Gas question

[BoostedToy]

I have a 2013 Roush Stage II. I have a VMP tune and 72mm pulley (versus the 75mm from Roush). It is tuned for 93 octane, which is relatively limited in the area I live in but there are a couple that have it. If in a pinch, I have Boostane and give it a little more than the ratios prescribe for 93 octane for a margin of safety.

With that, on custom tunes, including Roush, the timing is prescribed (open loop) versus from the factory where it’s running closed loop and is constantly analyzing and compensating. Running less than 91 effective octane in your Roush is going to be problematic. I would encourage 93 octane if you have it available. Keep in mind that over time, carbon build up and other age / wear related matters will further reduce effective octane. Your 91 octane on an engine with some wear and carbon build up could very well be operating at a lower effective octane as a result.

 

[Blu Bug]

If I was going anywhere that was likely to not have at least 91 octane available, I’d carry some octane booster such as Boostane. It’s a lot more space and weight efficient to use the octane booster mixed with available 87 octane pump gas than carrying gallons of 91+ octane fuel with you especially if it’s temporary.

Carrying octane booster was my first thought but after researching I found that the years I could locate a Roush supplement manual for all warned against using any additives. Is that overkill? Maybe but it gives me pause.

 

[Vash]

Roush has no control over exactly what brand of octane booster you use or what concentration, so of course they won’t recommend it. They also don’t want you using below 91 octane either, so your alternative is to carry octane booster for the times you may need it or call a tow truck. Either way, there’s enough info out there on which octane boosters perform as advertised and running 8-16 oz in a 36 gallon tank every once in a while isn’t going to harm anything. Most folks that have issues seem to be running very high concentrations of booster on a daily basis trying to mimic race fuel vs. trying to just get to 91 or 93. Otherwise, you shouldn’t notice any difference other than some color on your plugs and/or O2 sensors from the MMT.