Please Do Not Run E-85 on Stock Injectors.

Just don't do it please. I don't care what your tuner tells you. I know there has been talk that it's ok but I've not seen anyone provide proof that the stock injectors are ok at that fuel mass (25% greater than stock) and even a mild NA bolt on car like mine well here is proof it's not ok even on the stock intake manifold. GT350, CJ or Boss 302 manifold cars will be worse than this unless making less power than me somehow. My mods are 1 7/8" long tubes with catless X and straight through mufflers, Pmas intake, and my own custom E-85 tune using HP Tuners.

First up are two screen shots with the stock injectors.

Sorry the cursor is not in the right spot it is off in a different spot off screen so ignore the IDC reading of 82% that's not relevant or accurate here. The yellow line for IDC peaks at 97% at 6900rpms (ceiling in the scanner is 100% and you can see how close it is to the top line

Another shot with stock injectors this time with the cursor in the correct spot (just don't mind the retarded timing sine wave the ECM was limiting spark badly in first gear to limit torque until I figured out why)

Now with LU47s and same tune except rescaled for the new injectors.

Note that is just over 70% now and honestly the car is much happier now. It would sometimes show "inadequate fuel flow" as a driver demand torque limit source before but it does not anymore.

I have no freakin' IDEA what I'm looking at here but I do know that I would not run E85 in a car that has not been initially designed for it without upgrading fuel flow capability. It just doesn't make much sense given the much lower power density of E85.

I will try and remember to log my IDC.

I run E85 with an axle back, and a K&N panel filter. My MAFlb/in are routinely in the 43.5 - 44.1 range with the stock airbox.

BMR Tech said:

I will try and remember to log my IDC.

I run E85 with an axle back, and a K&N panel filter. My MAFlb/in are routinely in the 43.5 - 44.1 range with the stock airbox.

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You might be in the lower 90s IDC if stock headers and cats we just got IDC logging recently in an update so for a long while many were not even able to see IDC. Mine gets as high as 47lbs/min at times.

Interesting. Thanks for sharing the info on the IDCs.

I know Lund says no injector upgrades even including the GT350 IM which is really shocking based on what you are sharing here.

I know Shaun @AED recommends injectors for any E85 tune.


I am going to reach out to my tuner now and see if they can tell me what my IDC is on my FlexFuel tune. I am only E85 and CAI.

At least on my 2013 I thought it was a given to at least do the ford 47# injectors, such a cheap investment to feel safer and make sure you aren't maxing out the stocks.

Todd15Fastback said:

Interesting. Thanks for sharing the info on the IDCs.

I know Lund says no injector upgrades even including the GT350 IM which is really shocking based on what you are sharing here.

I know Shaun @AED recommends injectors for any E85 tune.


I am going to reach out to my tuner now and see if they can tell me what my IDC is on my FlexFuel tune. I am only E85 and CAI.

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I would definitely look at those yourself if you can.

kornflake7 said:

At least on my 2013 I thought it was a given to at least do the ford 47# injectors, such a cheap investment to feel safer and make sure you aren't maxing out the stocks.

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Yes but there are several tuners telling people they are not needed even on E-85 with high flow intake manifolds. If I had a GT350 manifold on my car I would have been over 100% and leaning out.

So are you talking straight e85 or flex fuel or both? I've been running flex fuel lund tune not straight e85 and car feels stronger but haven't dyno her yet. Now I'm worried. We pay lots extra for flex tune. And the solution is ford 47# injectors?

16s550 said:

So are you talking straight e85 or flex fuel or both? I've been running flex fuel lund tune not straight e85 and car feels stronger but haven't dyno her yet. Now I'm worried. We pay lots extra for flex tune.

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Mostly those running full E-85 on their flex fuel tunes which is what most do I would think is run E-85 when they can and 93 when they can't like on a road trip.

I thought this wasn't an issue with e85 as long as you drive your car often and run a tank of 91 or 93 octane once a month?

SpeedLu said:

I thought this wasn't an issue with e85 as long as you drive your car often and run a tank of 91 or 93 octane once a month?

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That won't have any effect on maxing out your stock injectors it helps the O2 sensors live longer though. Extra Water from the extra fuel combusting (water is a product of any combustion reaction and the more fuel that combusts the more water there will be). That extra water can kill the O2s in some cases if they don't drain out well.

I mean that's pretty much flex fuel cars have. Bigger injectors and higher pressure pump to keep up the flow.

Seems like it would be an issue for a GT350 car. Someone with GT350 and LTs should datalog and post their findings. Though I trust Lund.

jasonstang said:

I mean that's pretty much flex fuel cars have. Bigger injectors and higher pressure pump to keep up the flow.

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We have good high fuel pressure at 56psi vs 39psi for normal cars but we have rather small injectors that happen to flow 43lbs/hr due to that high base fuel pressure. I believe the stock injectors are around 32lbs/hr at 39psi. The LU47s flow 61lbs/hr at 56psi on our cars but only 47lbs/hr at 39psi. 61lbs/hr is 30% more fuel mass flow vs 43lbs/hr which is perfect for E-85 at close to stock power levels.