When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Tuning for E85 (or flex fuel) on stock 93 computer
Is fhere anyway I can do this?
yes i know i need more fuel, but ive already got an overbuilt fuel system as it is. 60 lb/hr inj and twin fuel pumps.
i tune with tunercat, i can set stoichiometric to whatever the ratio is supposed to be (richer) for e85.
will my stock o2 sensors monitor correctly if afr is set to the 10.7:1 (via tunercat) ? Or do they only work for 14.7:1 ratios?
What would i otherwise need to do for an e85 tune? Obviously richen up pe vs coolant temp and pe vs rpm tables.
but what about the speed density map vs rpm table? I imagine that would need fattened up as well (of couse the system learns....would it learn a different air-fuel ratio other than 14.7:1 - again, note i can specify other than stock ratios in the constants table).
Finally , another curveball is the ethanol fuels arent always e85. One fuel pump says it can vary anywhere from e35-85 (i cant renember the exact range but something like that). I wish i could install a flexfuel sensor but am i right the computer wont recognize that - or is there a work around someone knows of??
i am using the tunercat speed density $da2 w/ 2 bar map sensor definition file. Works great for my 93 octane tune
Yes, you can make it work. You need to set the afr at what your fuel requires, this helps the computer determine how much additional fuel is required for start up and throttle transition. A side not the car does not care what fuel you run target the lamda numbers you want in the gas scale and set those at the afr numbers in gas. The O2 sensor will read the oxygen in the fuel and target lamda on E85. You also need to tell the computer that your fuel injectors are .666 there actual size so it automatically injects the extra 33% additional fuel. If you have 60 lb injectors tell the computer you have 40 lb injectors.
It takes some playing but you can get the car to run.fine on E85.
Last edited by bjankuski; Jun 3, 2019 at 06:01 AM.
Yes, you can make it work. You need to set the afr at what your fuel requires, this helps the computer determine how much additional fuel is required for start up and throttle transition. A side not the car does not care what fuel you run target the lamda numbers you want in the gas scale and set those at the afr numbers in gas. The O2 sensor will read the oxygen in the fuel and target lamda on E85. You also need to tell the computer that your fuel injectors are .666 there actual size so it automatically injects the extra 33% additional fuel. If you have 60 lb injectors tell the computer you have 40 lb injectors.
It takes some playing but you can get the car to run.fine on E85.
Ok. Let me understand, for my 93 speed density w/ $da2 (tunercat 2 bar map version)...
So I dont need to mess with the VE tables (MAP vs RPM) , just:
1. Scale fuel injector size (lb/hr) constant by app. .666 (if using e85)
2. Set the stoichiometric afr constant to 9.9:1
3. Add more spark advance ?
up top 4000 rpm and above or more spark adv down low too ?
i have a wideband afr (for monitoring purposes only), i should see that display the 10.0:1 during normal drive (or whatever afr needs to be) w/ e85
what afr should i target for wot under boost w/ e85?
i can use the pe vs coolant temp and pe vs rpm table to fine tune to get that afr.
Ok. Let me understand, for my 93 speed density w/ $da2 (tunercat 2 bar map version)...
So I dont need to mess with the VE tables (MAP vs RPM) , just:
1. Scale fuel injector size (lb/hr) constant by app. .666 (if using e85)
2. Set the stoichiometric afr constant to 9.9:1
3. Add more spark advance ?
up top 4000 rpm and above or more spark adv down low too ?
i have a wideband afr (for monitoring purposes only), i should see that display the 10.0:1 during normal drive (or whatever afr needs to be) w/ e85
what afr should i target for wot under boost w/ e85?
i can use the pe vs coolant temp and pe vs rpm table to fine tune to get that afr.
Yes,
-Leave the VE table alone assuming it is tuned OK for gasoline, in other words dial in the VE like any car needs. (Do not scale it for E85, but that could work if the VE table can go above 100%, somethimes you cannot go above 100%, I cannot remember on the $da2 file if you can)
-Scale the injectors by .66 for E85 and .77 that if you are running E72, so forth and so on!
-Timing on E85 is very similar to gasoline, start with gasoline timing tables and maybe add a degree or 2 extra. (On my 1000 HP drag car running E85 I only added 2 degrees of additional timing when compared to gasoline and that was splitting hairs)
-The WB will read the same as gaoline when running E85 unless you set it to display E85 numbers. The WB reads lamda and then reports a number Lamda of 1 on gasoline is 14.7 AFR on E85 it is 9.8 AFR the WB will show 14.7 since it is reading Lamda but the AFR will actually be 9.8,
-Target a Lamda of .8 to .77 at WOT and that will be 11.5 to 11.7 AFR numbers displayed on the WB on the gasoline scale or 7.7 to 8.0 AFR numbers if you switch to E85 displayed numbers.
-Yes still use the PE vs RPM and temp tables to control the WOT PE AFR
Last edited by bjankuski; Jun 3, 2019 at 08:30 AM.
-Leave the VE table alone assuming it is tuned OK for gasoline, in other words dial in the VE like any car needs. (Do not scale it for E85, but that could work if the VE table can go above 100%, somethimes you cannot go above 100%, I cannot remember on the $da2 file if you can)
-Scale the injectors by .66 for E85 and .77 that if you are running E72, so forth and so on!
-Timing on E85 is very similar to gasoline, start with gasoline timing tables and maybe add a degree or 2 extra. (On my 1000 HP drag car running E85 I only added 2 degrees of additional timing when compared to gasoline and that was splitting hairs)
-The WB will read the same as gaoline when running E85 unless you set it to display E85 numbers. The WB reads lamda and then reports a number Lamda of 1 on gasoline is 14.7 AFR on E85 it is 9.8 AFR the WB will show 14.7 since it is reading Lamda but the AFR will actually be 9.8,
-Target a Lamda of .8 to .77 at WOT and that will be 11.5 to 11.7 AFR numbers displayed on the WB on the gasoline scale or 7.7 to 8.0 AFR numbers if you switch to E85 displayed numbers.
-Yes still use the PE vs RPM and temp tables to control the WOT PE AFR
Mine is not boosted, but Ed Hutchins tuned mine for both 93 octane and E85 (2 different chips) We were trying to pass emissions, but it makes a little more power on E85 due to timing.....
FWIW I run it on E85 all the time now, its available local, and it idles better......
Running 60lb injectors, 462 rwhp 11.3 compression.
Last edited by 93 ragtop; Jun 3, 2019 at 11:03 AM.
FWIW: E85 is likely overkill on a low boost/low compression port-fuel injected engine since you can't really utilize all of the knock resistance that it offers, especially when combined with water/methanol injection. It really shines on high boost, high compression and direct injection engines.
A mid-level blend such as E30-E40 should offer most of the gains of full E85 by adding internal cooling, oxygen and sufficient knock resistance without a big sacrifice in fuel economy. A mid-level blend is also less taxing on the fuel system (injectors and fuel pump). Many studies are out there on this topic. I would start with an E30 mix.
FWIW: E85 is likely overkill on a low boost/low compression port-fuel injected engine since you can't really utilize all of the knock resistance that it offers, especially when combined with water/methanol injection. It really shines on high boost, high compression and direct injection engines.
A mid-level blend such as E30-E40 should offer most of the gains of full E85 by adding internal cooling, oxygen and sufficient knock resistance without a big sacrifice in fuel economy. A mid-level blend is also less taxing on the fuel system (injectors and fuel pump). Many studies are out there on this topic. I would start with an E30 mix.
Its going to boil down to fuel availability (e85 vs those variable blends)...
or do you propose i mix it in my garage ? 🔥 j/k
a buddy recommended i buy a % ethanol readout and bring my laptop with me / tune it right then/there (at the pump) depending on the % ethanol in my fuel.
im also (knock on wood) hoping there arent parts of my fuel system that will be corroded by it.
mines a 93, there is no bladder or much rubber (i think the tank feed hoses at top are) to eat.
my fuel injectors are the latest style (replaced in 2010), so im sure they are safe
Mine is not boosted, but Ed Hutchins tuned mine for both 93 octane and E85 (2 different chips) We were trying to pass emissions, but it makes a little more power on E85 due to timing.....
FWIW I run it on E85 all the time now, its available local, and it idles better......
Running 60lb injectors, 462 rwhp 11.3 compression.
I am lucky to say, Will is one of my best friends and lives about 15 miles from my home. Will is probably one of the most knowledgeable people that can tell you what it takes to make a car fast. He knows his stuff!!
Designer Imagines A Corvette That Looks More Like a Corvette Than the Corvette
Slideshow: A Jaguar designer's personal project imagines what a modern front-engined Corvette might look like if Chevrolet revisited the golden age of the Stingray.
Tuning for E85 (or flex fuel) on stock 93 computer
