Base tune on CA 91 vs Race gas prior to e85
 

Did a quick search but couldn't find anything specific to my question.

Finishing up my Trackspeed EFR6258 build and nearing dyno time, which I will post in the welcome section soon, but my question is related to megasquirt and whether or not to base tune on CA 91 or race gas prior to e85 adjustments.

As far as I can tell, the e85 configuration really can only modify fueling and timing, and cannot adjust boost, which would be nice to add more of when running e85.

I recently finished building and breaking in my motor with 84mm 9.5 supertechs. Looking back I wish I had gone with the 8.6's for det protection on 91 octane.

When tuning for max power, I am assuming that tuning on CA 91 then e85, would yield lower overall power (both on the 91 and e85) than it would if I tuned with race gas 105+ and then e85 as I should be able to tune with higher boost on the latter and then still potentially add a bit more timing and "cooling effect" with the e85. Although it would afford me fuel options on the track after I run my 55gal drum of e85 dry.

​​​​​​​Thoughts?

yes you can. Vlad tuned my car such that pump delivered about 23 psi, and e85 went to almost 30

Assuming you are using an MS3, not trying to kludge a flex-fuel MS2 setup.

The MS3 will support separate boost tables for gas and E85 running in Flex mode, so you will set up two different boost target tables during tuning. I use this feature to run 17psi/300whp on gas and 23psi/415whp on E85 without having to open the laptop. The bias duty table and EBC settings are all the same, you just get a second target map for the flex map. You want to be careful with this feature and do a little testing in the E20-E25 range if you plan to convert back and forth, or just be careful and drain the tank of any remaining E85 at the track before you fill up with gas.

With a 6258, the octane of the gas you use when you blend in a full tank of E85 is not going to alter the power substantially. It might on a big-boost 6758 or 7163 setup, but you'll max the 6258 out before you reach that point. Pump E85 is probably blended with 91 at best, more likely 87, but in practice it doesn't matter.

If you plan to run the car on E85 most of the time, and just want a gas map for the occasional event when you run out of E85, I would tune for 100 unleaded (or whatever the worst race gas you can always get at the track is) on gas and go from there.

Thank you for the replies. I'm currently running a MSPNP2 so it looks like that multiple table setup really isn't an option.

Maybe it would be worth setting up a 91/e85 tune and then write another complete tune for dedicated E85? Or just splurge and go to the MS3.

Is the reason to totally drain the E85 prior to pouring in pump gas to make sure that it isn't upping the boost since it's sensing a small bit of e85 in the fuel?

Splurge for the MS3, you will not be satisfied with how the car runs on an MS2 with flex fuel. MS3 has dual maps for a wide variety of things that really need to be tweaked, such as AFR targets, WUE, ASE, cranking fuel, alternate overboost protection (really, really important). The alternate boost table is also there, but it's probably the least important of all the tables (you can do without alternate AFR targets, I guess). The rest of those are required if you want the car to start consistently in <60deg weather.

You are correct, you don't want the boost to walk up if you end up with an E15 or E20 blend unless you've confirmed that your mapping is safe at those levels (I would want to confirm on a dyno though), or set the blend curve up so that you don't dip into the alternate maps until you are at 25 or 30% ethanol. This will have a small negative effect on the fueling and ignition maps, but you typically run leaner on E85 anyway, so it won't be unsafe. I would probably go for the latter.

Purchased. Thank you for the advice.

Does the MS3 offer more advanced knock features compared to the 2 (ie worth running a factory knock sensor)? Talking to Shawn Church, the MS2's knock detection/correction is weak at best.

Having tuned both ecus on both fuels and flex many times, I can support that Andrews take is 100%.

Dann

The MS3 has very good knock sensing algorithms, good enough to rely on while tuning.

Not sure if you realized, I also sell and use MS3s in my own cars.

MSLabs Megasquirt MS3 Basic

So, i was going through my tune that I received, and I had him keep the boost table blending delayed a bit to ensure I have enough e85 before moving the duty cycle up, but it looks like its a TPS delay on the increase not based on ethanol percentage. See below. Should I change this to ethanol %?

https://cimg2.ibsrv.net/gimg/www.mia...37a1fd57cc.jpg


Thanks,
Ryan

You shouldn't even be using blend curve #6, all the flex blending is done in blend curve #8. #6 is for a boost switch controlled by something like an interior toggle or a water/meth flow sensor or something.

Post your Boost Control Settings page and your Table Switch/Dual Fuel page.

from the looks of it, he didn't set up different ve/ignition tables for flex, just used the standard flex compensation for fuel and timing.........


https://cimg7.ibsrv.net/gimg/www.mia...cee406eabe.jpg
https://cimg8.ibsrv.net/gimg/www.mia...b7897b03d6.jpg

Yeah. Post the ignition map. Either it's going to grenade the moment you put gas in it, or he left 30whp on the table on E85

https://cimg9.ibsrv.net/gimg/www.mia...df872da4af.jpg
https://cimg6.ibsrv.net/gimg/www.mia...327a8a3c26.jpg

That's a gas map, definitely not an E85 map. Are you sure you're looking at the right map?

I would call Church and ask him to explain, I would expect better from him so maybe you're looking at the wrong map or maybe he did separate E85 and gas tunes.

I had him give me 2 tunes, 14psi e85 and 16psi e85. Thats the 16 psi one. The 14 psi just adjusts the EBC solenoid duty cycle.

I think he only used the flex settings to add 6 degrees of timing to the gas map and called it good, and then he played with the boost duty until we got the power I wanted.

There are no other tunes/maps on the car. Here is a look at all settings menus.

He was definitely looking at the megasquirt manual while doing the tuning, so maybe hes not as familiar with the MS3 and the alternate tables it affords? Good to know there's potentially more power available.

https://cimg2.ibsrv.net/gimg/www.mia...85e23dc8a1.jpg
https://cimg3.ibsrv.net/gimg/www.mia...9b688a8e23.jpg
https://cimg4.ibsrv.net/gimg/www.mia...43749a7ece.jpg
https://cimg5.ibsrv.net/gimg/www.mia...6a6cabb5b8.jpg
https://cimg7.ibsrv.net/gimg/www.mia...ce1c9d2f81.jpg

Edit: found the right tuner.
Thanks,
Ryan Helmuth