Safe racing RPMs
10-16-2007, 11:52 PM
#1
2nd Gear Member
Thread Starter
Join Date: May 2006
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Posts: 237
Safe racing RPMs
I was just curious how many RPM it is safe to turn on stock internals in our 4.6s. I am going to have my heads professionally done but chances are they are going to want 8,000 rpms to get max power. I need to give an RPM limit to base the port and valve designs on... Cams and springs will be done so that wont be the problem, just the internals.
10-17-2007, 12:31 AM
#3
RE: Safe racing RPMs
After the research i put into my engine build (talking to machine shops, reading, ext.) I would not run the stock rods of a stock 4.6 2v above 6000k rpms. I'm sure it can hang with it above that for a little bit but if you put alot of time/money in head work and some hot street/strip cams your motor is going to want to see alot of time in the red line for it to make the power it's supposed to. I'm running stage 2 comp cams with stage 2 heads and it peaks out at 6700 rpms.. sooooo yeah im pretty glad i got forged rods and pistons. As far as the the stock crank i have no idea what rpms it can hang to, but my engine builder said it can hang till about 600hp. If your budget can handle it try and get forged rods and pistons so you can run high rpms without worries.
10-17-2007, 06:24 AM
#4
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Join Date: Feb 2007
Location: Maryland
Posts: 342
RE: Safe racing RPMs
well let me ask you this where did you get your forged pistons and rods, how much where they and on top of that how much was the install by the mechanic thanks. cuz i want to kenne bell the bullitt sometime and would feel alot better to do the bottom end.
10-18-2007, 12:24 AM
#7
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Join Date: Mar 2005
Location: Nashville/Knoxville, Tennessee
Posts: 4,687
RE: Safe racing RPMs
from what i have seen... its the crank that limits the rpms... lets say... a 99-01 cobra... it has the same pistons and rods to my knowlege. but its the crank that is different. it is forged. and those motors rev to 7k rpms. so i will say that the stock crank shouldnt rev very high. could have something to do with the balancing and such too.
10-18-2007, 12:26 AM
#8
5th Gear Member
Join Date: Mar 2005
Location: Nashville/Knoxville, Tennessee
Posts: 4,687
RE: Safe racing RPMs
oh.. my new shortblock with forged everything is good for 8000rpms... i just would never take it there, that is too high of rpm for any motor i would say, except like a honda. lol. i am going to limit mine to 7500rpms to be on the safe side.
10-18-2007, 12:42 AM
#9
RE: Safe racing RPMs
ORIGINAL: bullittracr
well let me ask you this where did you get your forged pistons and rods, how much where they and on top of that how much was the install by the mechanic thanks. cuz i want to kenne bell the bullitt sometime and would feel alot better to do the bottom end.
well let me ask you this where did you get your forged pistons and rods, how much where they and on top of that how much was the install by the mechanic thanks. cuz i want to kenne bell the bullitt sometime and would feel alot better to do the bottom end.