Just used Boostane - felt a nice difference in stock GT350R

[Angrey]

Right, but if it’s already not knocking and under the same ideal conditions on 93, how does it tell the difference between 93 and a higher octane. That’s what I’m not understanding.

The tune will run the motor at the edge of knock. With higher octane (knock resistance), that edge is a little more timing advance, which results in more power and more torque. When the fuel is a little on the crappy side, it'll back off a little timing to keep it out of knock, so it'll result in a little less power and torque.

And even perfect 93 knocks when in certain conditions. If you have an NGuage you can see the computer/tune pulling timing out when the car is at lower rpms and full load. The only time you'll ever notice knock (without an nguage or data logger hooked up) is when the fuel is so bad that it's exceeding the tune's limits to withdraw timing (so it's still knocking).

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[EFI]

When I look at my datalogs on 93, it’s pushing about 36 total degrees (30* base +6* of advance) and I’m seeing 0* of knock retard across the graph. Seeing that tells me that it’s not detonating whatsoever. But if it’s sensing detonation at +7 and higher degrees of advance and keeping it at +6 but it’s just not counting on the knock retard graph, then I can understand that the car picks up some power with the higher octane fuel. It’s just really counterintuitive to me if I’m understanding that right.

Are you logging a GT350 or the 17 GT in your profile? Because those will be a bit different. A high strung 12:1 engine will gain a bit more with higher octane than a relatively low strung 11:1 one. You may not be limited with timing but he may be.

And are you 100% stock tune or has that been modified by someone? I don't recall seeing that high timing when I was on the stock 16 tune but remember seeing in the 30s after I had the FR PP2 tune put on.

As you mentioned, these cars see a huge benefit from E85. And yes, some of that is from the inherent cooling properties of the fuel itself, but a lot of it is due to being able to run more timing. Thus even the N/A Coyote/Voodoo engines are being limited by 93 octane in terms of max timing. So a higher octane one, even without a tune adjustment, can see some power increase.

 

[junits15]

So you’re suggesting that stock Gt350’s run naturally with the knock sensors constantly regarding timing on the factory calibration?

My understanding is the calibration has a target total timing with the ability to advance under ideal conditions (no detonation knock, low CHT’s/IAT’s etc) or retard under bad conditions (Vice versa). But if the engine is already not knocking on 93 and it’s target timing is 30* with a +6* (for example), there’s no way for it to add more timing just from adding higher octane fuel. From what I’ve seen, there is no total timing difference between 93 and higher octane fuel on the factory calibration

please correct me if I’m wrong

the engine is absolutely already knocking on 93 in all weather conditions. That's how modern engines work, they want to run right at the knock threshold for maximum efficiency. The timing is constantly being added and pulled to maintain a predetermined level of knock.

It adds timing until it knocks then pulls timing to keep it from knocking too much, so when you add high octane fuel it will add more timing before it knocks and get you more power. Its a real thing

 

[gimmie11s]

Right, but if it’s already not knocking and under the same ideal conditions on 93, how does it tell the difference between 93 and a higher octane. That’s what I’m not understanding.

Its not a 2 dimensional table.

The spark table is effected by many things other than knock -- like mentioned earlier. Outside temp, IAT1, CHT, throttle position, load, fuel pressure, etc etc etc.

 

[NHMustangGuy]

In a very long winded way on my part, this is pretty much what I was wanting to say (or trying to at least lol). I’m not used to seeing any sort of knock retard on a factory calibration because they tend to keep it on the conservative side for obvious reasons. Like you said, if it’s giving it the full timing on 93 (say 34*), then it running 34* on a higher octane fuel doesn’t make anymore power than it did on 93*. If anything a smidge less but probably not where you would notice it.

Admittedly I’m lacking knowledge on the newer adaptive learning systems which is why I had these questions, and I definitely appreciate the answers.

I can say that the car is running differently and pulls harder on the Boostane. I have also read about all the independent Dyno testing that has been done where they did not change the timing of the vehicle that was being used and it showed an improvement without changing the tune. So, I am confident it works.

 

[Cav427]

Sir, this is the GT350 forum. We do not have any low RPM torque and our engines explode on a daily basis. We do not spin anything in 1st, 2nd, 3rd, 4th, 5th, or 6th except our FPC, which then explodes.

Sorry, I will now walk away slowly head down in the walk of shame shuffle.

 

[Red65]

the engine is absolutely already knocking on 93 in all weather conditions. That's how modern engines work, they want to run right at the knock threshold for maximum efficiency. The timing is constantly being added and pulled to maintain a predetermined level of knock.

It adds timing until it knocks then pulls timing to keep it from knocking too much, so when you add high octane fuel it will add more timing before it knocks and get you more power. Its a real thing

Makes sense now. At first, I thought the timing table had a hard maximum on these cars. Since it can keep advancing until it detects detonation and is able to ride that threshold, it would make sense for the car to pick up power with the octane increase. Appreciate the info!

 

[Red65]

Are you logging a GT350 or the 17 GT in your profile? Because those will be a bit different. A high strung 12:1 engine will gain a bit more with higher octane than a relatively low strung 11:1 one. You may not be limited with timing but he may be.

And are you 100% stock tune or has that been modified by someone? I don't recall seeing that high timing when I was on the stock 16 tune but remember seeing in the 30s after I had the FR PP2 tune put on.

As you mentioned, these cars see a huge benefit from E85. And yes, some of that is from the inherent cooling properties of the fuel itself, but a lot of it is due to being able to run more timing. Thus even the N/A Coyote/Voodoo engines are being limited by 93 octane in terms of max timing. So a higher octane one, even without a tune adjustment, can see some power increase.

The 17 gt in my sig is tuned. I was referencing both that and datalogs from other cars that I have seen before. I just didn't realize that the adaptive learning in these cars just keeps adding timing until detonation and is able to ride that threshold. Most of my knowledge is in older EFI systems and diesel, so I'm still learning the newer stuff. I do appreciate the information!

 

[NHMustangGuy]

Makes sense now. At first, I thought the timing table had a hard maximum on these cars. Since it can keep advancing until it detects detonation and is able to ride that threshold, it would make sense for the car to pick up power with the octane increase. Appreciate the info!

I will share that my research show's there is a limit to how much the timing will advance without changing the tune, so for example, if I were to try and raise my octane to something like 110 it would hurt performance VS help it. My research showed I can move it to around 100 and see a benefit without modifying the car or changing the tune dramatically.

 

[K4fxd]

When I look at my datalogs on 93, it’s pushing about 36 total degrees (30* base +6* of advance) and I’m seeing 0* of knock retard across the graph.

Thats a crap ton of advance. I find it very hard to believe that that amount is not knocking like crazy on 93. Should sound like hammers hitting the pistons.

Everything I find on the coyote chambers say 32 degrees is MBT. This is not a windsor or small block chev that needs that amount of lead to react all the fuel.

 

[K4fxd]

if I were to try and raise my octane to something like 110 it would hurt performance VS help it.

This is more BS, having too much octane will not hurt performance in any way. It will not help in any way either.

Tested on many dyno pulls.

 

[NHMustangGuy]

This is more BS, having too much octane will not hurt performance in any way. It will not help in any way either.

Tested on many dyno pulls.

This is not more BS, every car is different and will react differently depending on the car's ignition setup. Motortrend did a test on a car with 91, 100, 110, and 118 Octane. The 118 made less horsepower than the 100 and 110 because the car's ignition could not efficiently ignite the 118 obtain fule. It also reduced gas mileage.

 

[mavisky]

This is not more BS, every car is different and will react differently depending on the car's ignition setup. Motortrend did a test on a car with 91, 100, 110, and 118 Octane. The 118 made less horsepower than the 100 and 110 because the car's ignition could not efficiently ignite the 118 obtain fule. It also reduced gas mileage.

I wouldn't rely on Motortrend for "dyno knowledge".

After all they're the same morons who brought us this stupidity that tried to show a stock GT350 made 494 whp:

https://www.motortrend.com/news/201...=In the 2019 GT350 and,of torque at the crank.

 

[Grimreaper]

Makes sense now. At first, I thought the timing table had a hard maximum on these cars. Since it can keep advancing until it detects detonation and is able to ride that threshold,

There are several hard maxes with MBT tables usually being setup as the final do not go past regardless of octane. The knock sensors are only free to add when a gap is present between borderline and MBT/other limit tables. There is rarely any gain past MBT except maybe a feeling of increased response in lower load areas.

Thats a crap ton of advance. I find it very hard to believe that that amount is not knocking like crazy on 93. Should sound like hammers hitting the pistons.

agreed. certainly not a stock tune if so or maybe it was read inversed for the KR(-= adding, + = subtracting). or lower loads/transient to OP cam angles etc..


The benefit of having octane to spare is how the tune adds timing and the fact that 93 under certain conditions may be enough, but under others may not be ( and thats without the issues of fuel storage/supply chain etc). The way i see it is consistency is created from having reserve octane.

There are two levels of timing advance from the knock sensors based on recent activity. fast/slow. Also there is a learned octane/knock activity multiplier that raises and lowers borderline based on recent sensor activity (good or bad). think long term fuel trims.

during an event where knock sensors are adding timing, it will advance at a higher rate. once KR detected it pauses (or removes timng) and switches to slower advance rate (assuming the pause or small reduction was sufficient to stop the knock retard). if your throttle input is consistent and long enough, it may hit the end target it was going for, but you will be missing out in the short term. usually during a wot pull there is not enough time.

take 3rd gear, punch it at 2500rpms, borderline has a gap to mbt of 5 degrees from 2000 to 8500rpms. (no other scalars to keep this simple) knock sensors dont hear anything and timing is allowed to add quickly until mbt is reached. so by 3500rpms we have the full 5 degrees added in and riding mbt timing until throttle lift or knock is sensed. if no kr, 93 is enough, no power to be gained from more.

Assume for next pull it hit knock at 4500rpms, KR removes timing to get it to stop and pauses before starting to add again but at the slower advance rate. so we find ourselves at 5500rpms and missing 3 degrees of timing that is now being allowed back in slowly. Above 6000rpms the gt350 and gt usually only allows 1 degree very 6 seconds, vs 1 degree very 1/4 second for the fast rate. so by 8500rpms, we are still missing 3 degrees and as far as we know 93 would have been enough for the higher rpms but we will be doing without for safety (stock tune).

These events chip away at the learned octane modifier. this modifier can be logged to see what its currently at and is a good indicator of how its liking the current fuel. And it takes more timing being removed to stop KR once it starts than it would have to simply avoid it. Ex: takes 1-3 degrees to stop it but if we would have ran 0.5 degree less, we would have avoided it all together.

 

[Grimreaper]

OP id personally recommend 4-5 oz per tank vs half a can of professional. dont think you will see much benefit from more than that as it should bring the octane to around 97-98.

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