Why not just bump up the methanol injection and use it for knock protection as well? You shouldn't need knock protection while cruising. A lot of the big turbo (and I mean BIG TURBO) RX7 guys with 500+ whp run some combination of water and methanol injection tied to boost pressure and/or engine speed. The fancier ECU's can even tie it into knock detection and EGT.
My point is methanol is better a knock prevention the ethanol. Why not use it for knock prevention in boost and just add extra 93 octane?
It's funny how much the MS3/6 community has embraced E85. Most rotary guys hate it.
We don't have the ability to upgrade our Injectors and
Because corn is the elixir of life for a boosted car.
Example, on stock turbo and 93 octane, I made around 275whp and 300tq. On a 4 gallon e85 and 8 gallon 93 octane mix, 320/360.
On my 5858 when I was stock block we didn't even make a straight 93 octane map, as the block had 124k on it, and one bad tank of gas and zzb was imminent. On a e23 mix and 22psi I was at 380/350 and completely maxed out the stock fueling system.
Once I went built motor and to the pte 5862, I added the meth kit that sprays Pre throttle body because it was cheaper than adding 6th port (2 port injection Injectors spraying Pre throttle body). since we don't have actual DI Injector upgrades for the ms3/6, the 2000cc/min of meth I'm spraying gives me just enough additional fuel to run 28psi and the meth kit is pushed to near its limit.
Plus meth is a lot more expensive than e85. My meth only sprays at 10psi and higher and is on a progressive controller. Spraying 400cc/min at 10 pounds of boost and 2000cc/min at 28 pounds of boost. 5 gallons lasts me over a month.
We don't have a standalone ecu that works. We are limited by what Cobb has to offer at the moment with recalibrating the stock ecu. Which means 400whp or slightly less is the most we can make on the stock fueling system pushing 100% Injector duty cycle, and it usually takes some e85 to even come close to 400whp. Or your choice of 3 fueling methods if you want to make more more than 400whp. (I'm around 450-460)
1: methanol injection either Pre throttle body or at the intake manifold (as much as your kit can handle)
2. 6th port (4 stock Injectors plus 2 PI Injectors spraying Pre throttle body in any size you want (1000cc to 2200cc Injectors usually) + an upgraded in tank pump)... 6 total Injectors. Corn is mixed in tank because of low cost, ease of fill up and minimal reduction in mpg, as MBT can be reached between 3-6 gallons of total corn, and rest 93 octane.
3. PI kit (4 stock Injectors plus 4 PI Injectors spraying at the intake manifold + and upgraded in tank pump)... 8 total Injectors. Corn is mixed in tank because of low cost, ease of fill up and minimal reduction in mpg, as MBT can be reached between 3-6 gallons of total corn and rest 93 octane.
With options 2 and 3, you don't need a separate tank. Just mix your e85 and 93 and the additional Injectors are controlled separately with a split second controller and the stock Injectors are scaled to fuel at a constant rate once a certain maf voltage is reached via Cobbs software.
The Cobb software will also control all the rest of the stuff (timing, throttle tables, vvt, etc)
And not needing knock protection while cruising... That's a bit different as well. The ms3/6 ecu will advance timing til it sees knock during cruise and then pull it back. On 93 octane, it's common to see up to 7-8* of knock retard at part throttle as the ecu does its thing. On e23 (mix will vary by car and mods), I see zero KR, ever. Aside from a blip of 0.35* on spool up every now and then. Part throttle knock is very common and happens to damn near every ms3/6. So yes, it is needed. Again, a limitation of having to use the stock ecu and not having the standalone options everyone else has on other platforms.
And that's why you can't take an ms3/6 to any random place to get tuned. There's a handful of people that know these things inside and out, have tested and found the limitations and quirks that are ms3/6 specific, and that the community trusts to let them molest our ECU's.
Edit:
Newer boosted cars that are port injection love e85. Evo, sti, gtr , etc... Look at the fastest ones. If they're driven on the street, and making power, and not track only, they're using e85 in some capacity. Upgrade the Injectors and run Either a mix, or 100% depending on the tuning solution and/or hardware limitation. DI cars love it too. With meth injection, you always have it in the back of your mind "what if my meth tank runs dry?". A failsafe won't always save you in time. With e85, if fuel gauge isn't reading empty, you're likely good to go.
I've run an e85 mix between e23 and e33 for almost 100k miles since April 2014 in my ms3 without using straight 93 in that time because it works.