Re: Which is Faster, Bore & Stroke ?
[Re: cudaman1969]
#2891883
02/22/21 02:45 PM
02/22/21 02:45 PM
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Joined: Aug 2003
Posts: 43,292 Bend,OR USA
Cab_Burge
I Win
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I Win
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Looking at motor acceleration which will accelerate faster, short or long stroke ? The longer stroke should pull in more air and fuel but the ring friction on the longer stroke comes into play as well as how long the power stroke, pulses, pushes down on the pistons I think the larger piston top exerts more pressure on the crankshaft than the longer stroke does Which makes me think the bigger bore will, and does, makes more power compare to the longer stroke when trying to make the same C.I. motors
Last edited by Cab_Burge; 02/22/21 02:49 PM.
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
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Re: Which is Faster, Bore & Stroke ?
[Re: Al_Alguire]
#2891886
02/22/21 02:56 PM
02/22/21 02:56 PM
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Joined: May 2005
Posts: 2,007 Apollo, PA.
B1MAXX
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top fuel
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Apollo, PA.
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7000 rpm is the limiting factor IMO. Would likely flavor more stroke. But generally a bigger bore will make more power than more stroke, but when you are talking BB Mopar the bores are not very large for sure. The old saying bore makes power stroke moves where it happens. the only factory engine with a bigger bore is a 460 Ford. The 454 is 4.25 that is why there are so many aftermarket blocks for them. The 396/454 engines with rectangle heads have huge bore notches from the factory, the 396's are only 4.096. The un-notched oval port engines are only a 2.06 intake valve...........advantage Mopar. Bigger bore , larger valve. And when they did settle on a 4.25 bore they knew the only way to get a big valve un-shrouded was hemispherical.
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Re: Which is Faster, Bore & Stroke ?
[Re: B1MAXX]
#2891928
02/22/21 05:11 PM
02/22/21 05:11 PM
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Joined: Jan 2007
Posts: 685 pennsylvania
poboyengineering
mopar
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mopar
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pennsylvania
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Horsepower is a function of torque, torque is a function of force over a lever, Force, in this instance is a function of pounds/ sq inch. So a larger bore provides (at the same peak pressure) more psi. Limiting it to 7k rpm reduces this variable, but the higher psi will make more horsepower. I'm not an engineer, but an engineering student. Prove me wrong, and show me where the crossover occurs.
It may be ugly, but it sure is slow.
Girls comb their hair in rear view mirrors and the boys try to look so hard....
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Re: Which is Faster, Bore & Stroke ?
[Re: cudaman1969]
#2892013
02/22/21 09:14 PM
02/22/21 09:14 PM
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Joined: Jan 2003
Posts: 7,498 Minnesota
Hemi_Joel
master
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master
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Minnesota
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Two engines same brand, Ford 427 and 428, which is faster? Perfect example
[img]http://i.imgur.com/boeexFms.jpg[/img]31 Plymouth Coupe, 392 Hemi, T56 magnum RS23J71 RS27J77 RP23J71 RO23J71 WM21J8A I don't regret the things I've done. I only regret the things I didn't do. "Wise men talk because they have something to say; fools because they have to say something. ~ Plato"
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Re: Which is Faster, Bore & Stroke ?
[Re: cudaman1969]
#2892026
02/22/21 09:43 PM
02/22/21 09:43 PM
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Joined: Aug 2003
Posts: 43,292 Bend,OR USA
Cab_Burge
I Win
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I Win
Joined: Aug 2003
Posts: 43,292
Bend,OR USA
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Two engines same brand, Ford 427 and 428, which is faster? Which HP version of those two C.I. motors are you asking about? I'm not a Ford racer nor do I know much about those two F.E. motors but I have raced against them and even freshen a 1966 or1967 Holman and Moody boat 427 medium riser side oiler that had the inline dual Holley vacuum carbs. that had the 105 CC NASCAR wedge heads on it for a friend and neighbor He also had two 428 out of junkyard cars, one was a 1967 or 1968 Thunder Bird and the other one was out of a full size Ford station wagon around the same year as the T bird . The 1967 Shelby 428 motors and 1968 428 GT Mustang motors and the 1969 and 1970 Cobra Jet motors where rated at a different HP than the other 428 Ford install in their regular non HP passenger cars back then I liked the 427 motors the best of the two
Last edited by Cab_Burge; 02/22/21 09:46 PM.
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
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Re: Which is Faster, Bore & Stroke ?
[Re: Dragula]
#2892031
02/22/21 09:57 PM
02/22/21 09:57 PM
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Joined: Oct 2007
Posts: 4,210 New York
polyspheric
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master
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New York
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Too many variables, there is no single answer. I'm too tired to answer all the mistakes.
Boffin Emeritus
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Re: Which is Faster, Bore & Stroke ?
[Re: Cab_Burge]
#2892032
02/22/21 09:59 PM
02/22/21 09:59 PM
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Joined: Jan 2004
Posts: 8,343 fredericksburg,va
cudaman1969
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fredericksburg,va
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A friends 68 Mustang race car I drove. All eight mile. 427 tunnel port two fours could only muster 7.00 c-6 and 8” vert and 4.88 gears. Same combo except a 428 CJ- single 4- 7.10, IF we had a four speed I’m sure that TP would have been faster, felt lazy off the line. Both engines were basicly stock with a good cam. LOL we put a 250 Horse no2 on the 428 and went some 6.40s, that was a kick in the ass, 10.57 in the 1/4, never heard it shift, blew right thru the vert. Way back in early 80s
Last edited by cudaman1969; 02/22/21 10:01 PM.
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Re: Which is Faster, Bore & Stroke ?
[Re: Dragula]
#2892061
02/22/21 11:38 PM
02/22/21 11:38 PM
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Joined: Feb 2021
Posts: 70 Souderton
Taylor
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member
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Souderton
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Lets say rpm limit is 7k and engine size is 555.....There are a number of combinations to get near the cube limit, but which would be quicker? A smaller bore and big stroke, or a big bore small stroke? Let me ask you this.....What's the weight of the vehicle ? if it's 2600lbs Dart well sorted out chassis with a power glide, 4.500X4.375 , a 4500lbs 2014 Charger .....I'd go 4.40x4.55 and as many gears I could fit behind it.
04 Ram 4x2 11.66@ 122 4750LBS ...phat pig Moves for fully loaded truck with NA 345ci Hemi 2020 1320 Challenger....stock daily driver.
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Re: Which is Faster, Bore & Stroke ?
[Re: B1MAXX]
#2892153
02/23/21 10:31 AM
02/23/21 10:31 AM
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Joined: Jan 2003
Posts: 19,382 Las Vegas
Al_Alguire
I Live Here
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I Live Here
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the only factory engine with a bigger bore is a 460 Ford. The 454 is 4.25 that is why there are so many aftermarket blocks for them. The 396/454 engines with rectangle heads have huge bore notches from the factory, the 396's are only 4.096. The un-notched oval port engines are only a 2.06 intake valve...........advantage Mopar. Bigger bore , larger valve. And when they did settle on a 4.25 bore they knew the only way to get a big valve un-shrouded was hemispherical. Was not aware the OP was referring to factory blocks. I would assume since he is talking about 555" engine size on a Mopar site. So in my feeble mind we are talking aftermarket parts thus making factory dimensions a moot point in this discussion. I get it that Mopar guys have to defend the mother ship at all costs but in the instance of this discussion its irrelevant what the factory dimensions are. Ask anyone who is a Chevy drag racer which engine will run better a 555 or a 565. Anyone with any experience will pick the 565 all day long and twice on weekends. The difference, the bore size..
"I am not ashamed to confess I am ignorant of what I do not know."
"It's never wrong to do the right thing"
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Re: Which is Faster, Bore & Stroke ?
[Re: Al_Alguire]
#2892157
02/23/21 10:40 AM
02/23/21 10:40 AM
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Joined: Jul 2005
Posts: 336 Creston, Iowa
340man4ever
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The path to NA horsepower would be running the biggest bore, shortest stroke that would fit the block used, and or desired end engine displacement... ( ie...cubic inches)...IMHO
Curator at Adams County Speed Shop
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Re: Which is Faster, Bore & Stroke ?
[Re: 340man4ever]
#2892162
02/23/21 10:44 AM
02/23/21 10:44 AM
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Joined: Jan 2003
Posts: 19,382 Las Vegas
Al_Alguire
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I Live Here
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Comp Eliminator is a performance based cubic inch "limited" class. I don't know of ANYONE who chooses stroke over bore to get to the desired cubic inch number. Even the two blown SB combos I am aware of.
"I am not ashamed to confess I am ignorant of what I do not know."
"It's never wrong to do the right thing"
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Re: Which is Faster, Bore & Stroke ?
[Re: cudaman1969]
#2892170
02/23/21 10:52 AM
02/23/21 10:52 AM
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Joined: Sep 2014
Posts: 4,457 Washington
madscientist
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You don’t understand, ya gotta play with what you have available. Really like to see some of these 5” bore mopar engines. Like hitting a nail, short swing, nail won’t go deep, big swing that nail going clear thru. Bigger hammer might help a little but big swing gets the job DONE. One of the 5 basic tools, a lever! That’s what the transmission and rear axle are. Levers. You can move more with gearing than you ever will with stroke.
Just because you think it won't make it true. Horsepower is KING. To dispute this is stupid. C. Alston
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Re: Which is Faster, Bore & Stroke ?
[Re: Al_Alguire]
#2892234
02/23/21 01:05 PM
02/23/21 01:05 PM
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Joined: May 2005
Posts: 2,007 Apollo, PA.
B1MAXX
top fuel
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top fuel
Joined: May 2005
Posts: 2,007
Apollo, PA.
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the only factory engine with a bigger bore is a 460 Ford. The 454 is 4.25 that is why there are so many aftermarket blocks for them. The 396/454 engines with rectangle heads have huge bore notches from the factory, the 396's are only 4.096. The un-notched oval port engines are only a 2.06 intake valve...........advantage Mopar. Bigger bore , larger valve. And when they did settle on a 4.25 bore they knew the only way to get a big valve un-shrouded was hemispherical. Was not aware the OP was referring to factory blocks. I would assume since he is talking about 555" engine size on a Mopar site. So in my feeble mind we are talking aftermarket parts thus making factory dimensions a moot point in this discussion. I get it that Mopar guys have to defend the mother ship at all costs but in the instance of this discussion its irrelevant what the factory dimensions are. Ask anyone who is a Chevy drag racer which engine will run better a 555 or a 565. Anyone with any experience will pick the 565 all day long and twice on weekends. The difference, the bore size.. Only pointing out from the factory Mopar was on the right track big bore (bigger valve),short(er) stroke.
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Re: Which is Faster, Bore & Stroke ?
[Re: LSP]
#2892238
02/23/21 01:10 PM
02/23/21 01:10 PM
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Joined: Jan 2003
Posts: 10,016 Frostbitefalls MN (Rocky&Bullw...
gregsdart
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I Live Here
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More bore + more intake valve area = more hp.
Not some, not most, ALL the time. The evolution of most any normally aspirated performance engines bears this out.
8..603 156 mph best, 2905 lbs 549, indy 572-13, alky
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