I was looking on ebay at some new injectors for a 6.5TD and was wandering if there is a difference in them troughout the production years of this engine. I have a 92 with a MIP and was going to rebuild mine but if there the same I,ll buy new and have a set to rebuild later. The new Delphi ones they have listed cost about the same as it would for me to rebuild mine.

The n/a injectors have lower opening pressures (1750 psi) and the turbo injectors are somewhat higher (2050 psi) iirc.

All GM injectors use a Zero degree spray angle. The pattern does not change with pressure increases. The Zero angle means it sprays straight out from the nozzle whereas some spray out at a slight angle, like an inverted cone.
The naturally aspirated engines pop at 126bar./1827 PSI.
The turbo injectors pop at 142bar/2060 PSI.

82 model only OSD248 nozzle 126 bar. (coarse thread)

Early 6.2's OSD248 nozzle 126 bar.

Short Body 6.2's OSD253 nozzle 126bar.

All 6.5's OSD304 nozzle 126bar. (turbo popped at 142 bar)

Marine 0SD311 nozzle

Higher pressure does not equate to more fuel.

More efficient combustion...most definately.

Correct - within design limits, higher injection pressure results in finer fuel atomization, which is easier to ignite, maintain and complete combustion

BTW - glad to see ya postin' agin, spin...................

JD...still don't know if I'm comin' or goin'. Workin' hard never felt so good.

If higher pressure results in more power and better economy how come GM didn't do it?

Sound levels for one thing. I'm sure pump life, hot starts etc also play a role.

I'd hafta say Inj Pump wear - S went to a 4-plunger IP to get less aggressive ramps, which give less roller\camring wear.

Not to mention timing chain loading - shoulda had timing gears.

Also not to mention injector wear.

Etc - but you already knew that stuff, right?

You was just seein' if I was dozin', right, DP?;)

Need to keep you people on your toes. Too many people going with the flow. Somebody has to ask the tough questions.

Like > How do you know if the pump is pumping 92mm/3? Has anybody ever ran a Hot ECM with the pump on a test stand? Hmmmm?

Like > So what your truck looks like it's dumping 92mm/3 but is it usable ?

Like > Any proof Hi-Pops give 40 more Hp. and better economy on a dyno?

Like > Where's the proof of a faster ramp on a 5068 pump? What's the specs?

Like > Where does DP come up with this stuff?

Got a feel for most of that, DP, but I'd sure liike to spend some time on a flow bench.

Had a chance to buy a shop, but they weren't set up for the DS\cousins series, so I foolishly passed.

kick butt

kick butt

kick butt

Ah, well..............

Like > So what your truck looks like it's dumping 92mm/3 but is it usable ?

Definately not usable at low RPM and still can't use it all when maxed out @ WOT smacking 20 PSI, but then again i'm hoping the IC will cure that or the new modified GM-8 turbo/IC combo will cure it.

You got to get a bigger turbo. Ever look down the neck of the turbo from the exhaust manifold side. The dam thing chokes up big time. There ain't enough room in there to get the exhaust out. Got to go way bigger.

hmmmmmm

With the EGBP i have my exhaust seems to be gettin out fine.

Still think your measurements are flawed someway. Need two Identical gauges matched. I even think your wastegate might be opening up slightly during your runs relieving the pressure. Wish you would try it again under better conditions and matched gauges and a wired shut wastegate. Hope I don't offend you, I just think somethings missing in your test.

Isn't the problem with a larger exhaust turbine more turbo lag? if its choking up that could mean your dumping more fuel than required. I have very little experience with the 6.5...but I've experimented lots with my 2.4 diesel and when you only have 80hp at the flywheel you notice every horse you make. My experience has been the smaller the exhaust side the quicker the boost, just bumping your max boost does not improve your off the line times or how quickly the boost builds, just your top end power. The smaller turbine outlet acts as a venturi speeding up the exhaust gasses, thus turning the impeller faster and giving it the power to compress the air on the compressor side of the turbo. I guess the other way around it is to get a bigger exhaust side and a much smaller compressor side, and again that can create other problems to overcome, as the smaller turbine may not be able to provide enough boost at higher RPMS. all that being said you still need the bigger exhaust piping to get the spent gasses away from the turbo.
Other things I have gathered from my "experiments"
The leaner the diesel settings (adjustable on bosch rotary type pumps) the cooler the EGT's, also you cannot lean out a diesel and hurt it (unlike a gas engine) you can destroy an engine if it is over fueled.
A richer fuel setting also increases your max boost.(if all you did was turn up the fuel)
The smaller turbo, on my Toyota spools faster, stock would build 7psi around 3000RPM the smaller turbo would make 7psi at 2000RPM (both were CT-20 Toyota Turbos one from a 2.4 Toyota Truck the other from a 1.9 Toyota Camry) . The smaller turbo will spool almost instantly as you breathe on the throttle where as the larger turbo would take 15-20 seconds to start to make boost.BTW the 2LT diesel is slow and has no power in it's stock set up.
Oh, yeah putting Amsoil Cetane boost in a Toyota or VW is like adding a 4 barrel to a 350 SBC
Sorry I got side tracked off the 6.5 topic
My 2 cents

My analogy of the turbo is like this. You have one of those old water nozzles on your water hose. When you twist it wide open you get a lot of water out of it but no velocity. You twist it tighter and tighter and eventualy the stream is going way out there but there ain't much water coming out. Same thing with the turbo. If the restriction gets to small the exhaust ain't going to get out. Moral to the story; If your going to twist it tight get two nozzles to fill the bucket.

Still think your measurements are flawed someway. Need two Identical gauges matched. I even think your wastegate might be opening up slightly during your runs relieving the pressure. Wish you would try it again under better conditions and matched gauges and a wired shut wastegate. Hope I don't offend you, I just think somethings missing in your test.

No offence taken.
As to having 2 matched gauges i've done that just not like your seeing it. I ran my oilfield gauge strickly hooked to EGBP only and made numerous runs with the boost gauge and scanner hooked up for my first comparison and posted those results. I then upon further request ran my boost gauge in place of the EGBP gauge and did it all over again with slightly differrent numbers but still very low EGBP and used the scanner for boost pressures. If the boost gauge and scanner isn't good enough when its right on with the scanner then why are we telling everyone to get gauges for boost pressures? Maybe we should tell em to get 2 boost gauges cause we can't trust just 1? I am 100% sure on the numbers posted for EGBP. You think my wastegate is leaking @ 15 PSI, wouldn't it be near impossible for me to get 21 PSI then? Like you said, i could wire the wastegate shut but don't think it necessary, i've run a video camera under my hood watching the WG arm on WOT runs, it never moved when i had it tightened down with the spring.
Hope I don't offend you either.
I would like to see someone else do these tests with similiar mods to compare results.

Sound levels for one thing. I'm sure pump life, hot starts etc also play a role.

You mean high pops are louder JK? More injector clatter?

Need some backpressure tests. Anyone up to it?

Requirements:

(1) Engine capable of lets say 16 PSI
(2) Need two matched gauges (around 50 psi gauges, 1lb. increments)
(3) Wire the wastegate closed
(4) Exhaust Pressure to be measured pre turbo
(5) Intake pressure pre Intercooler if applicable
(6) Low restriction exhaust system (no Cat or Stock Muffler)
(7) Good grade hill to obtain a steady pull for consistant reading
(8) Stock turbo

Someone please apply and let us know.

I have one problem with the criteria. I would do the EGBP test with my spring controlled unit not wired shut. Wired shut would increase the back pressure beyond my normal use and not yeild my as is numbers.

I'm set for 15psi at the upper intake plenum/18 psi pre IC.

I'm adding the dual springs to see if it will go further.

Good point QM, i've been told the EGBP is very high under NORMAL operating conditions with hi boost, not by trying to make it hi by wiring the WG shut.

Did TD wire his shut on his tests?

I am trying to eliminate wastegate opening and ruining the test. By using a road with a grade the operator can control boost with the throttle. Not trying to see how high the exhaust pressure will go, just trying to see the differential in pressure.

I loaded mine as much as i could, up hill without it shifting, really bogging it right at a shift point, that was the best i could do, did it in every gear. C'mon QM give us some more numbers!

You know i can't honestly remember if that was the old IP on it or new IP??? I think it was the new one?

I loaded mine as much as i could, up hill without it shifting, really bogging it right at a shift point, that was the best i could do, did it in every gear. C'mon QM give us some more numbers!

You know i can't honestly remember if that was the old IP on it or new IP??? I think it was the new one?

iirc CR it was the old one