REVscene Automotive Forum - Shell 91 nitro+ vs. chevron 94

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Shell 91 nitro+ vs. chevron 94

shell 91 nitro just got introduced here in kamloops. Anyone know how it is? I've Been a chevron fanboy. Both my wrx and tundra are tuned to 94 octane. But this new 91 nitro has a 99 Ron rating whereas chevron 94 only has a 98 Ron rating. Would love some info if someone is informed as I am pretty clueless when it comes to the complexities of fuel

It all comes out of the same refinery with different additives, the difference you'll see would be minute.

From what I see, the main selling point of Nitro is engine cleaning, not an increase in octane or performance, best stick with the 94 if that is what you're tuned for.

Quote:

Originally Posted by murd0c (Post 8640720)

http://www.revscene.net/forums/68154...dien-fuel.html might help your question?

from that thread if anyone is interested.

Quote:

Originally Posted by Triballurker (Post 8182204)

This is kind of an interesting read. Its off of the Petro site. Maybe 91 with ethanol will offer more knock resistance.

Why is ethanol an effective octane booster?

The octane number written on the gas pump is Anti-Knock Index (AKI). It’s an average of two octane ratings using the same test equipment but using different operating conditions. The methods produce a Research Octane number (RON) and a Motor Octane Number (MON). Both were once considered important and that’s why AKI is an average of the two. With modern engines and fuels systems, recent studies have shown that RON is more important than MON. So in these cars, the higher the RON the better these cars perform. For an AKI rating of 91 the lower the MON the higher the RON. This difference is called sensitivity. All gasoline components have different sensitivity. Most hydrocarbon components have low sensitivity. Ethanol has high sensitivity and so, modern performance cars benefit from gasolines with ethanol. Why does ethanol have higher sensitivity? One reason is related to the cooler combustion that results from ethanol combustion. Higher knock tendency is directly related to higher combustion temperature.
Here is a comparison of two fuels with different octane with and without ethanol.

91 Grade - no ethanol
RON 97.2
MON 85.6

Ultra 94 - with ethanol
RON 101.5
MON 88

Notice the difference in RON number from 91 grade without ethanol (97.2) and the RON of Ultra 94 (101.5). The difference is 4.3 numbers. That is significantly more than the 3 numbers difference between 94 and 91 AKI labelled on the pump. That is why gasoline with ethanol can be the best performance fuel for today's cars.

looks like RON is the better number to go by for modern vehicles not the AKI octane rating on the pump, which would mean you should get better performance from Shell 91 than Chevron 94, which is also cheaper as well.

VIDEO BASED ON RON OCTANE, not AKI(north american) OCTANE

So based on the research Chevron 94(98RON) has less performance results than Shell 91(99RON). it boils down to if you like Techron or Nitrogen additives, as performance goes to Shell 91 Nitro+

I think ill switch the WRX and tundra over to Shell Nitro+, easy and free for me :)

Don't think Shell 91 nitro+ is cheaper than Chevron 94. I filled up two days ago and there was $0.19 bump compared to regular gas, $1.339 vs $1.529.

If I remember correctly, isn't Chevron 94 about $0.14 more than regular?

Quote:

Originally Posted by boibuddha (Post 8640752)

you are correct. they are the same price in kamloops right now actually. 129.9/L for both

guess it also boils down to Airmiles or Save-on Points lol

If your car is not tuned for 94 stick with 91 if your car requires premium.

Quote:

Originally Posted by Tegra_Devil (Post 8640735)

So based on the research Chevron 94(98RON) has less performance results than Shell 91(99RON).

I can't watch the video atm, but how do they compare in terms of real world knock prevention in a boosted vehicle?

Quote:

Originally Posted by underscore (Post 8640785)

I can't watch the video atm, but how do they compare in terms of real world knock prevention in a boosted vehicle?

they mostly tested on how ROM octane levels improve performance in cars without a tune and vehicles automatically adjusting to the fuel.

it shows that a base model joe blow car wont see any improvement. but cars in the level of a GTI and STI get performance improvements.

So basically, if your looking for performance on a semi-sportscar or full sportscar, you will get better results based on ROM levels compared to (north american AKI octane levels)

But to answer your question, the higher the RON rating the less likely you are to pre-ignite or detonate (remember fuels in north america use the AKI rating, so an 89 AKI octane could have a higher RON rating than a 94 AKI octane, because AKI averages out your RON and MON. you could have a high MON and low RON which will show you a high AKI octane, or a fuel could have a high RON and low MON, which would be the better fuel to choose as you always want the higher RON. RON maxes out at 100 for conventional automotive fuel(not included is race fuel)

Quote:

Originally Posted by Manic! (Post 8640763)

If your car is not tuned for 94 stick with 91 if your car requires premium.

the wrx is currently being fine tuned for chev 94 octane through Clark Turner tuning on my Cobb AP, ive been data logging for him and he has been tweaking. But he has been saying today that we should try Shell 91 because of the RON rating and see if we can squeeze a tiny, tiny bit more out.

The tundra auto tunes via the BullyDog tuner based on what fuel is in the system

I'm getting confused here with contradicting theories.
the MON number you want to be higher, not RON.
RON is done at idle(600rpm) while MON is done under load with higher rpm (900rpm)

Quote:

Research Octane Number (RON)
The most common type of octane rating worldwide is the Research Octane Number (RON). RON is determined by running the fuel in a test engine with a variable compression ratio under controlled conditions, and comparing the results with those for mixtures of iso-octane and n-heptane.

Motor Octane Number (MON)
Another type of octane rating, called Motor Octane Number (MON), is determined at 900 rpm engine speed instead of the 600 rpm for RON.[1] MON testing uses a similar test engine to that used in RON testing, but with a preheated fuel mixture, higher engine speed, and variable ignition timing to further stress the fuel's knock resistance. Depending on the composition of the fuel, the MON of a modern pump gasoline will be about 8 to 12 octane lower than the RON, but there is no direct link between RON and MON. Pump gasoline specifications typically require both a minimum RON and a minimum MON.

but then you have petro-can here saying RON is more important:

Quote:

Why is ethanol an effective octane booster?

The octane number written on the gas pump is Anti-Knock Index (AKI). It’s an average of two octane ratings using the same test equipment but using different operating conditions. The methods produce a Research Octane number (RON) and a Motor Octane Number (MON). Both were once considered important and that’s why AKI is an average of the two. With modern engines and fuels systems, recent studies have shown that RON is more important than MON. So in these cars, the higher the RON the better these cars perform. For an AKI rating of 91 the lower the MON the higher the RON. This difference is called sensitivity. All gasoline components have different sensitivity. Most hydrocarbon components have low sensitivity. Ethanol has high sensitivity and so, modern performance cars benefit from gasolines with ethanol. Why does ethanol have higher sensitivity? One reason is related to the cooler combustion that results from ethanol combustion. Higher knock tendency is directly related to higher combustion temperature.
Here is a comparison of two fuels with different octane with and without ethanol.

91 Grade - no ethanol
RON 97.2
MON 85.6
Ultra 94 - with ethanol
RON 101.5
MON 88

Notice the difference in RON number from 91 grade without ethanol (97.2) and the RON of Ultra 94 (101.5). The difference is 4.3 numbers. That is significantly more than the 3 numbers difference between 94 and 91 AKI labelled on the pump. That is why gasoline with ethanol can be the best performance fuel for today's cars.

from here:FAQs ? Questions, Answers, Octane, Gasoline Basics ? Petro-Canada

somebody wanna clear it up?

from my experience running 22psi in order of most resistant to knock:
1.92 chevron from the US
2.91 shell here
3.94 chevron here

ok I've used both and I saw absolutely no fucking difference.

Realistically, you probably need a dyno to see the difference. Just stick to Chevron, presumably they're better gas.

The difference will be negligible but I've always found shell 91 to be more stable under high load. The knock threshold isn't higher but more consistent where as chevron was less stable under high load. Neither Shell nor Chevron contain ethanol. If you want better performance but are knock limited you should look to spray meth or switch to e85....the latter probably unrealistic because of your location. If it were me I would go with Shell.

Have been wondering the exact same things over the past few weeks. Always was a Chevron guy with all my previous cars, but started using Shell 91 (no ethanol) once I got my Civic Si. Noticed recently that Chevron 94 (also no ethanol) is a few cents cheaper than Shell, but the car is tuned for 91 according to the manual.

i always fill up in the states. but when i'm home i use shell because chevron 91 or 94 performs worse then us 92. and shell performs like us 92.

my car has some lag/turbo delay on chevron. a-ok on shell and us 92. i've tried big name us stations and generic ones. no issues there. and it's been 2 years of 95% of all fills in us.

for reference i drive a 01 golf 1.8t with a chip and downpipe.

On a side note then, how does Shell 89 compare to everyone else's 91?

I would never get my car tuned for 94 octane in Canada....cause its not 94, stick tuning your car on a 91.

I've exclusively used Chevron pretty much my whole life, but this thread has convinced me to give Shell a chance.

shell 91 is the only one without ethanol too unless you're willing to fork out extra for chevron's 94.

Tuners at MNR told me put in Shell 91 when I took it in for a tune.

They said it is the most reliable gas available here, and also performs the best for my particular car (NA V6).

Keep in mind guys, that octane is actually a retardant, it stabilizes the combustion, but it also slows it down, and lessens the explosion. Therefore higher octane fuel is actually less powerful fuel volume for volume.

Shifting both vehicles to shell 91 In a week when their tanks are empty

Curious as to how WA's Shell 92 compares to our 91/94, since I pretty much only gas up there.

Quote:

Originally Posted by Akinari (Post 8641390)

Curious as to how WA's Shell 92 compares to our 91/94, since I pretty much only gas up there.

WA 92 >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>> Chevron 94

I was tuning for 94 and my max power I could achieve was 348WHP on a mustang dyno. Went across the street to fill Shell 92 in a jerry, and without doing any sort of adjustments, the car made 372 WHP the very next pull.

Nice...your ecu's IAM liked the US Shell

Shell 91 and chevron 94 are priced exactly the same....I think it's safe to say chevron is over compensating their octane rating.

Are they the same? Just filled up on shell 91, $0.20 more than regular. Anyone can confirm on chevron?

Lol I think I only use chevron because of advertising and marketing, and its easily more covenient. In Richmond, there is only 1 shell on garden city and lansdowne, but easily almost 10 chevrons