Well that sucks. Just thought that with either injector upgrades and aux fuel upgrade, that pump WHP would see a increase since the limiting factor is the OEM fuel system versus the pump gas if our FiSTs aren't making 300 whp. (Really seems like on pump, accurate WHP is like 250 to perhaps 270 with 91 and 93 versus many of our peers positions on the forum that we can hit 290 WHP to 300 WHP on pump with a big turbo upgrade and pump gas with some variation of fuel upgrade.)
I know that with some variation of an etune we can reach 320 WHP to 340 WHP on the Bosch injectors alone being tuned by Adam. But was just curious if there was any increase with pump gas is all. I appreciate it.
To my understanding, something like a hybrid or S280 on our engine is octane limited especially on 91, and just adding more fuel won't help, so you are not fuel system limited on pump gas.
With higher octane, you can push more boost and timing to make additional power, but doing so with ethanol blend requires even more fuel due to the lower AFR's required for ethanol and so you run up against fuel system limitations before falling completely off the right side of the efficiency island of a smaller turbo where is just becomes a fancy hairdryer. Most "maxed out" turbos are already running off the right edge, brute forcing more charge air into the cylinder by intercooling+fuel evaporation, but there are diminishing returns. You could theoretically push a small turbo even farther on pump by using an even more massive intercooler, but that causes its own problems.
A bigger (big) turbo can move more air more efficiently to make more power at lower boost on pump with less exhaust backpressure, but you pay the price in spoolup RPM on a small engine like a 1.6L.
If you were able to run higher octane racegas, you could easily max out the hybrid/S280 turbos to almost what ethanol can give (not quite) without even upgrading the injectors, and the fuel volume required is lower than with ethanol blends. You could make even more power on these turbos on E85, but that's typically done with much larger injectors on a port injected engine, and we are fuel limited by the scarcity of direct injection upgrades. Instead of +30% and squeezing a bit more with increased fuel pressure, a port injected engine on E85 would run something more like 2x to 4x larger injectors (or more). You could however get there on E85 with an Aux fuel setup (which is basically adding high volume port injection). This is the reason DI engine tuners like lower ethanol blends like E30 - less extra fuel volume required to get decent octane (94+). For older style port injection, once you head away from pump gas, there's really not a lot of point to enduring the hassle of blending something like E30 when you can easily just run full E85.
You can't directly compare flow ratings on DI vs port injectors because DI is limited by intake/exhaust valve opening where port injectors can add fuel for 2 full engine revolutions, but our injectors are probably in the 1200-1700cc range and can deliver fuel similar to something like 400-440cc port injectors. Port injected engines running E85 would typically run somewhere between 1000-1200cc injectors to hit 400hp, and 1600-2100cc to go higher.
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