14-12-2012, 01:32 PM
Jeez this thread is going mad 
To make a lot of injection you need a big pump.
To a certain extent it's IRRELEVANT what the pressure is. That is just the nature of CR systems. They want high pressures, so that is what we work with.
Have big holes at low pressure or small holes at high pressure. You can achieve your goal either way.
I personally don't give a damn if they run at 1bar or 100000000bar, you work with what you have, and that is a CR system, an ECU and all the calibrations running in the range of ~ 300 > 1500bar max injection pressure. You might come back 10%, or run 10% more or so, but going much out of those ranges is gonna cause you a real headache!
Working back from the standard makes a lot of sense if you ever want to have a car that even starts, or don't have £15k of simulation gear, a dyno, and weeks to re-build the entire bulk of maps to make the car work with a fundamentally different approach (say running 500bar peak and huge injector nozzles to make up the IQ's)
Yes, the flow is roughly inverse square with pressure increase, fluid dynamics basics. I didn't design the CR system, I just tune using it. If you can take a CR system and fundamentally change the raison d'etre for it, and make it relatively low pressure with huge flow nozzles, then you are kinda taking a walk into the unknown.
If someone is willing to spend the money and time on a project that starts with a blank sheet on injection, then they may as well start with a blank sheet on the engine as the costs are gonna be the same or more to do your own thing.
Ie, throw in a 123d engine and making it work will be cheaper by half or more I'd say!
Not trying to be negative, but there is some serious over-thinking in this thread.
Set a target, decide what you NEED to achieve it.
YES, the HP pump makes fuel hot.
YES, you can flow more with bigger nozzles and lower RP.
YES, it's not massively efficient doing that for big power needs.
YES loads of other things.
But it's your starting point.
If you can re-engineer from the ground up do-so... but I personally think you could just get 300bhp with a high flow pump (or two!?) and big injectors running near standard RP's from 300bar > 1500bar.
Why re-invent the wheel doing something mad like running 500bar max, or 100bar?
Dave
To make a lot of injection you need a big pump.
To a certain extent it's IRRELEVANT what the pressure is. That is just the nature of CR systems. They want high pressures, so that is what we work with.
Have big holes at low pressure or small holes at high pressure. You can achieve your goal either way.
I personally don't give a damn if they run at 1bar or 100000000bar, you work with what you have, and that is a CR system, an ECU and all the calibrations running in the range of ~ 300 > 1500bar max injection pressure. You might come back 10%, or run 10% more or so, but going much out of those ranges is gonna cause you a real headache!
Working back from the standard makes a lot of sense if you ever want to have a car that even starts, or don't have £15k of simulation gear, a dyno, and weeks to re-build the entire bulk of maps to make the car work with a fundamentally different approach (say running 500bar peak and huge injector nozzles to make up the IQ's)
Yes, the flow is roughly inverse square with pressure increase, fluid dynamics basics. I didn't design the CR system, I just tune using it. If you can take a CR system and fundamentally change the raison d'etre for it, and make it relatively low pressure with huge flow nozzles, then you are kinda taking a walk into the unknown.
If someone is willing to spend the money and time on a project that starts with a blank sheet on injection, then they may as well start with a blank sheet on the engine as the costs are gonna be the same or more to do your own thing.
Ie, throw in a 123d engine and making it work will be cheaper by half or more I'd say!
Not trying to be negative, but there is some serious over-thinking in this thread.
Set a target, decide what you NEED to achieve it.
YES, the HP pump makes fuel hot.
YES, you can flow more with bigger nozzles and lower RP.
YES, it's not massively efficient doing that for big power needs.
YES loads of other things.
But it's your starting point.
If you can re-engineer from the ground up do-so... but I personally think you could just get 300bhp with a high flow pump (or two!?) and big injectors running near standard RP's from 300bar > 1500bar.
Why re-invent the wheel doing something mad like running 500bar max, or 100bar?
Dave