rod journal size vs rpm

4speedracer · 12-20-2019, 01:34 PM

I know the smaller the better but,what would someone say the highest rpm someone could turn a steel 2.123 sbf rod crankshaft without issue. Thanks

Everett Hill · 12-20-2019, 02:12 PM

all the small block fords are steel which one stock or after market,I have turned mine 10,000 at times mostly 9,000 to 9,500

340Cuda · 12-20-2019, 06:22 PM

I would say with all the race engines with 1.88, 1.85 and smaller rod journals, turn all the RPM you want.

Ed Wright · 12-20-2019, 08:53 PM

Quote:

Originally Posted by Everett Hill

all the small block fords are steel which one stock or after market,I have turned mine 10,000 at times mostly 9,000 to 9,500

Wasn’t the question originally about crank journal diameter versus RPM?
That is about the surface speed of the bearing against the crank. Smaller crank journal diameter reduced the speed of the bearing against the surface of the crank.
Of course, you can usually get by with high surface speeds. Lower speeds improve reliability. “Honda rods” did not make mine any faster, but did reduce bearing wear.
Your results may vary.

James L Miller · 12-21-2019, 06:25 PM

How much power (or torque) can be run through the small journals? I bought a set of Crower rods with the Quad 4 bearing size. I would think the rear journal would take the most power (torque) through them, but only one cylinder is firing at a time.

12-20-2019, 01:34 PM	#1
4speedracer Junior Member Join Date: Sep 2011 Posts: 51 Likes: 0 Liked 10 Times in 6 Posts	rod journal size vs rpm I know the smaller the better but,what would someone say the highest rpm someone could turn a steel 2.123 sbf rod crankshaft without issue. Thanks

12-20-2019, 02:12 PM	#2
Everett Hill Junior Member Join Date: Jun 2007 Posts: 49 Likes: 0 Liked 4 Times in 3 Posts	Re: rod journal size vs rpm all the small block fords are steel which one stock or after market,I have turned mine 10,000 at times mostly 9,000 to 9,500 __________________ Everett Hill 2134 STK, SS

12-20-2019, 06:22 PM	#3
340Cuda VIP Member Join Date: Apr 2003 Location: Tulsa, Oklahoma Posts: 1,668 Likes: 3,844 Liked 799 Times in 336 Posts	Re: rod journal size vs rpm I would say with all the race engines with 1.88, 1.85 and smaller rod journals, turn all the RPM you want.

12-21-2019, 06:25 PM	#5
James L Miller Member Join Date: Apr 2005 Posts: 494 Likes: 6 Liked 25 Times in 16 Posts	Re: rod journal size vs rpm How much power (or torque) can be run through the small journals? I bought a set of Crower rods with the Quad 4 bearing size. I would think the rear journal would take the most power (torque) through them, but only one cylinder is firing at a time. __________________ Mopar 2 Ya!