Discussion
Does anyone have experience of using/handling ARP L19 bolts instead of 2000.
It's been suggested I should be using L19 rod bolts, but I am concerned about using an "unstable" material that can suffer hydrogen embrittlement - I'm not convinced, but even ARP themselves can't advise one way or other.
It's been suggested I should be using L19 rod bolts, but I am concerned about using an "unstable" material that can suffer hydrogen embrittlement - I'm not convinced, but even ARP themselves can't advise one way or other.
MattYorke said:
Does anyone have experience of using/handling ARP L19 bolts instead of 2000.
It's been suggested I should be using L19 rod bolts, but I am concerned about using an "unstable" material that can suffer hydrogen embrittlement - I'm not convinced, but even ARP themselves can't advise one way or other.
I thought they had a better material than L19 now anyway ?It's been suggested I should be using L19 rod bolts, but I am concerned about using an "unstable" material that can suffer hydrogen embrittlement - I'm not convinced, but even ARP themselves can't advise one way or other.
What application ?
They must either be a very small fastener or an extreme application if someone is recommending them ?
MattYorke said:
It's just a big block chevy. 6000rpm on a 4.375 stroke. It'll be getting carillo compstar I beam rods, which have the option of 2000 or l-19 bolts.
I'd think Carillo might be best to advise ? Sounds like the fasteners used will be pretty big though ?What are other guys using ? Is rod bolt failure an issue on other builds ?
MattYorke said:
It's just a big block chevy. 6000rpm on a 4.375 stroke. It'll be getting carillo compstar I beam rods, which have the option of 2000 or l-19 bolts.
6000 rpm and you're worried about what type of rod bolt to use? You're avin' a larf wiv us incha son? Got to be. Chocolate rod bolts would survive those paltry rpms. Well, as long as it's good quality chocolate like Cadburys.The piston acceleration at 6k rpm at that stroke is just under 29000 m/s^2. That's the same as a 2 litre Ford Pinto on a 77mm stroke at 7300 rpm and the stock 150,000 psi 9mm rod bolts on those will go 8k rpm as long as you like. The bigger bolts on the Chevy (ok so the pistons are bigger too) won't even know they're being asked to do any work at that speed. They'll just larf at you like wot I'm doing. 200,000 psi rod bolts are so overspecced at those rpms you could knock them down to 8mm ones to save a bit of weight and they'd still be too strong. But you're fretting about whether to even use 260,000 psi bolts? F**ks sake.
Just out of idle curiosity, if you're worried about rod bolts at 6k rpm how do you think people build 9k rpm big block drag motors that still stay together when the piston acceleration and rod bolt forces are 2.25 times higher? Unobtanium bolts? Magic bolts? Chicken entrails mixed into the oil?
I'll hazard a guess or three. You'll see this post within seconds because you're sat at home by a pc because you never leave home because of the risk. You've never crossed a road in your life coz that's just tempting fate. You might actually build this motor but you'll never drive it. Anything could happen. You never have sex without condoms and you wear a bag over your own head too in case hers falls off. You ain't a fan of the five second rule where if you drop food on the floor you can pick it up without it getting germs as long as you do it within five seconds. You have hand sanitizer in every room in the house. You don't shake hands, you fist bump like Howie Mandel. You throw food out two days before the sell-by date just in case.
Ok I've made me point. Grumpy old b
d mode off. Find something more important to worry about.Pumaracing said:
6000 rpm and you're worried about what type of rod bolt to use? You're avin' a larf wiv us incha son? Got to be. Chocolate rod bolts would survive those paltry rpms. Well, as long as it's good quality chocolate like Cadburys.
The piston acceleration at 6k rpm at that stroke is just under 29000 m/s^2. That's the same as a 2 litre Ford Pinto on a 77mm stroke at 7300 rpm and the stock 150,000 psi 9mm rod bolts on those will go 8k rpm as long as you like. The bigger bolts on the Chevy (ok so the pistons are bigger too) won't even know they're being asked to do any work at that speed. They'll just larf at you like wot I'm doing. 200,000 psi rod bolts are so overspecced at those rpms you could knock them down to 8mm ones to save a bit of weight and they'd still be too strong. But you're fretting about whether to even use 260,000 psi bolts? F**ks sake.
Just out of idle curiosity, if you're worried about rod bolts at 6k rpm how do you think people build 9k rpm big block drag motors that still stay together when the piston acceleration and rod bolt forces are 2.25 times higher? Unobtanium bolts? Magic bolts? Chicken entrails mixed into the oil?
I'll hazard a guess or three. You'll see this post within seconds because you're sat at home by a pc because you never leave home because of the risk. You've never crossed a road in your life coz that's just tempting fate. You might actually build this motor but you'll never drive it. Anything could happen. You never have sex without condoms and you wear a bag over your own head too in case hers falls off. You ain't a fan of the five second rule where if you drop food on the floor you can pick it up without it getting germs as long as you do it within five seconds. You have hand sanitizer in every room in the house. You don't shake hands, you fist bump like Howie Mandel. You throw food out two days before the sell-by date just in case.
Ok I've made me point. Grumpy old bd mode off. Find something more important to worry about.
out of interest.The piston acceleration at 6k rpm at that stroke is just under 29000 m/s^2. That's the same as a 2 litre Ford Pinto on a 77mm stroke at 7300 rpm and the stock 150,000 psi 9mm rod bolts on those will go 8k rpm as long as you like. The bigger bolts on the Chevy (ok so the pistons are bigger too) won't even know they're being asked to do any work at that speed. They'll just larf at you like wot I'm doing. 200,000 psi rod bolts are so overspecced at those rpms you could knock them down to 8mm ones to save a bit of weight and they'd still be too strong. But you're fretting about whether to even use 260,000 psi bolts? F**ks sake.
Just out of idle curiosity, if you're worried about rod bolts at 6k rpm how do you think people build 9k rpm big block drag motors that still stay together when the piston acceleration and rod bolt forces are 2.25 times higher? Unobtanium bolts? Magic bolts? Chicken entrails mixed into the oil?
I'll hazard a guess or three. You'll see this post within seconds because you're sat at home by a pc because you never leave home because of the risk. You've never crossed a road in your life coz that's just tempting fate. You might actually build this motor but you'll never drive it. Anything could happen. You never have sex without condoms and you wear a bag over your own head too in case hers falls off. You ain't a fan of the five second rule where if you drop food on the floor you can pick it up without it getting germs as long as you do it within five seconds. You have hand sanitizer in every room in the house. You don't shake hands, you fist bump like Howie Mandel. You throw food out two days before the sell-by date just in case.
Ok I've made me point. Grumpy old b
d mode off. Find something more important to worry about.Is this mystical L19 material really as fragile as some places might have you believe ? in terms of contamination, touching etc ?
I've found a no longer produced "cadburys" set since I'm not prepared to have unnecessary "sensitive" rod bolts in the motor. ARP couldn't give me an answer about their durability, David answered a question other than the one I asked for the sake of a jolly good rant, and all in all, no one seems to have a clue about the durability of L-19 over the long term in a marine engine.
Let's not ignore the fact that the piston acceleration is 29000 near BDC and is therefore compressive, the TDC side, in tension, is somewhat lower.
(Grabs tin hat and runs for cover......
)
Let's not ignore the fact that the piston acceleration is 29000 near BDC and is therefore compressive, the TDC side, in tension, is somewhat lower.
(Grabs tin hat and runs for cover......
)MattYorke said:
I've found a no longer produced "cadburys" set since I'm not prepared to have unnecessary "sensitive" rod bolts in the motor. ARP couldn't give me an answer about their durability, David answered a question other than the one I asked for the sake of a jolly good rant, and all in all, no one seems to have a clue about the durability of L-19 over the long term in a marine engine.
Let's not ignore the fact that the piston acceleration is 29000 near BDC and is therefore compressive, the TDC side, in tension, is somewhat lower.
(Grabs tin hat and runs for cover...... )
1g lower probably. I don't see how the piston that rises and falls at the same speed, would be subjected to less deceleration/acceleration forces at the top or bottom of the stroke. What about a flat engine?Let's not ignore the fact that the piston acceleration is 29000 near BDC and is therefore compressive, the TDC side, in tension, is somewhat lower.
(Grabs tin hat and runs for cover......
)Steve
Uh-Oh! One of us will get the baker wrath, could be you, could be me....
Think about the changes in the rod angle. I can't recall all the sums, but iirc if the rod angle were constant (or the rod were infinitely long),it would be the same, but since the rod angle varies (and hence why rod length to stroke ratio is also relevant to the peak g loads), it's not the same nr the top as the bottom.
Think about the changes in the rod angle. I can't recall all the sums, but iirc if the rod angle were constant (or the rod were infinitely long),it would be the same, but since the rod angle varies (and hence why rod length to stroke ratio is also relevant to the peak g loads), it's not the same nr the top as the bottom.
stevesingo said:
1g lower probably. I don't see how the piston that rises and falls at the same speed, would be subjected to less deceleration/acceleration forces at the top or bottom of the stroke. What about a flat engine?
Steve
It isnt the forces acting on the piston we are referring to here though. It's the rod bolts.Steve
When cylinders not on a power stroke have the piston yanked down the bore at very great speed. The only thing getting pulled hard, is the rod bolts ( and rod cap )
Shoving the rod/piston back up again is no big deal. Having to suddenly pull it all back down again, is the big deal. Doesnt really matter what opposition the engine is
MattYorke said:
I've found a no longer produced "cadburys" set since I'm not prepared to have unnecessary "sensitive" rod bolts in the motor. ARP couldn't give me an answer about their durability, David answered a question other than the one I asked for the sake of a jolly good rant, and all in all, no one seems to have a clue about the durability of L-19 over the long term in a marine engine.
It wasn't stated in the original question that this was anything to do with the bolts being in a marine engine but I don't see why that should be an issue. The bolts will after all spend their life covered in engine oil, same as in any other engine. Provided they don't get exposed to moisture before fitting they'll probably last a damn sight longer than either you or the boat given they're specced at nearly 8 times stronger than needed to cope with 6000 rpm.Edit - 6 times not 8. Misread a number.
MattYorke said:
Let's not ignore the fact that the piston acceleration is 29000 near BDC and is therefore compressive, the TDC side, in tension, is somewhat lower.
(Grabs tin hat and runs for cover...... )
T'other way round. Piston acceleration at TDC is around 80% to 90% higher than at BDC over the range of normal rod/stroke ratios.(Grabs tin hat and runs for cover......
)Edited by Pumaracing on Thursday 24th February 00:58
stevesingo said:
1g lower probably. I don't see how the piston that rises and falls at the same speed, would be subjected to less deceleration/acceleration forces at the top or bottom of the stroke. What about a flat engine?
Steve
If pistons did in fact rise and fall at the same speed that would be true but they don't do anything remotely like that.Steve
I remember being told as a kid, maybe by my grandad, that Colemans didn't primarily make their money from the mustard that people actually ate but the mustard they left uneaten on the side of the plate having taken far too much in the first place.
Something similar has always seemed to me to be true in many cases for the manufacturers of forged pistons, fancy conrods and uprated rod bolts, the majority of which aren't remotely necessary in the spec of engine they end up getting fitted into. In most cases OE parts are capable of handling anything even fairly highly modified engines can chuck at them.
Running through the equations for this engine makes the point. The I-beam rods are about 830g according to the Carrillo specs online. Length probably about 160 to 170mm but it's not critical. Pistons are unknown but I'll assume about 800g. Bolts are 7/16" x 20 tpi. L19 has a yield strength before plastic deformation sets in of around 215,000 psi.
The rod bolts carry all the reciprocating loads plus the top half of the rotating big end loads as the piston approaches and moves away from TDC.
Reciprocating mass consists of all of the piston mass plus the little end component of the rod mass which in general is about 1/3 of the total rod mass.
Rotating mass is therefore 2/3 of the total rod mass and the bolts carry half of this.
This gives us a reciprocating mass of 800 + 1/3 x 830 = 1077g and a rotating mass of 830/3 = 277g.
At 6000 rpm the total reciprocating and rotating rod bolt load calculates to about 3800kg.
Each bolt has a stress diameter of 9.92 mm and therefore a tensile yield strength of about 11,700kg for a total of 23,400kg. Safety factor is therefore just over 6 times the actual load.
ARP state they try and design race parts for a safety factor of 2 i.e. each rod bolt could in theory just handle the total load. RPM to achieve that in this particular engine = 10,500.
Theoretical instantaneous burst point at which bolt load is equal to bolt strength - 14,800 rpm.
For bog stock 150,000 psi UTS grade 10.9 bolts with a yield strength of 90% of that the bolt yield is 7,300 kg each, total 14,600 kg for a safety factor of 3.8
Max RPM for a safety factor of 2 = 8,300 rpm.
Burst point rpm = 11,700
Something similar has always seemed to me to be true in many cases for the manufacturers of forged pistons, fancy conrods and uprated rod bolts, the majority of which aren't remotely necessary in the spec of engine they end up getting fitted into. In most cases OE parts are capable of handling anything even fairly highly modified engines can chuck at them.
Running through the equations for this engine makes the point. The I-beam rods are about 830g according to the Carrillo specs online. Length probably about 160 to 170mm but it's not critical. Pistons are unknown but I'll assume about 800g. Bolts are 7/16" x 20 tpi. L19 has a yield strength before plastic deformation sets in of around 215,000 psi.
The rod bolts carry all the reciprocating loads plus the top half of the rotating big end loads as the piston approaches and moves away from TDC.
Reciprocating mass consists of all of the piston mass plus the little end component of the rod mass which in general is about 1/3 of the total rod mass.
Rotating mass is therefore 2/3 of the total rod mass and the bolts carry half of this.
This gives us a reciprocating mass of 800 + 1/3 x 830 = 1077g and a rotating mass of 830/3 = 277g.
At 6000 rpm the total reciprocating and rotating rod bolt load calculates to about 3800kg.
Each bolt has a stress diameter of 9.92 mm and therefore a tensile yield strength of about 11,700kg for a total of 23,400kg. Safety factor is therefore just over 6 times the actual load.
ARP state they try and design race parts for a safety factor of 2 i.e. each rod bolt could in theory just handle the total load. RPM to achieve that in this particular engine = 10,500.
Theoretical instantaneous burst point at which bolt load is equal to bolt strength - 14,800 rpm.
For bog stock 150,000 psi UTS grade 10.9 bolts with a yield strength of 90% of that the bolt yield is 7,300 kg each, total 14,600 kg for a safety factor of 3.8
Max RPM for a safety factor of 2 = 8,300 rpm.
Burst point rpm = 11,700
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