I've had a lot of questions regarding some of my comments regarding PI injection.
I'm not even close to the most experienced tuner but i have done a lot in the past and have found things out the hard way
The quick down and dirty.
The #55 injectors that people are using flow 55lbs @ 43.5 (578cc/Min) (standard psi for fuel injector flow benchmark and 99% of EFI engines) and we are running them at 72psi ( So they really flow 744cc/min)
Take Josh's (MR2 Josh) for example 861WHP 100% e85 and 80% IDC and his HPFP is about 80% from what he said. That is a $#@! ton of fuel and still has a lot of head room (80% is a good peak IDC). This is way to much for anyone running less than 860whp. Even though they are considered secondary fueling they need to be power matched to the engine. You want to be around 75% idc at your peak power/rpm to leave some head room and not over work the injectors. This can easily be done with a few calculations.
Batch firing is what scares me when the injector is open for such a short period at such a high power and RPM. Terry is only at 30 or 35% at 600+ on straight E85. To me that injection window is way to short and i wonder if thats why he is having timing pulls and cant figure it out. Here is the secondary PI injector window based off Terrys published results.
RPM IPW IDC
4000 10ms 33.3%
5000 8ms 33.3%
6000 6.65ms 33.25
I know its not 33% across the board it probably starts off lower and rises, so technically these numbers would be even smaller.
Normal IPW is more than double that.
With race fuel these numbers would be in upwards of 30% less. If your barley using them and don't plan on making much more power I would defiantly go to a smaller injector and increase the IPW. That's just me though. It's not a one size fits all.
On batch firing each injector is spraying at 6 different phases of rotational event.
What would help greatly is if we knew what the stock HPFP puts out with a 1.00 scalar so that we can maintain HPFP headroom and calculate remaining flow for PI for given HP levels.
Any insight on this. I'm sure if i sat down and thought it out with some calculations we could come up with a good guesstimate @Terry@BMS @SteveAZ
I wrote this up pretty quick and copied and pasted from PM's I've answered.
From my own tuning experience on normal EFI's, injector lag times and IPW are huge players in proper tuning. To each their own.
Please comment with any insight or added info.
I'm not even close to the most experienced tuner but i have done a lot in the past and have found things out the hard way
The quick down and dirty.
The #55 injectors that people are using flow 55lbs @ 43.5 (578cc/Min) (standard psi for fuel injector flow benchmark and 99% of EFI engines) and we are running them at 72psi ( So they really flow 744cc/min)
Take Josh's (MR2 Josh) for example 861WHP 100% e85 and 80% IDC and his HPFP is about 80% from what he said. That is a $#@! ton of fuel and still has a lot of head room (80% is a good peak IDC). This is way to much for anyone running less than 860whp. Even though they are considered secondary fueling they need to be power matched to the engine. You want to be around 75% idc at your peak power/rpm to leave some head room and not over work the injectors. This can easily be done with a few calculations.
Batch firing is what scares me when the injector is open for such a short period at such a high power and RPM. Terry is only at 30 or 35% at 600+ on straight E85. To me that injection window is way to short and i wonder if thats why he is having timing pulls and cant figure it out. Here is the secondary PI injector window based off Terrys published results.
RPM IPW IDC
4000 10ms 33.3%
5000 8ms 33.3%
6000 6.65ms 33.25
I know its not 33% across the board it probably starts off lower and rises, so technically these numbers would be even smaller.
Normal IPW is more than double that.
With race fuel these numbers would be in upwards of 30% less. If your barley using them and don't plan on making much more power I would defiantly go to a smaller injector and increase the IPW. That's just me though. It's not a one size fits all.
On batch firing each injector is spraying at 6 different phases of rotational event.
What would help greatly is if we knew what the stock HPFP puts out with a 1.00 scalar so that we can maintain HPFP headroom and calculate remaining flow for PI for given HP levels.
Any insight on this. I'm sure if i sat down and thought it out with some calculations we could come up with a good guesstimate @Terry@BMS @SteveAZ
I wrote this up pretty quick and copied and pasted from PM's I've answered.
From my own tuning experience on normal EFI's, injector lag times and IPW are huge players in proper tuning. To each their own.
Please comment with any insight or added info.