Performance 6.5 Injectors

[More Power]

There are a multitude of reworked injectors for the Duramax, Powerstroke & Cummins diesels. The hi-flow nozzles are usually the result of extrude-honing to increase fuel-rate (fuel passages are increased in size). The developers can show the flow rates for stock and their performance injectors. The current Duramax, Power Stroke & Cummins all use some form of high pressure common rail fuel injection systems. Common rail systems can push huge volumes of fuel through modified injectors.

The electronic 6.5's Stanadyne DS4 rotary fuel injection pump is limited in the amount of fuel it can deliver because of a finite volume in each of its four pumping plungers. Opening the nozzles beyond a certain point won't deliver more fuel because of this finite limit.

Hi-pop 6.5 injectors use higher-rate internal springs or additional shims to increase spring rate. This increases the "pop" pressure, which is the fuel pressure at which the nozzle begins an injection cycle. Higher pop pressure may improve atomization and combustion efficiency. Hi-pops may work fine when used with a healthy fuel injection pump, but they could also contribute to poorer starts or no starts, especially on a warm/hot engine if the injection pump is too worn. This is because an aging fuel injection pump might not be able to generate the fuel pressure it must to "pop" the injector at a typical 180-200 rpm cranking speed.

Many stock 6.5TD's dyno at about 160 rear wheel horsepower. I've been present at dozens of dyno events where, through the years, hundreds of 6.5L diesel powered trucks and Suburbans were dyno'ed. I absolutely know what they are capable of. Here is a series of questions that you should ask any vendor who wants to sell you a set of non-stock "performance" injectors for your 6.5L diesel.

1- What exactly is a 40 hp 6.5 injector?
2- Would they produce a 25% gain in horsepower from just a simple injector swap?
3- How are they different from a stock injector?
4- What is the flow rate for a stock injector, and what is the flow rate for a "performance" injector?
5- Does modifying the 6.5 injectors for additional fuel flow affect fuel economy or cold/hot startability?
6- Are there any dyno graphs - anywhere, that show a performance gain when comparing new stock injectors to new performance injectors?

Let me know if anyone knows the answers to these questions.

Maybe we need to do a product review. I now have access to a local Mustang chassis dyno...

Jim

[gmctd]

That would be interesting to compare a hi-mileage DS4 against a new or rebuilt version, both with standard injectors, then with hi-pop hi-flows, while connected to a scanner to catch the differences in idle rpm and timing.

Most of what we do is recognizeable by the PCM, which can compensate, accordingly.

PCM has no way of recognizing changes in injector pressure or volume - this is easily seen at idle, where PCM manages idle rpm on a per-cylinder basis.

So - what's it all about, alfalfa?

It would be some interesting tests.

[JeepSJ]

Yeah, I saw that post regarding the 40hp injectors and thought the same thing. Would it not be possible to put the 6.5 injectors through the same process to increase their flow?

[grape]

the volume comes from the stroke of the pump.........period. the larger nozzle decreases dwell time and makes the combustion and injection time "quicker" in crank degrees. So as to not be peeing fuel in while the piston is already way to far down to do any good............other than smoke and egt.

i doubt you'd see any power diff on the same engine.

[gmctd]

Except that the stronger spring delays injection while the pump is still building pressure to 'pop' that spring.

The volume between 1700psi and 2200psi is then lost - PCM doesn't know about that and doesn't compensate with the Fuel Solenoid - it is a fixed beginning\variable ending injection system.

Beginning of injection event, PCM closes FS, rollers are rising on the ramp, plungers are pumping their specific volume against the closed injector, building pressure.

At 1700psi inj pressure, injected volume is from that point on the ramp until PCM opens the FS at some point further up the ramp, ending injection.

At 2200psi, the rollers are further up the ramp when injection begins, but PCM still opens the FS at the same point further up the ramp.

PCM can attempt to correct for that at idle with the Cylinder Balance routines, but that's only at idle, used to maintain idle rpm in Neutral, Drive, A\C on or off or cycling, headlites on or off, anything that varies the load on the engine.

Even at that, hi-pop hi-flow injectors do not idle as smoothly as the standard versions, nor is idle speed stable, and can vary by 100rpm low.

Those Cyl Bal routines are not used off-idle.

The Injection Fuel Rate seen on the scanner is not measured - it is calculated, based on conditions with oem standard lo-pop injectors, spec'ed by engineering to ensure the camring and rollers would survive thru the warranty period, while still giving adequate spray pattern for economy.

'Course - I'm talking EFI DS4, you're talking mechanical injection DB2.....period.......and, as we all know, turning up the fuel on the DB2 effects the fuel rate from idle to full throttle, right?

That's why I would like to see dyno results compared to scanned data.

[Robyn]

I have talked to mark at Diesel fuel injection service in Portland about just such things.
His comments have been that these fancy injectors are real good for making more power in the sellers wallet.

I think its a gimic.
The DB2 Or DS4 was designed to run at a certain pressure and be able to deliver a pre determined amount of fuel as its max capacity and to have nozzles that are designed to work with these pressures and volumes.

I somehow think that maybe there are still folks out there that are trying to relate the nozzles of the 6.2/6.5 to the old "Injectors" of the 2 stroke detroits where they were the nozzle and the pump all wrapped into one.

We were always bumping the injector size on our little 318 Detroits a couple sizes to get a few more ponies, and usually a ton of black smoke in the process.

The little 6V71 I had in my first bus was set up with "city injectors" and IIRC it was rated at 260HPThe thing ran clean and got about 10 MPG on the road at 55mph at max governed speed of 2100 RPM.
Little Detroits were a happy little camper if you let them run at 2100 all day long.

Yup I think these so called performance injectors, at least considering how they are being marketed are just a waste of $$$$.
I will stick with locally rebuilt units that are set up to book spec for the engine.

I always ask Mark to be sure any he does for me are all to the top of the spec for POP pressure and that they dont vary much.
I am a firmy convinced that having the injectors matched closely is a good idea for engine durability.

If one or two are on the low end of the scale and the rest are scattered out with one on the high end it will IMHO make for a rougher running engine especially at idle.

Having the injectors all at the top of there spec does aid in good cold starts.
The spray is finer and easier to ignite.

If you could get some of these 40HP injectors it might be interesting to do some HP and mileage tests for sure..

Sounds like some of the goodies JC Whitney used to sell, maybe they still do.

Robyn

[6.5 Detroit Diesel]

I have the 40 HP Marine Perfomance Injectors from SS. Are you saying that they won't produce any more power than stock even after the pump (DB2) has been turned up? Even if not, buying this set was cheaper than buying stock one's locally.

[gmctd]

Those are marine injectors, designed for the 'marine' DB2 on marine engines - set up to push a big twin-engined cruiser for long hi-speed hauls across the bay.

They're known to make power with the DB2, but what about the DS4 - that is the question the dyno can answer.

[ronniejoe]

The HP claims from SS Diesel are just that...claims. They're bogus straight down the line.

[dieseldummy]

All I can say is that I just built a set of injectors with "marine" nozzels and the do make a difference. I have been running stock 6.2 injectors though... While they may not have netted 40 HP, they have added some more go to my old ride. I set them up with stock pop pressure and the pattern is just fine. I figure no need to add stress to an old injection pump...

[grape]

maybe we could have peninsular dyno a set with their home made fuel flow meter and live and die by their results................yeah i said it

[6.5 Detroit Diesel]

So RJ. Are you saying that SS Diesel saying that 40 HP can be gained with the injectors is a lie? Just curious why you would come out saying that it is bogus.

[ronniejoe]

He sells a chip that he advertises as an 80 hp increase. He sells injectors that claim 40 hp increase.

I seriously doubt that there is any dynamometer data to support those claims. I know by experience that one cannot add 80 hp to a 6.5 simply by changing the chip. At the very least, they are inflated marketing hype. To me, that is lying. To others, that is good advertising.

In my opinion, if one is to make a claim of adding a certain magnitude of power, one should have some data to support the claim and be willing to present it.

[Shikaroka]

I have been looking into adding a Dyno to my shop for a while now. I almost bought a used DynoJet a few months ago, and I wish I had. Someday I will have one, hopefully soon.
Once I have a dyno at my disposal, I will certainly do lots of back-to-back tests and research.

[gmctd]

Yeah - I keep waitin' for one of 'em to drop within my price range - easier to prove the stuff someone wants to install, on the rollers.

[grape]

dynojets are cheap, but you get what you pay for...........i know where there is one setting on the west side of houston lol.

[AndyL]

I'm no expert, but I still argue high flows on piston/positive displacement/syringe type injection pump are completely worthless!

Fill a syringe with 50mm3, when the plunger goes down, it doesn't matter how big the opening is, only 50mm3 is gonna come out!

[gmctd]

Can help at hi-rpm, where the injection window is narrow - re-read post #4

[dieseldummy]

I'm no expert, but I still argue high flows on piston/positive displacement/syringe type injection pump are completely worthless!

Fill a syringe with 50mm3, when the plunger goes down, it doesn't matter how big the opening is, only 50mm3 is gonna come out!

I used to think the same way you do, but have since changed my point of view. The before and after difference with "marine" nozzels is enough for me to recomend them to others. Are they worth the $550 most people charge? No IMO. If you think about it you will realize that the syringe analogy you used is only partial accurate. The thing you left out is what size of needle is on the end of the syringe. A 14ga needle will allow the syringe to be emptied faster than a 18ga needle. The marine nozzels are like the 14ga needle in the sense that they allow fuel to flow faster. The stock nozzels would be like a smaller gauge of needle. Just something to chew on...

[Kennedy]

Most of these so called 40HP injector claims are from people who have never tested them. This is why they have cheap injectors and claim numbers to sell product. I can say for a fact that the high flow/high pop injectors sold by Kennedy Diesel WILL deliver just shy of 10% increase in fuel delivery and are TRUE high pop. They were tested against a stock injector.

My best guess is 20-25HP max. I believe RJ makes 180RWHP where we typically see a stock 6.5 that is tuned well (exhaust etc) run about 150 RWHP. I have not done a back to back dyno test. I'll also add that in order to make power from this fuel there may be a need to increase boost.



P.S. Some people's ideas of high pop are not the same as others...