Tuned and Converted to Flex Fuel (2015 Silverado 5.3L)

5.3Nali · November 4, 2016

Kind of off topic but how much was your mpg affected by the cam swap? I'm assuming that cam has a much larger fuel lobe than stock.

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After all the mods so far I get around 9mpg

Highway mpg about 22-25 not really sure

jetlife · May 6, 2017

Completed my flex fuel conversion recently. I installed the GM OE sensor and had BB tune it. Install was extremely easy. I started off with a 1/4 to verify operation, and currently have about a 3/4 tank of e85.

The truck already feels so much more responsive. E85 combined with BB ecm and tcm5 tune is a perfect combo! Total cost of conversion (not including BB AutoCal) was about $75.

Gas mileage is down between 16.5/17, but with e85 at $1.99 and 89oct at $2.35 around me, so it is slightly cheaper to run e85. I would highly recommend it?

jetlife · May 6, 2017

Completed my flex fuel conversion recently. I installed the GM OE sensor and had BB tune it. Install was extremely easy. I started off with a 1/4 to verify operation, and currently have about a 3/4 tank of e85.

The truck already feels so much more responsive. E85 combined with BB ecm and tcm tune is a perfect combo! Total cost of conversion (not including BB AutoCal) was about $75.

Gas mileage is down between 16.5/17, but with e85 at $1.99 and 89oct at $2.35 around me, so it is slightly cheaper to run e85. I would highly recommend it!

jesse7munoz · July 20, 2017

Completed my flex fuel conversion recently. I installed the GM OE sensor and had BB tune it. Install was extremely easy. I started off with a 1/4 to verify operation, and currently have about a 3/4 tank of e85.

The truck already feels so much more responsive. E85 combined with BB ecm and tcm tune is a perfect combo! Total cost of conversion (not including BB AutoCal) was about $75.

Gas mileage is down between 16.5/17, but with e85 at $1.99 and 89oct at $2.35 around me, so it is slightly cheaper to run e85. I would highly recommend it!

With your conversion, did you only replace the sensor or did you have to convert the fuel lines/hoses as well?

I am looking to convert my truck to e85 soon.

16blkslvy · July 20, 2017

Jesse7, I ordered the conversion kit from Carl and I already had a tune being crafted for the ECM by another vendor when I bought the conversion kit. I believe the conversion kit will have all hardware needed for the conversion (per Carl's site) and then you just need your ECM tuned for the tables to be utilized with the e85.

bgweed · August 3, 2017

Completed my flex fuel conversion recently. I installed the GM OE sensor and had BB tune it. Install was extremely easy. I started off with a 1/4 to verify operation, and currently have about a 3/4 tank of e85.

The truck already feels so much more responsive. E85 combined with BB ecm and tcm tune is a perfect combo! Total cost of conversion (not including BB AutoCal) was about $75.

Gas mileage is down between 16.5/17, but with e85 at $1.99 and 89oct at $2.35 around me, so it is slightly cheaper to run e85. I would highly recommend it!

$75? Seems really low when I add up the price of the parts in post #16. Can you clarify what you did?

Jesse7, I ordered the conversion kit from Carl and I already had a tune being crafted for the ECM by another vendor when I bought the conversion kit. I believe the conversion kit will have all hardware needed for the conversion (per Carl's site) and then you just need your ECM tuned for the tables to be utilized with the e85.

Carl's kit looks to be the best route, but I'll wait to see what jetlife says above (considerable cost difference).

jesse7munoz · September 28, 2017

$75? Seems really low when I add up the price of the parts in post #16. Can you clarify what you did?

Carl's kit looks to be the best route, but I'll wait to see what jetlife says above (considerable cost difference).

I finally went ahead and got the sensor and will be delivered today. I will be installing the sensor tonight, and if all goes well, tuning tomorrow. Excited to see what the outcome will be! currently I am pushing 340RWHP and I am expecting to see atleast 10-15HP gain.

scott.moody.9401 · September 28, 2017

Damn. Some nice numbers there. So factory numbers look like a 25% drivetrain loss. That sounds like a lot to me. For some reason i was thinking 15% was more like the norm.

15 to 18% is for manual transmissions and 20 - 25% for automatics

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smrr1 · September 28, 2017

15 to 18% is for manual transmissions and 20 - 25% for automatics

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You do realize that my post was almost 2 years ago?

jesse7munoz · October 9, 2017

After some issues with the post office losing my package, I finally got the sensor installed, turned on and tuned. Jumped from 340RWHP to 352RWHP. Definitely feel the power increase, I even feel like it shifts smoother than before. After 100 miles of driving, my city MPG went down from 15mpg to 11mpg, but with the price of e85 way lower than 93 octane gas, I feel like I'm saving a lot of money. Install was a breeze, got it done in about 45 minutes - 1 hour. Did not have to change any fuel lines or hoses. I simply cut the fuel lines, attached the sensor with 3/8 couplers, tune, and that's it!

RideZX6R · October 9, 2017

Nice numbers - I saw similar gains on my '17 Camaro with E85.

I don't see a need to spend more money on gas on my truck since it's a DD so I'm not going to convert, nice to see the gains are good though

getto822000 · February 5, 2021

On 10/9/2017 at 1:18 PM, RideZX6R said:

Nice numbers - I saw similar gains on my '17 Camaro with E85.

I don't see a need to spend more money on gas on my truck since it's a DD so I'm not going to convert, nice to see the gains are good though

I took my 2018 Tahoe to CJ Tunes over a year ago. Converted it to E85, along with a 6.2L intake manifold and throttle body, as well as AirRad intake tube and air filter. The end result was amazing. Never dyno'd it but I would guess maybe about 450/450 crank? It HAULS BALLS, and has performed flawlessly for 15,000 miles.