Highest Octane For Stock ECU??

USNA94 · 09-03-2009, 06:37 PM

Quote:

Originally Posted by semtex

Well, it will if it's oxygenated, won't it? Or am I missing something? I understand the higher octane won't do anything, but the oxygenation helps doesn't it? (Not that I'd spend the money on that stuff to run on a regular basis, mind you.)

Not really, we oxygenate gas to to reduce carbon monoxide that is created during the burning of the fuel. It's an environmental thing, not a performance thing. One of the additives used to do this is ethanol and we all know what that does to performance.

Paul@AEperformance · 09-03-2009, 07:06 PM

Don't know if this was posted yet, but in the users manual it mentions to run 96 oct

or mix until you can find better gas.

Got a kick out of that when i read it.

Makes me miss Ohio, (sunoco 94) =)

semtex · 09-03-2009, 07:08 PM

Quote:

Originally Posted by USNA94

Not really, we oxygenate gas to to reduce carbon monoxide that is created during the burning of the fuel. It's an environmental thing, not a performance thing. One of the additives used to do this is ethanol and we all know what that does to performance.

Hmm... in that case, do you know what accounts for the 14whp gain that was achieved from the XXX Oxygenated Race Fuel?

USNA94 · 09-03-2009, 07:17 PM

Quote:

Originally Posted by wstar

The big question mark with our cars is: given a stock ECU, is the stock ECU smart enough to tune itself upwards for a higher octane fuel automatically? We already know that the stock ECU knows how to de-tune itself when presented with lower-octane fuel by using sensors to detect the onset of knocking and making the appropriate adjustments.

It's my understanding that it "tunes" itself using the knock sensor. There is no octane sensor. When it detects the onset of knock using the knock sensor the ECU throttles back thereby reducing performance. If there is no knock when running 91 octane and definitely no knock when running 101 octane, the ECU would never know the difference and run the same. It doesn't open up the throttle any more or provide more power. It just knows there is no knock happening. And the energy content of the gasoline does not go up with octane. 91 octane fuel has ~32MJ/liter of energy, 101 octane fuel has ~32MJ/liter of energy, 121 octane fuel has ~32MJ/liter of energy so the power of the engine is the same. The higher octane will allow you to run a modified engine with a higher compression ratio to get more power though.

semtex · 09-03-2009, 07:24 PM

Quote:

Originally Posted by Paul@AEperformance

Don't know if this was posted yet, but in the users manual it mentions to run 96 oct

or mix until you can find better gas.

Got a kick out of that when i read it.

Makes me miss Ohio, (sunoco 94) =)

Here's a screenshot of what it says in the manual.

I'm not sure what they mean by "Research octane number" though.

Chan Chee Hoe · 09-03-2009, 07:34 PM

Quote:

Originally Posted by semtex

Here's a screenshot of what it says in the manual.

I'm not sure what they mean by "Research octane number" though.

This "RON" system is used in Europe,all Asia,Austraila & of course S'pore....

bigaudiofanat · 09-03-2009, 07:46 PM

Quote:

Originally Posted by kannibul

That's the whole problem right there.

Higher octane gas isn't better for your car...

I agree, if your car was made for regular than you burn regular. I mean yes in my civic I have ran a few tanks or premium with a fuel injector cleaner and a few times on race night but there was no real reason for it. If it takes a certain kind of gas that is what you should use. End of story.

37Z · 09-03-2009, 07:51 PM

104 Sunoco race fuel on a re-tune!!

Blown32 · 09-03-2009, 08:21 PM

Apparently this is one of those subjects that you can beat to death.As I said in my last post there are those that insist race gas will make more power in the Z because they just don't know any better.
The 370Z in stock form is NOT going to make more hp with race gas instead of the recomended fuel by the manufaster.Plain and simple!
Some know the real deal and others are lost.It is a shame that these gimmicks catch some and they waste there money!
So anyone advertising any different are looking to draw attention,don't know what they are talking about or looking to make a buck on the public that just isn't familiar with the performance world.
As for the additional 14 hp on just race gas with a stock 370z is pure bull at its best!
Guys in the race world spend thousands of dollars to gain every little bit of hp to have an edge over there competiter but a stock motor with premium fuel versus race gas is a waste of money!No advantage power wise unless its been modified with the compression raised to the point it will detonate on pump fuel!
As to the oxgeanated fuel that is a whole different type of fuel.The first post if I recall was about higher octane fuel.

JoeD · 09-03-2009, 08:31 PM

Quote:

Originally Posted by Blown32

Apparently this is one of those subjects that you can beat to death.As I said in my last post there are those that insist race gas will make more power in the Z because they just don't know any better.
The 370Z in stock form is NOT going to make more hp with race gas instead of the recomended fuel by the manufaster.Plain and simple!
Some know the real deal and others are lost.It is a shame that these gimmicks catch some and they waste there money!
So anyone advertising any different are looking to draw attention,don't know what they are talking about or looking to make a buck on the public that just isn't familiar with the performance world.
As for the additional 14 hp on just race gas with a stock 370z is pure bull at its best!
Guys in the race world spend thousands of dollars to gain every little bit of hp to have an edge over there competiter but a stock motor with premium fuel versus race gas is a waste of money!No advantage power wise unless its been modified with the compression raised to the point it will detonate on pump fuel!
As to the oxgeanated fuel that is a whole different type of fuel.The first post if I recall was about higher octane fuel.

This is what I've been saying all along.

ZzzZz · 09-03-2009, 09:44 PM

Yes. Let's talk about at the pump of the majority of gas stations. It's not about educating people about race gas, 120 Octane gas, or the "more octane is always better" mentatility. It's about finding out what the 370z runs best on and possibly saving money to boot.

Let's talk about what almost all members here can get:
91 vs 92 vs 93 vs 94 AKI

External factors aside (engine condition, temperature,), will a stock 370z be able to gain anything performance-wise by pumping higher than 91 octane gas?

Quote:

Originally Posted by Blown32

The first post if I recall was about higher octane fuel.

Shunya · 09-03-2009, 11:17 PM

Quote:

Originally Posted by Izzoh

It's not a bad thing. You said you did internal work which probably raised your compression ratio that rasied ratio usually will cause a car to Ping (detonate) running lower octane (87,89,91) rated gas. Running 94 will allow you to take advantage of the mods that you did to your engine by tuning.

Higher Octane dosen't increase HP/TQ it just helps to keep Pistons from coming out the side of the block or through the oilpan by helping reduce Knocking and Pinging. Tuning is where you get your HP from.

hahaha well I just think it's better to give my baby better food

Quote:

Originally Posted by Izzoh

That would raise your compression def. over what 91 would safely let you handle. How high where you reving and what compression where your pistons ?

it's at 12.1

Quote:

Originally Posted by kannibul

Sorry, I thought you were driving a Z.

What do you do if you can't get 94 octane?

Why go to 94 octane unless you're running 12:1 or greater compression?

you're on the right track it's 12.1

Quote:

Originally Posted by Izzoh

I think she drives a type R or has a type R swap those are 11.5:1 from the factory so giving that list of internal work I'm assuming it's been rasied to the 12:1 or higher. Most that I know go 12.5:1 on their B-series if they're sticking to NA.

It's a Type R

and it eats most of the k-swaps in town

wstar · 09-03-2009, 11:26 PM

Quote:

Originally Posted by USNA94

It's my understanding that it "tunes" itself using the knock sensor. There is no octane sensor.

We agree on this, although I think the new knock sensors are supposedly picking it up much earlier, when it's a tiny hint of a knock. You don't actually have to get to where you're risking damage to have the sensor "see" it and adjust.

Quote:

When it detects the onset of knock using the knock sensor the ECU throttles back thereby reducing performance. If there is no knock when running 91 octane and definitely no knock when running 101 octane, the ECU would never know the difference and run the same. It doesn't open up the throttle any more or provide more power. It just knows there is no knock happening. And the energy content of the gasoline does not go up with octane. 91 octane fuel has ~32MJ/liter of energy, 101 octane fuel has ~32MJ/liter of energy, 121 octane fuel has ~32MJ/liter of energy so the power of the engine is the same. The higher octane will allow you to run a modified engine with a higher compression ratio to get more power though.

Here's where we potentially differ (not that I'm solidly in the other camp either, I'm just playing out their side of the argument as best I can, and it's reasonably sound, but has question marks):

The way that the ECU responds to knock is not to "throttle back" literally with the throttle, but to retard the timing, which eliminates the knock at the cost of performance and efficiency. You mentioned this yourself in an earlier post, but I just wanted to be clear on that issue:

Quote:

However, burning fuel with a lower octane rating than required by the engine often reduces power output and efficiency one way or another. If the engine begins to detonate (knock), that reduces power and efficiency for the reasons stated above. Many modern car engines feature a knock sensor which detects knock, and then sends a signal to the engine control unit to retard the ignition timing. Retarding the ignition timing reduces the tendency to detonate, but also reduces power output and fuel efficiency.

Similarly, if you put 110 race gas in a car that was designed and tuned for 93, there's lots of "knock headroom", so to speak. With the higher octane fuel in the tank, a tuner can go into the ECU parameters and advance the ignition timing more aggressively than stock to create more power than was possible on 93 octane due to the higher resistance to knocking the 110 fuel has (the inverse of what we described above, where retarding it reduces power and helps avoid a knock). There's still only X MJ/liter of energy in the higher-octane gas, but by being more knock-resistant, it allows a more aggressive spark timing advance, which results in increased horsepower.

I *think* we both agree on the above - that by tuning the ignition timing manually with an ECU programmer up as far as you can without knocking, on any modern-ish car where that is possible, you can get more horsepower out of 110 gas than 93 gas, even though they both have the same MJ/liter of potential energy within them.

The question mark is whether the ECU is smart enough to do this by itself. Some have claimed that when it detects absolutely no hint of knocking, it slowly advances the timing more aggressively until it finds the first hint of it, and thus self-adjusts upwards (more aggressive spark timing, more power) for higher-octane fuel in much the same manner that we know it self-adjusts downwards for crappy fuel.

Nobody has put out any hard evidence that this is true, but people have mentioned it, and the 110 race gas dyno results seem to indicate that *something* is going on, and this explanation kinda fits the bill.

USNA94 · 09-04-2009, 01:10 AM

Quote:

Originally Posted by wstar

We agree on this, although I think the new knock sensors are supposedly picking it up much earlier, when it's a tiny hint of a knock. You don't actually have to get to where you're risking damage to have the sensor "see" it and adjust.

Here's where we potentially differ (not that I'm solidly in the other camp either, I'm just playing out their side of the argument as best I can, and it's reasonably sound, but has question marks):

The way that the ECU responds to knock is not to "throttle back" literally with the throttle, but to retard the timing, which eliminates the knock at the cost of performance and efficiency. You mentioned this yourself in an earlier post, but I just wanted to be clear on that issue:

Similarly, if you put 110 race gas in a car that was designed and tuned for 93, there's lots of "knock headroom", so to speak. With the higher octane fuel in the tank, a tuner can go into the ECU parameters and advance the ignition timing more aggressively than stock to create more power than was possible on 93 octane due to the higher resistance to knocking the 110 fuel has (the inverse of what we described above, where retarding it reduces power and helps avoid a knock). There's still only X MJ/liter of energy in the higher-octane gas, but by being more knock-resistant, it allows a more aggressive spark timing advance, which results in increased horsepower.

I *think* we both agree on the above - that by tuning the ignition timing manually with an ECU programmer up as far as you can without knocking, on any modern-ish car where that is possible, you can get more horsepower out of 110 gas than 93 gas, even though they both have the same MJ/liter of potential energy within them.

The question mark is whether the ECU is smart enough to do this by itself. Some have claimed that when it detects absolutely no hint of knocking, it slowly advances the timing more aggressively until it finds the first hint of it, and thus self-adjusts upwards (more aggressive spark timing, more power) for higher-octane fuel in much the same manner that we know it self-adjusts downwards for crappy fuel.

Nobody has put out any hard evidence that this is true, but people have mentioned it, and the 110 race gas dyno results seem to indicate that *something* is going on, and this explanation kinda fits the bill.

I agree with all of your points.

As far as the ECU being smart enough to adjust up on it's own I don't know enough about how it works to say. Would be cool if this were true though I wonder what the limit is as you can only adjust timing so much I would think.

USNA94 · 09-04-2009, 01:19 AM

Quote:

Originally Posted by semtex

Hmm... in that case, do you know what accounts for the 14whp gain that was achieved from the XXX Oxygenated Race Fuel?

I think this is more of a terminology issue than anything else.

To me, oxygenated is meant in the government regulation sense in which oxygenation is used to control emissions and reduce pollution.

Maybe they use "Oxygenated" differently because it sounds better and sells more gas but really what they are selling is a blended fuel that has a higher energy content and is more appropriate for racing and most likely not street legal. This could count for the documented Hp gains. JP-5 or aviation fuel has a higher energy content than standard gasoline. I'm sure it would boost horsepower as well but i'm sure you would have some serious knock.

09-03-2009, 07:06 PM	#62 (permalink)
Paul@AEperformance The370Z.com Sponsor Join Date: Aug 2009 Location: At the Track Posts: 194 Drives: All sorts of Fast! Rep Power: 16	Don't know if this was posted yet, but in the users manual it mentions to run 96 oct or mix until you can find better gas. Got a kick out of that when i read it. Makes me miss Ohio, (sunoco 94) =) __________________ http://i10.photobucket.com/albums/a1...Ejdmbanner.gif

09-03-2009, 07:51 PM	#68 (permalink)
37Z Enthusiast Member Join Date: Jun 2009 Location: Florida Posts: 476 Drives: 370Z MB 6M -sold Rep Power: 263	104 104 Sunoco race fuel on a re-tune!!

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09-03-2009, 08:21 PM	#69 (permalink)
Blown32 Enthusiast Member Join Date: Aug 2009 Location: N.J. Posts: 289 Drives: 09 370Z Blk sport 6T Rep Power: 16	Apparently this is one of those subjects that you can beat to death.As I said in my last post there are those that insist race gas will make more power in the Z because they just don't know any better. The 370Z in stock form is NOT going to make more hp with race gas instead of the recomended fuel by the manufaster.Plain and simple! Some know the real deal and others are lost.It is a shame that these gimmicks catch some and they waste there money! So anyone advertising any different are looking to draw attention,don't know what they are talking about or looking to make a buck on the public that just isn't familiar with the performance world. As for the additional 14 hp on just race gas with a stock 370z is pure bull at its best! Guys in the race world spend thousands of dollars to gain every little bit of hp to have an edge over there competiter but a stock motor with premium fuel versus race gas is a waste of money!No advantage power wise unless its been modified with the compression raised to the point it will detonate on pump fuel! As to the oxgeanated fuel that is a whole different type of fuel.The first post if I recall was about higher octane fuel.