Anyone have proof that a long stroke makes torque?
This isn't about what's plentiful, cubes ultimately determine the tq/hp, then things like compression, induction, cam events determine the shape and curve. You don't see big bore short stroke on the street because of expense. In racing valve curtain generally means more than displacement because it's usually limited, so you turn it higher, means you need more head flow. More head flow comes from bigger bore and bigger valve. The rpms in a street deal never tax said engine in normal driving. That's why I suggest the ls3 build, more cubes than you say you need, bigger bore for the ls3 style heads though for what you are doing a cathedral is probably the better choice (and makes the bigger bore not needed 4.0 is plenty) and use a good 3.9 or 4.0 stoke crank and still use a good rod. You said it, displacement always wins in NA.... No one in their right mind limits the max cubes that a budget can afford...
Thread Starter
On The Tree
Joined: Jan 2014
Posts: 136
Likes: 1
From: Nebraska
Oddly enough, I stumbled across an off-the-shelf combination that looks like it would work to make a short stroke. long rod 350 with a rod/stroke ratio of 2:1.
LSX block bored to 4.125
Stock 4.8L crankshaft with 3.27 stroke
Eagle 6.560 inch long H-beam rods (.927 pin)
Mahle pistons with 1.045 compression height (4.125 bore, .927 pin)
Yields 11.88:1 compression with 64cc heads & .045 head gasket
Yields 11.43:1 compression with 64cc heads & .058 head gasket
Yields 10.97:1 compression with 70cc heads & .045 head gasket
Yields 10.59:1 compression with 70cc heads & .058 head gasket
LSX block bored to 4.125
Stock 4.8L crankshaft with 3.27 stroke
Eagle 6.560 inch long H-beam rods (.927 pin)
Mahle pistons with 1.045 compression height (4.125 bore, .927 pin)
Yields 11.88:1 compression with 64cc heads & .045 head gasket
Yields 11.43:1 compression with 64cc heads & .058 head gasket
Yields 10.97:1 compression with 70cc heads & .045 head gasket
Yields 10.59:1 compression with 70cc heads & .058 head gasket
Oddly enough, I stumbled across an off-the-shelf combination that looks like it would work to make a short stroke. long rod 350 with a rod/stroke ratio of 2:1.
LSX block bored to 4.125
Stock 4.8L crankshaft with 3.27 stroke
Eagle 6.560 inch long H-beam rods (.927 pin)
Mahle pistons with 1.045 compression height (4.125 bore, .927 pin)
Yields 11.88:1 compression with 64cc heads & .045 head gasket
Yields 11.43:1 compression with 64cc heads & .058 head gasket
Yields 10.97:1 compression with 70cc heads & .045 head gasket
Yields 10.59:1 compression with 70cc heads & .058 head gasket
LSX block bored to 4.125
Stock 4.8L crankshaft with 3.27 stroke
Eagle 6.560 inch long H-beam rods (.927 pin)
Mahle pistons with 1.045 compression height (4.125 bore, .927 pin)
Yields 11.88:1 compression with 64cc heads & .045 head gasket
Yields 11.43:1 compression with 64cc heads & .058 head gasket
Yields 10.97:1 compression with 70cc heads & .045 head gasket
Yields 10.59:1 compression with 70cc heads & .058 head gasket
chances of ring flutter. Guys like Joe Sherman and even Bill "Grumpy"
Jenkins found that the rod/stroke ratio never really mattered much from a
power standpoint. Obviously the piston gets lighter but the rod gets heavier.
Definitely a law of diminishing returns. Ring seal is everything for NA apps.
IIWY I'd run a 1.5 C.H. piston (Wiseco with the thermal top coating and the
anti-friction skirt coating); with a 6.125" rod the piston would be at 9.26".
Popping out of the 9.24" deck by .020" would put the quench at .040 by
running the .058" gaskets.
Staging Lane
Joined: Nov 2010
Posts: 66
Likes: 0
I'm going to toss my hat into the ring.
Long stroke does not make more torque by itself. Increasing stroke (thereby increasing cubes) does increase torque, but for the same displacement, power/torque output will be almost identical.
Compare for example an Olds 455 (4.126 x 4.25) versus a Buick 455 (4.313 x 3.9). Equipped with the same head flow, cam timing, compression, etc, they will both have nearly identical tq and hp outputs at the same RPMs. The big difference in the two is peak potential. Getting the Olds to breathe with the small bores, and getting it to spin fast with the long stroke are an issue.
It doesn't matter that the Olds has a longer stroke, it still has the same torque output at the same RPM when all other factors are the same.
Long stroke does not make more torque by itself. Increasing stroke (thereby increasing cubes) does increase torque, but for the same displacement, power/torque output will be almost identical.
Compare for example an Olds 455 (4.126 x 4.25) versus a Buick 455 (4.313 x 3.9). Equipped with the same head flow, cam timing, compression, etc, they will both have nearly identical tq and hp outputs at the same RPMs. The big difference in the two is peak potential. Getting the Olds to breathe with the small bores, and getting it to spin fast with the long stroke are an issue.
It doesn't matter that the Olds has a longer stroke, it still has the same torque output at the same RPM when all other factors are the same.
Thread Starter
On The Tree
Joined: Jan 2014
Posts: 136
Likes: 1
From: Nebraska
Compromised I got sick, nearly lost job. Had to face the fact that I don't have the time or ability to do any of the work myself, not even the install. Settled on a budget build from Thompson Motorsports. 5.7L 355HP. It was great to work through the details with Kyle Thompson. Awesome service. I'll post an update once the truck is done and broken in.
The 5.7 will run on the 5.3L stock tune, but needs a real tune to wake it up. I'll provide subjective before/after comments on the experience.
If circumstances ever change, I'll start with a G8 with a 6 speed, then try the LSX based build. Who knows, something better may be available by then.
The 5.7 will run on the 5.3L stock tune, but needs a real tune to wake it up. I'll provide subjective before/after comments on the experience.
If circumstances ever change, I'll start with a G8 with a 6 speed, then try the LSX based build. Who knows, something better may be available by then.
Thread Starter
On The Tree
Joined: Jan 2014
Posts: 136
Likes: 1
From: Nebraska
I'm going to toss my hat into the ring.
Long stroke does not make more torque by itself. Increasing stroke (thereby increasing cubes) does increase torque, but for the same displacement, power/torque output will be almost identical.
Compare for example an Olds 455 (4.126 x 4.25) versus a Buick 455 (4.313 x 3.9). Equipped with the same head flow, cam timing, compression, etc, they will both have nearly identical tq and hp outputs at the same RPMs. The big difference in the two is peak potential. Getting the Olds to breathe with the small bores, and getting it to spin fast with the long stroke are an issue.
It doesn't matter that the Olds has a longer stroke, it still has the same torque output at the same RPM when all other factors are the same.
Long stroke does not make more torque by itself. Increasing stroke (thereby increasing cubes) does increase torque, but for the same displacement, power/torque output will be almost identical.
Compare for example an Olds 455 (4.126 x 4.25) versus a Buick 455 (4.313 x 3.9). Equipped with the same head flow, cam timing, compression, etc, they will both have nearly identical tq and hp outputs at the same RPMs. The big difference in the two is peak potential. Getting the Olds to breathe with the small bores, and getting it to spin fast with the long stroke are an issue.
It doesn't matter that the Olds has a longer stroke, it still has the same torque output at the same RPM when all other factors are the same.
TECH Apprentice
Joined: Feb 2014
Posts: 328
Likes: 1
From: Baton Rouge La
I'm going to toss my hat into the ring.
Long stroke does not make more torque by itself. Increasing stroke (thereby increasing cubes) does increase torque, but for the same displacement, power/torque output will be almost identical.
Compare for example an Olds 455 (4.126 x 4.25) versus a Buick 455 (4.313 x 3.9). Equipped with the same head flow, cam timing, compression, etc, they will both have nearly identical tq and hp outputs at the same RPMs. The big difference in the two is peak potential. Getting the Olds to breathe with the small bores, and getting it to spin fast with the long stroke are an issue.
It doesn't matter that the Olds has a longer stroke, it still has the same torque output at the same RPM when all other factors are the same.
Long stroke does not make more torque by itself. Increasing stroke (thereby increasing cubes) does increase torque, but for the same displacement, power/torque output will be almost identical.
Compare for example an Olds 455 (4.126 x 4.25) versus a Buick 455 (4.313 x 3.9). Equipped with the same head flow, cam timing, compression, etc, they will both have nearly identical tq and hp outputs at the same RPMs. The big difference in the two is peak potential. Getting the Olds to breathe with the small bores, and getting it to spin fast with the long stroke are an issue.
It doesn't matter that the Olds has a longer stroke, it still has the same torque output at the same RPM when all other factors are the same.
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Verdad Gallardo TECH Apprentice
Joined: Feb 2014
Posts: 328
Likes: 1
From: Baton Rouge La
OK then just play like they are the same engine Olds or Buick but different bore stroke and rod but same cubic inches.
Thread Starter
On The Tree
Joined: Jan 2014
Posts: 136
Likes: 1
From: Nebraska
Well, when someone pays Thompson Motorsports to make a big bore version of the motor I just bought we'll know. Until then it's all theory and BS.
On The Tree
Joined: Jul 2007
Posts: 187
Likes: 0
From: KCMO
I only skimmed, but if building a max torque truck motor and already factoring LSX block purchase, why not go with Max ci 45X" and small duration cam. It would make more power <4000rpm than any 350" motor regardless of bore/stroke combo.
Or build a stout budget 6.0 with a stock iron block, small cam and positive displacement blower on top. 3000rpm with 10lbs of boost will make big torque to pull up a steep grade. At any rate a motor built with no intentions of going above 5500-6000rpm don't need all the high dollar pricy parts most guys seek who are wanting a reliable 7500rpm
Or build a stout budget 6.0 with a stock iron block, small cam and positive displacement blower on top. 3000rpm with 10lbs of boost will make big torque to pull up a steep grade. At any rate a motor built with no intentions of going above 5500-6000rpm don't need all the high dollar pricy parts most guys seek who are wanting a reliable 7500rpm
Same intake, cam, heads, exhaust, etc. just because you don't like the example doesn't make it wrong.
Thread Starter
On The Tree
Joined: Jan 2014
Posts: 136
Likes: 1
From: Nebraska
It's a wrong example because the cubic inches changed when the stroke changed. The only way to tell if torque is produced through stroke is to change the bore/stroke and leave everything else including the cubic inches the same. Your example is less valid than the Olds vs Buick one above.
Thread Starter
On The Tree
Joined: Jan 2014
Posts: 136
Likes: 1
From: Nebraska
I only skimmed, but if building a max torque truck motor and already factoring LSX block purchase, why not go with Max ci 45X" and small duration cam. It would make more power <4000rpm than any 350" motor regardless of bore/stroke combo.
Or build a stout budget 6.0 with a stock iron block, small cam and positive displacement blower on top. 3000rpm with 10lbs of boost will make big torque to pull up a steep grade. At any rate a motor built with no intentions of going above 5500-6000rpm don't need all the high dollar pricy parts most guys seek who are wanting a reliable 7500rpm
Or build a stout budget 6.0 with a stock iron block, small cam and positive displacement blower on top. 3000rpm with 10lbs of boost will make big torque to pull up a steep grade. At any rate a motor built with no intentions of going above 5500-6000rpm don't need all the high dollar pricy parts most guys seek who are wanting a reliable 7500rpm
TECH Apprentice
Joined: Feb 2014
Posts: 328
Likes: 1
From: Baton Rouge La
I will answer the original question.
Anyone have proof that a long stroke makes more torque?
If you have two engines both are 351 cubic inches. The one with the lower rod ratio 1.5 rr will make more torque even if the stroke is shorter at the lower rpm range than a longer stroke with a 1.6 rr.
Anyone have proof that a long stroke makes more torque?
If you have two engines both are 351 cubic inches. The one with the lower rod ratio 1.5 rr will make more torque even if the stroke is shorter at the lower rpm range than a longer stroke with a 1.6 rr.
I will answer the original question.
Anyone have proof that a long stroke makes more torque?
If you have two engines both are 351 cubic inches. The one with the lower rod ratio 1.5 rr will make more torque even if the stroke is shorter at the lower rpm range than a longer stroke with a 1.6 rr.
Anyone have proof that a long stroke makes more torque?
If you have two engines both are 351 cubic inches. The one with the lower rod ratio 1.5 rr will make more torque even if the stroke is shorter at the lower rpm range than a longer stroke with a 1.6 rr.
Sticking with the 70s stuff compares all the 400 lift, 8 to one compression, with crap cylinder heads; most of which struggled to make even 200 horse.
Chevy was 4.125" X 3.75" with a 5.565" rod length 1.48 rod to stroke ratio
Pontiac was 4.125" X 3.75" with IIRC 6.63" long rod
Ford 400M was 4' X 4" and I think a 6.59" rod
Mopar was 4.342" X 3.38" with a 6.358" rod
Olds 403 not too sure 4.36" X 3.38"..maybe ?? long rods for sure
Ford's M engine probably had the best of the junk heads (canted style)
Olds and Poncho had flatter valve angles and 30 degree seats which promote low lift flow...but the ports were terrible
Chevy and Mopar heads were complete garbage....similar with small ports and valves
Lol, the definition of torque or moment about any point in a plane axis is force times the perpendicular distance or length...
i.e. if we set stroke to zero, torque = zero because any number times zero is zero, there would be no torque
i.e. if we set stroke to zero, torque = zero because any number times zero is zero, there would be no torque
TECH Senior Member
Joined: Jun 2016
Posts: 22,298
Likes: 3,619
From: Central Cal.
So now we know, you know the definition of torque. And that contributed to this thread, HOW??