The bigger injector, less fuel psi theory?

[~The Jester~]

On a side note, being a professional firefighter, I know a thing or two about hydraulics.

So, YES! Given a "standard" pump pressure, the bigger the nozzle, the less pressure at the nozzle. It's all physics bro.

PSI and VOLUME are completely different things. I can give you 197,002 PSI fuel pressure in a 1/8" line, is the VOLUME going to be there? Helllz no. Conversely, I can also give you (literally) 6,000 GPM in a 5" line. Pressure? NONE. Prolly 5 or 6 PSI at best. Your injectors depend on the "pressure" to correctly atomize the fuel, but your motor depends on the VOLUME to make the ponies.

"Brake Specific Fuel Consumption". Live it, Learn it, Love it! Remember that, look it up when you get a chance. Basically it takes "X" amount of fuel to produce "Y" amount of horsepower. PERIOD. It's all about Kinetic energy, or "STORED" energy. That one gallon of fuel can physically only make "X" horespower, no matter WHAT engine you run it throuh. You can have the best of the best heads, intake, cam, etc etc. But if the FUEL isn't there, it's not gonna make the numbers. Bottom line.

At first it's confusing, but after you get into it, it all sorta falls in line and makes sense.

What we're shooting for here is "X" GPM at "Y" PSI. The X is what our motor NEEEEEDS to make the ponies, the "Y" is what the fuel system has to deliver to make our injectors and such work properly. It's a combination of the 2 that makes the whole darn thing work.

Daaaaam! I just read that, and confused myself! LOL I'm not 100% sure on alot of things, but this I AM. Ask Jeff, Andy, etc etc, they'll agree with me here. Or, at least I hope they do!

[Dark_5.0]

Originally Posted by ~The Jester~

On a side note, being a professional firefighter, I know a thing or two about hydraulics.

So, YES! Given a "standard" pump pressure, the bigger the nozzle, the less pressure at the nozzle. It's all physics bro.

PSI and VOLUME are completely different things. I can give you 197,002 PSI fuel pressure in a 1/8" line, is the VOLUME going to be there? Helllz no. Conversely, I can also give you (literally) 6,000 GPM in a 5" line. Pressure? NONE. Prolly 5 or 6 PSI at best. Your injectors depend on the "pressure" to correctly atomize the fuel, but your motor depends on the VOLUME to make the ponies.

"Brake Specific Fuel Consumption". Live it, Learn it, Love it! Remember that, look it up when you get a chance. Basically it takes "X" amount of fuel to produce "Y" amount of horsepower. PERIOD. You can have the best of the best heads, intake, cam, etc etc. But if the FUEL isn't there, it's not gonna make the numbers. Bottom line.

At first it's confusing, but after you get into it, it all sorta falls in line and makes sense.

What we're shooting for here is "X" GPM at "Y" PSI. The X is what our motor NEEEEEDS to make the ponies, the "Y" is what the fuel system has to deliver to make our injectors and such work properly. It's a combination of the 2 that makes the whole darn thing work.

Daaaaam! I just read that, and confused myself! LOL I'm not 100% sure on alot of things, but this I AM. Ask Jeff, Andy, etc etc, they'll agree with me here. Or, at least I hope they do!

Pressure and volume are one thing but we are not talking about a steady stream here. The eu has the ability to adjust the pulse width as well.

[~The Jester~]

Originally Posted by Dark_5.0

Pressure and volume are one thing but we are not talking about a steady stream here. The eu has the ability to adjust the pulse width as well.

Yep! You're right! I'll be the first to admit that I know Jack about fuel injection, but fluid dynamics, I DO know about.

Given the stated fact that the ECU can adjust pulse width ie "duration" of the fuel pulse, if the pressure and/or voume isn't there, then we're not living up to our potential. Right?

Picture it this way, I have 1 bazillion PSI flowing though a 1/32" line, and my ECU tells that injector to hold open for so-and-so milliseconds. Seeing as how that there is no VOLUME behind that 1 bazillion PSI, the fuel pulse will "fizzle", or die out. I understand we're talking milli-seconds here, but with that in mind, wouldn't it be better to have a full "fuel signal" throughout the injector pulse? Think about it bro!

A constant AMPLE fuel supply is where it's at. Carb or fuel injected, doesn't matter. A CONSTANT AMPLE fuel supply! Return, return, return. Send TOO much up front, let the motor take what it wants, and send the rest back to the tank. Trick here is to let the motor have "priority".

Volume DOES NOT equal pressure! But BOTH are needed for a properly operating fuel system. I know what you're saying, and it makes sense. But THINK about it for a few minutes.