Runn

Has anyone converted to E85?

I run my car on a 50-50 mix right now without any problems. I have added to the VE-table thats all. Looking for bigger injectors before i move up to 100% E85.

Does anyone have info of the Flex fuel vortec´s tuning... mainly what the PCM changes when it uses E85 or Gas.

GuitsBoy

iTrader: (4)

The flex fuel vehicles have a sensor that can tell whats in the tank, and how much fuel to flow. If you convert for E85, im pretty sure youll have to keep it to e85 and you wont be able to run the car on regular gas without changing your tune again.

What mods do you have? I believe you need to add about 40% extra flow when you figure in what injectors you need. Youll also need a big fuel pump or possibly a double. Might have to swap to a larger fuel line as well. From what I understand the rest of the fuel system (what little you arent going to replace) whill hold up to e85, although this is only what ive heard, ive not done this myself, although i have entertained the idea...

Runn

I´l be running 100% E85 at all time.

The 5.3 flex fuel has 33lbs injectors instead of 28lbs... I think the fuel pump is going to be enough if not i´l change it.

z_speedfreak

iTrader: (3)

running E85 doesn't require different seals or anything? doesn't alc eat away at rubber? D_run how much are you paying per gal of E85? and how many stations are around you? I still havn't seen any around me.

Runn

There are E85 stations everywhere here... Volvo, Saab, Ford all sell flexifuel cars. E85 are alot cheaper.

E85 does not eat away the rubber... look at the E85 vortec engines they have the same rubber.

Runn

I have #42 injectors that i am going to install and then run with 100% E85. And try to tune in the car. But all help and tips are welcome

So a comparision between the timing on gas and E85 from a vortec E85 would be nice. Anyone know where i should look or ask?


And have found this, Maybe it´s only the VE table that is changed when driving on E85?

Bombguy99z28

I thought about it, but once I calculated injector needs to support 400rwhp @ A/F ratio of ~9:1 @ WOT, I decided not to.

VORTECFCAR

iTrader: (2)

I proposed multiplying your injector constants by .68 to achieve the proper stoichiometric ratio. That should compensate for the difference between 14.7:1 stoich for gasoline and the 10:1 stoich of E85.

Bombguy99z28

part throttle isn't really the problem, lambda is lambda and the o2s will compensate. WOT is the problem, where the higher injectors would be needed. 42lb injectors might support 400rwhp, but no one has really tried it yet. Apparently my old thread is no longer on the forum that had some info in it.

horist

ask and ye shall receive
https://ls1tech.com/forums/pcm-diagnostics-tuning/411115-new-e85-question-o2s-lambda.html

(right now due to the perf issues , search only goes back to the beginning of the year... so it's a little tricky to find old posts)

Runn

I had a look at the flexifuels BIN-file and what i can se they only changes Stoich.

OK.. so the flexfuels change the stoich (and what i can see thats the only thing that changes when the sensor senses the E85 is in the gastank), but i should be able to change the VE instead right?

Since the stoich for E85 is 9.765 i think changing the Stoich AFR to 9.765 feels like the right thing to do... Then the PCM can use the stock VE-table.

This is what i plan to do...
Return my VE table to stock (because it is tuned to 50% E85)
Change my Stoich to 9.765
Fill up the tank with 100% E85
Tune in my VE (while checking for knock)

Any ideas?


The O2 sensors would still work. They don't understand AFR, they only understand rich/lean. If you are using regular or E10 the stoich AFR is ~14.7:1 (as you well know) and when the O2s are switching, this is the AFR it is indicating. When you are using E85 (AFR 9.765:1), the O2s will still work, switching between rich/lean. It's just that the point they are switching at is 9.765:1. You have to know what fuel you are burning to properly interpret the information the O2 sensors are providing.
Lambda 1 is always Lambda 1 no matter what you drive your car on, the o2 sensor doesn´t care if the AFR are 14,7 or 9.765... it measures the available o2 in the exhaust gases.

Bombguy99z28

All you should have to change is stoich, and make sure your PE calculations put you around 6.9-8.5 (equivalant lambda of 12.5-13.2 in a gasoline engine).

Runn

Yes, I will have a look at the PE calculations, But since the PE is calculatet with stoich AFR that is changed to 9.765 there shouldn´t be any problems.

Bombguy99z28

Correct. Get some dyno time and post up what makes the most power.. I'm curious, I'd bet you could actually run it a bit leaner and with more timing due to the octane difference.

Runn

Yes more timing is needed...

Runn

My car run´s great on 100% E85... i´m almost finished with my VE, but it doesn´t look like the gasoline one at all.

Now i´m wondering about the PE, how much more fuel does E85 want....