93 Octane In Mojave

[Dryfly24]

Hey, don’t knock it! I’ve been running 93 in my JT and my hair started growing back. I’ve noticed my pecs getting bigger too. . .

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[firemedic2714]

I use 89 octane. I have a 6-speed. I like to do a lot of second gear stops (roll up to a stop sign where no other vehicles are waiting to cross and instead of stopping and shifting into 1st, I slow down to a speed high enough that it doesn't "lug" the engine, but I can pull away in second gear). When I used 87, it would constantly induce knock. After inswitched to 89, the knocking is gone.

 

[mtbgordon]

My '24 nighthawk is lifted on 35s and I recently noticed a knock at higher RPMS 3/4/5 gear in the 3500+ rpm range. I ran my tank practically dry and filled with 93, after about 10 miles of driving I floored it and the knock went away. Coincidence? Maybe.

Will continue to test.

 

[Minty JL]

I run 89, again it runs better

 

[ShadowsPapa]

My '24 nighthawk is lifted on 35s and I recently noticed a knock at higher RPMS 3/4/5 gear in the 3500+ rpm range. I ran my tank practically dry and filled with 93, after about 10 miles of driving I floored it and the knock went away. Coincidence? Maybe.

Will continue to test.

Too many variables to say anything specific - such as gear ratio of the axle, what sort of load it was under, etc. - Detonation doesn't typically happen at higher RPM. Why? Not enough time for it to detonate or be squeezed enough by the flame front to induce self-ignition.
10 miles isn't a great timeframe either.
Detonation is usually lower RPM under a load, accelerating in a gear that places a heavier load on the engine, increasing chamber pressures and so on. If everything was totally equal, load and so on, chamber pressures actually drop over 3,000 RPM or so, and in our case, the valves open farther over 3,000 RPM.

So far, in 5 years and 2 JTs, and towing, hauling, whatever, I've yet to see a difference going from 87/88 or so up to 93. Even towing, the mpg and power wasn't actually better and it didn't run better.
Mine does seem to like U88 just fine and it's often 15-20 cents cheaper so I usually go with that.

 

[sharpsicle]

We couldn't just let this thread die? Really??

 

[rharr]

I run fuel oil in mine all the time and it knocks all the time, any suggestions?

 

[mtbgordon]

Too many variables to say anything specific - such as gear ratio of the axle, what sort of load it was under, etc. - Detonation doesn't typically happen at higher RPM. Why? Not enough time for it to detonate or be squeezed enough by the flame front to induce self-ignition.
10 miles isn't a great timeframe either.
Detonation is usually lower RPM under a load, accelerating in a gear that places a heavier load on the engine, increasing chamber pressures and so on. If everything was totally equal, load and so on, chamber pressures actually drop over 3,000 RPM or so, and in our case, the valves open farther over 3,000 RPM.

So far, in 5 years and 2 JTs, and towing, hauling, whatever, I've yet to see a difference going from 87/88 or so up to 93. Even towing, the mpg and power wasn't actually better and it didn't run better.
Mine does seem to like U88 just fine and it's often 15-20 cents cheaper so I usually go with that.

Stock 3.73 gears. It happens about 99% of the time not just up hills, but on the flat. I was just on the highway before filling it up and it was doing it. Could be the added weight of the tires, and the stock gearing. My guess is the vehicle is working harder. I do plan to re-gear in the spring. The other option is to drive it like a grandpa.

Like I said I will continue to drive around and use a higher octane. If the noise comes back maybe I am dealing with something else.

 

[mtbgordon]

We couldn't just let this thread die? Really??

nope! haha

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