Re: 427 small block
[Re: Streetwize]
#857222
11/18/10 08:58 PM
11/18/10 08:58 PM
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Joined: Nov 2004
Posts: 4,330 Lynchburg, VA
Leon441
master
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master
Joined: Nov 2004
Posts: 4,330
Lynchburg, VA
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I have a 427 build I started years ago. Just don't need it.
It is 4.125" bore with a 4" stroke. Considerably more worth while than a smaller bore with longer stroke. You have to remember stroke pretty much moves your power range down in RPM. I did it due to J heads and 59 degree lifter angle. No neeed to turn it 8,000 with a 4" stroke can make the same power at 7,000.
Career best 8.02 @ 169 at 3050# and 10" tires small block power.
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Re: 427 small block
[Re: mopar dave]
#857225
11/18/10 11:28 PM
11/18/10 11:28 PM
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Joined: Jan 2003
Posts: 9,924 Weddington, N.C.
Streetwize
master
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master
Joined: Jan 2003
Posts: 9,924
Weddington, N.C.
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With the same heads once you go over 4" stroke you're rate of gain per cube increase will slow down, above the torque peak the RATE of acceleration slows as the VE drops, in your case (same heads and compression)the longer stroke isn't getting the proportional rate of increase in airflow to offset the increase in frictional losses.
Long stroke small blocks like Andy's example are built and tuned to achieve the highest average torque, and a flat broad torque curve without much variance (achieving at least 85% of peak torque over a ~2800-3400RPM band...the right intake manifold is important here too)...peak HP is not really the primary target. If Andy wanted more hp at that approx size he would have bored that 340 Resto (siamese) block to it's max ~4.22" IIRC) and shortened the stroke to something like the 3.79" , plug that in and you should see more HP per cube but a little less peak torque...and at a somewhat higher RPM...if you really examine it you'll see the frictional losses are lower....because the piston speed is lower at any given RPM. This is most apparent above the peak torque RPM.
Last edited by Streetwize; 11/18/10 11:33 PM.
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