Gains from Ethanol..

[diss7]

Went into NZEFI to ask about possible gains from running ethanol in the new ae86 setup, but they're closed until next Monday.

Discussing the fuel system design with Simon from SURFAB, and we're at a bit of a disagreement as to the gains I would see from running an ethanol mix.

He believes I will see more power from the setup by running the fuel, as he has seen numerous examples of cars tuned on pump gas, make more power on ethanol.

My line of thinking, is that power is related to the turbo. As the entire setup is governed by the turbo, as power is realitive to the quantity of air. As I plan on running the turbo at/near capacity, I would see no gain.

I understand that usually a car is tuned to a set point. Running ethanol means more timing and boost can be added, hence more power.

I'm not saying that more timing could be added, but again, how would it result in more power if the boost pressure remains the same??

I'm missing something...?

[Dell'Orto]

I understand that without more boost/timing/compression you wont make anymore power with ethanol.

[strx7]

with the same boost you can run more advance which means more HP from the same CFM (and therefore same psi)

[Al]

E85 even lets CT series turbos make some power.

http://youtu.be/6C_RhRZi6X4

[matt dunn]

with the same boost you can run more advance which means more HP from the same CFM (and therefore same psi)

correct, with just fuel and timing you will increase the power without changing boost pressure,

On my car it was about 30-40 hp from Avgas to E30 at the same boost,
( 60+ hp with a bit more boost too)

To make hp you need peak cylinder pressure at a certain degree after TDC depending on rod angle, about 17 Deg ATDC from memory.
To get that to happen you need to start the burn earlier to allow enough time for the pressure to build,
how soon depends on the fuel, but most older NA Dist stuff we aimed for 36 deg BTDC.

With turbo cars you can never get near that,
15 - 20 is probably thye normal under boost,
so if you can add a bit more timing will help.

[diss7]

Thanks for the info.

[Lith]

My line of thinking, is that power is related to the turbo. As the entire setup is governed by the turbo, as power is realitive to the quantity of air. As I plan on running the turbo at/near capacity, I would see no gain.

I'm not saying that more timing could be added, but again, how would it result in more power if the boost pressure remains the same??

Argh, manufacturers giving hp ratings on turbochargers has been a point which has irritated me for years - it propagates misunderstanding and misinformation. Turbochargers have no say in what happens to the air they pump out after they move it, air is a very important part of the equation of what makes power - but by no means the final word. All a turbocharger compressor does is redistribute air as a result of being pushed by exhaust gas passing through a turbine attached by a shaft, all the fancy stuff which makes the power happens in the middle.

Here is a bit of an example of how the goodness of ethanol as a fuel and a good setup combine to demonstrate the uselessness of turbo hp ratings. The first full street EVO to do an 8s run was running a 700hp rated Precision PT6262 CEA turbo on the side of a fairly serious 4G63 running big boost and E85. If you ponder it, there is no way this is making 700hp or less: http://www.youtube.com/watch?v=xuT3P5Sb2us

On the other hand, there is no way you'd make anywhere near 700hp on the same turbo with Diesel, and to be fair it would be a struggle to even get near 700hp on 91 RON petrol. Funny how they never state what fuel, boost, or general setup that power rating is for - reason being, it is ultimately a very generalised thumbsuck which by no means represents all combinations.

[gt4dude]

On a similar note,

I'm tuned for 98, to run E10, should I blanket my fuel map with +3.3%?


E10 from my understanding is 95+10% ethanol, with a total octane rating of 98, i'm guessing this means i cant add any extra timing?

[pureadrenalin]

On a similar note,

I'm tuned for 98, to run E10, should I blanket my fuel map with +3.3%?


E10 from my understanding is 95+10% ethanol, with a total octane rating of 98, i'm guessing this means i cant add any extra timing?

I'm the same, tuned on 98.
If you run E10, you roughly lean out by 0.3-0.4 lambda. So if your tune is conservative enough to let you do this, then you don't need to blanket change your map.
I however am already tuned a little under 12 (11.8ish), and without as you say inriching by ~3.3%, I'm not willing to lean out by another 0.3-0.4.

[gt4dude]

ahh i dont want to lean out either, my tune is pretty good for AFR its as linear as possible starting from 13.5 in low revs and falling to about 12.5 by the redline

but my ignition advance is on edge (engine especially prone to knock due to head and block skimming)

i was just wondering if +3.3% was the correct amount to add to my injector correction, and if that increase is directly proportional to the net result of 3.3% more fuel per cycle, etc

[Lith]

ahh i dont want to lean out either, my tune is pretty good for AFR its as linear as possible starting from 13.5 in low revs and falling to about 12.5 by the redline

but my ignition advance is on edge (engine especially prone to knock due to head and block skimming)

i was just wondering if +3.3% was the correct amount to add to my injector correction, and if that increase is directly proportional to the net result of 3.3% more fuel per cycle, etc

What boost are you running? And out of interest where did you get the +3.3%?

For what it's worth, if it were mine and I were going from 98 to a DEFINITE E10 using 95oct as a base and I was going to do a blanket adjustment I'd add 4%. I wouldn't touch the timing unless you aren't sure if it will always be 10% eth then I'd consider pulling it back a tad.

[gt4dude]

I searched all over google looking for the answer to my question, couldn't find anything definite. All I could find was that ethanol requires approx 33% more juice than petrol to make the same Lambda, so since its only E10 I got 3.3% from 33%


the final row of load cells in my maps will become unavailable to me as my duty cycles will exceed 100% so this means a max boost of approx 1.1-1.2bar and possibly a 6800rpm limiter


apex pfc has its own method for calculating load points based on a mix of TPS and MAP

[Lith]

I searched all over google looking for the answer to my question, couldn't find anything definite. All I could find was that ethanol requires approx 33% more juice than petrol to make the same Lambda, so since its only E10 I got 3.3% from 33%


the final row of load cells in my maps will become unavailable to me as my duty cycles will exceed 100% so this means a max boost of approx 1.1-1.2bar and possibly a 6800rpm limiter

apex pfc has its own method for calculating load points based on a mix of TPS and MAP

I had no idea what ECU you were using

If you are that close to 100% duty in practice (are those cells implied, or do you actually hit them?) then you are probably pushing your fuel system too hard already - I always was under the impression GT4s have generous fuel systems!

There is a lot of talk around the net from people who know very little about what they are talking about in regarding to ethanol (among other things) - it is a bit of a minefield. To correct fuelling to suit stoich for straight ethanol needs >60% more fuel to scale the table versus straight petrol - though using straight ethanol is pretty unusual. The calculation to scale for the amount of extra enrichment for different blends (ie, 10%) is obviously not quite so simple either.

[gt4dude]

this is my fully calculated duty cycle on 98




with the 98 map as a base, i made these changes to ignition to make a 95 safe map




and now with E10, my plan is to start with the 95 map, add 3-4% fuel, change all those corrections back to about 1-2deg retard and possibly trim off the retard a little from the curve pattern its created

[Lith]

What are the highest load cells you reach at full throttle? And how did you decide on the cells to retard timing on 95? They look a bit erratic.

Otherwise sounds plausible - I'd go for 4%.

[gt4dude]

with 98 and full boost (max boost it was dyno tuned for-see below) I briefly hit the bottom of the load axis and tappering off as the revs reach the redline




i dont expect to run anywhere near 1.5bar on 95 or E10 so i set my boost tap around 1.1-1.2bar

baseline run 98 octane, 1.1bar of boost




diluted my 98 with 95 and started knock-tuning



next day, i added more 95 and repeat the process until i had all 95 in my tank and knock counts were consistent with the same run on 98

[gt4dude]

I dont have a wideband to see whats going on so at this stage i'm just doing my research before i commit to a tank of Gull force 10.

the place i'm staying is approx 250kms away from the nearest 98, so i'm carrying 20L containers of 98 across the country, but this isn't ideal either

[Lith]

Ok, seems sensible - a lot of the high rpm low load stuff is probably a red herring. The ethanol will definitely substantially improve knock tolerance, 95 mixed with 10% ethanol should take similar timing to straight 98 so pulling 1-2degrees should be fine or even arguably conservative.

If adding 4% across the board isn't safe, then your existing tune isn't either It looks like you only just nudge the 22000 load cell at the kind of rpm where you are at risk of hitting 100% duty cycle, the boost is tapering off very quickly and it looks like it is closer to 19000 (85% currently).

If in doubt, don't thrash it. Do you have closed loop lambda enabled on the PFC? If so, most of your cruise/light load stuff will be auto adjusted anyway.

[gt4dude]

No one uses narrowband o2 correction, it goes out of whack according to most FC datalogit tuning guides

and im guessing this means my o2 sensor is fu*ked anyways

[Lith]

Haha sweet, never tried using it tbh - most of my tuning has been with Links.