" Lol... that escalated quickly. Was wondering if the valve was bleeding off pressure during injection dead time between shifts programmed in the auto, vs nls on the manual that fires injectors the whole time. Doesn't seem to be the case necessarily, but the valve is still a good place to look. I want to try some stuff too now that I have my car back!

Should I mention I can datalog on my cellphone now via Bluetooth with the jb4? Bahaha, handhelds AND laptops be damned! Although that AP was handy sometimes.

'Merica "

" DI gives you a few percent more VE due to charge cooling in the cylinder drawing air in. It's a couple of percent, so not exactly trivial, and allows for higher knock resistance without huge octane. All these benefits are solely from DI for ya sticky :-)

But there are some very big drawbacks as have been brought up, and if the benefits outweigh the drawbacks is hard to say. DI does help fuel economy, but it's by no means cleaner than pfi either. It's dirtier actually, all things equal.

I think that fuel wise I'm siding with bullet and Terry, there's really no injector limit I can see. RPM wise, it's starting to seem fuel isn't a major limiting factor. Gotta start at the bottom I guess, replace what needs to be replaced. Good info in this thread though. Starting to understand this system a little better. "

" Yep he's the man. Dug this up from my post on n54tech.

http://dspace.mit.edu/bitstream/hand...5670245.pdf?.. is the disertation. From 2011, a friend of mine knew the guy and thought I would be interested in his thesis. My friend has good taste because I was, it was a good read! Well, the parts I read, and of those, the parts I could make sense of. If you're super bored enjoy :-) "

" There's a paper that used a turbo DI gm engine and compared DI to PFI for all sorts of things from knock to flame progression with different DI injection timing with the incoming air. I think there was a section on droplet size and how heat from compression affects vaporization when they compared ethanol blend fuels. I'll see if I can dig it up. It was a big dissertation from a MIT guy with the head of sloan as corresponding author. I like reading things from sloan. But pretty much the same as what you're saying. Issues to keep in mind but not necessarily game breaking. Time will tell, though. Valve float and airflow from all components need addressed first. "

" I wonder- does this happen on the 6mt during NLS? "

" [QUOTE=BavarianBullet;457655]Ok, here's my take on why DI works and I wouldn't fear running out of injector for practical purposes on an N54 before I figure the block will split in half or the crank walks and grenades everything (about 1200HP? WAG):

fig A Continental's Piezo Injector datasheet used in the N54 (takeaway: injector moves about 35 g/s of fuel and seems to scale practically linearly given the example of 14.5 mg/injection at .4ms PW)

Attachment 30658

Fueling example using goal of 1150CHP/1000WHP at 6000rpm:

6000rpm / 60sec = 100 Revs/sec "

" Is the valve you're talking about on the hpfp the one that regulates pressure? If so I'd definitely try to find the trend between pwm, pressure and rpm. Probably modifiable in a table still hidden, but "position after shift" pwm could be reason for crash/recovery... maybe in part due to low load targets? Regardless if you can find out how it works the answer could be simple and electrical/tuning for the post shift dip. "

" Supplemental *cough* fuel *cough* injectors? Whatever happened to that thread? Somebody was going to be testing a TB spacer plate in california IIRC with two sizable injectors...

Not that I'm ungrateful for upgrades to the stock system or anything... just sayin... sometimes it feels like one step forward two steps back on the fuel stuff. I guess phasing in buckets of meth could work too for a little kick to the redline fueling wise.

I would like to point out that fuel injector limits vs engine speed have yet to be determined. Maybe somebody nice with access to lots of logs could plot the duty cycle vs rpm at steady torque? Maybe we can determine how quickly the injectors will dry up from that. "

" Port fueled cars only inject into open valves under certain conditions with sequential injection setups. Batch fire port fuel cars rarely ever get an open valve. Even sequentially fueled cars puddle gas on the closed valve after a certain RPM due to the fuel demands. So port fueled cars have nearly 4 strokes of time to inject fuel, although you don't want to run the injectors over 80% duty cycle. FWIW- 100% duty cycle would be spraying 100% of the time, or for all 4 strokes. 80% is spraying for over 3 of the strokes. DI cannot do that, it can only spray for just over one stroke. "