Do I need rod bolts?
I have a 2001 5.3, what rod bolts does it have? Are the 2001+ LS6 type or did only the car motors get them? Also, how are cracked rods recondition? The way I look at it is if you're going to tear your motor down, buy $90 - $200 rod bolts, pay to have your rods recondition, hone and install new rings, buy gaskets...etc, you might as well spring for aftermarket rods, right?
honestly yes. which is what i did the 2nd time around. the first time, i installed them just to find out they needed resized. long time ago, i didnt know any better because i read threads just like this filled with bickering back and forth between what is right and wrong.
then, i removed them, and resized them myself so i didnt have any machine shop bill. so at this point i was 120 bucks in the hole.
no big deal. but now im building a 370 and decided i needed to use a different rod because after many many miles and hard abuse, the resized rods IMO have had it. so insted of resizing another set of rods i just sprung 300 bucks for a set of Scat I beam forged rods with ARP bolts already in them.
then, i removed them, and resized them myself so i didnt have any machine shop bill. so at this point i was 120 bucks in the hole.
no big deal. but now im building a 370 and decided i needed to use a different rod because after many many miles and hard abuse, the resized rods IMO have had it. so insted of resizing another set of rods i just sprung 300 bucks for a set of Scat I beam forged rods with ARP bolts already in them.
Yea, $200 for just the katech rod bolts...300 for scat I beam seam to make more sense. Do you know what bolts my 2001 5.3 truck motor came with. It is going in my 2000 S10, hopefully with a rear mount turbo. I am only looking to make 400 hp at the wheels...I know I can make that much without a turbo, but I want to leave the motor mild and get good mileage as it will be a true daily driver. I only plan to spin it to 6000-6200
Teching In
Joined: Jan 2011
Posts: 10
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From: DODGE CITY, KS
any time you change the bolts out in these rods to a bolt with a higher tensil strength. it will have more clamping force. which will cause the housing bore to distort. typically more torque causes the mating surfaces to spread appart, and the top to bottom measurement will shrink. i just put arp 180,000 tensil strength bolts in my rods last month, and with the stock bolts torqued up the housing bore was at 2.2247". or bottom of spec. and was round with in .0001". after installing the new arp's the bore was now .001" out of round. 2.2252" at the parting edges and 2.2242" up and down. So i honed it to 2.225 and left theparting edges .0002" big. the bearings are thinner at the parting edges anyway.
i plan on spinning mine to 7000. if that is what it likes. 1/4 mile time wise.
ARP 180,000=$80, ARP 220,000=$90(i just found on sale), katech 280,000=$200. all would require honing back round. our price at work is 8$ a piece. i think the only think kaytech has going for it at that price is you don't have to reballance. like you would with aftermarket rods.
If i were you i would change them as soon as i got a chance. the 6300 im not so worried about for short periods but the 6800 is pushing it. and its only a matter of time before you stress the bolts to much or beat all the press out the bearings.
search google for arp ls1 rod bolts and you will find the 220,000 arp's or $90
stress on the rod is applied exponetially. and the higher the reciprocating weight the faster the force will rise.
hope this helps.
i plan on spinning mine to 7000. if that is what it likes. 1/4 mile time wise.
ARP 180,000=$80, ARP 220,000=$90(i just found on sale), katech 280,000=$200. all would require honing back round. our price at work is 8$ a piece. i think the only think kaytech has going for it at that price is you don't have to reballance. like you would with aftermarket rods.
If i were you i would change them as soon as i got a chance. the 6300 im not so worried about for short periods but the 6800 is pushing it. and its only a matter of time before you stress the bolts to much or beat all the press out the bearings.
search google for arp ls1 rod bolts and you will find the 220,000 arp's or $90
stress on the rod is applied exponetially. and the higher the reciprocating weight the faster the force will rise.
hope this helps.
any time you change the bolts out in these rods to a bolt with a higher tensil strength. it will have more clamping force. which will cause the housing bore to distort. typically more torque causes the mating surfaces to spread appart, and the top to bottom measurement will shrink. i just put arp 180,000 tensil strength bolts in my rods last month, and with the stock bolts torqued up the housing bore was at 2.2247". or bottom of spec. and was round with in .0001". after installing the new arp's the bore was now .001" out of round. 2.2252" at the parting edges and 2.2242" up and down. So i honed it to 2.225 and left theparting edges .0002" big. the bearings are thinner at the parting edges anyway.
i plan on spinning mine to 7000. if that is what it likes. 1/4 mile time wise.
ARP 180,000=$80, ARP 220,000=$90(i just found on sale), katech 280,000=$200. all would require honing back round. our price at work is 8$ a piece. i think the only think kaytech has going for it at that price is you don't have to reballance. like you would with aftermarket rods.
If i were you i would change them as soon as i got a chance. the 6300 im not so worried about for short periods but the 6800 is pushing it. and its only a matter of time before you stress the bolts to much or beat all the press out the bearings.
search google for arp ls1 rod bolts and you will find the 220,000 arp's or $90
stress on the rod is applied exponetially. and the higher the reciprocating weight the faster the force will rise.
hope this helps.
i plan on spinning mine to 7000. if that is what it likes. 1/4 mile time wise.
ARP 180,000=$80, ARP 220,000=$90(i just found on sale), katech 280,000=$200. all would require honing back round. our price at work is 8$ a piece. i think the only think kaytech has going for it at that price is you don't have to reballance. like you would with aftermarket rods.
If i were you i would change them as soon as i got a chance. the 6300 im not so worried about for short periods but the 6800 is pushing it. and its only a matter of time before you stress the bolts to much or beat all the press out the bearings.
search google for arp ls1 rod bolts and you will find the 220,000 arp's or $90
stress on the rod is applied exponetially. and the higher the reciprocating weight the faster the force will rise.
hope this helps.
and the later 01+ rod bolts are rated to 160,000psi
I have no idea if these numbers are right though.
Does anyone have a program to estimate the stress on a rod bolt at different rpms?
heres there ratings The new ones are grade 12.9 metric so that is:
minimum yield strength = 159541 psi
minimum tensile strength = 174045 psi
Last edited by mtuggle86; May 6, 2011 at 12:32 AM.
My opinion is.. If you don't want to do a rebuild, keep the revlimit at around 64-6500 and don't change the rod bolts. If you want to spin higher rebuild with forged rods and good bolts. Really.. if you rev it another 300 or so RPM it's not going to make much difference so just back off of that.
If you want to make good power and not change them pick a cam that makes good power in that RPM range. Its silly as **** to put in bolts to rev a couple hundred RPM's when you don't have to... if you build your setup around it.
The rule of thumb is if you do rod bolts you resize the rods. So it's simple, keep the RPM's down since that is the killer of rod bolts or put in forged rods with good bolts and rev it to the moon.
It's all about what you want to do with your setup. And really you can have a very high power setup without spinning it to 7k.
To each their own, but the simple fact is at high RPM's rod bolts stretch and or break, so the question is why are you spinning it so high? with the right matching of parts you don't have to spin it that high.
If you want to make good power and not change them pick a cam that makes good power in that RPM range. Its silly as **** to put in bolts to rev a couple hundred RPM's when you don't have to... if you build your setup around it.
The rule of thumb is if you do rod bolts you resize the rods. So it's simple, keep the RPM's down since that is the killer of rod bolts or put in forged rods with good bolts and rev it to the moon.
It's all about what you want to do with your setup. And really you can have a very high power setup without spinning it to 7k.
To each their own, but the simple fact is at high RPM's rod bolts stretch and or break, so the question is why are you spinning it so high? with the right matching of parts you don't have to spin it that high.
My opinion is.. If you don't want to do a rebuild, keep the revlimit at around 64-6500 and don't change the rod bolts. If you want to spin higher rebuild with forged rods and good bolts. Really.. if you rev it another 300 or so RPM it's not going to make much difference so just back off of that.
If you want to make good power and not change them pick a cam that makes good power in that RPM range. Its silly as **** to put in bolts to rev a couple hundred RPM's when you don't have to... if you build your setup around it.
The rule of thumb is if you do rod bolts you resize the rods. So it's simple, keep the RPM's down since that is the killer of rod bolts or put in forged rods with good bolts and rev it to the moon.
It's all about what you want to do with your setup. And really you can have a very high power setup without spinning it to 7k.
To each their own, but the simple fact is at high RPM's rod bolts stretch and or break, so the question is why are you spinning it so high? with the right matching of parts you don't have to spin it that high.
If you want to make good power and not change them pick a cam that makes good power in that RPM range. Its silly as **** to put in bolts to rev a couple hundred RPM's when you don't have to... if you build your setup around it.
The rule of thumb is if you do rod bolts you resize the rods. So it's simple, keep the RPM's down since that is the killer of rod bolts or put in forged rods with good bolts and rev it to the moon.
It's all about what you want to do with your setup. And really you can have a very high power setup without spinning it to 7k.
To each their own, but the simple fact is at high RPM's rod bolts stretch and or break, so the question is why are you spinning it so high? with the right matching of parts you don't have to spin it that high.
I don't get it if gm is willing to throw a warranty on the ls6 spinning 6600 it should be able to handle that without much problem. They test these engines for hours at there rev limit before they release them most of the time.
This is from the chief designer of the ls6
The LS6’s fuel cut-off is at 6600 rpm. Of course, the first question geargeek Corvetters are going to ask is,
"What happens if I change the rev limit so I can run harder on the drag strip?" We asked Dr. John what
keeps the LS6 from rev’ing to 6800 or so. "Fuel cut-off," he replied laughing. On a more serious note, he
added, "With the current hardware, my recollection is the valves float about 6800-7000 rpm. The concern is
all the other parts in the engine, not just the valve train. We can work on the valve train to get it to go that
higher speed. Then we start being concerned about oil film-thickness in the rod bearings, rod bolt strength
and piston temperatures. Even though we upgraded our piston, if we were to go with higher speed, we’d
have to go with another improved piston as well as upgraded piston pins and I’m talking about forged
pistons and floating pins. We’d also have to go with an improved strength rod.
A lot of the hot rodders reading this might trivialize GM Powertrain’s position and say, "Heck, what a bunch
of wimps. Just put some bigger valves springs on, bigger injectors and change the rev limit. Considering
that viewpoint, we asked Dr. John why the conservative approach. "You could run an LS1 or an LS6 to
seven grand," Juriga answered, "and not immediately put a rod through the side of the block. What is a
concern is how often and how long your run the engine like that. We have our durability goals that say we
gotta be able to run these engines for 125,000 miles at a certain confidence level. If we had the engine
running at those higher speeds, we’d have to validate the engine at the higher performance level for that
period of time and that’s something we’re not ready to do right now."
Last edited by mtuggle86; May 6, 2011 at 02:37 PM.
Your entitled to you own opinion but why are so many people worried to spin the 01+ bolts past 6500. Gm put a warranty on them in the ls6 its stock rev limiter was 6600.
I don't get it if gm is willing to throw a warranty on the ls6 spinning 6600 it should be able to handle that without much problem. They test these engines for hours at there rev limit before they release them most of the time.
This is from the chief designer of the ls6
The LS6’s fuel cut-off is at 6600 rpm. Of course, the first question geargeek Corvetters are going to ask is,
"What happens if I change the rev limit so I can run harder on the drag strip?" We asked Dr. John what
keeps the LS6 from rev’ing to 6800 or so. "Fuel cut-off," he replied laughing. On a more serious note, he
added, "With the current hardware, my recollection is the valves float about 6800-7000 rpm. The concern is
all the other parts in the engine, not just the valve train. We can work on the valve train to get it to go that
higher speed. Then we start being concerned about oil film-thickness in the rod bearings, rod bolt strength
and piston temperatures. Even though we upgraded our piston, if we were to go with higher speed, we’d
have to go with another improved piston as well as upgraded piston pins and I’m talking about forged
pistons and floating pins. We’d also have to go with an improved strength rod.
A lot of the hot rodders reading this might trivialize GM Powertrain’s position and say, "Heck, what a bunch
of wimps. Just put some bigger valves springs on, bigger injectors and change the rev limit. Considering
that viewpoint, we asked Dr. John why the conservative approach. "You could run an LS1 or an LS6 to
seven grand," Juriga answered, "and not immediately put a rod through the side of the block. What is a
concern is how often and how long your run the engine like that. We have our durability goals that say we
gotta be able to run these engines for 125,000 miles at a certain confidence level. If we had the engine
running at those higher speeds, we’d have to validate the engine at the higher performance level for that
period of time and that’s something we’re not ready to do right now."
I don't get it if gm is willing to throw a warranty on the ls6 spinning 6600 it should be able to handle that without much problem. They test these engines for hours at there rev limit before they release them most of the time.
This is from the chief designer of the ls6
The LS6’s fuel cut-off is at 6600 rpm. Of course, the first question geargeek Corvetters are going to ask is,
"What happens if I change the rev limit so I can run harder on the drag strip?" We asked Dr. John what
keeps the LS6 from rev’ing to 6800 or so. "Fuel cut-off," he replied laughing. On a more serious note, he
added, "With the current hardware, my recollection is the valves float about 6800-7000 rpm. The concern is
all the other parts in the engine, not just the valve train. We can work on the valve train to get it to go that
higher speed. Then we start being concerned about oil film-thickness in the rod bearings, rod bolt strength
and piston temperatures. Even though we upgraded our piston, if we were to go with higher speed, we’d
have to go with another improved piston as well as upgraded piston pins and I’m talking about forged
pistons and floating pins. We’d also have to go with an improved strength rod.
A lot of the hot rodders reading this might trivialize GM Powertrain’s position and say, "Heck, what a bunch
of wimps. Just put some bigger valves springs on, bigger injectors and change the rev limit. Considering
that viewpoint, we asked Dr. John why the conservative approach. "You could run an LS1 or an LS6 to
seven grand," Juriga answered, "and not immediately put a rod through the side of the block. What is a
concern is how often and how long your run the engine like that. We have our durability goals that say we
gotta be able to run these engines for 125,000 miles at a certain confidence level. If we had the engine
running at those higher speeds, we’d have to validate the engine at the higher performance level for that
period of time and that’s something we’re not ready to do right now."
It does appear though that Katech is doing something to get away with not resizing, and I trust that Katech knows their ****. But I really am curious what they are doing that others aren't that allows you to not resize, I am assuming that they are factoring tensile strength and torque specs into an equation to maintain equal clamping force but since the bolt is stronger it has far superior resistance to stretch.
By the way after reading your sig I am curious about your car. I like the parts you used, what does it put down and what does it run at the track? PM me if you would like. Sounds like an awesome bang for buck setup.
Hey poeple , I just wanted to add a thing or 2 . When talking about rod bolt breakage , frequency is the killer , specifically a certain freq ,,,,,,,like the opera singer breaking the wine glass at a certain note or freq . So while 1 guy does'nt have any issues at 7000rpm's it may be because He was'nt hanging around that detrimental rpm . That and every build is going to amplify different freq at different rpm's because of variables in parts and techniques building so having said that You never know for sure . The last poster hit the nail square on the head when He said why push it into the window of most likely it will stay together in 1 peice. So keep You're rpm's reasonable and feel confident that You're engine will stay in 1 piece or spring for the parts and pull the motor . Yes , the 5.3's have the same upgraded bolts , they are kind of a ARP copy of their "Wave-Lock" bolts .
I've seen 2 different torq procedures from ARP both for the sportsman rod bolts , 1 says something like torq them to 45lb/ft and the other says using their stretch gauge torq until there is roughly .0005" of stretch . So I was curious to see where their bolts started to stretch , so I started at 35lb and increased the value by 3lb/ft at a time until I reached 58lb/ft at which time with a caliper that measures in thous/inch I could detect some bolt stretch ,,,,,maybe .0003 . Also I measured the rod as best I could with the tools at hand and found between .001" and .0015" change in the rod . I imagine there would be more change with the added stresses and heat of the engine .
I've seen 2 different torq procedures from ARP both for the sportsman rod bolts , 1 says something like torq them to 45lb/ft and the other says using their stretch gauge torq until there is roughly .0005" of stretch . So I was curious to see where their bolts started to stretch , so I started at 35lb and increased the value by 3lb/ft at a time until I reached 58lb/ft at which time with a caliper that measures in thous/inch I could detect some bolt stretch ,,,,,maybe .0003 . Also I measured the rod as best I could with the tools at hand and found between .001" and .0015" change in the rod . I imagine there would be more change with the added stresses and heat of the engine .
Oh and im glad you brought up the frequency thing. I think most people don't realize at that high of RPM's a harmonic vibration can start up and become bad enough real quickly that it will vibrate so rapidly and violently it will rip and shred the bottom end all to hell. Hence the "harmonic balancer" and its purpose. (harmonic balancers don't completely stop all chances of having harmonic vibrations purely on their own, but greatly reduce them)
What type of harmonic balancer do you run?
I guess I better pull my motor, tear it down and resize my rods.
I can't believe how lucky I must have been running with ARP for well over 10,000 miles and pass after pass, on a 150 shot spinning it 7000 rpm in every gear, without resizing my rods... I wish I would have just spent three times as much on the super mystical Katech's so I wouldn't have to go back and do this. ;P
I guess I better pull my motor, tear it down and resize my rods.
I can't believe how lucky I must have been running with ARP for well over 10,000 miles and pass after pass, on a 150 shot spinning it 7000 rpm in every gear, without resizing my rods... I wish I would have just spent three times as much on the super mystical Katech's so I wouldn't have to go back and do this. ;P
Last edited by MPFD; May 12, 2011 at 03:55 PM.
TECH Senior Member
Joined: Apr 2002
Posts: 6,080
Likes: 17
From: So.Cal.
Ive seen that the 97-00 rod bolts are rated at 135,000psi
and the later 01+ rod bolts are rated to 160,000psi
I have no idea if these numbers are right though.
Does anyone have a program to estimate the stress on a rod bolt at different rpms?
heres there ratings The new ones are grade 12.9 metric so that is:
minimum yield strength = 159541 psi
minimum tensile strength = 174045 psi
and the later 01+ rod bolts are rated to 160,000psi
I have no idea if these numbers are right though.
Does anyone have a program to estimate the stress on a rod bolt at different rpms?
heres there ratings The new ones are grade 12.9 metric so that is:
minimum yield strength = 159541 psi
minimum tensile strength = 174045 psi
I'll use these numbers:
rod length = 6.098"
stroke = 3.622"
pin offset = ? does anyone have a number for this...? if not, I'll assume 0.000".
Give me a few minutes (it's not a program, I have do plot a graph and do some calculations)...
Edit: I also need to know the mass of a piston, pin, and rod.
Last edited by joecar; May 12, 2011 at 08:37 PM.
TECH Senior Member
Joined: Apr 2002
Posts: 6,080
Likes: 17
From: So.Cal.
Maximum piston acceleration is at TDC, graph shows stock configuration (L=6.098", R=1.811") to be -2.3488 in/rad².
First, convert rpm to rad/s (divide by 60, multiply by 2*pi).
Then multiply -2.3488 by (rad/s)², divide by 12 in/ft, divide by 32 ft/s²/g, this gives g force on piston:
6000 rpm -> 628.3 rad/s -> -2412 g
6300 rpm -> 659.7 rad/s -> -2662 g
6600 rpm -> 691.2 rad/s -> -2922 g
6900 rpm -> 722.6 rad/s -> -3194 g
7200 rpm -> 754.0 rad/s -> -3477 g
(i.e. g force goes up as rpm²)
(negative means in downward direction toward crank)
Then, take piston/pin mass and add half of rod mass, multiply by g from above, this gives the tensile force on the rod, divide by total cross section area of two rod bolts, this gives the tensile stress [psi] seen by each bolt.
First, convert rpm to rad/s (divide by 60, multiply by 2*pi).
Then multiply -2.3488 by (rad/s)², divide by 12 in/ft, divide by 32 ft/s²/g, this gives g force on piston:
6000 rpm -> 628.3 rad/s -> -2412 g
6300 rpm -> 659.7 rad/s -> -2662 g
6600 rpm -> 691.2 rad/s -> -2922 g
6900 rpm -> 722.6 rad/s -> -3194 g
7200 rpm -> 754.0 rad/s -> -3477 g
(i.e. g force goes up as rpm²)
(negative means in downward direction toward crank)
Then, take piston/pin mass and add half of rod mass, multiply by g from above, this gives the tensile force on the rod, divide by total cross section area of two rod bolts, this gives the tensile stress [psi] seen by each bolt.
Last edited by joecar; May 16, 2011 at 11:19 PM. Reason: Fixed [units] typos in graph
TECH Senior Member
Joined: Apr 2002
Posts: 6,080
Likes: 17
From: So.Cal.
The installed rod bolts are in static tension (some amount of stretch places the material partway up the linear part of the stress-strain curve), i.e. preloaded stress; this stress is found by knowing how far the bolt turned while in tension, the thread pitch gives strain (displacement as a fraction of length of the stretched part of the bolt) which on the S-S curve gives a stress value;
the piston/crank flying past TDC adds the dynamic stress calculated in the previous post to the static preload stress, when the total stress exceeds the yield point the bolt deforms, when it exceeds the tensile strength the bolt breaks.
the piston/crank flying past TDC adds the dynamic stress calculated in the previous post to the static preload stress, when the total stress exceeds the yield point the bolt deforms, when it exceeds the tensile strength the bolt breaks.
Last edited by joecar; May 16, 2011 at 11:21 PM.
TECH Senior Member
Joined: Apr 2002
Posts: 6,080
Likes: 17
From: So.Cal.
The g force produces about 40000-70000 psi (for the g force range shown two posts ago) as I estimated without measuring piston/rod mass and bolt diameter; the preload is about 100000 psi as I estimated without measuring bolt turn nor looking up a S-S curve;
so 40000+100000 = 140000 psi is safe with some safety factor/margin.
so 70000+100000 = 170000 psi is getting close with no safety factor/margin.
so 40000+100000 = 140000 psi is safe with some safety factor/margin.
so 70000+100000 = 170000 psi is getting close with no safety factor/margin.
Last edited by joecar; May 16, 2011 at 11:22 PM.
What type of harmonic balancer do you run?
I guess I better pull my motor, tear it down and resize my rods.
I can't believe how lucky I must have been running with ARP for well over 10,000 miles and pass after pass, on a 150 shot spinning it 7000 rpm in every gear, without resizing my rods... I wish I would have just spent three times as much on the super mystical Katech's so I wouldn't have to go back and do this. ;P
I guess I better pull my motor, tear it down and resize my rods.
I can't believe how lucky I must have been running with ARP for well over 10,000 miles and pass after pass, on a 150 shot spinning it 7000 rpm in every gear, without resizing my rods... I wish I would have just spent three times as much on the super mystical Katech's so I wouldn't have to go back and do this. ;P