Hello,

I've been tossing this idea around for my next project, and was hoping for a sense check from all of the experience on this board? I'm planning a low-ish compression (9.5:1) 6.0L Gen 3/4 in a square body suburban with a full time 4wd (NP203) transfer case, 4L80E, 3000+ stall, and 3.42 gears. Mild cam (</= 220 intake), and 15psi max boost (turbo). This is planned to be a year round semi-daily driver. Holley makes a dual injector low ram intake manifold for both cathedral and square port heads. What I would like to do is run some stock GM injectors for the main fueling off of the main fuel tank (31 gallon), and run 87 octane, but then fully switch it over to a secondary fuel system with E85 when under boost. I think I can package at least 7-10 gallons in a secondary fuel tank. I would do a stock GM flex fuel pump in this secondary tank, feeding a surge tank to feed the secondary injectors. I know it adds a lot of expense/complexity with a completely separate fuel system, but the primary one would be very simple and not require anything special. E85 is readily available around me, the trouble is when I get out of this immediate metro area, it is virtually non-existent. Also, when I get out of this state, I usually cannot even find 93 octane, usually 91. It is a bit difficult to estimate how often it would be under boost and the amount of fuel consumption from the secondary tank, but I don't think it would be THAT much for the occasional and brief heavy foot, while 95% of the time you are just driving normally.

I am planning on using a Dominator ECU, so the controls portion would be manageable, with all of the safeties in regards to running low on the secondary fuel tank, boost and timing control, etc. I have searched quite a bit and do not really find much on people setting up a system like this. Maybe because it is just a bad idea? I have run a Whipple(7-8 psi) on a Yukon with a flex fuel sensor, and it kind of sucks when I have to run 91 or 93 and reduce the timing accordingly, lol. Then you also have to watch the stations that try to gouge you on premium fuel prices.

Thank you in advance for any input!

 

Your dual-fuel setup is overly complex and a potential headache. The Dominator can handle it, but it's a lot of extra plumbing, wiring, and failure points for minimal gain.

Just run a single, properly sized fuel system with a flex fuel sensor. Use a big in-tank pump (like a Walbro 450) and good lines. This lets you run E85 when you have it and safely dial back timing for 91/93 octane when you don't. The ECU will handle the blend automatically. It's simpler, more reliable, and achieves the same goal.

 

Considering the application, I really wouldn't do that. That low ram is going to kill all the torque off boost and even with a dual fuel high ram, you need all the torque you can get. If you want the capability, you could run the dual fuel tanks with just a flex sensor and let the computer do all the work. I am considering a dual fuel system for my AMX build, but I'm thinking about running a Nitromethane mix another tank, won't mix w/ gasoline.

 

Thank you both for the input! Maybe I am best to just do meth when under boost? I am not sure of the best intake, for low/mid rpm torque, that is friendly to modify for individual cylinder meth injection. Even considering going with a carb flanged intake manifold with injector ports, and then doing a carb plate meth injection just to ensure reasonably even cylinder distribution, though all I can find are single plane intakes that probably aren't any better than the Holley low/high ram for mid range. I know some guys dump it right in the intake behind the throttle body, but to me that is asking for trouble with distribution.