I'm running E85 and it is costing me more in E85 at $2.70/gal than 91 at $3.20/gal, so I would like to improve my E85 mileage. I copied hiboost's ign adv table from the beginning of this thread and got 19.2mpg under perfect conditions (level cruise, 58mph, 50*f) normally I get 15-16mpg in mixed driving.

My logged timing was 31*-37* at 52-65 load, 2500rpm, 20-25% throttle using Hiboost's table so I bumped the timing up to 44 in the 40-70 load cells from 2000-3000rpm but I have not tried it in the car yet.

Seeing as I am running E85 (slower burning I guess) should I increase my timing even more? (I am keeping an eye on my knock count while testing this tune)

 

I think part of the reason I see such dramatic results is the free flowing mods I'm running place me at 35-45% load cells during cruise at 65-75 mph and the extra 3*-4* timing boost really helps. I would imagine that E85 could allow greater timing at higher loads, although the knock threshold is different with E85 so going too far may actually hurt MPG. Best bet is to find an identical stretch of highway that you can repeat the test with cruise control before and after the changes.

Then look at the logs for an equal time period and use Excel's ability to do a running average of the cells selected to compare average speed, psi (which will be in vacuum or negative psi), load, injector duty cycle, injector pulsewidth, timing, rpm, TPS, and maybe even airflow. If you compare averages for all of these things you can get a pretty good idea if increasing timing is actually increasing power output at that TPS or starting to decrease again. You want to have the timing high enough to be at the peak of that efficiency curve and it will be a different number at difference speeds and RPM's so it's not easy to get this exact!

As long as you have the time to test all of that you should be able to find out the best settings for various RPM's and loads and then interpolate between them as needed to be close enough. If you put all that work in, definitely report back your findings!

 

Just wanted to share that I am getting 22 city 26-27 highway with 45 degrees.. open loop cruising at 15.5 afr, 60mph-70mph. fuel trims at 2.47 and 2.17

What would be the lean cruise limit? could i cruise at 16 as long as i dont see knock?

 

Just for share, I've noticed that with the same afr (15.5) at the same rpm range and 65 mph with a TP I can get 27 mpg with stock cat 25-24...

 

my results aren't as good as others, but hopefully some data points
these runs were done on relatively flat ground, 70 mile runs (except for last get to that later) mileage checked by refueling, 70 mph on cruise. 2.2L 750xp, TMP cams


intake timing exhaust setting ign mileage observed vacuum observed on level
15, -20, 40, 19.4, 8
0, 0, 40, 21.2, 9
20, 0, 40, 21, 8
25, -10, 42, 20.5, 7-8
5, 0, 42, 21.4, 9-9.5
10, 0, 42, n/a, 8-8.5
0, 0, 42, 23.1, 9.5-10


Apparently, the TMP already have enough overlap and dwell, the best results are no advance on intake. last run did have a short range where speeds dropped a little, hence the mileage may be exaggerated. it looked like if I dropped to 60 or even 65 there was a big change, much more vacuum, hence I would believe the mileage will go up a bunch if I slow down.


Hope this helps

 

im getting about 32 mpg on highway cruise with full bolt ons

 

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