Engine master episode on different octane fuel

stumblinhorse

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Glad they finally released this to youtube. I watched it when it was in motortrend. You don’t have to watch the whole thing. And the last 5 minutes they marry in another episode about alcohol fuels.

But the proof here is that octane had no effect on horsepower at all. Something that I have know for many years. Many will say they get better mileage etc. But that is not true. Octane is purely a detonation inhibitor and does nothing to increase power.
Engine masters episode 81
 
Glad they finally released this to youtube. I watched it when it was in motortrend. You don’t have to watch the whole thing. And the last 5 minutes they marry in another episode about alcohol fuels.

But the proof here is that octane had no effect on horsepower at all. Something that I have know for many years. Many will say they get better mileage etc. But that is not true. Octane is purely a detonation inhibitor and does nothing to increase power.
Engine masters episode 81
This is good information. Note that the guy did say he would not run 87 on that engine on the street due to risk of detonation. Detonation absolutely kills engine power and detonation under high engine loads is bad for the engine. Still best to run good fuel in high performance engines like the 392 to prevent detonation.

Probably could get by with lower octane some of the time, but a hot day, heat soaked engine and heavy loads likely need the high octane to suppress detonation.

In some applications, higher octane allows you to tune for more horsepower by running more timing and leaner air fuel ratios. In our engines, likely no difference in power, unless you encounter detonation, which is something I really don't want to do........

I had to run 93 octane in our old f-150. For whatever reason, that thing would ping like crazy under light loads, but not under heavy loads. The ford EEC-IV put in a lot of timing advance at part throttle...........we didn't drive the truck much so the easiest fix was just to run 93 and be done with it.......
 
I have seen and it`s not 100% true, it depends on your cam lobe,lift and duration and all other components.They have also shown how header tube length makes a difference, cross tube exhaust X pipe help scavenge exhaust etc...
If you have a stock engine with the factory tune in it rarely will you see an increase in HP and TQ with Definitely less chance of detonation. BUT when you add a tune to your engine you will see where your increases will be.

The stock perimeters in the factory is more then on the side of caution. When building the engine you have to take into mind what is it going to used for? Marine, TQ down low, towing etc.

So if you WANT more out of your engine you have to give it what it needs to get there. You don`t want a small block spinning at max TQ at 6500 if your a rock crawler.

If they would have changed the perimeters with the tune, or the jets in a carburetor you would differently see a horsepower increase that matches the fuel octane

I also have had my Ford Raptor with a twin turbo V-6 450 hp at the crank and 510 lb-ft of torque along with having other engines from bikes, cars, boat engines, outboard and inboard,motorcycle, race car engines of all types on the dyno
I know that it did put down bigger numbers with higher octane. I have run VP fuel, aviation fuel and currently using Boosted to bring my numbers where I want them, you can over octane your engine too and cause other issues.
 
Good vid. But they don’t really get into the crux of the 392 debate… why High Octane, or premium is required. Octane is an additive, and as mentioned above, all about prohibiting untimed detonations - or “knock.”

When a manufacturer builds a high compression, high performance, highly tuned engine - it can be very sensitive to, and damaged by untimed detonation. Knock sensors address this in the majority of applications by reducing output and the manufacturer will put the “recommended” label on it for premium for the best performance. Ford is a great example of this. The HEMI is not such an application. It’s designed specifically for power and FCA did not want that power sacrificed by sensor programming, and we get the “required” label.

Could you run 87 in the 392 and not lose power? Sure. It’s programmed not to. Would I want to risk it? Hell no.
 
Good vid. But they don’t really get into the crux of the 392 debate… why High Octane, or premium is required. Octane is an additive, and as mentioned above, all about prohibiting untimed detonations - or “knock.”

When a manufacturer builds a high compression, high performance, highly tuned engine - it can be very sensitive to, and damaged by untimed detonation. Knock sensors address this in the majority of applications by reducing output and the manufacturer will put the “recommended” label on it for premium for the best performance. Ford is a great example of this. The HEMI is not such an application. It’s designed specifically for power and FCA did not want that power sacrificed by sensor programming, and we get the “required” label.

Could you run 87 in the 392 and not lose power? Sure. It’s programmed not to. Would I want to risk it? Hell no.
Well said
 
If they would have changed the perimeters with the tune, or the jets in a carburetor you would differently see a horsepower increase that matches the fuel octane

I also have had my Ford Raptor with a twin turbo V-6 450 hp at the crank and 510 lb-ft of torque along with having other engines from bikes, cars, boat engines, outboard and inboard,motorcycle, race car engines of all types on the dyno
I know that it did put down bigger numbers with higher octane. I have run VP fuel, aviation fuel and currently using Boosted to bring my numbers where I want them, you can over octane your engine too and cause other issues.
They did change timing and air fuel ratio with the different octanes. Still did not affect max HP on this engine. If engine had higher compression or different cam that could've been a different story....

Boosted engines will generally make more power with higher octane due to detonation being the limiting factor in tuning. With lower octane you have to pull so much timing out on boosted engines that it hurts power.

I think the point they are trying to make is if the engine does not need the octane to prevent detonation that higher octane is not going to give more power.

And perhaps part of the reason that engines make more power with a tune is that they were not tuned for 100% max power from the factory in the first place.... Also that tuned engine might be closer to its detonation threshold and factory tunes probably allow for a bad tank of gas or even someone accidentally putting in 87...............conservative tune to keep from having warranty claims.
 
Knock sensors address this in the majority of applications by reducing output and the manufacturer will put the “recommended” label on it for premium for the best performance. Ford is a great example of this. The HEMI is not such an application. It’s designed specifically for power and FCA did not want that power sacrificed by sensor programming, and we get the “required” label.

Could you run 87 in the 392 and not lose power? Sure. It’s programmed not to. Would I want to risk it? Hell no.
So the 392 doesn't have a knock sensor? Interesting. I figured most modern high performance engines would. That is good to know. No way I would run 87 in the 392 either... Just not worth worrying about it to save a few dollars.
 
So the 392 doesn't have a knock sensor? Interesting. I figured most modern high performance engines would. That is good to know. No way I would run 87 in the 392 either... Just not worth worrying about it to save a few dollars.
Every engine has a knock sensor in the last 20 years…. 392 is no exception
 
It would interesting to see if the ECM has picked up or logged any engine knock on your motor stumblinhorse. Especially as hot of under the hood engine temperatures as these beast run. I would imagine the ECM just pulls timing to prevent the knock IF present with the 87 Octane?? In the old day's pulling a heavy load with a engine knocking you would drop a gear and back off the skinny pedal, problem solved. I never had internal engine damage were a engine failed after engine knock. To me premium fuel is just like a 3k mile engine oil change, Cheap insurance, but in a pinch I would run 87 Octane fuel and increase the mile interval between oil changes IF circumstances warranted it.
 
Good vid. But they don’t really get into the crux of the 392 debate… why High Octane, or premium is required. Octane is an additive, and as mentioned above, all about prohibiting untimed detonations - or “knock.”

When a manufacturer builds a high compression, high performance, highly tuned engine - it can be very sensitive to, and damaged by untimed detonation. Knock sensors address this in the majority of applications by reducing output and the manufacturer will put the “recommended” label on it for premium for the best performance. Ford is a great example of this. The HEMI is not such an application. It’s designed specifically for power and FCA did not want that power sacrificed by sensor programming, and we get the “required” label.

Could you run 87 in the 392 and not lose power? Sure. It’s programmed not to. Would I want to risk it? Hell no.
I had worked closely with a company called Gear Heads, all they do in the high perf. diesel world is tuning. I had spoken with them several times while data logging while driving the truck. According to them in simple terms, the factory computer has parameters for everything and by opening up or changing the perimeters is what is going to give you the extra shot in the arm. I just had to change the spark plugs to step cooler. They advertise one of their tune`s as having an Auto Octane booster, it will change the tune within limits to keep it from knocking all the way to being in the power band
This is standard from the factory but its just been opened up to change the values for the higher octane
 
Glad they finally released this to youtube. I watched it when it was in motortrend. You don’t have to watch the whole thing. And the last 5 minutes they marry in another episode about alcohol fuels.

But the proof here is that octane had no effect on horsepower at all. Something that I have know for many years. Many will say they get better mileage etc. But that is not true. Octane is purely a detonation inhibitor and does nothing to increase power.
Engine masters episode 81
Maybe I’m missing something.
Didn’t we know this? Or, growing up doing tear downs and rebuilds, modifying, etc., some of us learned early on and just assumed we all knew this. 🤷🏻‍♂️
 
Maybe I’m missing something.
Didn’t we know this? Or, growing up doing tear downs and rebuilds, modifying, etc., some of us learned early on and just assumed we all knew this. 🤷🏻‍♂️
so many people think that running premium gives more horsepower…. Better mileage… it is the opposite. If you have too much octane than you need you are using more fuel than you need…. If you aren’t pinging you don’t need more octane for any reason…. so run the octane that you need… and 10.9 :1 compression ratio will never need 93 octane.
 
so many people think that running premium gives more horsepower…. Better mileage… it is the opposite. If you have too much octane than you need you are using more fuel than you need…. If you aren’t pinging you don’t need more octane for any reason…. so run the octane that you need… and 10.9 :1 compression ratio will never need 93 octane.
I’m aware… 🤓
add in VVT, and it lends to more compensation for variations. Not a cure all, but helps some.
 
Great video! I learned a lot by watching videos like these, thanks for posting it. :)(y)
I don’t want to hijack the fuel focus but I really want to share these two videos about our Hemi 392 Gen III. This is my first V8 and I learn more about this orange Hemi monster everyday. Thanks!
 
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Hmmm… I’m interested in the oil pan.
 
You have to watch the front engine cover assembly that's the difererence between the first run of the 392's with the aluminum engine oil pans and the run's after June 2021 with the steel pan, RKKRAWL dropped his pan and tried to bolt up the new later style steel pan and that is where the difference is and why they won't work. So if you are going to try and switch out a aluminum pan to a steel pan make sure the Windage Tray for the early model 392 will fit the steel pan bolt pattern, easy way to make sure the new pan will work. I also have a new $250 steel oil pan in my parts inventory that won't work! So if anyone ever takes out there steel oil pan with a rock or what ever I know where you can get one...
 
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