08-12-2012, 08:13 PM
All higher pressure does is shorten injection times for the same injected amount. That is handy if your injections are getting too long.
Bigger injectors can do the same shorter injection at the same pressure, but of course you need a pump that can still flow the high volume!
If you want to run 1500bar peak on an 1800bar sensor just map it for less peak pressure.
Running MORE pressure than you need at any given point is costing you power in parasitic losses (the HP pump costs power to run!)
What really matters most is the pump for your torque and thus power curve. You need X injected in Y time to make power Z. You do that calculation across the whole rpm range. There is a limit due to the pump.
The injectors then have a limit but as we have seen we can make about 200bhp at 4000rpm, and 320lbft at around 2250rpm (both Pete's VNT car) with these injectors with the appropriate pump behind it, so better injectors are really not needed to that kinda point.
It's probably best more to look at what power/torque you want, and the curve shape, and then see what you'd need to achieve different options.
Ie, sticking with standard pump/injectors in good condition, what is the best curve shape I can achieve (assuming the perfect turbo)
Upgrading injectors only, what can I achieve (probably not much more than standard if at all as the pump is what is limiting things)
Upgrading pump only, what is the peak torque curve shape I can achieve (again assuming perfect turbo)
Finally upgrading both to well known items, what is the peak curve you could get...
I might try work this out soon.
Hmmm
Whatever you do the limits will likely be on the quality of the bits themselves rather than the original specification of them! So whatever you buy, budget to buy/recondition it to be in top condition to expect to get anything like the best performance from it
Dave
Bigger injectors can do the same shorter injection at the same pressure, but of course you need a pump that can still flow the high volume!
If you want to run 1500bar peak on an 1800bar sensor just map it for less peak pressure.
Running MORE pressure than you need at any given point is costing you power in parasitic losses (the HP pump costs power to run!)
What really matters most is the pump for your torque and thus power curve. You need X injected in Y time to make power Z. You do that calculation across the whole rpm range. There is a limit due to the pump.
The injectors then have a limit but as we have seen we can make about 200bhp at 4000rpm, and 320lbft at around 2250rpm (both Pete's VNT car) with these injectors with the appropriate pump behind it, so better injectors are really not needed to that kinda point.
It's probably best more to look at what power/torque you want, and the curve shape, and then see what you'd need to achieve different options.
Ie, sticking with standard pump/injectors in good condition, what is the best curve shape I can achieve (assuming the perfect turbo)
Upgrading injectors only, what can I achieve (probably not much more than standard if at all as the pump is what is limiting things)
Upgrading pump only, what is the peak torque curve shape I can achieve (again assuming perfect turbo)
Finally upgrading both to well known items, what is the peak curve you could get...
I might try work this out soon.
Hmmm
Whatever you do the limits will likely be on the quality of the bits themselves rather than the original specification of them! So whatever you buy, budget to buy/recondition it to be in top condition to expect to get anything like the best performance from it
Dave