LB7: New Injector Design
- Thread starter Relentlesscummins
- Start date
My opinion:
Good idea, but that should affect coolant loss and overheating more than anything else. If it affected injectors, then you'd see far more problems with CA-emissions trucks than the rest of the country. But thats not the case. Additives, extra filtration, where you buy your fuel, battery voltage, etc, it doesnt seem to matter if you do these things or not, you'll still eventually have problems.
What is the one thing that makes LB7s different from the later generations? Not firing voltage, as LLYs fire at roughly the same voltage as LB7s. LBZ's less than that. IMO its a design issue (injector body + under the valve covers) and also heat related, and nothing can be done to fix that.
Its too bad they came in so late to the game, but Id have loved to see something like DTS's cupless heads back in 2004. I wonder if they would've helped with cooling around the injectors and if injector life would've been prolonged.
You just have to face it, injector replacement is a fact of life with owning an LB7. There's just no getting around it.
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Tom, lly's fire at 48v, lb7s fire at 96v, so there is a difference. Ben said it had to do with voltage years ago. I have a set of injectors from my core motor, and one of the injectors was burnt blue from high voltage (imo). I think if we used an lly ficm (if its possible), our injectors would last longer.
From my previous experience with DC voltage i would say that a lb7 injector would still operate on a 48 volt system BUT i dont think they will work with a LLY ficm for some reason. If there was another way to supply lb7 injectors with 48volts i think it would work. I used to have a starter for my dragbike that would work on 12 volts, 24 volts and 48 volts also iirc. Im not positive on this info. so please BEN don't beat me up to bad when you tell me im wrong:hug:
OK, thanks Vaz. I was basing what I said on LLYs firing at ~95v, which is what I was told long ago. If they are firing at 48v, then it would be interesting to find out if the guy who swapped to LLY heads/injectors but used the LB7 electronics (the "I have seen the impossible" thread) is having any problems now.
Yes, lower voltage should help. That might help with any excessive heat that high # is generating.
being an electrical engineer I do not think the firing voltage is root cause on injector failures but could be a factor. years ago the thought was the higher voltage was causing the injectors to run hotter.
I do not think that is the case, the voltage causes the action and is probably not coincident in time with any current flow so therefore power dissiapation at the injector is minimal by design. Now it is possible that as the injector wears this dissipation could go up. Also the temperature dependence of the Voltage/current relationship could be the key here which is why the Isuzu was so concerned about maintaining constant temps on the injectors which led them to implement the cups. Kind of difficult to do when the upper body is being splashed with hot oil(So you may have a temp gradient across the injector body). So I do agree with others that probably a poor thermal design in the injector implementation in the head is root cause, but I do feel from (ancedotal readings of threads) California head trucks do have a higher failure rate. Not sure if it is due to lower flow and overall poorer quality manufacturing, but from my readings the Cali trucks fail at a higher rate.
One more bit of info, I did try the GM injector cleaner(another thread) and these two injectors I pulled out(70k of service) where pretty clean. There some small amounts of carbon that just flaked off. I have never seen injector tips that clean.
So I agree, you will be replacing injectors more often on LB7's, and if it is a few every 3 or so years, I am ok with that.
I do not think that is the case, the voltage causes the action and is probably not coincident in time with any current flow so therefore power dissiapation at the injector is minimal by design. Now it is possible that as the injector wears this dissipation could go up. Also the temperature dependence of the Voltage/current relationship could be the key here which is why the Isuzu was so concerned about maintaining constant temps on the injectors which led them to implement the cups. Kind of difficult to do when the upper body is being splashed with hot oil(So you may have a temp gradient across the injector body). So I do agree with others that probably a poor thermal design in the injector implementation in the head is root cause, but I do feel from (ancedotal readings of threads) California head trucks do have a higher failure rate. Not sure if it is due to lower flow and overall poorer quality manufacturing, but from my readings the Cali trucks fail at a higher rate.
One more bit of info, I did try the GM injector cleaner(another thread) and these two injectors I pulled out(70k of service) where pretty clean. There some small amounts of carbon that just flaked off. I have never seen injector tips that clean.
So I agree, you will be replacing injectors more often on LB7's, and if it is a few every 3 or so years, I am ok with that.
Really? Your ok with changing out injectors every three years? That's crazy many would dissagree with that me included. That's approx 45,000 miles on a average.
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I'm with Tom on this. I think that if we look at the changes in the LLY that GM made has to hold the clues. Although the injector cleaner will give you a smoother running truck I don't believe it's a fix for failure. As said it was thought dirty fuel was the culprit and everyone bought in and added filtering. Yet failures continued.
I'm positive GM knows why they fail. With the LLY they lowered the voltage and moved the injectors outside the valve covers. It is in my opinion they didn't do that just for ease of service. Now I believe they made some changes in the tip but that is probably not involved in failure. Has to be a combination of these two elements probably more so on heat.has anyone really looked at in a side by side of the LLY and LB7 injectors? Let's face it the injector failure went away with the LLY.
The only wrench in this theory ,there always has to be is the guys running modified injectors. That is also where this tool who started this thread Comes in. What is the failure rate there or is there no way to tell? Also how come some fail and some don't ? In addition you have the individuals that have ran performance devices that have increased injector cycle duty. I don't even believe there is a link there or maybe that's why the modified once last because the cycle has been reduced. I know that some felt the Edge Box contributed to failure. What sucks is still some 11 years later no one has determined the exact cause, that blows!
I could be heading to my forth set in under 70000 miles! Or am I considering the stock ones were changed because of balance rate and a injector knock. Next set had A dead cylinder which was a injector. The set that is in there now the balance rates are climbing and possible run ability as in fluctuating idle. With the exception of the dead one perhaps all I needed or need is the injector cleaner. None were ever replaced under GM policy of high return rate or fuel in oil.
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I'm with Tom on this. I think that if we look at the changes in the LLY that GM made has to hold the clues. Although the injector cleaner will give you a smoother running truck I don't believe it's a fix for failure. As said it was thought dirty fuel was the culprit and everyone bought in and added filtering. Yet failures continued.
I'm positive GM knows why they fail. With the LLY they lowered the voltage and moved the injectors outside the valve covers. It is in my opinion they didn't do that just for ease of service. Now I believe they made some changes in the tip but that is probably not involved in failure. Has to be a combination of these two elements probably more so on heat.has anyone really looked at in a side by side of the LLY and LB7 injectors? Let's face it the injector failure went away with the LLY.
The only wrench in this theory ,there always has to be is the guys running modified injectors. That is also where this tool who started this thread Comes in. What is the failure rate there or is there no way to tell? Also how come some fail and some don't ? In addition you have the individuals that have ran performance devices that have increased injector cycle duty. I don't even believe there is a link there or maybe that's why the modified once last because the cycle has been reduced. I know that some felt the Edge Box contributed to failure. What sucks is still some 11 years later no one has determined the exact cause, that blows!
I could be heading to my forth set in under 70000 miles! Or am I considering the stock ones were changed because of balance rate and a injector knock. Next set had A dead cylinder which was a injector. The set that is in there now the balance rates are climbing and possible run ability as in fluctuating idle. With the exception of the dead one perhaps all I needed or need is the injector cleaner. None were ever replaced under GM policy of high return rate or fuel in oil.
If dts can have cups welded into a lb7 head, is it not feasable to have a cup designed for a lly injector and weld that in? Or can you not put a lly injector under our valve covers or for that matter, work in the heads? If you ran a lly ficm, would it trigger off 48v and cooperate with the lb7 ecm?
LOL new inectors right from Bosch!! Maybe if GM bought 200 000 of them they would make them otherwise they will just tell ya to piss up a rope. Simon and I both tried to get 60 over injectors directly from Bosch and even talked to a couple different people at Bosch Racing. We never even got past a basic quote for some and soon after never heard back from anyone at Bosch again.
Stick a fork in the LB7 injector issue cuz it's done. They revised injectors in the newer engines to fix the issues they had so basically now you either buy new from GM or aftermarket reman and expect to only get a 100 000 miles at best out of them and this is if you keep your fuel system in tip top condition! Sorry guys, but those are the facts.
Stick a fork in the LB7 injector issue cuz it's done. They revised injectors in the newer engines to fix the issues they had so basically now you either buy new from GM or aftermarket reman and expect to only get a 100 000 miles at best out of them and this is if you keep your fuel system in tip top condition! Sorry guys, but those are the facts.
At this moment there is no other explanation but this thread is bullshit as he has failed to respond except in some other thread he was asked and said that they were working great or something like that.
Beats me why somebody would start a thread like this then never respond, not like he's new around here either.
Oh well every time he (relentless) post it'll be brought up so he'll be haunted. Serves him right? Allow others to judge ,myself disappointed he didn't at least man up and say he was mislead.
Beats me why somebody would start a thread like this then never respond, not like he's new around here either.
Oh well every time he (relentless) post it'll be brought up so he'll be haunted. Serves him right? Allow others to judge ,myself disappointed he didn't at least man up and say he was mislead.
Lol at these replies. What got me is he said the design came from cat. And cat uses everyone else's shit. With the latest revisions from bosch I imagine they're as good as they'll ever get. Don't yall think?
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they don't even make their own class 8 motors now, they are partnered with navistar. correct me if i'm wrong on this guysWhat do you mean Cat use's everyone else's stuff
Oh, I thought we were talking about injector designs... I didn't know we were talking about Caterpillar stepping out of the class 8 market. I don't deal with those little sissy engines anyway, carry on. Great thread by the way:rofl: