Mercedes sets them to 135 bar,which I think is 1950 psi. I still didn't decide what psi to set them too. I might be able to get a little more fuel from the fairly stock ip at a low pop psi. GM went from 1600 psi na to 1950 psi turbo. So if I'm running 40 psi boost I should have 3200 psi injectors ?
Exactly, this is important when considering the system as a whole. If you increase cylinder pressures you have to consider what the injector is trying to inject into. The stock injector pop pressure was for a turbo running about 10psi. That is because 10psi of boost when compressed to 21:1 can make 1800psi air your injecting into. So its not going to atomize that well if it only pops around 1900psi. My guess is this is the main reason GM upped it to 2100psi for turbo use. Now, push 20psi and the 2100psi pop is inadequate, which is why I recommend everyone set their pop to at least 2250psi (I think at least a few guys have done this). I had my marines set at 2350psi and all injectors will settle a little lower over time. Now if you want to run 30psi sustained with 20:1 CR, then your pop should really be increased to at least 2500psi.
To run 40psi boost, your cylinder air pressure at TDC could be 3500psi (considering static CR of 20:1). The dyanamic CR (from intake closing after BDC and blowby) is a little lower than the static CR, so pressure is somewhat lower than that. I would say you would want set it for 3000psi pop for 40psi of boost if maintaining 20:1 CR. Me personally, I would lower the CR to 18:1 if running more than 30psi of boost, because it will bring down the cylinder pressure during compression stroke significantly. With 18:1 CR and 40psi then can probably get away with 2700psi pop injectors.
The IP will still push through high cylinder pressure though, just likely cause more burnt and mucked up nozzles and what not, maybe cause leaking injector and scratch up cylinder walls and burn a hole in the piston. These IPs will push nearly 10,000psi at full output at high RPMs. The pop only starts the injection, and it goes higher during the event. Definately dont want to lower the pop pressure.
Starts better than ANY other 6.5 I ever saw. Hot or cold. Has a rattle similar to a cummins. A beautiful sound!
My next set is set at 3200. Going for max atomization. My experience has been- less smoke, more power, and obvious fuel mileage improvement. This is a db2 with the screw turned in, on a 94, with a gm8. Otherwise it is stock.
6.2Turbo can comment here, because I think in the past he said the DB2 would lock up between 4000 and 5000psi at idle RPMs. If thats true then cranking RPM wont be able to push much over 3000psi, could be struggling to do that. Testing that limit would be a good experiment. It may cause a little more wear and tear constantly having to push to 3000+ psi at crank and idle, when in normal idle injection it may only hit 2500psi. Being able to get those type of readings pressure readings would be awesome to make some judgment on durability impact. I dont suspect that there is any negative impact just up to 2500psi or so.
Its that injector noise and clatter that a lot of people dont really want, and its already a noticeable difference just going up a couple hundred psi. I am really encouraged to see it working at 3000psi pop, but have you compared to 2500psi or 2700psi, ect... anything over stock 2100-2200psi?
I was in contact with Monark (A US sales rep and their direct production manager) for about 6 months (this was over a year ago) about making nozzles for our injectors. The US sales rep even claimed they had made them once in the past. I was considering buying 300 of them just to get it rolling (the lowest production order). However, eventually they just caved and said they were incapable of retooling to make them. That was a big disappointment, since as stated, the Bosch German nozzles are rare and all old stock.
