Taking the Pressure to the Max

[TC]

As I'm always thinking outside the box, I got to thinking here, in a EFI setup could running a really high fuel pressure and have a really short opening pulse on the injector get you better fuel economy. What I'm getting at is if you ran like 200psi of fuel pressure, you would be able to pulse the injector for a shorter period of time, and if the higher pressure would cause the fuel to be atomized finer that you would be able to use less fuel and still make the same power.

And can you run a motor on just plain old gas fumes. I know gasoline in it's gaseous state is very flammable, which would allow for a 100% burn of the fuel during the combustion cycle.

Anyway just a couple of thoughts, what you guys think.

[min301]

Re: Taking the Pressure to the Max

Let me know how that works, Alex. ;)

[Matt Cramer]

Re: Taking the Pressure to the Max

Formula 1 engines run similar pressure levels or even higher, but that's mostly so they can run sequential injection that actually gets all the fuel in the intake valve at their super-high redlines.

I believe Bosch tried that with more street oriented setups in the early days of EFI and concluded it did little more than create a bigger leak hazard. Engines typically get at least 98% of the fuel burned anyway...

[70.5CAMARO]

Re: Taking the Pressure to the Max

i would think that the joints where the lines meet would all need to be similar to brake lines, that way to eliminate any leaks, standard compression fittings and orings i dont believe would hold up. also the injector system would have to be deisel similar in my mind, very strong springs and heavy, heavy solenoids. the over all cost would overweigh the gain you would get in fuel economy. you figure to gain what like maybe 5 mpg? or possibly a 1/4 sec in the 1/4. I dont think its worth all that. what would that cost? 2k? more?

[bnjny]

Re: Taking the Pressure to the Max

Um, Is this not similar in idea to what is already out there? Direct injection is used with very high fuel pressure... Or am I off base with my assumption that we are talking about the same thing?

[min301]

Re: Taking the Pressure to the Max

I think your on, HPGDI has been around.

[Mr4Speed]

Re: Taking the Pressure to the Max

I've read on some other forums where the standard GM TPI injectors vaporize better at higher pressures but they were talking about running them at 50psi at idle instead of the standard 40psi.

[goat racer]

Re: Taking the Pressure to the Max

My high compression, aluminum headed, solid roller cammed, gear driven Duramax has a fuel rail pressure of 26,000 psi! That will make it atomize!!
Scary to even think about.

[fabricatordave]

Re: Taking the Pressure to the Max

my only thought is if you were trying this what would you use for injectors .todays injectors wont stay closed at that pressure

[SpiderGearsMan]

Re: Taking the Pressure to the Max

too much pressure and the [gasoline] injectors don't close
lets not get into duramax LB9 injectors -ugh !!!
please change your fuel filter every other oil change

[dieselgeek]

Re: Taking the Pressure to the Max

the better thing to figure out for more consistent fuelling would be injectors that don't have to be "pulsed" to meter their fuel flow. ONe of the benefits of a carb over EFI (that many carb guys fail to realize) is that the "constant flow" of the carb makes for more consistent fuel mixture than the pulsing on/off of injectors. The Formula One guys place the injectors WAAAY up the intake tract to help even out the mixture that's waiting to be sucked into the combustion chamber.

My understanding is that there isn't much more atomization to be had (for gasoline) at existing MPFI pressures. The reason Direct INjection setups are so high pressure (gas AND diesel) is because the time window available to inject the fuel is a LOT shorter going into the combustion chamber, than it is when spraying it into the intake. Think about it: inside the combustion chamber, you only want to spray fuel when the intake valve is closing or nearly closed, and be done by time the spark event happens. So, you get a MAX available duty cycle time in DI engines, of like 20%

On MPFI, you can spray up to 100% duty cycle (most OEMs cap at 85%). Thus, you can get away with lower pressure (because you have more time available to get a given quantity of fuel into the engine)

[SpiderGearsMan]

Re: Taking the Pressure to the Max

GM is making stupid power with DIRECT INJECTION
300+ hp 3.6 and the 2.0 turbo 260 hp - nice

[joe_rocket45]

Re: Taking the Pressure to the Max

The Formula One guys place the injectors WAAAY up the intake tract

I saw this in a video one time, more like an open plenum with injectors spraying into it, it looked almost like a BBC Profiler intake with the blower injector plate, I wish I could find that video.

haha, here it is!

http://www.youtube.com/watch?v=o_QyUD6V5_I

[fabricatordave]

Re: Taking the Pressure to the Max

here is a different one http://www.youtube.com/watch?v=AKyP1...eature=related

[goat racer]

Re: Taking the Pressure to the Max

lets not get into duramax LB9 injectors -ugh !!!
please change your fuel filter every other oil change

'06 LBZ. Hav'nt had a problem with those yet. Hey those early D-max injector jobs make my pay check bigger!!

And yes, a factory fuel filter every 15K. ;D I've seen too many trucks towed in and all they needed was a filter change.