The E85 Mystery

Jordo!

Boost pressure fights fuel pressure -- so long as AFR's are maintained, the pressure may drop, but it would technically be sufficient.

If it skews lean under the right conditions, and there's no more bigger pump or injectors to use (or if there's driveability issues -- poor spray pattern/atmomization/cylinder wetting from the injectors or too much pressure from the pump for a smooth idle), I suppose you could try a rising rate/variable fuel pressure valve.

I thought switching to a return system brought with it a whole host of potential running and tuning issues (including possible vapor lock) under all circumstances except high load and high boost -- maybe I'm mistaken?

It all depends on how much more fuel you need to maintain the same torque levels. If you need, say, 20% more fuel, you need 20%+ more pump. Sounds like the OEM pump will be struggling with that.

Synolimit -- see what the infamous 250+ whp E85 Z is using. Sounds like that's what you would need. I think there's at least one other member on here who switched to an E85 safe set-up too.

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