87 octane vs 93 octane

Oct 15, 2007 | 10:16 AM

Vardar

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From: USA

1999 C43

87 octane vs 93 octane

Hello there...

I always wondered if I use 89 octane instead of 93, what would happen, will it hurt the engine, if yes how?

Can someone explain please? How does quality or grade of fuel effect the engine?

Thank you in advance.

Oct 15, 2007 | 11:02 AM

ohlord

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300E a couple 1994 w124wagon E320 Wagon/,1971MGB Track/Rally, MG Midget Autocross ,2000 E320 wagon.

You

have a high compression,high performance engine.High test fuel is needed to provide the level of knock resistance the engine needs to run at that high compression.The ECU will compensate for some level of pinging or knock under some load values,it can not adjust for the lack of octane in the lower regular fuel.It in the long term will hurt your engine and will reduce your performance.
ohlord

Oct 15, 2007 | 11:18 AM

E55 PWR

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e55

if you own an AMG, you MUST run premium, simple as that

Oct 15, 2007 | 11:34 AM

Vardar

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From: USA

1999 C43

I realize that. I was just curious why. I never used 87 0r 89 octane before, even when I drove 98 Cherokee years ago..

Quote:

Originally Posted by E55 PWR

if you own an AMG, you MUST run premium, simple as that

Oct 15, 2007 | 08:36 PM

Jons95c36amg

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From: Desert

02 CLK 55 AMG,09 C63 loaded with P30

Sunoco used to have ultra 94oct. Now premium is 93. My c36 likes BP brand.

Oct 15, 2007 | 10:40 PM

steve s

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From: San Francisco, CA

1996 C36 AMG, 1995 Volvo 850 Turbowagon

Quote:

Originally Posted by Vardar

I realize that. I was just curious why. I never used 87 0r 89 octane before, even when I drove 98 Cherokee years ago..

it may not have been the best if the cherokee demanded only 87. higher octane resists knock. high compression and induction forced engines may have higher potential of detonation. this is when the compressed gas and air mixture spontaneously ignites before the spark plug ignites. this is especially true in high load situations or when the ambient temperature is high, such as during the summer months. higher octanes reduce this potential. but by doing so, it also reduces the combustability of the mixture, making it harder to ignite. yada yada i think that is the gist of it. if ur enigne required only regular 87 octane, then adding 93 would probably have decreased its mileage, even if it is a mini difference.

Oct 15, 2007 | 10:54 PM

ECTurboGSX

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98 C43, 15 Alfa 4C LE, 18 Tesla Model 3 DM Perf, 08 Duc S1000, 02 Duc 998, 98 Duc 748, 01 Miata

As was stated before, octane resists combustion. As temperatures and pressures increase dramatically during the combustion process, the fuel may ignite prior to the spark ignition. This is especially prevalent in engines with high compression ratios or forced induction. If you use lower octane fuel, your mixture may pre-ignite and when you are dealing with pressures in excess of 160 psi and temperatures over 1600 *F, big explosions that happen before they are supposed to is a bad thing.