Performance 6.5 Injectors [Archive] - TheDieselPage.com Forums

More Power

03-10-2007, 16:58

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

03-10-2007, 17:35

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

03-10-2007, 21:58

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

03-11-2007, 11:51

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

03-11-2007, 11:54

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

03-11-2007, 12:20

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

03-11-2007, 13:46

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

03-11-2007, 14:56

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

03-11-2007, 15:25

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

dieseldummy

03-11-2007, 18:39

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

03-11-2007, 20:32

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

03-11-2007, 22:57

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

03-12-2007, 05:16

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

03-12-2007, 08:13

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

03-12-2007, 08:23

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

03-12-2007, 10:13

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

03-12-2007, 10:46

gmctd

03-12-2007, 11:05

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

dieseldummy

03-12-2007, 12:35

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! :D

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

03-12-2007, 14:20

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...

Robyn

03-12-2007, 14:47

I agree with RJ and JK

Its a real bummer for the unknowing folks out there to get hoodwinked into buying this crap.

Any dyno that will test rear wheel power can surely be used to do comparisons.
Even if the dyno is not completely accurate at least you can tell if you added anything with whatever you did in the way of mods.

I have used both engine and chassis dyno's and the chassis dyno sure tells the story as far as seat of the pants usable HP.

Back in my boat racing days we used an engine dyno a lot to do testing on different combinations of engine setups.

We also ran all of our engines on the dyno to break them in and check for any issues prior to installing in the boat.

Was a far better way than having to haul the boat to the river and fight all the fools while we made a few passes.

Well I am going to stick with locally rebuilt injectors and pumps.

I have never had any issues with the local rebuilder I use. I think if folks stay with dependable local rebuilders or the fine folks that advertise here they will do fine.

Ebay and other online outlets are full of stuff that looks and sounds great BUUUUUUUUUTTTTTTT!!! Buyer Be Ware

I can see where under very high output that the special marine injectors will definately be advantagous to get the fuel in within the optimal burn window.

I also dont see any reason for selecting these for a pickup application no matter what the use. (Performance marine)

Just my 2 cents worth

Robyn

AndyL

03-12-2007, 15:30

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

The injection "speed" is determined by piston/plunger speed, correct? Unless the factory nozzles are so small mechanical twist, IP line expansion occures, etc I do no believe dwell is a factor either.

IMO Dyno testing is not reliable enough to test for this as well. I've never once seen any dyno within 20HP on the same config. Have no idea which Dynos these are, just crowd pleasers at IRP.

Volume testing/measuring is the only way to be sure.

More Power

03-12-2007, 15:42

Good thread! :D I would not, however, go so far as to call someone a liar without reliable and verified dyno data in hand - even then I would give the claim maker some percent of leeway due to a difference in dynos and powertrains. I'd prefer to let the data speak for itself. Till then, I can ask questions... ;)

Jim

gmctd

03-12-2007, 17:44

I think if they want to advertise specific increase, they should at least list the associated improvements required for the product to be effective.

That's correct, Andy - but you generally don't put the marine injectors on a truck yer granny drives up to wally-world to get her hadacol flask refilled.

You would be trying to get the last ounce of performance out of a truck with 18:1's, -4911 cranked to the hilt, 4" exhaust, HX35 or so, and etc, where you would be pulling thru the upper rpm range, and the narrow injection window would benefit from the reduced delay of the hi-flows.

And, the increased injection pressure would produce finer mist, reducing the size of the sprayed fuel globules, decreasing the time to complete combustion

The 'marines' are good for hi-performance in the upper rpm ranges - what do they do for a truck that's used for towing, or the truck you drive to work every day, trying to get better fuel mileage.

The finer spray-mist would certainly help fuel economy - would also help to make more power.

How effective are they with indirect injection?

I'd like to see some data on that - particularly on the EFI system that's been 'hot-chipped'

AndyL

03-12-2007, 17:53

That's correct, Andy - but you generally don't put the marine injectors on a truck yer granny drives up to wally-world to get her hadacol flask refilled.

You would be trying to get the last ounce of performance out of a truck with 18:1's, -4911 cranked to the hilt, 4" exhaust, HX35 or so, and etc, where you would be pulling thru the upper rpm range, and the narrow injection window would benefit from the reduced delay of the hi-flows.

So, in your opinion, high flows offer no realistic gains in a stock 6.5 with say less than 80mm3?

GMCTD, thoughts on the correct testing method to dis/prove their worth?

gmctd

03-12-2007, 19:02

That's correct - only thing they seem to do for a stock truck is mess with the idle - and, again, I'm talking DS4 with hi-pop\hi-flow injectors.

Hi-pops, with or without hi-flow nozzles, do create finer spray-mist, which is good for combustion - hi-flow is not needed for street-use, meaning a work-about play-about truck.

But hi-pops are hard on the camring and rollers - ceramic rollers won't cure that, even with hi-lubricity fuel.

I'd like to see the tests run with the Tech2\equiv, maybe carcode, autoengineuity, wester's, etc, scanner set to monitor Des\Meas Timing, Fuel Rate, FI pulse width, Fuel Temperature, for each run.

Tests run with +3.5deg Base Timing and -0.5deg TDCO, then with +8.5deg BT and -1.94deg TDCO on stock injectors first, then on the marine versions
Or, at least, injectors matched to the lower limit - what is it, 1785psi? - and matched to the high limit - 2215psi? - whatever the lo-pop and the hi-pops are now considered to be.

Same thing with the reflashes.

(that's prolly pushin' the wish-list a little too far, but how else will you dis\prove the claims?)

Stock flash\timing\injectors, then hi-pops, then hi-pop\hi-flows, then the reflash\-1.94 timing with stock, then the hi-pops, then the h-p\h-f injectors.

AndyL

03-12-2007, 19:31

Opinions on dyno repeatability?

We need to recruit a Stanadyne shop and a few CC cups.

sidehackbob

03-12-2007, 20:34

Please allow me to flaunt my ignorance..

Why not use "6.2 low pops" to get the full fuel load out of the mech 6.5 pump,
It could be timed to begin the squirt at the right time right?
sounds awful easy to get "more flow"

gmctd

03-12-2007, 21:53

My answer to that would be that you would lose a valuable component of the spray 'pattern'.

The higher injection pressure creates finer spray, results in better burn, which results in increased power

More flow would not benefit if any of it failed to ignite and fully combust - that is the problem with mechanically injected Diesel engines at upper rpm ranges

Far as dyno repeatabilty, the same operator on the same dyno, each test run where the ambient temperature remained the same cool 60deg all day, stable humidity, blower in front of the charge-air cooler to maintain constant IAT for each test, in-tank fuel temperature maintained at close to ambient so in-pump fuel temperature would reflect the actual work the pump was doing with the different injectors, driving tire tread temps would remain stable with the cool ambients, drive-train temps could be stabilized for all the tests - I think the tests would be reliable for baseline.

Those factors varying from cool in the morning for the first test, to drivetrain and tires and rollers smoking for the last tests in the heat of the day would throw the tests off

DA BIG ONE

03-12-2007, 23:04

Would a higher pressure lift pump benefit IP and injector performance on the 6.5td, or?

gmctd

03-12-2007, 23:33

There has been some discussion that turning up the housing pressure in the DS4 will result in crisper injection pressure events - it presently runs from 25psi at low rpm to over 125psi at hi rpm.

Excess fuel is returned to the tank.

One thing that must be remembered when considering upgrading the lift pump - Diesel fuel foams, easily - warm Diesel fuel foams very easily.

More warm fuel returned to the tank will further aerate the fuel, causing even more problems at low fuel levels in warm weather - DTC35\equiv, injection pulse width too short - usually results from bubbles in the fuel.

Higher pressure pumps are also usualy higher volume pumps - the replacement solenoid-type flow-thru pumps like the oem version on your truck are produced in several ranges up to 14psi and 35gph, and those are designed to shut off when they reach spec'ed pressure.

They are direct replacement, and IIRC, Bill and JK both offer a version for high performance - and, they are flow-thru if they die, which won't leave you totally stranded.

The ideal would be to maintain ~5psi at full throttle when 'hot-chipped' or 'hot-flashed' - we're doing some experimenting with inlet\outlet diameters in the fuel cannister and DS4 inlet, with the upgraded solenoid pumps, to enable more volume at the lower pressures, while maintaining the pressures.

Upgrading the EFI 6.5 Diesel fuel supply system is not quite as easy as with a gasser

Increasing supply pressure on the DB2 must also be managed, as increased housing pressure severely effects the advance system

Kennedy

03-13-2007, 08:29

I ran my 96 with std programming HF/HP injectors, my boost control and intercooler and got excellent results.

Unfortunately this was before my dyno. I feel that the HF/HP injectors and a good healthy increase in boost is a VERY good recipe for power/performance and there is no idle issue whatsoever. I'm not sure where this came from...

AndyL

03-13-2007, 08:34

JK, any comments on the repeatibility of Dyno testing? Within the resolution of injector testing?

Shikaroka

03-13-2007, 12:04

It doesn't really matter how "accurate" a dyno is, as long as it's consistant and you use the same machine each time.
I think it would be very difficult to do back to back tests comparing injectors. It takes a good bit of time to change them out and chances are, some other variables are going to change as well. It may not be that important and it may still give you a good idea of the performance value, just don't take the numbers to the bank.

robertb6963

03-13-2007, 17:58

So you folks are saying you can't get 40hp out of these injectors, btw I'm ordering the 40hp injectors from SS next week (cheaper than stock).

Then how does Bully Dog sell ..............240HP injectors..........................?
(For Cummins that is.)

Its a thinker!!!!

6.5 Detroit Diesel

03-13-2007, 19:01

robertb6963 So you folks are saying you can't get 40hp out of these injectors, btw I'm ordering the 40hp injectors from SS next week (cheaper than stock).

Then how does Bully Dog sell ..............240HP injectors..........................?
(For Cummins that is.)

Its a thinker!!!!

This is what I have been wondering too. Like I said, even IF the injectors aren't able to give more power, they are cheaper than stock ones and over 15,000 kms later, still no troubles.

gmctd

03-13-2007, 20:09

No - the problem is, if you installed those injectors in a showroom stock Cummins, you would not get 240 more HP - takes a few other tweaks to get there.

That would appear to be a big rip-off to the uninitiated forum-illiterate newbie owner who'd just plunked down the bucks and poked them into his new truck - based on that advertised claim.

robertb6963

03-13-2007, 20:42

I know what you mean, if you mean people should know to do other upgrades before adding injectors (intake, ext, pyro, chip, etc). I always thought injectors were a great way to add lots of power, am I wrong? Do they add just a little? Because 240HP is kinda silly I think.

gmctd

03-13-2007, 21:27

Now you know why MP started this thread - who's got the deep skinny on this stuff, or can we duplicate it?

rtphillips370

03-23-2007, 23:30

Dam, I wish I saw this thread a bit sooner...

I just bought these from US Diesel for my 1999 6.5TD:

[(8) 6.5L Performance Injectors +30-40hp / 94-00
# 1040166B
Your Price: $499.00

1993-00 6.5L Turbo Diesel Performance Injector Set (8) +30-40hp, +60 lb ft torque
[ More info ] [ See more like this ] ]

I take it this is the sort of items / claims that are being discussed here? I have yet to have them installed as I am waiting for my Kennedy Intercooler to arrive to go along with these injectors, I also purchased the KD turbo controller and a 4" exhaust from JCW and new injector lines (OEM replacements). I was hoping these items would significantly increase performance of my 6.5TD, but now i am beginning to wonder... almost concerned to the point that I may have been one of those fooled by the '+30-40hp' claim.

I hope I am wrong and it all works out in the end, but i wont know till it is all installed in April sometime by my mechanic.

ronniejoe

03-23-2007, 23:37

You will see improved performance from the items that you mentioned. The sum total might approach 40 hp gain.

The fact is, it takes a system approach to make power with the 6.5... Power that won't go away on a hot day at high altitude. Sometimes, big power can be made for a very short time, but cannot be sustained for 200 miles of trailer towing. The heat management issue must be dealt with to sustain increased performance.

rtphillips370

03-24-2007, 00:25

The fact is, it takes a system approach to make power with the 6.5...

I hope I have put togther a 'system' orientated improvement for sustained trailer towing. The next item next year will be a new computer, i was looking at the plug and play offered at US Diesel for $575 but now I am not so sure and will definately do more research on it before making any more investments such as this.

ronniejoe

03-24-2007, 07:05

For a good perspective on how to do this (there are variations and other ways), read the series of articles in my signature (if you haven't already).

I just noticed that the articles have been taken down from the website. They are available in book form here (http://www.thedieselpage.com/65bookii.htm).

Robyn

03-24-2007, 08:55

I agree with the idea that to make sustainable performance with the 6.2/6.5 engine family one must use a package plan that includes

Good base engine buildup
Properly modified pistons
Heads that have been reworked to beef up the weak issues
A completely reworked fuel system.
Aftercooler is a must
A good free flowing performance exhaust system
Special attention paid to the cooling system to insure the ability to get rid of the extra heat.
Possibly a look at the vehicles gearing so the combination will be optimal.

To sum it up I think that many of the companies that advertise the goody yum items that supposedly add X amount of power are simply preying on the buying public and interested only in the $$$ they can reap rather than building a business built on honesty and trust.

Its easy to advertise wonderful numbers and there is always a certain percentaqe of folks that will rise to the bait and buy the product.
In the end however the customer is unhappy and feels that he/she has been ripped off resulting in the industry as a whole getting an eye of suspicion cast upon it.

In my business I try hard to go the extra mile and give the customer their monies worth and only advertise that which I can realistically deliver.

Its too bad we have people that dont have this work ethic.

The company that makes the aftermarket PMD replacement (I wont mention any names) has failed to live up to their claims and now does not return any phone calls.

Far too much of this stuff goes on.

It will all come out in the wash.

later

Robyn

simon

03-25-2007, 16:49

I posted a question a month ago about pop pressure and got no bite on that one.
Since than I learned from the fellow i got new standard nozzles from that the pop pressure for my 95 6.5 was 2200 psi, so i set them accordingly.
Is this right or wrong??

The truck runs fine at idle as well as full load.

On a couple of 6.2's I have the injectors are set at 1700 psi, wich the manual calls for.

So I will ask again what pressure is hy pop supposed to be ???

AndyL

03-25-2007, 16:55

Standard 6.5 Turbo pop, ~1900 psi, high pop = ~2100.

Robyn

03-25-2007, 21:47

My feeling on the Hi POP units is that unless you are starting life off with a specially set up high output pump thats set on kill I would stick with the standard pressure injectors.

Hi pop will give a slightly better/finer spray mist rersulting in a better burn "maybe"

I also wonder what this is going to do over time to the IP when working things harder to produce the higher pressures.

I stuck a set of squirts in a 6.2 that I had purchased from a shop that I had not dealt with before and they had set them to 6.5 pressures.
The little diesel rat rattled really good.
On a cold morning it sounded like an unhappy powerstroke.
OH YEAH Buddy.
Never had any issues with it though

simon

03-26-2007, 21:50

rtphillips370

05-08-2007, 01:35

Well last week I installed a 4" exhaust from JC Whitney and could definitely feel and hear the difference. The power increase although mostly likely modest is definitely noticeable. My Kennedy inter-cooler arrived this morning...

So i look forward with earnest to see how well it turns out with the cooler and installing new injectors, moving the FSD to an external mount and adding the boost controller. Thanks for the input, ill keep ya posted...

simon

05-15-2007, 22:55

Well I gues I did set Mine a tad high at 2200 psi.

Well that's to bad, I aint gonna peel them back out.

The wife says the truck is climbing the hills like a raped ape sinds i changed the nozzles, we'll see how the pump is gonna last, it is in there for at least 180000 km.

My Wife put over 6000 km on the 2200 psi nozzles since i installed them.

The engine starts and runs better than ever before.

One wiff of smoke the moment she fires, then no smoke at all.

verry crispy acceleration, lots of power, and it used only 1 ltr oil in those 6000 km. mind you i vented the CDR to the outside.

Total km on the truck 313400.

I am a happy man

Hubert

09-04-2007, 19:15

AndyL

09-04-2007, 19:28

Couldn't find a spec, but I'd bet that is a common rail setup.......

Hubert

09-04-2007, 19:33

That looks to me the bigger nozzle equals faster combustion ie penetration rate which matches the "marine" steady higher rpm operation. I don't know what the system is just thought it was pretty interesting.

JeepSJ

09-06-2007, 16:17

Check this out

It appears all else being the same a larger nozzle will create a larger "flame" or more penetration is what it actually references. Maybe better overall combustion with higher fuel rates or better heat distribution into cylinder? Don't know if anything is measurable as far as power/performance but the image appears like there is a difference.

I hope this link works because I doubt I could find it again.

http://public.ca.sandia.gov/ecn/orifice.php

That is a very cool link. It is interesting to see the difference in the spray/flame pattern at different temperature and pressure and nozzle size. Based on that, I'd say that bigger nozzles and higher pressure are a good thing as you increase boost. The higher cylinder pressure has a significant affect on the spray pattern and penetration, and the bigger nozzle with higher pressure would compensate (at least partially) for that.

AndyL

09-06-2007, 16:30

JeepSJ

09-06-2007, 23:42

136Mpa = 20,000PSI, defiantly common rail. For the 6.5 application I don't believe comparing a 2000psi injection event to a 20,000psi is apples to apples. But then again I can't find my Fluid Dynamics degree laying around either!!

I was hoping for some evidence against the mythical "Performance High flow Injectors."

We are not comparing 2000 to 20000 here. All this is showing is that with an increase in fuel pressure there is an increase in flame penetration into the chamber.

Hubert

09-07-2007, 06:23

I thought the link was pretty good and does support at least a little credibility for different injectors for the "marine" application. 6.5 pressures are a lot lower and IDI is a different animal but I think the link does show fair comparison for nozzle size. It references penetration rate of fuel and flame front into cylinder. I did not see any documentation of any power differences but does show there is a difference in spray pattern/combustion to nozzle size.
It has always struck me that marine injectors/nozzles are OE name brand parts at least from all the reading I think they are OE for marine applications. We are not talking some joe injector shop marketing his modified injector. Is the HP rating of marine engines higher? I have assumed they are and thought the pump was turned up and engine set for more HP since adequate cooling could be guaranteed with the application. Combined with the fact economy is less of a concern with recreational applications and emission requirements are different too.

Like posted earlier several times it does not make sense to me that just changing injectors will give any appreciable HP gain. But after viewing link I think it can definately be argued injector differences can be matched for application ie I think marine injectors are better for steady hi RPM operation and or maybe higher fuel delivery. And then maybe not necessairly for anything other than better emissions. HP gains are probably due to IP fuel delivery increase only.

stacker

09-11-2007, 19:25

TurboDiverArt

09-14-2007, 13:08

Hay guys now where do i start i just bought a 93 3500 dually with 6.5 td whats the first step to helping her pull a 28 ft 5th wheel weighing around 9k and will i be disappointed in comparison to my 454 gmc. Like to keep it simple powerful and reliable. thanks

In In my opinion, upgraded cooling system (I think yours has the old single thermostat setup), intercooler and good free flowing air cleaner. Once the intercooler is on you cam make yourself a boost fooler so you don't throw a code when you turn up the boost some. I'd raise it form the stock 8-psi to 12-14 once intercooler. A better exhaust with downpipe always helps.

With the above it should be comparable towing wise to your 454 but get better gas mileage.

Art.

93GMCSierra

09-14-2007, 20:17

DmaxMaverick

09-14-2007, 20:23

I am sorry if this has been answered before, however I have a 93 6.5 td an I was looking at the turbo, it is a GM-3 and there does not seem to be a wastegate on it. it looks like a rod with a spring holds a butterfly valve closed when the exhaust pressure gets enough it forces the valve open.
If that is correct How could you increase the boost?

Welcome to the Forums!

That thing you described is the wastegate. It's just mechanically controlled. Increase the boost by increasing the spring tension. By whatever means. Be careful, there is a point of no return (meltdown). I would not recommend adjusting it w/o gages. EGT, at least to keep from getting too hot, and a boost gage to see the results of adjustment.

93GMCSierra

09-14-2007, 22:00

Welcome to the Forums!

That thing you described is the wastegate. It's just mechanically controlled. Increase the boost by increasing the spring tension. By whatever means. Be careful, there is a point of no return (meltdown). I would not recommend adjusting it w/o gages. EGT, at least to keep from getting too hot, and a boost gage to see the results of adjustment.
Thank you, yes I am going to get some gauges, I have been looking into that, besides boost and EGT what other gauges are recommended.
I have had this truck for about a year, however I have only just started looking into how to modify it. I pull a heavy 3 car gooseneck but only on occasion an I like the power to buck the wind an climb hills but when not hauling I want very decent mileage as well.

TurboDiverArt

09-15-2007, 05:02

Thank you, yes I am going to get some gauges, I have been looking into that, besides boost and EGT what other gauges are recommended.
I have had this truck for about a year, however I have only just started looking into how to modify it. I pull a heavy 3 car gooseneck but only on occasion an I like the power to buck the wind an climb hills but when not hauling I want very decent mileage as well.
Transmission temp.

Art.

93GMCSierra

09-15-2007, 06:50

Transmission temp.

Art.

Even on a manual transmission?

TurboDiverArt

09-15-2007, 09:29

Even on a manual transmission?

Oh, sorry about that. Didn't read closely enough!

Art.

More Power

10-25-2007, 11:15

I talked to a fellow member yesterday about an ongoing problem he's been having with his DB2 6.5. He told me he ordered and installed a "marine" fuel injection pump and matching injectors from a non-marine vendor some time ago. The engine ran horribly. Some time later he installed a freshly rebuilt on-road DB2, which helped, but the engine still ran rough.

Then, he ordered a set of stock injectors from another vendor (who doesn't advertise here). These were installed, but the two of the eight leaked fuel at the joint where the two halves of the injector meet. There were no markings on the injector bodies - anywhere. No manufacturer name, no model identification, nothing... Sounds like China to me.

The Robert Bosch injector I have sitting on my desk has "Robert Bosch" and "Made in USA" imprinted on the injector body...

So, he replaced these leaking injectors with two original injectors he'd saved that had 150,000 miles on them. The engine ran a lot smoother and they didn't leak. Now, he's thinking about replacing all eight injectors with new ones. I recommended he deal with a certified fuel injection shop that sells name brand parts.

The glow plugs.... He was recently sold a set of eight glow plugs... that did not have any identifying markings on them. The vendor claimed they were as good as or better than the AC-60G.

His low-compression 6.5 struggled greatly to start when cold, even after modifying the glow controller to produce a 15-second first glow.

While one of the injectors was out, he watched the tip of the glow plug while someone turned the ignition key to run. The glow plug tip didn't turn orange, it didn't turn red, it didn't glow any color... The truck owner could feel a little heat when sticking his finger down the hole (just short of touching the glow plug tip).

So, he's installed a fresh set of 8 ACDelco AC-60G plugs, which allow quick and smoke-free cold starts.

Jim

alteredspeed

11-20-2007, 06:35

Robyn

11-20-2007, 08:30

I personally would have yours rebuilt by a reputable shop and have them set to the top of the POP spec. Also request that they pay a little extra attention to detail and get them all as close to each other as possible.
This will make your engine run smoother all the way across the RPM spectrum.

IMHO this also stops some of the harmonic vibes that can lead to issues.
If the injector pop pressure is all over the map from one to the next it can vary timing a bit which will not help the cause any.

Good luck

Robyn

More Power

11-20-2007, 10:27

I have a 6.2 which i will be adding a banks sidewinder to soon. I have The DB-2 pump that has just been rebuilt and the fuel turned up a bit. My question is should I have the stock injectors rebuilt or buy new ones. And if the answer is new, where and what source should I get them from. Also I due have a good Diesel fuel injection shop close.

www.usdieselparts.com (http://www.usdieselparts.com) is a supporter of this site and has been in the diesel fuel injection business for 60 some years. They are an authorized reman/retail center for Stanadyne, Bosch, Delphi and others.

Jim

alteredspeed

11-21-2007, 05:34

Have a injection pump question. Bought injection pump in the process of having it rebuilt. A guy i know said the pump # that i have is junk. He is a big mouth and a Ford Guy, (not that that is bad)LOL. Are all DB-2 pumps created equally? Or should i have the diesel guy stop rebuilding this one, a little worried scence i payed 100.00 for the pump and some where between 550.00 and 650.00 dollars to have it rebuilt, he said depending on if the cam ring is worn and a couple of other things. Is that price range fair? Buy the way the pump # is DB-2829-4267. My reserch showed it was 84-85 military pump. Pleas help I really dont want to waste money. (who does with diesel being 3.37 in VA)

More Power

11-21-2007, 10:07

Among the Stanadyne fuel injection pumps, they were more or less created equal. In part, the model number reflects its fuel calibration and any factory upgrades that may have been added through the years. That's why the model numbers change over time.

For example, if the seal composition or a governor ring assembly is changed, the model number will change. This allows the industry to know what the build and upgrade level is for a given pump.

Jim

alteredspeed

11-21-2007, 12:07

Is the pump mentioned in my last post a good one or should i keep looking.

More Power

11-21-2007, 13:06

If you are running (or think you might eventually run) a turbocharger, the DB2-4911 is one of the best choices for the 6.2/6.5 - along with matching injectors. I'm not a fan of mixing and matching pumps and injectors. When we got to the fuel injection system in our 6.5 Project truck back in late 1998, I acquired a marine DB2 and matching marine injectors from Peninsular.

Otherwise, any 6.2 DB2 pump built since the mid 90's will be just fine for a 6.2. The various seals in the 6.2 DB2 were made from Viton beginning in 1983, which works fine with the ULSD. The quality of the pump depends on the quality of the rebuild. Not all moving components are replaced during a typical rebuild. The head & rotor for example, are only replaced about every 3rd or 4th rebuild. Things like pumping plungers and rollers, most bearings and all gaskets & seals are replaced at every rebuild. Other parts are replaced during a rebuild only when they don't meet Stanadyne's specs. I was told once that a Stanadyne shop doesn't make any money or even loses a little when they have to replace the head & rotor. Most pumps with bad H&R's are scrapped as a result.

Jim

Robyn

11-21-2007, 13:09

If the pump is rebuilt back to MIL specs it will be a fine little pump for your oil rat.

Robyn

More Power

11-27-2007, 13:16

I received a call this morning from a very unhappy 6.5 owner. A number of upgrades and repairs were added to his '95 6.5, which resulted in losing about 8 miles per gallon. New cylinder heads, performance Prom, wastegate mods, FSD/PMD relocation kit, and last but not least - "40-horse" injectors were added.

To help isolate the problem, I asked the owner to re-install the factory Prom, then drive the vehicle long enough to clearly identify any fuel economy changes. If no help, I suggested he install genuine Bosch factory-spec 6.5 injectors. I asked that he provide followup, and I'll report here what he has to say when I learn more.... ;)

Jim

ThreeQuarter

03-17-2008, 15:25

Hey MP--Any news from the unhappy owner?

Robyn

03-17-2008, 16:01

The corelation between the gains in performance directly influence the weight of the right foot as in how it is applied to the loud pedal.
The more the turbo whines and the more the beast growls the heavier the foot becomes.

The lust for the adrenaline rush as the little diesel beast comes to life increases with every improvement along the power curve.

My opinion is that there is a great likelyhood that the fun factor is taking over and allowing the horse to drink heavily at the fueling pond (MPG) as in sluuurrrrp, YUM YUM.
Or more clearly the black smoke factor. :D

If I run my Dahooooley with a sane foot on the throttle the Town mileage will average about 15-16 and Hwy at 18-20

Now with the new chip and a few other things that were done the little pony loves to run and it feeeeeeels sooooooo good.
If Im romping it around and enjoying the power the town mileage will drop to about 12.

This very well could be the issue.

The only way to objectively acertain whether the power improvements are the culprit would be to have an objective 3rd party drive the truck very conservatively and see what happens.

My 94 Burb is bone stock with absolutely stock components including a KITTY.
The early prom is still in the ECM as is the 5068 IP still fitted to the engine.
This rig will consitently knock down 21=Hwy and 17 City.
Now as far as power goes, it would be pressed hard to yank a sick whore off a pot. :eek:

Bet me our friend here is not seeing a heavy right foot.

Power is heat and heat takes fuel.

Now there could be other issues that we have not heard about yet too.

Later and Best to all

Robyn

More Power

03-17-2008, 22:12

Hey MP--Any news from the unhappy owner?

Actually yes... I've heard from him a few times since my last post - as recently as yesterday. He's been running the factory EPROM for the past few months, and the mileage came back. He's planning to upgrade the cooling system now, with the upcoming summer towing season.

Jim

Robyn

03-18-2008, 08:06

This does not supprise me at all.
Most of the factory chips are very conservative when it comes to fuel flow.

If I remember correctly 68cc max is stock. The performance chips are in the neighborhood of 91.

Seems to me I was told that the DS4 is maxed out at 91cc

Along with some other changes that come with the chips this could certainly account for the changes in fuel economy.

Robyn

93GMCSierra

03-18-2008, 11:10

one question I have though, and this does depend on watching the foot that controls the pedal, if you upgrade for performance that means the motor works less at a given rpm, to maintain speed for example, thus in the long run you should see better fuel economy. is that completely false?

Robyn

03-19-2008, 08:05

YES AND NO

The addition of a free flowing exhaust (preferably cat free is possible)
A free flowing intake air filter and all other items such as injectors and such right up to snuff.

This will allow the best possible power with any given amount of fuel.
The power chips on the other hand allow far more fuel to be available and also modify the timing curve across the powerband.
The shift characteristics of the tranny are also modified too.

The additional fuel and subsequent turbo boost enhancements that the modified chip allows produces the extra power.
Using what is available is going to use more fuel.

A long distance cruise test with the truck on the cruise control at say 65 mph should show some improvements over stock.

The overall tendency though is, if the horse can run better the driver will let it do so and enjoy the ride.

The addition of a free flowing exhaust alone should help with MPG and engine life due to the reduction in thermal stress.
This would be confined to using the factory programing.
Once the chip is changed, all bets are off.

I personally did not swap the chip looking for MPG. The added power was a big issue.

With added power one should expect the real possibility of seeing some loss in fuel economy.
Afterall power is made from burning fuel, doing so efficiently is one thing but that only goes so far.
Power can be equated to BTU"S per hour produced and each pound of fuel only has so many BTU"S
How the engine uses this is the key to its overall efficiency.

Some of our engineer types can probably add some 40 line equations to this explanation but this is the best I can offer.

Efficiency will take MPG only so far then it will level off.

More fuel will take performance just so far then it will reach the limits of the engine design (Point at which it melts) :eek:

Just some thoughts.

Bnave95

03-30-2008, 17:01

A good vender who advertise at The Diesel Page is the way to go.
Here some history
GM DS4 pump @ 47,323 7-16-1998
New long Block @ 59,303 6-24 -1999
DSG Gear & Cooling Mods @ 77,900 5-17-2000
JK High Flow injectors @ 83,700 9-3-2000
Amsoil duel filtration @ 127,900 2-1-04
FSD @98K & 135,600 on cooler
SOL-D @ 135,600 #2 driver @ 136,115 and running same.
Pump and Injectors are running strong.
Truck mileage @ 161,326
Last week,2nd trans rebuild. First rebuild was at 65K
BTW it's good to see you all :)

Hubert

06-11-2009, 19:17

There was another post somewhere that made me rethink marine injectors and Hi-pop's and I thought I would share some thoughts....

It was posted that peak IP/line pressure and injection pulse line pressure was actually much higher than the "pop" pressure of the injectors.

So it dawned on me I have sized pressure cleaning nozzles before and pumps pump a flowrate then you select the nozzle size to build restriction and thus pressure. You have to match them up too big of nozzle and too little flow won't build pressure. Too small of nozzle increases pressure and can choke flow.

So I posted this

Thinking about it further... why the line pressure might exceed cracking pressure is maybe this...

It is kind of sorta like an airplane holding its brakes and reving the engine for a short runway take off. The opening pressure of the injector is also kind of like a mechanical switch so the injection pump won't pee diesel into the cylinder with the wrong time (early) and/or without adequate pressure to produce a good spray pattern.

If the injectors did not have a "pop" pressure the IP would more "slowly" (relatively) build pressure with rotation and pee fuel into the cylinder early then build pressure and spray the middle and last bit. And the combustion time would be all over the place.

In general (really always for positive displacement) pumps pump a flowrate and a nozzle makes the restriction and restriction makes the pressure. (With pumps there generally are relief valves/byapsses etc to control pressure but pumps don't necessarily pump a pressure its a combination of flow and restriction that makes pressure). Without a nozzle the IP would just pee fuel into the cylinder. With a smaller nozzle and more flowrate in a short burst puts higher line pressure and may strain the pump ie hi rpm hi fuel rates.

MAYBE? marine injectors actually may be easier on an IP during hi rpm than you might think even though they POP a little higher. They just open later to insure adequate pressure/flow to produce the desired spray pattern with the bigger orifice in the nozzle.

And this is what makes timing a bit hairy with hi pops/marine injectors with lower flow IP's. You have to match the pop pressure to the orifice size to get good spray then the fuel solenoid closed time has to be timed accordingly so the PCM gets what it expects.

Robyn

06-12-2009, 06:39

The marine injectors are fine when used with an IP that is set up to use them.

Our trucks have an IP that can deliver a set amount of fuel and do so at a specific rate of flow.

The injectors are speced out to pop at a given pressure. The specs have a minimum and a maximum.

I have found that the best way to go is to have the injectors set up to near the top of the specs and to be sure that they are all equal in pop pressure.

Having them scattered all over the map is just poor tech.

The cyl to cyl ballance can and will be effected somewhat by a radical difference in pop pressures across the 8 different injectors.

The quest for more power and performance from the 6.2/6.5 engines has led so many folks to jump on many different band wagons in search of Eldorado :)

The truth is that properly set injectors along with an IP that is set to deliver the amount of fuel that the engine can burn efficiently is the best that one can hope for.

Air supply (Turbo and aftercooler) and its efficiency.
An exhaust system that will allow all the spent gasses to flow out easily.
Cyl head flow work (port matching etc)

The magic pill, screw in horse power is not in the cards, at least not by using Marine injectors.

Marine injectors coupled with an IP set up for marine use (Larger displacement) will do wonders but must be used as a package to reap the benefits.

The truck cooling systems can't handle that amount of heat rejection.

In speaking with a well known local IP shop, I have discussed this subject in detail, the larger marine injectors will do little to make more power with the use of the standard automotive IP.

My personal thoughts are very much to the point, this stuff is being siezed upon by profiteers, and sold to the unwary/unknowing public as a quick way to make King Kong out of the little 6.2/6.5

I have seen adds like "40+ HP injectors" just scew these little babies in and feel the difference.

Now here is what will happen in many cases.

Joe down the street has a 1995 Burb that has 190K on the clock and gets the hots for more power.

Over the last many years the injectors in his truck have slowly lost pop pressure and the nozzles have worn away to the point that they are fuctioning poorly.

Hard cold starts is quite apparent along with poor mileage and less that optimal power due to a poor spray pattern and a low pop pressure.

Now screw in the new "marine injectors" the pressure is back up where it should be along with the spray pattern being where it should be.

Joes truck now starts right up and really runs great. Power is where it should be (or closer) and the mileage is back too.

Here is the 40+ hp gain. No real gain at all, just repairing what had go away over the 190K miles.

Very likely, using good factory spec injectors on a sound engine would have yielded exactly the same results.

I like having my injectors set even and to near the top of the POP spec

Cold starts are far quicker and cleaner in cold weather. The engine runs smoother overall and will get better economy (if driven to do that)

Just some thoughts.

Robyn

Konrad.INc

04-25-2010, 22:58

Hello

I have had couple of questions burning in the back of my mind about fuel injectors for some time now. You might have to excuse me, being an engineering major I have to have all the gritty details on things. I have been looking at new fuel injectors for my 1984 6.2L J code for awhile now. I am trying to get as good of fuel economy as possible out of this motor while leaving it N/A and I am wondering about these "high pop" injectors. What would the pressure difference be between a regular and high pop injector? How do marine injectors differ from automotive injectors? What kind of specifications are injectors usually rebuilt/built to? Does anyone flow match injectors to make everything as smooth and efficient as possible? I am assuming that high pop injectors are what I'm looking for, who sells these? Lastly, just kind of an off question, how often should injectors be rebuilt or replaced. I have never replaced injectors on my 190000 mile truck but it does smoke on startup and is a little bit of a pain to start in the winter.

Any knowledge helps
Thanks

More Power

04-26-2010, 12:36

Theoretically, a higher POP can increase the atomization efficiency and possibly power/fuel economy. Only if a vendor posts what pressure his injectors pop at, it's only an adjective that means (or should mean) some pressure higher than specification for a particular application.

There is a downside to higher pop pressures if your fuel injection pump is worn or when the injection pump and fuel are hot. Due to manufacturing tolerances within the injection pump's pumping plungers, a hot thin fuel and a worn fuel injection pump might produce hot starting problems or low power problems when the engine is hot - with a higher injector pop pressure.

Matching pop pressures within a set of eight is a good idea, but unless you have a shop do it for you, you'll get a set of standard spec injectors with spec pop pressures (which pop somewhere within a range of acceptable pressures). It's a tedious process to match injectors because shims are used to vary spring rate within the injector. Flow rates should be fairly consistent between injectors because flow is determined by the injector orifice and the injection pump's pumping volume. Spray patterns are usually not an issue with new or rebuilt injectors, but the patterns do degrade over time - as does pop pressure.

Marine injectors sometimes have a different orifice diameter and/or pop pressure. I've written about this in an article now available in the subscriber section.

The pump & injector manufacturers recommend replacement on the order of 75K miles. Our recommendation is to track fuel economy, startability and general performance. If you notice a decline, it may be time to consider replacing the injectors once other causes are ruled out.

Jim

Robyn

04-27-2010, 06:39

In reference to the "POP" pressure and how these injectors work.

The injectors in the 6.2/6.5 engines have a sping loaded valve that the fuel pressure must overcome in order to get past.

The fuel pressure builds up to "POP" in a scant few miliseconds. Once the POP is reached the valve lifts off its seat and the fuel passes through the nozzle ports and into the engine.

As the fuel delivery reaches the end of its cycle (Pump plungers have exhausted the fuel in them) the pressure starts to drop off and the valve in the injector slams shut.

These injectors when working properly will make a noticeable clicking sound as they close.

6.5 TD engines will in many cases have a noticeable "clicking sound" coming from the heat shield on the turbo. This noise can be moderated by placing a gloved hand on the heat shield. The noise is the closing of the injectors and is telegraphed through the manifold and turbo.

Now all this said.

The marine injectors have larger nozzle openings and can pass more fuel in a given injection cycle.
There is really no advantage to installing a set of Marine injectors in your "C" engine as the IP can only deliver X amount of fuel.

IMHO, most gains seen by folks installing these Marine or HP injectors are likely seeing improvement due to the fact that their injectors were crap anyway,and the new injectors simply got the "POP" and spray patterns back to a more normal level.

The IP is what controls the amount of fuel being delivered.

As Jim mentioned if the IP is tired and loose, the higher pressure injectors can cause hot start and other issues.

I tend to believe that 100K miles is sort of a magic place as far as useful life span.

I have seen injectors and IP's go way beyond these numbers but the performance, mileage and cold start ability fall off dramatically.

I have run 6.5's way past 200K but cold starts were like a mosquito fogger on a cool morning.

The actual line pressures during normal running will rise to the "POP" then maintain the given pressure across the injection event, then as the fuel is depleted and the pressure drops off and the flow can no longer hold the valve off it seat the injector abrubtly closes.

Hope this helps understanding how these injectors work.

Robyn

Konrad.INc

04-27-2010, 11:11

To start with, I actually have a J code engine. However I do understand that the volume of fuel delivered per cycle is largely dependent on the injection pump instead of the injectors. I replaced my injection pump last november when it started acting up and I could not get the truck to go more than 35mph without huge clouds of gray/whiteish smoke comming out of the exhaust. Currently I do look like a "mosquito fogger" every time I crank up and the engine is cold. I have been talking with one of the advertisers on this site about injectors and he says that the high pop injectors run 150bar and the regular injectors pop around 130-135bar. If the injection pump is fairly new would it be safe to postulate that the injectors will wear in/out with the injection pump? EG when the injection pump has say 50K miles the injectors will have worn out a little bit and the pump still should be able to operate them properly? On another note, does anyone suggest one brand of components over another (bosch, Sandyne or delphi)?

Thanks again