HP limit on LLY injectors.
- Thread starter McRat
- Start date
Pat, you should type up more notes! 
Its like reading your "log book" :spit:
good info share!:hug:
Its like reading your "log book" :spit:
good info share!:hug:
Ok so now after messing with B1010 (regulator current) in efi I actually got my rail pressure to hold 23,000psi with ~3100ms pulsewith. This is supposed to be a 500rwhp tune. So if I ran to around 3400pw I would be at 875rwhp?
With the LLY can we command over 23,000psi? I still have the stock FPRV no shim.
What does everyone think that the maximum pulsewith someone should use if they are running the stock shift points (~3200rpms)?
I am running the stock shift points but sometimes in first and second it will rev up to a max of about 3400rpms, but if the stock components don't make good power up there there might be no advantage to running higher shift points, especially when running 2x stock pulsewidths.
So can we command more pressure for the LLY/LB7? Can you command 26k psi like the LBZ/LMM? Ive never had a p1093 and ive seen rail spike to around 25-26k. So what is stopping us from going higher pressure?
With the LLY can we command over 23,000psi? I still have the stock FPRV no shim.
What does everyone think that the maximum pulsewith someone should use if they are running the stock shift points (~3200rpms)?
I am running the stock shift points but sometimes in first and second it will rev up to a max of about 3400rpms, but if the stock components don't make good power up there there might be no advantage to running higher shift points, especially when running 2x stock pulsewidths.
So can we command more pressure for the LLY/LB7? Can you command 26k psi like the LBZ/LMM? Ive never had a p1093 and ive seen rail spike to around 25-26k. So what is stopping us from going higher pressure?
SHIM !!!! YOUR FUEL PRESSURE RELEASE VALVE you have an LLY there are no excuses for not having it done, I went from 13.0 to 12.47 just from shimming my FPRV
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Depending on your setup, but if you have a tunning only truck bringing your PW up probably won't do much maybe even bring down your rwhp actually since you don't have enough air for all that fuel.
You can command more pressure but as said your relief valve is gonna limit you.
My shift points for partial throttle (normal driving) are stock, only Full Throttle shift points are raised.
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Im trying to shim my FPRV but trying to get a chance to do it.
When it opens will I know it, will rail pressure fall a lot?
I am sitting on about 30psi of boost and no smoke once the turbo is spooled, but my vane position is in the 50-60% range so im going to see if i can lower that some. I just don't get how 3100us at 23,000psi makes around 500rwhp, but 3300us makes 875rwhp on stock injectors?
When it opens will I know it, will rail pressure fall a lot?
I am sitting on about 30psi of boost and no smoke once the turbo is spooled, but my vane position is in the 50-60% range so im going to see if i can lower that some. I just don't get how 3100us at 23,000psi makes around 500rwhp, but 3300us makes 875rwhp on stock injectors?
At 23,200psi (160MPA) the fuel rail relief opens on the LB7/LLY, the LBZ/LMM open at 26,100psi (180MPA).
Shim the valve and you will be good till infinity!!
no...thats not when they open...
thats the max rail pressure each generation runs from the FACTORY. WHY would the factory tune it to run at 160/180mpa max if thats when the releif valve opens. Think about it. The second you went WOT, then the releif valve would open...
ben
FPRV opens when there is a spike in the pressure. Usually when the demand drops drastically and the pump does not respond quickly enough. Defuels during shifts are good for causing the spike.
I personally don't know what the setting is, but I can assure you it is North of 23,000 PSI stock. Just not North enough.
I personally don't know what the setting is, but I can assure you it is North of 23,000 PSI stock. Just not North enough.
I logged it Ben. My LBZ opened as soon as it exceeded 180MPA. The LLY one I put in after my PPE Race valve was giving me grief popped at just a shade over 160. So those are the numbers I am going with for cracking pressure.
When I look through my torque limiting tables and other tables, my pressure is usually a couple MPA below the max at 100mm3 of 179.8MPA which I am assuming is GM's safety margin.
I would bet they crack open at WOT if it were to spike a little like possibly do to wheel spin on ice or something but the defuel would likely allow the pressure to recover and the valve to seat again so you may not notice it. I know when mine defuels it takes a second before it fuels hard again.
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You are very unlikely to catch the pressure spike from a defuel in a log. When your injectors stop draining the rail as fast as the pump is putting out fuel, the pressure will jump in a huge hurry.
Then again, once a FPRV pops, it doesn't seem to hold as much pressure from then on....
Then again, once a FPRV pops, it doesn't seem to hold as much pressure from then on....
This question is a little off topic, but anyone ever cracked a hard part from too much pressure and no relief?? ie, no vlave or shimmed too high.
Wes, i may have blown an LB7 injector or two from high psi but its purely speculation on my half. The dual feed line removes the FPRV on mine. This is back before i had EFI when i was running a PMT so no way to log it. I seem to recall making some runs shortly followed by fuel in the oil. Balance rates were off and wouldnt hold rail psi like before. I verifyed it running with the v/c off and it peeing diesel out from an injector body. That said, i drive the crap outta it and plenty of WOT so no deffinitive way to know till it happens when im logging.
Im trying to shim my FPRV but trying to get a chance to do it.
When it opens will I know it, will rail pressure fall a lot?
Do a bottle test
I just don't get how 3100us at 23,000psi makes around 500rwhp, but 3300us makes 875rwhp on stock injectors?
2 cp3s and enough air to burn the fuel
