Thread: Running e85 on stock fuel system

E85 is just more forgiving.

I've trapped 110mph on a weak stock pump leaning me out in the 13's.

Originally Posted by darkhorizon

For reference on "it will probably run bad"

The race cars with turbos... run 18:1 afr at cruise with lower than gas egt.. on stock timing.

I have tested wot afr from 10.5 to 13.5 with very little power difference inbetween. Not to say there are situations where you would want rich or lean setups but for the "I wanna run e85 and a smaller pulley" guy its going to work fine.

So you ignore the injector offsets and just adjust other fueling to sustain your Afr then?

Originally Posted by 91parkave

So you ignore the injector offsets and just adjust other fueling to sustain your Afr then?

hes saying with 42.5s yes. 42.5s are around 30% bigger and with E85 you need 30% more fuel so with a stock tune, E85 and a set of 42.5's it might run perfect. If the injectors dont quite flow rated volume or flow more, if your "E85" is more like E75 or any other factors, it might run like **** or run your LTFTs off the scale. If you already have a tuner I see no reason to not just dial everything in correctly in the PCM.

I get what he's saying. It just seems so ass backwards to just plug in injectors and hope for the best..its just to easy now and days to have the proper injector data put in to get it right

If you have a tuner yea its easy to do it right. If you wanted to run straight e85 on the cheap and drop a few pulley sizes...

Originally Posted by darkhorizon

"hope for the best" is pretty dumb. I am scanning and I get to watch my fuel trims stay about +7 or so across the board on full E85. Its a bit rich for me but it helps the weak fuel system out a bit and I want it to be richer than normal at WOT because im running a pretty small pulley and I want the intercooling bonus. Anything short of 1/4 mile runs (fuel system) and im around 10.8 afr at wot and 14.5-15.0 at cruise on stock timing and a stock narrowband running +7 trims. You cant "tune" that car any better than it is... If I wanted better MPG i would just unplug the o2 sensor and clear the trims for open loop lean cruise... no tuning still. Dont bring the "you can run so much more timing" debate in here... Ive been there and done that only to find stock or less timing is ideal on e85. I am making the best trap speeds on 14 degrees timing and e98 on the 9 second car.



As mentioned in the other thread, you cant change offsets or min pulsewidths in any 3800 PCM i have found. Ive tried both the 98 and 01 code sets so if you have insights let me know.



What is "it"? You keep eluding to this magical thing but you never seem to explain it. Same with these magical offset tables...



I have HPT, DHP, an EFI live, as well as built 3 megasquirts and tuned ~20 AEM/haltec/powerFC/Hydra standalones from scratch. Are you trying to say im "doing it wrong"? Care to explain what "it" is I can do better?

inj.jpg

These are the tables im reffering too. i understand 3800pcms are very basic compared to per say LSX PCM's however as said earlier i know that every injecotr set reacts diffrently to vacum, ign voltage and has a effect on its overall performance, Im not doubting your work over the years, im just curious how you profess to run things like you do.

Originally Posted by darkhorizon

Those tables do not work in 3800s. The mapping is there but it isnt used.

Ive done a pretty good job explaining everything here... what part of it is missing?

If there was a "good job" there would be no question about it. Most everything tuning related in 3800 land is parott talk off what some on else says etc...if a working example like why this and that people would have a easier time understanding tuning methods.

How would mixing or running e20 and or e30 affect the stock injectors?

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Originally Posted by darkhorizon

The lsasing world is more diluted with bs than the gtp world anymore. Its refreshing going over to the tuner cars where these random crazy "wrong things to do" dont exist. For some reason people think because thry have hptuners they have to go in and throw years of engineering data in the garbage and put their own insanity in.

That's your perspective. No one is throwing your data and hard work away. But when you're a self proclaimed expert Don't get flustered when people ask....why does 1+2 =3.

Now Im tempted to buy some 42.5s and a smaller pulley.

I would love to run e85. It pretty much flows from the faucets around here. Much easier to obtain than 91. But all this is way over my head, and sounds expensive.