What octane fuel for 420's?
04-08-2011 | 10:09 PM
#1
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Joined: Oct 2000
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From: Carlisle, MA USA
What octane fuel for 420's?
I have stock 420hp 454's in my Formula. What octane fuel do they require? I have always been running super but I am wondering if I am tossing money out the back of the boat.
Jon
Jon
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04-10-2011 | 12:13 AM
#3
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From: www.bajaboatowners.com
Yes you have!!! Pretty much all Mercury Marine including racing engines will run on 87 Octane. Now this doesn't include the SC motors.
04-10-2011 | 02:03 AM
#4
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From: USA
My trusty 1990 Mercruiser HP sales brochure calls for 91+ octane in all the HP465, HP500, HP500 Bulldog and SC engines.
That being said, the 420 will probably run fine on 87, but I'd do a few runs & read the plugs before I would trust it.
04-10-2011 | 08:08 AM
#5
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Charter Member #232
Joined: Oct 2000
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From: Carlisle, MA USA
I have run it on 89 in the past as that can be all that is available on the lake and it seems to run fine on that. I guess if I was doing a poker run and running it hard then I woudl certainly go with super. What I am wondering is if the average day out with the family if I am ok with lower octane, or even if lower octane is prefered.
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