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Resident Ford Nut
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10,075 Posts
Discussion Starter #1
So all else being equal if both engines make 750hp at 6,750 would the smaller engine with more compression ( pop) be more responsive, rev quicker and be funner to drive ?

Just asking :)bulb

S CP :)bulb
 

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steelcomp was here
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26,515 Posts
Too many unknowns.
What's the application?
Where's peak tq on both engines?
Are we assuming that the smaller engine has more compression, or maybe the bigger engine is just a bad combination? Maybe the 470 is a dyno queen and the 512 has much better average powe, or could be the reverse...

At least the thread isn't titled "something to fight over"... ;)
 

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Registered
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1,299 Posts
So the 470 more compression= race gas? 512 pump gas? I'm going with the cheaper pump gas combo if everything else is equal.:D
 

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Or Seth, either one
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3,270 Posts
Always cool when the underdog makes the cut, but... you know the old saying. Cubic inches are KING. :|err

Even if it is only 42 ci. That's only 7 ci short of 10% larger!

Now, the story changes if the underdog costs waaayyyy le$$.

If it's more than $1k less... The 470's lookin good to me! :D
 

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Resident Ford Nut
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10,075 Posts
Discussion Starter #6
Maybe the 470 is a dyno queen and the 512 has much better average powe, or could be the reverse...

At least the thread isn't titled "something to fight over"... ;)
Well the thought did cross my mind......;)

I was thinking a river race 19' 4 person jet boat. typical river racer play boat. The smaller engine has more "bang" per Cu in I was wondering if you could feel that in throttle response. If you've ever ridden a stock Honda old XR-600 with 9.4:1 compression and then a slightly pumped-up one with 11:1 man does that wake them up.
Other mods help and it does make more hp but the throttle response is a huge difference.

S CP
 

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Premium Member
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25,975 Posts
I thinking the 512. Like Steel said, the max power may be the same, but what does the inder the curve look like. You really can't compare the 2 XB motors because they are the same size with more compression. Power was probably up across the board.
Almost any engine with a narrower power band but with the same max ouput will be more if a maintanence hog. Jetting becomes more critical, as does timing.
In a recreational jet, I'd be all over the 512.



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Living in a cage of fear
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Which one came from a Suburban?????:)bulb
(Or in your' case, an Expedition):)hand:)hand
 

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Resident Ford Nut
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10,075 Posts
Discussion Starter #9
Always cool when the underdog makes the cut, but... you know the old saying. Cubic inches are KING. :|err

Even if it is only 42 ci. That's only 7 ci short of 10% larger!

Now, the story changes if the underdog costs waaayyyy le$$.

If it's more than $1k less... The 470's lookin good to me! :D



I was thinking about making it something like the 512" at 720hp at 6,200 and the 470" at 750 hp at 6,600 just to mix it up, assumming the boat is a typical weekend river racer 19' deal.

S CP
 
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