What's you're opinion... stroke vs. bore
02-25-2015 | 06:54 PM
#12
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From: On A Dirt Floor
Stroke give you mechanical leverage. (rod center is farther from the crank center) but also increases rotational load. If I had to do just one for the most improved performance, I would do stroke for a heavier boat.
I would go the shorter stroke and bigger bore in lighter boat to possibly increase rpm response (reduced rotational load).
OR, a couple of beers later, the first crank might be in the second motor, rod length and wristpin height allowing!
I would go the shorter stroke and bigger bore in lighter boat to possibly increase rpm response (reduced rotational load).
OR, a couple of beers later, the first crank might be in the second motor, rod length and wristpin height allowing!
Combustion pressure greatly falls off (pressure decay) right after TDC and is near nill by the time you get to the area the longer crank arm would give you ' much more leverage.'
On the bigger bore side of this subject, don't forget, the larger piston has more surface area than a smaller one. Same psi against a larger surface area = more force.
Just throwing in info without really getting into a possible debate on this subject.
Last edited by SB; 02-25-2015 at 07:05 PM.
02-25-2015 | 07:13 PM
#13
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From: taxachusetts
what about aspiration? Does anyone think there could be a difference in need for aspiration? Would the shorter stroke benefit more from a larger volume runner, and the longer stroke benefit more with a slightly smaller runner volume? I'm thinking it would benefit more from the velocity, but the difference is prolly more theoretical than physically realistic.
02-25-2015 | 07:15 PM
#14
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From: taxachusetts
we are talking about our girlfriends,right.
02-25-2015 | 07:55 PM
#15
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From: Olmsted Falls,Ohio Marblehead,Oh
02-25-2015 | 07:58 PM
#16
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From: bel air, md
Largest bore shortest stroke with the shortest Rod shortest deck height is how you make power. The longer stroke will have more frictional losses due to the longer stroke. also with the shorter stroke/ piston travel you can spin the motor 10,000 rpm and not have to worry about piston speed. Just a little more food for thought in a big block the larger the piston you can stuff in the bore the stronger the piston. :-)
Last edited by Black Baja; 02-25-2015 at 08:01 PM.
02-25-2015 | 08:11 PM
#17
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From: bel air, md
Let's say, for comparison sake, that we were comparing 2 engines, both were measured at approximately 502 cid. One motor is a 4.25 stroke and 4.34 bore, the other is a 4.00 stroke 4.47 bore. All other components are the same.
What's your opinion on these motors?
One better for lighter boats?
Or they both the same... a cube is a cube no mater how you measure it?
Are they going to have different aspiration needs?
What's your opinion on these motors?
One better for lighter boats?
Or they both the same... a cube is a cube no mater how you measure it?
Are they going to have different aspiration needs?
02-25-2015 | 08:16 PM
#18
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Tim, technically speaking, a 502 stroker motor is doing both. Keep in mind, you cant bore a Gen IV 454 to 4.500 bore. Besides, I'm also looking at engines available to purchase. So doind both isnt an option. Plus im looking at a higher cost for the shorter stroke.
02-25-2015 | 08:28 PM
#19
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From: Olmsted Falls,Ohio Marblehead,Oh
Tim, technically speaking, a 502 stroker motor is doing both. Keep in mind, you cant bore a Gen IV 454 to 4.500 bore. Besides, I'm also looking at engines available to purchase. So doind both isnt an option. Plus im looking at a higher cost for the shorter stroke.
I would go with bigger piston..thats not a 454 block and gives you more options later....
