Premium Gas

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In 9 posts, the OP has made no mention of a loss of speed while driving uphill.

The issue is the desire for more power. The question was whether or not that would be possible by using fuel with a higher octane rating.

Using 91 octane will make no difference. If we haven’t beaten that concept to death, we’ve at least beaten it into submission.

You may receive more prompt responsive your new questions by starting a new thread.
 
Landshark said:
In 9 posts, the OP has made no mention of a loss of speed while driving uphill.

The issue is the desire for more power.
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I was trying to understand what the need for more power while driving uphill meant.

Is he losing speed, trying to accelerate, or just too much noise?

Maybe we should just block each other, if you do not feel my post was appropriate.
 
ClarityBill said:
I also consider your statements ridiculous.
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We have a moderator who determines what is appropriate.

The “Ignore” feature is available to each of us to utilize on an individual basis.

If you truly believe your statement above, even though you paraphrased many of my ridiculous statements in post #58, than the “Ignore” feature may be something for you to consider.
 
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ClarityBill said:
I was trying to understand what the need for more power while driving uphill meant.

Is he losing speed, trying to accelerate, or just too much noise?

Maybe we should just block each other, if you do not feel my post was appropriate.
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I did not lose power, but in steep and winding climbs around 35-40 mph the car doesn't have enough power and engine RPMs go way up. I have encountered this on a few occasions in Sierras. To be more specific climbing to Monitor pass from Lake Tahoe, climbing from 395 to Lake Tahoe (Kingsbury Grade), and climbing from Mono Lake area via Conway Summit on CA 395. You won't encounter this unless you go to these type of high elevation mountain ranges. In regular freeway driving the car is effortless, these are different operating conditions.

I contacted Honda to get information about starter/generator specs and premium gas, they have not responded yet.
 
I also experience rpm that I think are too high. Do you know what the rpm were? (I hit 3932 on a hill today at 62 mph.)

It does appear the rpm is governed by the speed required in the generator head, so any change in the gas engine (including premium fuel) would not change the operational rpm.

This entire explanation / argument is based on the fixed output of the generator head relative to rpm. This brings up the question of how the generator used for regenerative braking is able to smoothly modify output? And how are the paddles able to modify the output of that generator? (Since they are both rare-earth generators). If the car is controlling the output of the main generator head separate from rpm, premium fuel could make a difference in rpm.

As a work around:
It appears the rpm is determined by how low the battery is below the target charge level: I use an HV reset to put the system back into gear mode at higher speeds. Does the HV reset work at these low speeds?

I am disappointed that Honda does not use more of the remaining battery to supplement the power of the gas engine.
 
ClarityBill said:
I also experience rpm that I think are too high. Do you know what the rpm were? (I hit 3932 on a hill today at 62 mph.)

It does appear the rpm is governed by the speed required in the generator head, so any change in the gas engine (including premium fuel) would not change the operational rpm.

This entire explanation / argument is based on the fixed output of the generator head relative to rpm. This brings up the question of how the generator used for regenerative braking is able to smoothly modify output? And how are the paddles able to modify the output of that generator? (Since they are both rare-earth generators). If the car is controlling the output of the main generator head separate from rpm, premium fuel could make a difference in rpm.

As a work around:
It appears the rpm is determined by how low the battery is below the target charge level: I use an HV reset to put the system back into gear mode at higher speeds. Does the HV reset work at these low speeds?

I am disappointed that Honda does not use more of the remaining battery to supplement the power of the gas engine.
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Unfortunately I don't use a device to measure RPM. I guess it was around 5000 rpm based on my experience with cars with a tachometer. I think they should add a climbing mode or mountain mode where the car can combine engine and battery power. Like a 70-30 mix that gives you around 100 miles range.

One way to do this is to cap engine RPM, for example in mountain mode whenever engine rpm has to exceed for example 4500 rpm, cap it at 4500 rpm and use battery for additional power.
 
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Agzand said:
One way to do this is to cap engine RPM, for example in mountain mode whenever engine rpm has to exceed for example 4500 rpm, cap it at 4500 rpm and use battery for additional power.
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If you cap engine rpm, the question is what do you do when the battery goes dead?

The obvious answer is allow the engine to go to a higher cap. If the engine can't keep up at this new maximum, the car would have to lose power.

I believe the Clarity currently operates with a modified version of what you are describing. Anytime you are in HV mode, the battery is supplementing the gas engine power. The gas engine maintains reasonable rpm until battery has lost too much charge, then the rpm starts to climb. RPM continues to climb as the battery gets weaker and weaker.

The more important question for the Clarity design is, How do you decide the battery is 'dead'?
It seems the Clarity uses a relative battery charge, instead of an absolute battery charge, to determine how the engine rpm should respond.

When the battery charge drops 11% from the starting point, the engine will be at full rpm. If you start HV at 50% battery, the engine will be at full rpm if the charge drops to 39%.

Seems like a better design would have been to allow the battery to drop to 5 or 10% absolute charge before ramping up the rpm.
 
Agzand said:
Unfortunately I don't use a device to measure RPM. I guess it was around 5000 rpm based on my experience with cars with a tachometer.
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I would actually include your situation in the 'too much noise' category. You don't like what you are hearing.

Reducing the rpm would obviously alleviate this issue.

Many of us have assumed that Honda has built the car to protect ifself from rpm being too high: This means there is not a real problem with the rpm, but the perception of a problem. This perception is common, and I agree that it sounds really bad. Most of my passengers have been alarmed by the high rpm of the Clarity.

The higher octane may give a smoother burn, less noise in the exhaust, and the perception of a better operation.
 
At the risk of fanning the flames...

I agree with the camp that feels the car has been designed and optimized for 87 octane. That is what the manual recommends, and I am unwilling to accept a 'conspiracy theory' that Honda is only saying this to avoid scaring away buyers when they really know that higher octane is better !!

If there is any potential performance increase with higher octane fuel, that benefit can only be reaped if the anti-knock system can essentially 're-tune' the vehicle on the fly to take advantage of the higher octane.

If the anti-knock system can indeed re-optimize for the higher octane (I doubt this), I am willing to bet that any performance increase is trivial and no human will be able to perceive any difference.

Deviating from the manufacturers recommended fuel in order to maybe perceive 'better operation' which is highly likely to be trivial (while the added cost of premium fuel is not trivial) is a non-starter for me.
 
MrFixit said:
At the risk of fanning the flames...

I agree with the camp that feels the car has been designed and optimized for 87 octane. That is what the manual recommends, and I am unwilling to accept a 'conspiracy theory' that Honda is only saying this to avoid scaring away buyers when they really know that higher octane is better !!
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The manual actually recommends 87 or higher.
 
Agzand said:
87 or higher.
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You're right... Again, could be the boundaries of the anti-knock features. Designed to be OK with a minimum octane, and probably works fine with premium too. Some cars actually recommend premium. By no means does this mean that the car runs better with higher octane.

By all means, run some higher octane. If you really feel that you can perceive 'better' performance in some way, report back and I will accept your judgement.

I operate with a high percentage of EV anyway, and don't think I could even do a fair comparison with different gas.
 
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ClarityBill said:
Anytime you are in HV mode, the battery is supplementing the gas engine power.
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In HV mode a variety of situations may occur to propel the vehicle.

1) The ICE powered generator and the batteries may supply electricity to the traction motor.

2) The ICE powered generator, alone, may supply electricity to the traction motor. While this is happening, surplus electricity may be used to charge the batteries.

3) The car may actually revert to EV mode for brief periods, while in HV mode, and power the traction motor from the batteries while the ICE is not running. This is a function of HV mode.

4) What Honda refers to as Engine Drive Mode, is, in my opinion, also a function of HV mode. The ICE drives the front wheels directly, while at the same time the generator can charge the batteries.

5) The Clarity powertrain development document indicates that the batteries can also power the traction motor while the ICE is directly powering the wheels in Engine Drive mode.

There are cases while in HV mode, in which the batteries are not supplementing the gas engine power.
 
Agzand said:
I did not lose power, but in steep and winding climbs around 35-40 mph the car doesn't have enough power and engine RPMs go way up.
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ClarityBill said:
I use an HV reset to put the system back into gear mode at higher speeds. Does the HV reset work at these low speeds?
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Engine Drive mode may engage at speeds of 45mph and above, given the correct circumstances. Namely, low power demand.
 
MrFixit said:
By all means, run some higher octane.
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I have 93 octane in my tank, and it really seems quieter to me.

I burn about a tank of gas per week, so I thought I would be a good fit to try premium. I had to run out the tank, and I have only gone 150 miles of HV with the premium.

I hate the noise of the high rpm, so I often wear earplugs while driving. Tuesday night, I had a 140 mile round trip (two 70-mile legs with charging in the middle). I got about 35 miles on EV, so each leg was completed with HV. I hit 3584 rpm as peak (OBD recorder always active). The engine sounded like I always wanted it to - gentle purr, not a generator running. RPM pattern seemed the same, but each rpm level seemed quieter.

Today I drove about 120 miles (80 HV / 40 EV), and hit 4320 rpm on one hill. The car sounds wonderful! Just my opinion, but I am impressed.

This is preliminary, and very subjective (possibly biased) results, but I thought worth reporting.
 
ClarityBill said:
I have 93 octane in my tank, and it really seems quieter to me.

I burn about a tank of gas per week, so I thought I would be a good fit to try premium. I had to run out the tank, and I have only gone 150 miles of HV with the premium.

I hate the noise of the high rpm, so I often wear earplugs while driving. Tuesday night, I had a 140 mile round trip (two 70-mile legs with charging in the middle). I got about 35 miles on EV, so each leg was completed with HV. I hit 3584 rpm as peak (OBD recorder always active). The engine sounded like I always wanted it to - gentle purr, not a generator running. RPM pattern seemed the same, but each rpm level seemed quieter.

Today I drove about 120 miles (80 HV / 40 EV), and hit 4320 rpm on one hill. The car sounds wonderful! Just my opinion, but I am impressed.

This is preliminary, and very subjective (possibly biased) results, but I thought worth reporting.
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Well that is encouraging! I am going to try if I get a chance, unfortunately I don't drive long distances these days due to COVID. But it would be nice if others can try and report if they see similar trend.
 
On my driving this week, I hit 5225 rpm, and the sound was dramatically reduced. I don't think I will be wearing earplugs anymore. I don't worry about the HV reset either, I can't hear the rpm increase well enough.

I am on my second tank of 93 octane, from a different gas station.

The difference between 87 and 93 is spectacular. I am wondering if the people with a severe angry bee problem got into some 86 octane - I never really pay attention to octane, so I assume other people ignore it also.

I used the sound meter app on my phone, and it measured less than 70 dba. My previous measurements were over 80.
 
Thanks for reporting back with your experience.
Although this seems counter-intuitive to me, your results speak for themselves.
It will be interesting to see if this inspires others to try it, and if they obtain a similar result.

I don't think our usage is appropriate to legitimately evaluate this (mostly EV). If we went on a long trip where we expected to go through multiple tanks of gas, I would consider trying it, for a good side-by-side comparison.
 
I’ve been using premium gas for over 6 months now after hearing the reduction in noise. I have not seen much improvement in terms of performance or fuel economy though. However, since I exhaust my EV range everyday, the extra bit of money to reduce the engine noise is worth it.


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