control. That's why it's timed with the fuel getting sprayed into the cylinder after the compression ignition point is already achieved, you have to time the ignition. You can't run constant pressure to a "dumb injector". It will never open to let fuel in.

Volumetric Effencicy in TD engines are roughly figured at 3:1. But if you are running a big turbo or two, maybe higher compression, improved flow, etc you can push to 4:1. That means at peak your 400 psi you generate can be at 1,600 psi. so your opening pressure of the injector has to be above that to work at all. 6.5 probably peak in the 3.5:1 area.

If you run your pop tester in a pressurized chamber, you'll see your true injection pattern, much different than on the bench in open atmosphere. Keep that in mind when determining your numbers.

Sounds like you basically are looking for a larger IP. The electronics added to this base design IP was never intended as an improvement. It generates less power, not more. It it less fuel efficient, not more. The only reason the ds4 was created was to meet the obd2 regulations that said fuel volume and timing events must be able to be monitored by computer. Not better, just monitored. Keep in mind the Honda carburetor the rest of the world got to use on gas engines that had more power, efficiency, 1/2 less pollution. They fought to use it here and was shut down because there was no ability to monitor it by the gubmint kompuerz.

Any changes you make to the system would be shot down by emissions standards anyways, so just switch to a big db2. You can go to twin IP set up. Gm in its place and the ford in front for the reverse rotation. The Ford needs to feed the factory injectors because it can push more fuel, and the GM IP pushes it's fuel through the smaller tipped stream injector that spray through the glow plug holes.

Really with the fuel you can run a fully built db2 and use of propane as supplement fuel and nitrous so you can burn it all in time before the exhaust valve gets too far open. Just start with a very stoutly reinforced bottom end.


Here is another option. The old fords HEUI don't get all there pressure from the ip, the engine uses a secondary oil pump to amplify the pressure in the injector. If you switch to those injectors, run a common rail fuel pump to bring them the diesel set at a pressure below pop pressure, then use the ds4 or db2 to pump oil to the injectors oil inlet, timed so the oil increased pressure causes the injection event when you need it, Maybe.

How much more fuel can the HEUI injectors move in the same amount of time? Engine oil aerates way worse than diesel fuel so that will mess with the IP contoroling the timing. Another can of worms.

You can come up with a system to do it, Infact many ways to do it- 8 linear fuel pump instead of 1 rotory and feed cps signal to control timing of them.

Look into some of the IP used in big rigs, you'll find a couple that are adaptable.

My question is -Why? There are pump builders that can get more out of a db2 than an 7.5 or 8 liter engine can swallow. The $ you spend doing it is easier spent on known technology to get enough power to blow up any 6.5 including the p400.

Heavily built db2 will still last 200,000 miles.

I'm with Will on this. If you want a common rail engine, then buy one that started life that way, or swap one in like TheFermanator did. Even Ferm has gone on record that he would not swap another Duramax into a GMT 400 Suburban.

The 6.5 is a relatively simple and cheap diesel. It can be made to perform better, but within its design limits. Beyond the limits and they self deatruct.

 

[schiker]

Just Pondering. I don't mean like a gasser just the kits are $$$$. Just thinking this might could be done something like this.

Plumb a common rail pump into rotor with the plunger ports plugged and take out the shoes and cam followers. The common rail pump would have to be de-rated to max DS IP outlet pressure high enough to fire the dumb injector but at constant pressure wouldn't they pop open and spray similar to normal? Trigger a solenoid valve with the optic sensor to have the common rail pump feed the rotor at appropriate time just like the cam ring pumps the plunger. Stop injecting as commanded and FSD would open meter valve just like normal dumping excessive line pressure 6.5 injectors shut and repeat. Most of the original system might could remain the same just piggy back on it sort of.

Benefits would be timing might could adjust near real time with RPM and don't know if constant high pressure on the mechanical injector might help ?

 

[Will L.]

Go grab a cp3 and ds4 from the junkyard and give it a whirl.