[DWR]

Curious, has anyone dynoed or at least have “butt dyno” results of the gain (or lack there of) of simply installing a FF sensor and enabling the stock tune on an SS? I’m debating on installing one and simply enabling the tune for a bit. Of course I’ll either seek out a custom tune, or possibly do it myself in the end.



Yes I know there is much more gain from a custom e85/flex fuel tune. I just curious if there is any gain from running e85 on the OEM FF tune.

[cjperformance]

Been a while since i saw the orig ff tune... arent the values all negative in the adder table? My impression on my 2017 SS was that it really wasnt ever set up or intended to be enabled... i can only speak to my own setup.

[DWR]

Originally Posted by cjperformance

Been a while since i saw the orig ff tune... arent the values all negative in the adder table? My impression on my 2017 SS was that it really wasnt ever set up or intended to be enabled... i can only speak to my own setup.

Haven’t pulled out the laptop to look at my tune yet but all the videos I’ve watched on it it appears everything (minus changing the AFR chart) was already set up, just needed to enable everything.

[cmitchell17]

Originally Posted by DWR

Curious, has anyone dynoed or at least have “butt dyno” results of the gain (or lack there of) of simply installing a FF sensor and enabling the stock tune on an SS? I’m debating on installing one and simply enabling the tune for a bit. Of course I’ll either seek out a custom tune, or possibly do it myself in the end.



Yes I know there is much more gain from a custom e85/flex fuel tune. I just curious if there is any gain from running e85 on the OEM FF tune.

I don't think there will be any "gain" over the stock calibration. We know GM never released a flex fuel capable LT1, but I still think they calibrated the spark timing tables for E85. I think any "gain" will either be negeligiable (less than 5hp/torque). I don't think there is any "free" hp they left. To me it's more about ensuring the engine is running without knock and knock retard and ensuring it's running on the high octane timing values.

With that said just going to E85 from gas as long as you were not knocking on either fuel, then yes there should be a gain, just from the extra oxygen alcohol fuels have. With ethanol you inject a fuel that has extra oxygen in it (oxidizer) so basically it's like nitrous. The problem is the extra oxygen also displaces some of the hydrogen to where it also lowers the energy content. The end result is a small net gain from just the chemistry and heating value, but that dosent have anything to do with ethanol's higher octane number which allows optimal timing to be run.

GM used to publish Dyno charts of the LS stuff certifies to SAE J1939 (they can't underrate or cheat with this certification) which also had the E85 numbers. But you win have to extrapolate those to the GEN V LT1 based stuff since I haven't seen them give out a chart on E85 with these. You could get these from wayback machine since GM has since taken them off their media site long ago.

[wnta1ss]

If you mean flashing a tune into your car that enables the flex sensor that you just installed, then yes, the original gm flex timing tables did gain power when E85 was used in my 2017. You will need to also fix the stoich tables, and there's some other stuff you could do in your initial tune. But I did this (just enabling the flex) initially upon installing a flex sensor on my SS. I gained .164 sec in the 1/4 mile with ethanol using the factory flex timing back in late-2016, times from different days and different tracks admittedly.

[DWR]

Originally Posted by wnta1ss

If you mean flashing a tune into your car that enables the flex sensor that you just installed, then yes, the original gm flex timing tables did gain power when E85 was used in my 2017. You will need to also fix the stoich tables, and there's some other stuff you could do in your initial tune. But I did this (just enabling the flex) initially upon installing a flex sensor on my SS. I gained .164 sec in the 1/4 mile with ethanol using the factory flex timing back in late-2016, times from different days and different tracks admittedly.

Thats great to hear! What would be your estimation on hp/tq gain on OEM? Yes I know the stoic values need to be altered. Also, how was E85 cold starts?

[lt4camaro]

Originally Posted by DWR

Thats great to hear! What would be your estimation on hp/tq gain on OEM? Yes I know the stoic values need to be altered. Also, how was E85 cold starts?

According to Jannetty, tuned E85 can add a 10% horsepower difference over a factory tune LT1. Factory tune LT1 is approx 400 hp to the wheel, a conservative E85 tune on like a 70E content fuel is 440 rear wheel HP. Keep in mind though a conservative tune on 93 octane can reach 420 hp to the wheel .

[cmitchell17]

Originally Posted by DWR

Thats great to hear! What would be your estimation on hp/tq gain on OEM? Yes I know the stoic values need to be altered. Also, how was E85 cold starts?

I estimated it at about 20-25rwhp peak, and if you look at GMs dyno graphs that's about how much more they made over regular gas.

That's most likely 100% due to the decreased stoich ratio allowing the engine to burn about a third more fuel for the given air. If your engine was knock limited with high intake air temps then you will gain more by bringing timing where it needs to be. Ethanol also has more heat capacity so assuming your ethanol and gas are the same temp coming from your fuel tank, then your air charge will be cooler with ethanol, this will also increase your air charge density, but it's a small amount.

[wnta1ss]

Originally Posted by DWR

Thats great to hear! What would be your estimation on hp/tq gain on OEM? Yes I know the stoic values need to be altered. Also, how was E85 cold starts?

I'm guessing around ~20hp was gained on my SS by enabling the flex sensor and using E.

Cold start does crank longer than pump gas. Really noticeable on a cooler morning in the 40s.

[DWR]

Originally Posted by wnta1ss

I'm guessing around ~20hp was gained on my SS by enabling the flex sensor and using E.

Cold start does crank longer than pump gas. Really noticeable on a cooler morning in the 40s.

Sounds like I’ll be installing and enabling FF for a bit then. Thinking I’m going to drive up to see pray performance to get a full bolt on plus cam setup… but need to ping him for pricing.


Just hopefully the bug doesn’t bite me too hard afterwards and make me want to go FI… (would love to go Hellion twin turbo but I kind of want to run straight e85, with out getting into the ridiculous fuel system cost and I kind of like the idea of how unassuming a bolt on car can be)

[laynlo15]

Killer Performance just completed my DSX install and I have the tune ready to install but going to get a baseline first, hope to do that tomorrow. My C7 gained over 30 rwhp with just the addition of the sensor and custom tune and that was on E70. I think it will very between tuners on how much timing they are adding in the FF tables. We added 5 degrees over the stock tune on that setup as well as on my 2022 Lt1. Stoich and PE will also need some adjusting. My C7 made just under 400 rwhp and we made over 430 rwhp. They were on different dynos but both Dynojets. This time they'll be done on the same dyno so it will be more reliable data then before. The big deal is my C7 went 12.06@116 on 93 and 11.58@120 on E85/tune only. All in all its a good amount of power for the little amount you spend to add it.

[KingLT1]

It depends on the year and model. My 2016 SS had the flex spark populated but the Stoich table was not properly populated to run E. On a 2019 ZL1 neither the Flex Spark or Stoich table was properly setup to run Ethanol. If I had tried to run E on either of these cars without at least populating the Stoich table properly, the Fuel Trims would of likely went extreme positive and triggered a CEL.

So when you open the tune file with HPt, make sure to look up [ECM] 12300 and see if the entire table is set to 14.1084. If it is then you can not run Ethanol and it will need to be adjusted. The Stoich ratio changes for different Ethanol percentages.

[DWR]

Originally Posted by KingLT1

It depends on the year. My 2016 SS had the flex spark populated but the Stoich table was not properly populated to run E. On a 2019 ZL1 neither the Flex Spark or Stoich table was properly setup to run Ethanol. If I had tried to run E on either of these cars without at least populating the Stoich table properly, the Fuel Trims would of likely went extreme positive and triggered a CEL.

I knew the stoich values had to be changed but I thought everyone was reporting that spark was already filled in… anyone know specifically on a 2018 SS, possibly 1LE?

[KingLT1]

Originally Posted by DWR

I knew the stoich values had to be changed but I thought everyone was reporting that spark was already filled in… anyone know specifically on a 2018 SS, possibly 1LE?

Ok but your initial post said "simply enabling stock tune". I addressed that for others that might read this post. The answer is NO you can not simply enable the FF sensor on a stock tune and run E.

Either way If it doesn't have the flex spark table populated post here or in the tuning section and I will get you what you need. There isn't really anything custom far as tuning for E on these cars. You dial in the 93 tune first, then enable the FF sensor, adjust the Stoich, Alcohol PE, Flex Spark tables, and it's pretty much 90% there. Some adjust the Alcohol cranking spark table to help with cold starts.