Graham regarding that Gen III motor

[XfireZ51]

Graham,

Just curious that the Gen III motor u built uses 8 injectors rather than the 16 the production LT-5s use. I get that part of the reason for using 16 injectors was so u could achieve emissions and idle qualities while still retaining performance in WOT conditions. Small pulse width is easier to control w a smaller injector, at least w a constant fuel pressure.
Using BSFC and a 20% headroom for the injector, u would be using ~ 42#injectors, correct?

When I bumped the power on my 84 Xfire to 280rwhp, I obviously needed more injector, but idle suffered. Used a VAFPR to vary fuel pressure from 10# at idle to 20# for WOT. The ECM I used supported that by calc’ing a new BPW for the differing kPa levels.

What strategy was implemented in order for the Gen III to use one larger injector and still be able to control PW for idle etc?

[grahambehan]

The spt were there to ensure the secondary lobe was not not active during low load operation idle and emission territory. The cam profile switching planned for the next gen negated that need. The nigh torque profile switched to the high power profile at predetermined rpm. The linearity of the inj was good to well below the pulse width required plus the next generation of ECM was not planned to support 16 inj.

Graham

[XfireZ51]

IIRC, thought I read that the C6 ZR1 used fuel pumps providing 3 levels of fuel pressure depending on power output invoked.

[grahambehan]

IIRC, thought I read that the C6 ZR1 used fuel pumps providing 3 levels of fuel pressure depending on power output invoked.

Yes the c6 zr1 does, thought we were talking gen 3 lt5.

Graham

[XfireZ51]

Yes the c6 zr1 does, thought we were talking gen 3 lt5.

Graham

No I was absolutely asking the LT-5(the real one) not the LS-9. I was just recalling a different strategy used for same reasons.