Stock 9.8 VIII turbo with 1000cc and one Walbro 255

Log 1:
7000 rpm
21.3 psi
10.9 AFR (gas configured wideband)
87% IDC

Log2:
7125 rpm
20.1 psi
11.2 AFR (gas configured wideband)
82% IDC


I don't see how the max PSI matters when it comes to IDC's, but since you asked it was 27psi in log 1 and 26psi in log 2. Logged with JDM MAP.

 

First tank of E85. Probably more like E75. No tuning except to dial in the injector scaling. Running FIC 1050s scaled at 696 cc/min. I'm finding that FIC 1050s are pretty much exactly 2x the flow capacity of stock injectors.

7000 rpm
20.0 psi
11.0 afr (gas configured)
70% IDC

With more tuning, I suppose I'll hit about 80% IDC.

Pump gas values are:

7000 rpm
20.0 psi
11.0 afr
47% IDC

 

I think another big factor is fuel rail, fuel lines and fuel pumps being used. By simply switching from a inline walbro 392 to a bosch 044 my A/F ratio went from 12.5:1 to 11.5:1 and my duty cycles dropped from 98% to 94%. So it runs richer and runs less duty cycle. Now that I have it dialed in at 11.7-11.8ish I am down to 92% duty cycle.

 

The more powerful pump is pushing up the fuel pressure.

 

The base fuel pressure stayed the exact same at 50psi. I checked it and didn't touch the regulator.

On the top I believe it is simply keeping up now, where the walbro was not keeping the 1:1 ratio as boost got really high. The 392 is nowhere near as good as the bosch in the 80-90psi range.

 

ok, I checked, and you're not on the stock turbo, so not surprising that a more fuel pumping power made a difference. Stock turbo setups should be fine with a Walbro. Max boost I figure I'll see at 7000 rpm is 22 psi which gives a fuel pressure of 65 psi (or maybe less since the Evo base pressure is closer to 40 psi). A Walbro can flow 4 liters/min at 65 psi. If my FIC 1050s are at 85% IDC, that's 3.4 liters/min. More realistic is probably about 80% IDC since which gives 3.2 liters/min. So there's still a reasonable (but not fantastic) amount of additional fuel flow available with stock turbo setups. My concern with a stock turbo is not for the Walbro but the fuel rail.

 

Stock VIII turbo, FIC 950s, 25 falling to 22-23, 62% max IDC.