E85Forum.com

hotrod · Joined: 19 Apr 2005 Posts: 872 Location: Colorado

I'm a happy camper, I just ran the WRX through the Colorado emissions test with my new home made FFV setup, and passed with flying colors.

100% summer blend E85 with an extra 1.5 gallons of gasoline added to the summer blend, on Harvey's baseline tune, I have a single Spintech high flow cat in the exhaust now.

For those of you that don't know the Colorado emissions test is a driving cycle,(I/M 240 test) on an AWD dyno test so these are under driving condition tail pipe emissions on E85 .

http://www.aircarecolorado.com/im240tst.htm

Engine has 59K miles on it, with over 100 drag strip passes on it, no detectable oil consumption, converter is new.

Fredster · Joined: 20 Nov 2006 Posts: 111

hotrod · Joined: 19 Apr 2005 Posts: 872 Location: Colorado

A cautionary note for anyone playing with E85 seeking to copy my home made FFV project. After some testing today, I think I would have to issue a strong caution to using the "autotune mode" if you are running any significant boost levels (over 8-12 psi).

As you know, I recently have been running a bit lean, and part of that was due to the recent change over from winter to summer blend E85. Well I managed to scare myself today! I have recently been exploring fuel economy issues with the E85, using the midrange fuel pressure setting and let the system use LTFT's only to handle the E85, starting from a safe tune at a 50/50 gasoline-E85 blend. The result is, I made a few too many tweaks to lean the mixture out, working entirely in the low boost range.

I first did a bit of logging and found that driving like a normal human being in daily traffic, I rarely went over 2-3 psi boost in typical city traffic. On the few occasions that I did, I seldom was on boost long enough to get over about 8 psi boost (this was in economy driving mode, ie easy into the throttle avoiding WOT squirts).

I have been driving on the summer blend E85 now for a couple weeks so all the fuel trims had fully stabilized and today was a nice cool day with some light sprinkles of rain, so I thought it was a good time to do a couple of WOT runs and see what was happening under those conditions.

I found that I was running lambda 1.02 ( 15:1 gasoline AFR) all the way up to 18 psi. Eeeeeekk! Surprised

Needless to say it did not take me long to get out and crank up the fuel pressure to 55 psi. That dropped my Lambda under WOT open loop down to 0.82.

The good news is, I was expecting it to be a bit too lean, so had been purposely avoiding flogging on the car hard. I was also so lean I was over on the lean side of the high detonation mixtures. No harm no foul, but just a red flag and a word to the wise, it is easy to get so carried away "tweaking the system" that you go a bit too far!

All that said, I think it still has some possibilities for folks that are willing to run low boost or NA setups strictly for the true FFV capabilities but I would not recommend it now, especially on the summer blend E85 if you like to run the car hard.

Autotune would work fine if you also had a water injection setup however.

The other observation is that the single best thing you can do to increase your fuel milage is to change your boost curve! I have a Blitz DSBC which has 4 settings (channels) and I can set the boost gain independently on these channels. By running a very low gain on the first channel I can create a situation where in day to day driving my boost seldom gets up above 3-6 psi and a full WOT pull will only go up to about 1/2 of the max boost limit I have set. Then by simply twisting the knob to channel 2 which has a higher gain on it I have a normal agressive boost profile.

Using the low gain setup I bumped my fuel milage from 18 mpg to almost 24 mpg with no other changes. In short agressive quick spooling boost curves are your enemy if your looking for good fuel milage.

Larry

Alcohol · Joined: 17 Apr 2007 Posts: 634 Location: Central Wisconsin

Hotrod- do you have any exhaust gas temp monitoring devices on this car? Have you looked at the spark plugs for lean indication?

hotrod · Joined: 19 Apr 2005 Posts: 872 Location: Colorado

Alcohol · Joined: 17 Apr 2007 Posts: 634 Location: Central Wisconsin

Thank you Larry- I was curious what your indicators were.

BravoFox · Joined: 14 May 2007 Posts: 2 Location: South Africa

Hi Larry.

I am glad to see someone playing on a Scooby with E85. Very Happy

I myself drive a 2006 Impreza 2.0R(Australian Spec).
Basically the same 2 liter engine as your WRX but only N/A.

Myself cannot start to play with this, as E85 is not available yet in South Africa. But should not be that far away...

My only question at this stage, do you have any concerns that the ethanol will deteriorate your fuel system?

I know this is a basic E85 question that maybe needed to be asked elsewhere, but I’d like to hear your opinion since you also drive a Subaru.

hotrod · Joined: 19 Apr 2005 Posts: 872 Location: Colorado

BravoFox · Joined: 14 May 2007 Posts: 2 Location: South Africa

Wow! That is great to hear. After 5 years and no visible damage is great news.

Obviously, once I can get E85, I will not be able to directly apply your recipe because of the non-turbo design, but it should be possible to get it done in the end.