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big bore build vs. stroked

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Old May 12, 2009 | 07:44 PM
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Default big bore build vs. stroked

what is the difference between them i heard a guy tell me he doesn't like stroked because the pistons spin faster than what their suppose to and crack. I am clueless, so I need the help.lol!

which has more potential, one more little question if i stroked the 4.6 into a 5.0 will the 4.6 mods still work with the car. how far can i stroke it, 5.0 seems good but 5.4 be better.
Old May 12, 2009 | 09:56 PM
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Larger bore and larger stroke both do different things. Longer strokes are nice because it increases the engine's torque output, especially at lower rpm. The piston has a higher velocity, but good quality parts will withstand extreme rpm that you're unlikely to see in a street engine. Bigger bores are good for increasing power everywhere and help the heads flow better by unshrouding the valves, but they also weigh more and you're limited to the bore size by the wall thickness and/or bore spacing on the block.

Stroker kits are a dime a dozen these days, and are one of the cheapest and easiest ways to make more power.
Old May 12, 2009 | 10:31 PM
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would a big bore and stroker kit work well together, any issues or concerns?
Old May 12, 2009 | 11:56 PM
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Other than not having traction?

If I had the bones I'd get a big bore Dart 302 block, 4.125" x 3.4" and have a 363(big bore 347). As long as the block is capable of holding the power, a big bore stroker will make an crapload of power. Most factory blocks can't be bored over very much though.
Old May 13, 2009 | 01:28 AM
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big bore and stroker kits are a waste of money on a modular... go 5.4 and then add big bore if you want to try and add some cubes... but it would still be pointless
Old May 13, 2009 | 12:01 PM
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go 5.4, i don't think they have many mods for 5.4, i don't really know much about engines but if i HAD A BIG BORE STROKER how much HP and torque will i be pushing, my car has no mods at all.

why do you say its not worth it?
Old May 14, 2009 | 03:03 PM
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with a 5.4, bored and stroked (roughly 6.1L), race ported 4v heads (310cfm), cams, sheetmetal intake and high compression (12:1 to 13:1) and carb conversion you would probably see somewhere between 450-600rwhp, there are alot of factors to consider, but to be in that upper range you would be burning c-16 and it would be way to wild for a street car. There reason its not worth it is because modular blocks are too small, and modular heads are crap (for any kind of crazy N/A stuff). These motors need boost. But even if you did boost, the roughly 50 rwtq you would gain from spendin 4K on the bore and stroke (yes that is a min, of how much it will cost + plus the internals and heads) its just a waste, You would be way better off spending that money on getting race port 4v heads, and 2003+ 5.4 navi block, and then add boost.
Old May 14, 2009 | 03:07 PM
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ohh and the 5.4 block is stroked out as far as you want to go stock anyway, its rod ratio is already going to be limited to 7000 rpm as it sits and most dont like to go over 6,000. Some people buy them and de-stroke them to 5.2, but that is not necessary unless you plan on spinning 10k rpm.
Old May 14, 2009 | 08:16 PM
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Default big bore vs stroker

Originally Posted by Fobra
ohh and the 5.4 block is stroked out as far as you want to go stock anyway, its rod ratio is already going to be limited to 7000 rpm as it sits and most dont like to go over 6,000. Some people buy them and de-stroke them to 5.2, but that is not necessary unless you plan on spinning 10k rpm.
stroking the 4.6 to 5.0 is not that much xtra if you are already purchasing a forged 4.6 s/block. this adds 21 cubes which makes an additional 20+ft lbs tq. which is nice to have. there are no major adverse effects on the pistons from this design. big bore modulars will have a 3.70 bore instead of the stock 3.552 bore. there are several ways to achieve this but the most reliable method is to buy a ford racing 3.70 bore block which is engineered that way from the get go. sleeving 3.552 blocks to 3.70 is a crap shoot as far as reliability is concerned and is expensive. ford racing has a GT iron 3.70 block in the $1600 range and aluminum versions for $4000. if you had a 3.70 block combined with a 3.75 crank, that would make a 323cid engine and with good heads will make a stout mod motor.........
Old May 15, 2009 | 08:58 PM
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thank you guys for all your inputs, so a 5.4 is not a modular engine. I have read about the 5.4 conversion but I heard they are hard to fit in a stock stang. wouldn;t it be harder to fit it if after being stroked and bored it will be 6.1?

about the compression ratio, is 12:1 good, what does it mean, does it mean it can support more boost?

what is destroked? is it cheaper than stroked and bored? Thing is I am building my stang to be a drag car but same time trying to keep it for everyday driving.

will gt40 be the best to put in, in this case?

Last edited by stang123456; May 15, 2009 at 09:42 PM.



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