LB7: SAC 45 overs, who is running them?
- Thread starter THEFERMANATOR
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Lb7's was the only ones that got vco's, lly+ got sac's from the get go. These are motorspirts nozzles which have 8 holes instead of 7 like stock, not sure on the angle as I really haven't been able to find many details on them. I know these particuliar ones have been out for roughly 2 years from what I can find. I'm not to keen to roll the dice on uet another set of vco's after the short life I've seen a few run into recently.
Got a delivery from the man in brown today. Hoping Wednesday after the fat guy stuff is over, I can take care of this fat guy's truck and get er done. Going over the flow chart, I'm seeing some anomolies here between the SAC's and VCO's. The flow doesn't look to be much higher than 30 over EXERGY's were as I want to say they flowed 155-158 at 160 and 1700 whereas the sac 45's seem to be around 165-168, but looking in the lower pressure areas they flow ALOT less fuel. So I played around some with LLY tables, and the flow rates started making sense, so I'm going to do some playing around once I get it together and do some actual hands on testing to see whats what between the 2.
That's what I've seen, the SAC injectors flow less at low pulsewidths, but start to move with the longer durations and high pressures.
I'm running PW tables similar to stock LB7 down low, and it seems to work fine, though, so I think they are more different on paper than in reality.
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I'm running PW tables similar to stock LB7 down low, and it seems to work fine, though, so I think they are more different on paper than in reality.
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Just out of curiosity, I pasted an lly table against an lb7, corrected to bring the differences together, and everything made sense. Going to do some logs to see how fuel rates change when rail pressure is changed just to see.
With going from Exergy 30 overs to the stock BMS nozzles I didn't have to change pulse. They were a true 50 percent over when comparing all the different sets that I have done or sold.
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So are you saying that the LB7 injectors with SAC nozzles act like stock LLY injectors? That LLY fueling tables could be used as a base to tune them? Just trying to understand.
They do seem to behave more like LLY injectors, but I don't know if a stock LLY table would work or not. Mine are 75% over SAC and I had to do some table work before I was happy with them.
They don't need as much timing as the LLY seems to, though, in my experience.
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They don't need as much timing as the LLY seems to, though, in my experience.
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From what I'm seeing, the flownumbers for the 45 over sacs don't even remotely match up anywhere with astock tune file, but if I use a stock lly table and correct it back for the larger nozzles(lly nozzles are smaller than lb7), all of the sudden the flow sheet numbers start making sense. Larger injectors would need less timing to quite a degree vs stock lb7 or stock lly, but sac nozzles at low rpm's nldo need quite a bit more timing than the same sized vco nozzle due to when a vco injector is triggerred, the fuel only has to pressurize the orifices then spray out, with sac nozzles you have to pressurize the chamber that the orifices feed from then the orifices before they inject fuel. As rpm's increase this lag decreases, and it also decreases with increased pressure(both of which explain why the lly has so much more timing in both the pilot and main tables as well as commands a larger pilot shot in the idle only areas). I'm just trying to get a game plan together before I go tuning mine. I had another tuner tell me to just pull 10% out and up idle pressure to 40 from 35, but from what I'm seeing, I think this way would work, but not work how I want my tunes to perform. I've spent over a year working out little quirks in my tune that others thought I was imagining, to say I'm OCD would be an understatement. My current tune is pretty good, but it's still not what I would consider to be 100%.
Part of me is dredding writing a new tune knowing how much time I put into one, but another part of me is excited to try something new. Need to do some quick logs before I tear mine down to get some baseline numbers for the lower fueling areas, then I can do some datalogging of displayed fuel rate, pulsewidth, and pressure, and formulate a fueling table that will be pretty close to actual. I'm not so concerned with 30mm3 and above as those areas get modified anyways, but I at least want to get up to 20mm3 pretty close.
Part of me is dredding writing a new tune knowing how much time I put into one, but another part of me is excited to try something new. Need to do some quick logs before I tear mine down to get some baseline numbers for the lower fueling areas, then I can do some datalogging of displayed fuel rate, pulsewidth, and pressure, and formulate a fueling table that will be pretty close to actual. I'm not so concerned with 30mm3 and above as those areas get modified anyways, but I at least want to get up to 20mm3 pretty close.
From what I've read, they each have there stengths and weakness's. Vco's are supposed to clean up better since they don't have that chamber between the seat and orifices that causes a delay in pressure rise and injection. Vco's are supposed to be used where emissions are a concern since they are fairly precise in how they control the fueling, but there design carries some flaws. Sac's are supposed to have more even spray since there openings to the spray orifices are not the sealing surface and a wear area. Also the chamber between the seat and orifices allow sac's to have a more even spray pattern as pintle opening doesn't effect when the fuel hits the orifice. I'm very interested in learning what these smaller ones do, and hope to post up some findings since theres so little feedback out there on them.
I've been doing research on this as well, as I'm having the same issue only a lighter hazing than you're having. From what I gather 45 overs will be perfect for a stock LB7 and give you that little extra play room for power upgrades. So same as you I will be biting the bullet here soon unfortunately.
I've already done decided I'm doing the 65% SAC as I'll be needing them later down the line.
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Thanks Ferm. Thats kind of what I was getting at, I just may have mis-spoke it.
I put a set of 45%s in my extended cab
Just got it running the other day but it has some issues that need to be straightened out before I can take it for a drive
It's been a few months since I drove it & I changed a couple other things so I won't notice a difference
It'll be nice to get some mpg back & not have a smoke trail following me around, that was getting embarrassing at stop lights
Just got it running the other day but it has some issues that need to be straightened out before I can take it for a drive
It's been a few months since I drove it & I changed a couple other things so I won't notice a difference
It'll be nice to get some mpg back & not have a smoke trail following me around, that was getting embarrassing at stop lights
I had to have my SUB for Christmas for a road trip to the inlaws, so I flushed mine to buy me some time so I could do them when I get home. Got the new set sitting on the bench waiting, and wouldn't you know it, mine have cleared up and it's running great again. Now I'm kicking myself for having ordered new injectors, but I know if I hadn't it would have gone the other way. I'm pretty sure new nozzles would fix mine as its holding rail great, not returning much fuel, just had the infamous blue smoke at idle(then again, the facebook experts said injectors can't cause blue smoke. Guess I owe some people some money back and figure out why injectors fixxed there blue smoke problems).
Finally getting these put in. Made an interesting observation of them. The stock vco's have the orifices up high on the taper and all on the same plane to inject at the same angle. The sacs have a much smaller tapered tip and have the orifices split on 2 planes. I couldn't get a good picture, but you can definately see an orifice up high, then one out the taper so that 4 are high up and 4 are out near the tip of the nozzle. I'll post comparisons pics, but they don't show up very well, and I'm not about to pull apart one of the new ones just so I can spray test them to show the difference.
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