496 H.O Mag Fuel Type
#1
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Thread Starter

Hey,
Just wondering what everyone's running for gas in their 496 Mag HO, I like always run 93 in my stuff, but I have seen multiple forums saying that the computers programmed to run 87 because it burns faster, and that 93 burns slower due to the higher octane, so you lose out on HP. 93 is a cleaner burning fuel though, so will that add longevity to the motor?
Just wondering what everyone's running for gas in their 496 Mag HO, I like always run 93 in my stuff, but I have seen multiple forums saying that the computers programmed to run 87 because it burns faster, and that 93 burns slower due to the higher octane, so you lose out on HP. 93 is a cleaner burning fuel though, so will that add longevity to the motor?
The following 2 users liked this post by AllDodge:
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#4
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There was a dyno a while back that tests stock and modified 496/8.1. (Below) There is only a 1/2 to 1 horsepower difference between 87 and 93. Thats it! Lets be honest, in stock form the 496 is a low compression, iron head truck engine. Its basically designed for 87. Even modified or highly modified, I see no difference in speed or power, matter of fact, I think the soot on the transom is worse with 93. Now, 87 marine is better IMHO than street 87 gas station fuel, but thats another topic.
mercury-marine-496-mag-performance-parts-upgrade-magazine-article.html
mercury-marine-496-mag-performance-parts-upgrade-magazine-article.html
#5
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Thread Starter

There was a dyno a while back that tests stock and modified 496/8.1. (Below) There is only a 1/2 to 1 horsepower difference between 87 and 93. Thats it! Lets be honest, in stock form the 496 is a low compression, iron head truck engine. Its basically designed for 87. Even modified or highly modified, I see no difference in speed or power, matter of fact, I think the soot on the transom is worse with 93. Now, 87 marine is better IMHO than street 87 gas station fuel, but thats another topic.
Attachment 576972
Attachment 576972
#6

87 in your 496. Anything higher is pointless. Tons of stock 496 evidence to show this and some evidence of higher octane being problematic such as sooty transoms and loss of performance.
93 doesn't burn cleaner. Higher octane is only a requirement of the manufacturer to prevent detonation in high compression engines.
93 doesn't burn cleaner. Higher octane is only a requirement of the manufacturer to prevent detonation in high compression engines.
#7
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87
#9
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The following 2 users liked this post by Keith Atlanta:
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