freewayman
Well-known member
- Joined
- Oct 30, 2023
- Messages
- 202
- Reaction score
- 267
- Location
- Wyoming
- Current Ride
- 2023 F150 Tremor | 3.5EB | 401A Oxford White
Personally I don't think you would get much more power out of an 87 tune, maybe 20-30 HP. Unless you want to tune more so for different transmission programming.
Also - It would be advisable to run 91+ if you are tuned, even if the tune is calibrated for 87. I would be wary of LSPI personally. Remember the 3.5 ecoboost is originally tuned for 91 even from factory, it just pulls timing to be able to run 87. So even for stock motors I think running 91+ is the best bet for longevity, the engine doesn't need to constantly pull timing under load. Remember when it pulls timing there is less combustion efficiency, hotter exahust temps, etc. When the ECU senses higher octane fuel it can advance timing and fire near maximum brake torque timing, this means conbustion is more controlled and smoother = less vibration, consistent combustion pressures. Also results in cooler combustion. Also, remember for the engine to be able to run 87, its doing so because it retards timing based on very small knock, over a long period of time who knows if this would add up. I can't tell you for sure. The last thing is typically there are more additives in 91+, i.e. Shell V-Power Nitro+, helping reduce carbon buildup. Relevant for dual injected engines like the current 3.5 ecoboost, the port fuel injection is washing the intake valves so we can actually take advantage of detergents in the fuel to help with this cleaning mechanism. Not so relevant for DI only engines like the first gen 3.5 ecoboost. Overall, long term and way past the warranty period I'm not sure if it would make a signficant difference but in theory it would.
All that said this is just my 0.02, not knocking you for running 87, many people do and their 3.5ebs last a very long time with no issues, just explaining why you might want to consider 91
