heui injector life expectancy / calculation

[donjuane237]

I will throw this out there while I wait for a response to my other post. I just started working on diesel engines 3 weeks ago because i bought a 99 f350 psd that would not start and ran terrible when it did. until that point i thought diesel engines ran because the glow plugs were on all the time (dont laugh to hard!) so that tells you my inexperiance with diesels. once i got the truck home i searched the internet for hours and used the info to figure i had an injector problem so i removed the injectors only to be amazed at how many internal and external parts have to work together at such an extremly fast pace to make the motor function correctly. So being in the "why does it break" field (not an engineer) the first thing i did was a mock calculation to see how many times does an injector fire over a 100,000 mile engine life cycle. first i figured an average rpm at 100,000 would be roughly 1800 rpm. since the injectors fire twice every intake stroke the rpm directly coinsides with injector cycles so 1800 rpm = 1800 injector cycles per minute (icpm) so 1800 icpm = 108,000 injector cycles per hour (icph). next i figured and average mph for 100,000 to be around 45 mph so 45 mph / 100000 miles = 2222 hours of operation on the engine. third take 108,000 icph * 2222 hours of operation = 240,000,000 injector cycles per 100,000 miles. after looking at the injector internally and seing how complex the operation of it is and how precise it has to work i am surprised psd owners do not have to replace/rebuild every 4200 miles (10,000,000 injector cycles). I figure 10,000,000 cycles would be a high life expectancy for what these go through. given they are lubricated 100% of the time and machined to exact specifications so there is no metal to metal contact makes them last as long as they do. even though it still does not convince me that they can last for 200,000,000 cycles even when they do. then factor in the wiring harnesses and injector control module that have to send/switch voltage at a millisecond pace for all those cycles and thats where my brain shuts off and i can now longer comprehend how the engine works like it does for as long as it does. sorry so long but hope the info helps people to look into who is rebuilding their injectors because that is why percision is key to long injector life. an injector that does not have the components machined to exact specifications would probably last 1,000,000 cycles at best (500 miles). any other "useless" info you would like to know about component use just ask and i will try my best to get you info.

[JimTJr]

Waaaaaaayyyyyyyy TOO Much time on your hands........ [img]/ubbthreads/images/graemlins/rolleyes.gif[/img]
Guess if you run dirty fuel,,and dont change your oil you can get down to maybe a 100,000,000 cycles.....
Why do you say they fire two times each intake stroke? (Because they are split shots?) Not really a complete fireing each stroke,,,,,

[YotaTrailRunner]

first off it fires once ever other revolution so acording to your math a 100,000 mile engine would have had its injectors cycled 19,988,000 times

[curtcon]

What???

[Ran440]

Huh?

[Pat Dolan]

First of all, the injectors fire once EACH every SECOND revolution, so at 1800 rpm, that is only 900 cycles per minute, 900 cycles per mile (at 60 mph) or 54,000 per hour. The "split shot" is not a second injection event (as it would be in an HPCR system) but only a mechanical diversion of the injection stroke in HEUI.

The life expectancy is also a matter of lubication. The injector is only constantly lubricated if it is fed nothing but fuel. In the HEUI system - especially the stock FoMoCo 7.3 version - a lot of air seems to get there, so some injectors in one engine may only last 100,000 miles (a mere 90 MILLION cycles of highway cruising), while the next one (or engine) may go 500,000 with ease.

You honesty and curiosity are refreshing, but you will soon discover that trying to make rhyme nor reason of HEUI will make you nuts - at which time you will fit in just fine around here. Welcome to the best diesel enthusiast site on the internet. It seems you are ready to dive right in to the deep end.

Pat

[klhansen]

[ QUOTE ]
...but you will soon discover that trying to make rhyme nor reason of HEUI will make you nuts - at which time you will fit in just fine around here.

[/ QUOTE ]

He's absolutely right!!! [img]/ubbthreads/images/graemlins/biggrin.gif[/img]

[clamgulch]

[ QUOTE ]
So being in the "why does it break" field (not an engineer) the first thing i did was a mock calculation to see how many times does an injector fire over a 100,000 mile engine life cycle.

[/ QUOTE ]

Warmest wishes to you in your new found insanity amongst the insane! I personally am in the "how fast can I break it" field (not an engineer either). I made a mockery of calculation by injecting too much rocket fuel (methanol and hydrogen peroxide) into my engine followed by having my truck towed home so I could replace the head gaskets.

Trust me, your injectors will last longer than you'll want them to once you figure out what "mini-me's" and "Swamps" is all about...
[img]/ubbthreads/images/graemlins/wink.gif[/img]
Besides, your engine will last 300,000 miles or until you do something stupid like put rocket fuel into it...

[Pat Dolan]

Trust me, your injectors will last longer than you'll want them to once you figure out what "mini-me's" and "Swamps" is all about...
[img]/ubbthreads/images/graemlins/wink.gif[/img]

[/ QUOTE ]

Or even stage IIs [img]/ubbthreads/images/graemlins/wink.gif[/img]

[Kwikkordead]

Only gas engine fuel injectors fire twice per intake stroke. Theres differing design strategies on each car, but for the most part, that's how they are designed.