Speedway Motors
Region: US
Monday 15 June 2026 03:18:07 GMT
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polkins :
That’s a wide stance my guy
2026-06-15 15:07:44
119
OnDeFritz :
Rpm capabilities are 100% dictated by cam profiles, valve train geometry, and spring rates. Unshrouding valves improves VE, nothing more or less.
2026-06-15 11:09:56
15
D Boss :
accuracy of this post 12%
2026-06-15 12:57:33
5
scottyH20 :
No replacement for displacement
2026-06-15 11:50:13
5
the_cj7_guy304 :
The 289 and boss 302 were much better high rpm than the Chevy 302 it had more midrange power compared to the ford’s bc of its cam
2026-06-15 13:34:22
5
jacksonmotorsport :
Teach me your ways Master Jedi
2026-08-03 17:56:53
3
ttrotter88 :
The 5.4 dohc fords pulled RPM pretty damn well. I’ve also seen, and built, under square 460 fords that pull rpm like crazy. Much of it comes from cam and valvetrain specs and components have more effect on how quick an engine pull rpm’s as well as how high it can rev.
2026-06-15 22:51:05
2
Evan :
Gahhh, I love learning this stuff
2026-06-17 03:35:24
4
MoodManDew :
Piston speed is the killer of many things, mostly my bank account
2026-06-17 00:47:19
5
A random guy :
Mostly true, yes - but there are exceptions. A prime example is the Audi 4.2 BNS code (later CNFS code) V8 in the B7 / B8.5 gen RS4 - an undersquare engine with a bore of 3.33in against a 3.65in stroke, redline at 8,250rpm producing over 400 horsepower. The piston crowns are doing F1 engine speeds at that top end 🤯
2026-06-16 10:00:15
3
Zac ravioli :
/6 mentioned rrrrahahahahhaahhhh
2026-06-15 04:56:23
4
ChoppperJim :
This is good stuff...thanks.
2026-06-16 00:10:09
4
Wesley Snyder :
over square under square strait to jail
2026-06-15 05:50:44
6
Airheaded Aviator :
Its more accurate to say undersquare helps with making high rpm. Given enough money and materials you could do whatever you want for rpm, but at a pricepoint you'll likely struggle
2026-06-15 16:50:22
3
M021180 :
Oversimplified. Larger valves also limit rpm’s.
2026-06-15 05:54:05
5
James Beckington :
put your feet a bit further apart
2026-06-16 09:24:35
2
JP :
Everything makes power, build to your budget 😎
2026-06-15 06:07:18
2
Chris :
great information
2026-06-15 22:21:07
3
Cletus McVato :
How can I reach 7000rpms in a 351sbf?
2026-06-16 03:46:16
1
Jeff Heisler :
Very well explained!
2026-06-16 16:16:13
1
Bull Nation Car unit :
never knew about it
2026-08-05 09:10:38
1
John Morgan :
BBC 4.500” x 3.76” absolute monster.
2026-06-17 22:17:05
2
Fett :
chrysler 400 4.34 inch 110 mm bore 3 3/8 stroke 85.7 mm. classic engine to hot rod
2026-06-17 00:48:52
1
kylebooth211 :
It doesn't have to be, it just makes it easier. all the crank and rods need to do is not explode at redline and be as light as possible. I suppose the piston can't go faster than the speed of sound in the combustion chamber so I guess that would be the only real limit that would require a shorter stroke.
2026-06-25 01:04:42
1
jasonkliemann :
but remember torqe moves mass and more stroke more torque
2026-06-15 10:17:53
1
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