Injector size vs Fuel pressure

[BlackBird_SR71]

MS 2 3.0 board. 3.42 firmware. TS 3.018

When setting injector size, is that determined at a baseline standard of 43.5 psi ( 3 BAR ) The system we are working on has a static FP of 37.6 PSI. I'm thinking I would have to set injector size to 289cc ( Flow recalculated to 43.5cc ) . This would affect the VE table, would it not?

[Gs1327]

There is a flow calculator on this page:
https://www.rceng.com/technical.aspx

You need to enter the flow rate at your actual running pressure.

[BlackBird_SR71]

There is a flow calculator on this page:
https://www.rceng.com/technical.aspx

You need to enter the flow rate at your actual running pressure.

Yes, that's the calculator I use. OK, so that would be the stock 260cc then.

We have a problem with having to run excessively low VE cell values at idle RPM. Sorting some hardware issues out, but I guess I can rule out incorrect injector size values entered. I'll start another thread on the VE Tables. Thank you.

[slow_hemi6]

Incorrect dead time can have a big effect on low rpm VE values. Other settings like mutiply MAP and include AFR also affect the VE values.

[BlackBird_SR71]

^ older D atsun 280Z Low-z injectors. 260cc L28 Turbo injectors. Using dead time of between 1.0 to 1.2ms right now. Trying to get exact data, but hard to find. Also the issue is that the injectors are old, and latency can increase with age.

On the positive side. At 1.0ms latency and using PWM, the pulse width is dead nuts stable at 1.3ms... which seems reasonable. Also I can get the a maximum vacuum reading of 19.0 in/hg . This is good on a 7.5 Cr engine that is well used. Can go over the top of Bell curve for Rich best Idle and Lean best idle... at either 1.0ms or 1.2ms so I think we're OK

A NA engine with the same fuel pressure (37 to 37.6 psi with FPR hose disconnected ) runs 188cc injectors. VE table generated:

VE Table 188cc NA.jpg

VE Table generator for Turbo Engine and 260cc injectors. Calculated VE table cells at idle down to 14 with low loads.

ScreenShot002.jpg

[BlackBird_SR71]

^ Here is the requested AFR table for the 260cc injector size ( Turbo Ve calculation ). Same requested AFR table used for calculating 1880cc, but only up to 100Kpa load.

AFR #5.jpg