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1997 - 2003 Ford F150 General discussion on the Ford 1997 - 2003 F150 truck.

Engine Builders talk.

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Old 03-25-2016, 12:20 PM
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I'm running 11.2:1. Static compression doesn't mean squat. Dynamic compression determines if you will have knock or not.
Old 03-25-2016, 12:28 PM
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Exactly, dynamic compression is the biggest factor of knock/octane needed, I'm building a 12.1:1 377 for my chevy mud truck that has a dcr of 8.2:1 that should easily run on 93
Old 03-25-2016, 01:58 PM
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Originally Posted by white89gt
It is indeed that burr. Is is something you just file off?
Damn robots!

From what I recall, Ford replaced the complete pass side head.. Under warranty and after IF you biatched enough and new the correct number to call lol.. That was way back when tho. I haven't heard of a fix.
Old 03-25-2016, 04:04 PM
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Originally Posted by Loudnproudford
Exactly, dynamic compression is the biggest factor of knock/octane needed, I'm building a 12.1:1 377 for my chevy mud truck that has a dcr of 8.2:1 that should easily run on 93
Exactly. My dynamic compression ratio is around 10.6:1. Definitely on the limit of running pump gas.
Old 03-25-2016, 08:59 PM
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Rule of thumb in the chevy world is 8-8.5:1 dcr and a max of around 220 cranking cylinder pressure on 93 octane, it is a little harder building engines using carbs and hei ignition, can't pull timing or fuel like fuel injection without the engine running like a turd. Oh I remember the early days of nitrous and distributors, glad they're gone.
Old 03-25-2016, 09:05 PM
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That's for heavy trucks, cars can have dcrs much higher
Old 03-25-2016, 09:56 PM
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So how do you find your dcr? And what exactly makes that lower than the static cr
Old 03-25-2016, 11:09 PM
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Originally Posted by Jbrew
Damn robots!

From what I recall, Ford replaced the complete pass side head.. Under warranty and after IF you biatched enough and new the correct number to call lol.. That was way back when tho. I haven't heard of a fix.
This is a dowel pin thing, isn't it?
Old 03-25-2016, 11:22 PM
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Originally Posted by 2thousand5.4
So how do you find your dcr? And what exactly makes that lower than the static cr
If you Google it there are lots of calculators out there. I have a few bookmarked.
Old 03-25-2016, 11:29 PM
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Originally Posted by jprevat
If you Google it there are lots of calculators out there. I have a few bookmarked.
Awesome thank you


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