: Octane Question



brian-nicola
04-05-12, 06:39 PM
Only one station in town has 93+ and that is Chevron. All the others the best is 91. Any issue do you think with 91? (normal city driving of course) 93+ for stomp and steer w'end drives....

cruiser68
04-05-12, 08:42 PM
No issue. In higher elevations you don't get better than 91. Worst case it will retard timing if it starts knocking.

Smokin_Cache
04-05-12, 08:57 PM
I feel like I am getting ripped off when I travel to a state that sells 91 at the price we get 93 for. I remember traveling through a state somewhere that had 5 octane selections at the pump. Can't remember where. The 76 stations use to have a pump with 100 on the east coast. That was when the had the NASCAR contract.

Trapspeed
04-05-12, 09:51 PM
100 octane is such a great thing. Love that stuff.

brian-nicola
04-05-12, 10:23 PM
Thanks for the repies...I remember SONOCO 100 octane. Now you have to go to the airport for AV100
Here in British Columbia 91 is 1.48/Ltr = 5.62 per US Gallon

GMX322V S/C
04-05-12, 11:31 PM
Our motors are designed to run on 91 R+M/2. Anything beyond that would be a hedge against pulling timing under extreme conditions, but the motor will protect itself just fine on 91 regardless.

100 is also available at selected 76 stations here in SoCal. Regarding AvGas, if it's leaded, it'll poison your cats if you're running them.

V locity
04-06-12, 08:38 AM
Plus, if you're timing's not tuned to the 100, not really any upside...

Fireverm
04-06-12, 01:06 PM
I feel like I am getting ripped off when I travel to a state that sells 91 at the price we get 93 for. I remember traveling through a state somewhere that had 5 octane selections at the pump. Can't remember where. The 76 stations use to have a pump with 100 on the east coast. That was when the had the NASCAR contract.

You are aware that 91 octane has more "gas" in it than 93 right? Refined gasoline starts out at a low octane and then is diluted with crap that doesn't burn to raise the octane of it so it can be compressed more before spontaneously exploding. You can take 87 octane and inject water to give you 110 octane if you wanted. All of those "additives" they put in premium gasoline are marketing nonsense, it doesn't make the gasoline more powerful, it actually makes it less powerful by volume. However, the benefit of higher octane is that you can compress it more before it explodes, so even though it is less powerful fuel per volume, you make up the difference and then some if you are compressing it more.

But your vehicle needs to take advantage of that fact. If your vehicle is designed to be able to run 91, in almost all situations, running 100 octane will in fact make less power unless you are able to increase the cylinder pressure either by adding more boost in a forced induction setup (like ours) or by changing the heads or pistons to give more compression.

Bottom line, if your car is setup to run 91, it will make less power and be slower running higher octane than specified unless your car is specifically configured to take advantage of higher octane.

tedcmiller
04-06-12, 03:11 PM
The CTS-V is specified for 91 octane minimum. Where I live the only octanes available are 89 and 93, so I go with 93 to meet the minimum spec.. If the car is unmodified it should run fine on 91 octane. Anything over 91 octane (if the car runs OK) is a waste (for normal street driving or the track). Those people who think 100 octane is wonderful (for stock CTS-Vs) are kidding themselves. The same goes for my motorcycles (2008 and 2012 H-Ds).

Pphilthy
04-06-12, 07:14 PM
Running 100 octane will make your car less powerful...? lol - these cars are developed to run a minimum of 91 from the factory, but it will make more on 100 octane, not less... Most ECU's are designed to pull and add timing based on dynamic advance tables that are enabled based on certain criteria, air intake temps, knock, exhaust has temps, etc... The bases of your post is technically correct given all things equal, but not applicable in a boosted car with modern ECU capabilities... Running higher octane fuel than the minimum required 91 will place your ECU in the happy zone and allow it to run full programmed timing = more power and for longer because of the added cooling effect of the higher, slower burning fuel...

Also, higher octane fuel isn't made by just adding water, haha. Go ahead and try that on your car and let us know how it works out for you... There's a reason why fuel companies use octane boosters with nitrogen carriers. Most use methanol, isopropyl alcohol, naptha, xylene, toluene), benzine, hexane, nitro benzine, aniline, etc., but they never tell you exactly what or how much they use - its called trade secrets... Those additives they add to the fuel do a lot to combat all of the negative effects of running unleaded fuel, such as varnish and deposit build up, storage life, reaction to oil, etc... These aren't issues with leaded fuel but are with unleaded...

Granted, you will make much more power by tuning your car to optimize the timing for the higher octane... But there is no way you'll make less HP - the statement is true if you run lower octane as the ECU will pull timing and will run much hotter....

Fireverm
04-06-12, 10:45 PM
Running 100 octane will make your car less powerful...? lol - these cars are developed to run a minimum of 91 from the factory, but it will make more on 100 octane, not less... Most ECU's are designed to pull and add timing based on dynamic advance tables that are enabled based on certain criteria, air intake temps, knock, exhaust has temps, etc... The bases of your post is technically correct given all things equal, but not applicable in a boosted car with modern ECU capabilities... Running higher octane fuel than the minimum required 91 will place your ECU in the happy zone and allow it to run full programmed timing = more power and for longer because of the added cooling effect of the higher, slower burning fuel...


Also, higher octane fuel isn't made by just adding water, haha. Go ahead and try that on your car and let us know how it works out for you... There's a reason why fuel companies use octane boosters with nitrogen carriers. Most use methanol, isopropyl alcohol, naptha, xylene, toluene), benzine, hexane, nitro benzine, aniline, etc., but they never tell you exactly what or how much they use - its called trade secrets... Those additives they add to the fuel do a lot to combat all of the negative effects of running unleaded fuel, such as varnish and deposit build up, storage life, reaction to oil, etc... These aren't issues with leaded fuel but are with unleaded...


Granted, you will make much more power by tuning your car to optimize the timing for the higher octane... But there is no way you'll make less HP - the statement is true if you run lower octane as the ECU will pull timing and will run much hotter....


I emphatically disagree with several of your points.


These cars in stock trim will certainly make less power on 100 octane than 91. Now I'll grant you that you might be able to come up with a scenario where this is not the case, like where the IATs are so high it is pulling obscene timing while using 91...like....let's say if you are doing the dyno run out in the sun in Death Valley in July. And in that situation, the power output will be substantially reduced in either case so who cares.


In standard temps and pressures the ecu may not pull much timing, if any at all, while running 91 under high load. It's not like they designed this powerplant to run super inefficiently on even the highest octane pump gas available nationwide and that there is a ton of timing overhead that can be tapped into. I can just hear that conversation now, "Hey somebody tell the powerplant engineers that I want a new platform based on a 6.2 liter LS block. Tell them I want forced induction, preferably supercharged. Tell them I want it called LSA. Oh, and one more thing....tell them to design it to run most efficiently on 100 octane and then for the actual production run we'll just retard the **** out of the timing so the customers can run it on 91."


As temps rise, the ecu will certainly adjust timing depending on the load, but there is only so much you can do with timing. The adjusting that the ecu will do with the timing is an attempt to try to minimize the loss of power from your theoretical maximum, not primarily as a power adder above and beyond. If what you were saying is right, then why would anyone run forced induction when we can make shit loads of power just by running high octane gas and advancing the timing?


100 octane has lower specific energy per volume than 91 and the only way to really make that loss up is by increasing the compression, which in stock trim isn't happening just because modern day ecus are magic.


Also, I didn't say that higher octane gasoline is made just by adding water. I stated that you could effectively increase your octane by injecting water into the combustion chamber, as many race cars have done. If you don't believe me, science and google are your friend. The additives they put in are non-combustible compounds that dilute your gasoline and decrease it's specific energy so you can compress it more before it explodes. Many compounds will work, there is nothing special about the blends of bullshit the petroleum companies put in there if all you are trying to do is raise the octane. And that's why initially we turned to leaded fuel, it was added to the gasoline to increase it's octane rating by lowering the specific energy of the fuel.


So back to my bottom line, in stock trim you will make less power running 100 octane over 91 unless your normal stomping grounds are on the day side of Mercury.

V locity
04-06-12, 11:48 PM
^^^ Nice siphering Fireverm! Gasoline has the same BTU's or thermal conversion regardless of burn rate (octane). So if you want more power, at the same compression, you need more fuel & oxygen. There are additives for gasoline like say Propylene Oxide that would allow you to richen the mixture to a small extent & hence get more power.

More commonly though, we see NOS. Oxygen spray with more (gasoline of the same octane). The amount of power these systems produce is only limited to how much your motor can handle.

Then, there's the old trick, for those in the know, of going down to the local Sherwin Williams :D

GMX322V S/C
04-07-12, 01:14 AM
Toluene?

Tampa2Dubai
04-07-12, 02:56 AM
I emphatically disagree with several of your points.


These cars in stock trim will certainly make less power on 100 octane than 91. Now I'll grant you that you might be able to come up with a scenario where this is not the case, like where the IATs are so high it is pulling obscene timing while using 91...like....let's say if you are doing the dyno run out in the sun in Death Valley in July. And in that situation, the power output will be substantially reduced in either case so who cares.


In standard temps and pressures the ecu may not pull much timing, if any at all, while running 91 under high load. It's not like they designed this powerplant to run super inefficiently on even the highest octane pump gas available nationwide and that there is a ton of timing overhead that can be tapped into. I can just hear that conversation now, "Hey somebody tell the powerplant engineers that I want a new platform based on a 6.2 liter LS block. Tell them I want forced induction, preferably supercharged. Tell them I want it called LSA. Oh, and one more thing....tell them to design it to run most efficiently on 100 octane and then for the actual production run we'll just retard the **** out of the timing so the customers can run it on 91."


As temps rise, the ecu will certainly adjust timing depending on the load, but there is only so much you can do with timing. The adjusting that the ecu will do with the timing is an attempt to try to minimize the loss of power from your theoretical maximum, not primarily as a power adder above and beyond. If what you were saying is right, then why would anyone run forced induction when we can make shit loads of power just by running high octane gas and advancing the timing?


100 octane has lower specific energy per volume than 91 and the only way to really make that loss up is by increasing the compression, which in stock trim isn't happening just because modern day ecus are magic.


Also, I didn't say that higher octane gasoline is made just by adding water. I stated that you could effectively increase your octane by injecting water into the combustion chamber, as many race cars have done. If you don't believe me, science and google are your friend. The additives they put in are non-combustible compounds that dilute your gasoline and decrease it's specific energy so you can compress it more before it explodes. Many compounds will work, there is nothing special about the blends of bullshit the petroleum companies put in there if all you are trying to do is raise the octane. And that's why initially we turned to leaded fuel, it was added to the gasoline to increase it's octane rating by lowering the specific energy of the fuel.


So back to my bottom line, in stock trim you will make less power running 100 octane over 91 unless your normal stomping grounds are on the day side of Mercury.

FYI .. european/export spec cts-v's are rated at 564bhp, due to running on 95-98 octane

http://www.cadillaceurope.com/en/index.php#/cts-v-sedan

V locity
04-07-12, 09:13 AM
So then my wifes GS350 should make 556hp because it uses the same octane as the V?

Look, I had a 13 hp difference on my base dyno runs last week, 1 minute apart & on the same fuel both pulls. I didn't change to a lower octane one minute later:

http://www.cadillacforums.com/forums/2009-cadillac-cts-v-performance-mods/256234-baseline-mustang-dyno-bone-stock-2011-a.html

Once again, Gasoline, regardless of how fast you allow it to ignite, creates the same amount of energy or thermal conversion (heat).

Maybe this will help... Diesel creates more power in the form of BTU's (thermal conversion) than the equivilant amount of gasoline, yet it's octane level is under 30% that of gas...

Pphilthy
04-07-12, 10:41 AM
lol - you are wrong on so many fronts... I got a Pepsi challenge for you, take your car to a dyno and do three consecutive pulls on 91 octane, and then fill up with 100 octane and do three more consecutive pulls - you'll be back here eating your words for a the reasons I've already posted...

The slower more controlled burn of the higher octane fuel will allow the ECU to provide access to the full timing tables and control heat, knock and pre-ignition far better than 91 octane... The 91 octane runs will lose power at a much higher rate as the ECU pulls timing...

You also DiD say the you can turn 87 octane fuel into 110 by just adding water HAHA! Now you're not going to man up and admit yore wrong...? Water injection which was pioneered back in the old turbo charged F1 days was used to reduce temps, not increase compression or octane... lol


I'm sorry, but you are just making me laugh now...

GMX322V S/C
04-07-12, 10:58 AM
Different rating systems (DIN vs. SAE HP and RON only vs. R+M/2 octane rating). This has been discussed before in these forums. There is no difference in output using the same rating systems.


FYI .. european/export spec cts-v's are rated at 564bhp, due to running on 95-98 octane

http://www.cadillaceurope.com/en/index.php#/cts-v-sedan

Kluch
04-07-12, 11:14 AM
Ahhhh! Which fuel nerd do I believe?

Pphilthy
04-07-12, 11:24 AM
Kluch, I don't know his tuning experience or how many boosted cars he has built, but he isn't making much sense...

Meth injection will increase the octane, NOT water lol. That comment in it of itself is enough to ignore anything he posts haha

V locity
04-07-12, 12:32 PM
lol - you are wrong on so many fronts... I got a Pepsi challenge for you, take your car to a dyno and do three consecutive pulls on 91 octane, and then fill up with 100 octane and do three more consecutive pulls - you'll be back here eating your words for a the reasons I've already posted...

The slower more controlled burn of the higher octane fuel will allow the ECU to provide access to the full timing tables and control heat, knock and pre-ignition far better than 91 octane... The 91 octane runs will lose power at a much higher rate as the ECU pulls timing...

You also DiD say the you can turn 87 octane fuel into 110 by just adding water HAHA! Now you're not going to man up and admit yore wrong...? Water injection which was pioneered back in the old turbo charged F1 days was used to reduce temps, not increase compression or octane... lol


I'm sorry, but you are just making me laugh now...

I would agree that there is a small amount of wiggle room in the, read this (factory programmed ECU timing), that could create a nominal amount of HP change from a "slightly higher" octane rating under certain circumstances. But, If you think you're going to see "real" power increases in proportion to octane rating increases, I'll throw the "Pepsi Challenge" back @ ya. Let's make it more interesting too. Assuming you own a V2??? (and your V is still 100% stock) go find some BP, "VP110" (the highest rated unleaded out there) & drive it around for a few tank fulls. If your emmission system is still alive, go to the dyno & post it up for us. According to your logic... ~20% higher octane will equal an extra, say 100 hp. I won't be putting that stuff in my car till it's built & tuned for it!

Fireverm's post on water injection & octane is correct too:

http://en.wikipedia.org/wiki/Water_injection_(engines)

FLTRI
04-07-12, 02:32 PM
Kluch, I don't know his tuning experience or how many boosted cars he has built, but he isn't making much sense...

Meth injection will increase the octane, NOT water lol. That comment in it of itself is enough to ignore anything he posts haha

You should probably stop now, you're just embarrassing yourself at this point.

Just saying'...

Fireverm
04-07-12, 03:29 PM
Kluch, I don't know his tuning experience or how many boosted cars he has built, but he isn't making much sense...

Meth injection will increase the octane, NOT water lol. That comment in it of itself is enough to ignore anything he posts haha

Man, this guy is something else, lol.

He's right. I just can't believe it, but I am so wrong and he has rightfully called me out like the intellectual fraud that I am. But at least on the bright side, with all of this new found knowledge.... I don't need my V anymore for spirited driving. I'll just start running my bone stock 2012 Chevy Cruze Eco with it's turbocharged 1.4L inline 4 on straight octane booster and I'll never miss the V's power again. I figure since it can run 86 octane and it's even newer than my 2011 V, it's ecu shouldn't have a problem to bring up the stock 138hp to over 500. Just think how much octane booster and Cam2 110 octane you can buy if you just bought this sweet baby for 18k instead of 65k for the V....amIright?

Pphilthy
04-07-12, 06:23 PM
Listen - I have a great amount of knowledge and if you guys know it all, then I really will just stop now and wish you the best of luck...

My posts were correcting blatant wrong statements made here - injecting water turns 87 octane into 110 octane, and running 100 octane will make less power than 91 octane on a forced induction car, etc... I provided a detailed explanation on why that is the case and you guys are just trying to take my posts out of context now... I never said you will gain huge power, that's you little boys stirring the pot - I said you would NOT lose power and would actually make more than 91 octane!

Water injection by itself isn't going to give you any gains - it will act as a cooling agent and knock suppression at best - METH injection will provide more power by increasing the octane rating and doing a much better job of cooling vs water... With tuning of course... I don't need a google reference, I've been there done that for the past 15 years...

I know that I'm new to this forum but believe me, I'm not new to high HP forced induction cars...

baabootoo
04-07-12, 06:59 PM
So are the Canadian dollars and gallons still the same as ours?

V locity
04-07-12, 07:57 PM
think 3 tanks of VP110!!! Then post your dyno....

http://www.tinygif.com/data/media/19/ben_stiller_do_it.gif (http://www.tinygif.com)