3 in journel on a stroker crank hold togeather

You'll be better off with a 3.375-3.5" journal size. The 3" will hold for a while, but the bigger ones will last a lot longer.
 
I have a 9.75 stroke, 6.375 bore, about 9 to 1 compression. Been running since 2004 with no problems yet. Has been pulled pretty hard in 10,200 lb. class many times. Works real well.
Oh yes it has a 3 inch journal!
 
Tree Topper, Your 3" journal should be very reliable at 622 cu in. We're running 3" journals on A's with more cubes than that, and just replaced a crank after 6 years (before it broke). The engine in question will have 896 cubes, almost half again more than yours, and needs the bigger journal to have decent reliability. Mike
 
well iv been running this crank for 7 yrs with 3 in journels 7.5 block thats 832 cubes block went bad so if im gonna replace block to 7 3/4 im going with a new crank shaft befor it breaks
 
Yes I know this is not a very big G as compared
to what is being built these days, but this set up has worked very well for me. Been very reliable. Don't use the engine up very often even in heavy classes. Lots of fun.
 
(quoted from post at 06:17:31 01/31/13) A 3.5" journal has 1.361 times more material than a 3.0" journal.

Yes, this would be correct for cross sectional area. The strength of the journal in tension is proportional to the cross sectional area. However, for a crankshaft, strength in torsion and strength in bending are more important than strength in tension.

If I could repeat your calculations for clarity: The cross sectional area is proportional to the diameter raised to the second power (diameter squared). For a 3" journal we have 3^2 = 9 and for a 3.5" journal we have 3.5^2 = 12.25. 12.25 divided by 9 = 1.361; increase in strength in tension.

The strength of the journal in torsion and in bending is proportional to the journal diameter raised to the fourth power. For a 3" journal we have 3^4 = 81 and for a 3.5" journal we have 3.5^4 = 150.06. 150.06 divided by 81 = 1.85; increase in strength in torsion and bending.

In conclusion the 3.5" journal is nearly double in stength for the more important torsion and bending modes.

With all respect - hopefully this adds to your post. Ken
 
It's all good with me. Left the torsion and
bending out for simplicity.
Actually the 4th power is going to take some
refreshing and thinking about. It's been a while.
Have to wonder with the airflow being limited by
valve and and port size along with the short cam
timing. Is gaining that last 1/2" to 1" of stroke
that requires a skinny cam, 3" journals and a
relocated cam really worth it?
 

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