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Old 03-18-2002, 12:23 PM
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bored 30 over engine help

I might be able to get my hands on a 1999 4.6L bored .030 over engine from an F150. How much power can i expect from this engine? I don't know much about the whole bored and stroke stuff. I know what they are, but i've never done this. If the engine does it have it already, will i need larger pistons, or just piston rings, or both? Anyone know of a good book that shows this stuff?

thanks.
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Old 03-18-2002, 03:21 PM
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A .030 will only yield about a 1% hp increase, if the rest of the engine is left the same. If you are only getting the block, you will need new pistons and rings. Unless the rest of the engine has been tweaked with, a .030 bore is not worth the money for the hp it yields.
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Old 03-18-2002, 03:40 PM
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1% horsepower? that sucks.

Well, i can always swap it with the 3.8 that i have in my thunderbird right? I hope it has the same bolt pattern.

Any advice about books describing boring an engine?
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Old 03-18-2002, 04:18 PM
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Quote:
Originally posted by Dissonance
Any advice about books describing boring an engine?
just look for any ford engine service manual that involves overhauling or rebuilding engines. they'll explain bore and stroke and boring engines to increase displacement. good luck!
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Old 03-18-2002, 08:34 PM
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Dissonance-

Why has a 99 engine already been rebuilt/bored out? On that engine, I wouldn't expect that it was done to add horsepower, but would be to fix ragged out cylinders. If they bored out a 99 engine that was in good condition to increase performance, that was a waste of time and a good factory block. They bore/enlarge the cylinder diameter at a machine shop. This requires larger matching pistons and rings; no piston height change. If you're rebuilding this engine, and the bores are in good shape, you won't need new pistons. Good shape would mean that tolerances were adequate to hone the cylinders (not bore), re-use the pistons (if in good shape), and buy a new set of .30 over rings.
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Old 03-18-2002, 10:51 PM
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All valid points Max. Also, the more material that you remove from the cylinders the easier it becomes for them to be distorted by thermal expansion and mechanical forces. It makes it harder to keep thespecs and tolerances within the acceptable ranges.
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Old 03-19-2002, 09:08 AM
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thanks for all the input. I appreciate it.

I'm probably gonna keep the engine, and work on it by installing forged parts to the internals. I would like to eventually drop that new engine into my truck and have a 150-200 shot of nitrous on it. Its gonna be a long project, but since its gonna be on a stand, i'm gonna take my time, and do my reading.

thanks again.
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Old 03-19-2002, 02:05 PM
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Wouldn't boring it 30 over bring it to a little less than 10% larger? If so I think you'd notice a little more than a 1% increase in H.P. (1% would only be between 2.3 and 2.6 H.P)

Last edited by STX/98; 03-19-2002 at 02:11 PM.
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Old 03-19-2002, 03:00 PM
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Dissonance, If you plan on spraying, then I highly recommend that engine. Just have it tested for cracks and all. For a nos engine, definitely get some forged slugs (JE, Ross, Probe) and good rods (Eagle). While you're at it, o-ring the heads and have some work done to them.

STX/98,
A .030 bore increases displacement by approximately 5. For example, a chevy 350 bored .030 over increases displacement to a 355.
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Old 03-19-2002, 03:40 PM
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Hell, yeah.

this is exactly the opportunity that i've wanted. I've wanted to do all this to my trucks engine, but i need my truck to go to work and i cant take a couple of months off to do it all. This way, i get to take my time and hopefully do it all the right way.

Port, polish, grind, shave, forge, and maybe even stroke it.

There goes my payceck for the next few years.
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  #11  
Old 03-20-2002, 03:37 AM
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A .030 increase in bore is a standard for rebuild and is not really intended as a displacement increase. To calculate engine displacement use the following....

bore X bore X stroke X .7854 X number of cylinders = cubic inches

I don't have the specs for a 4.6 handy but as an example a .030 overbore on a 5.0 (4" bore and 3" stroke) adds only 4 cubic inches. Most blocks won't handle much in the way of extra bore, so any real displacement changes require a change in stroke. Adding .4" of stroke to a 5.0 adds 39 cubic inches.

Sean Hyland Motorsports has stroker kits for the 4.6 in a couple different sizes. The smaller ones use stock blocks, the bigger ones require block work as they press in a larger sleeve.
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Old 03-20-2002, 03:37 AM


 
 
 
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