dpantazis
#12
i am a geek......
guys-
i would be very leery of putting in mondo head studs. don;t forget that each component of the system has been carefully value-engineered by Navistar. sure, they may have skimped a bit on the head studs for the sake of manufacturing economy, but consider that they probably designed in a 'fuse' to minimize catastrophic failure too. similarly the installation of those fasteners would also be value engineered.
so being the geek that i am, i looked into the different head stud manuf's.
ARP: i am an engineer with a fundamental knowledge of metallurgy. i sat here reading it and wanting my desk references because it was so poorly worded and presented. i am actually a little offended by their catalog. they have crammed a whole bunch of engineering info into their catalog- its intimidating marketing. there is no need for all that gobledey gook in there. I actually wonder why anyone would manufacturer and market an alternator bolt that is 100x stronger than would seem necessary.
i find it curious that ARP only lists nuts not studs for the 6.0. maybe i am reading their catalog wrong.
reading the A1 Tech's catalog, its a more honest and better presented product. i don;t feel that they are trying to bully me into believing that their products are better and that i HAVE to buy their product.
anyhow, the fundamental difference between the H11 tools steel and the AISI 8247 is what those steels were designed for.
The H11 is a chromium hot work tool steel. the AISI is a high carbon steel. remember that these steel designations are 50-100 years old and their original intended uses are long gone. the tool steel in its nature is going to maintain its toughness at high temperatures and stresses, maintaining a sharp cutting edge. that is not to say it would work well as a stud.
the AISI steel is a general purpose high carbon steel with many different applications.
.................H11................AISI8740
Element......Weight %.........Weight %
C..............0.33-0.43.........0.38-0.43
Mn............0.20-0.50.........0.75-1.00
Si.............0.80-1.20.........0.15-0.30
Cr.............4.75-5.50.........0.40-0.60
Ni.............0.3..................0.40-0.70
Mo............1.10-1.60.........0.20-0.30
V..............0.30-0.60.........Not specified
Cu............0.25.................Not specified
P..............0.03.................0.035 (max)
S..............0.03.................0.04 (max)
Tensile Strength
(Mpa)........Not specified.......695.0, 25 annealed at 815°C more
Yield Strength
(Mpa)........Not specified.......415.8
Elongation
(%)..........Not specified.......22.2
Reduction
in Area (%).Not specified.......46.4
notice how the H11 does not quantify the Tensile, Yield or Elongation values? its because it is not needed for its intended application. this is not to say that EITHER is better. its only to show you how each alloying element is controlled and what properties are being tailored.
when you get to these levels of performance, either is going to be way stronger than stock.
but like i said before, be making the head studs stronger and almost stretch - proof, now you are going to be stressing the next weakest link in the system. thing is, what is that going to be? the gasket? the head? the threads in the block?
dennis
guys-
i would be very leery of putting in mondo head studs. don;t forget that each component of the system has been carefully value-engineered by Navistar. sure, they may have skimped a bit on the head studs for the sake of manufacturing economy, but consider that they probably designed in a 'fuse' to minimize catastrophic failure too. similarly the installation of those fasteners would also be value engineered.
so being the geek that i am, i looked into the different head stud manuf's.
ARP: i am an engineer with a fundamental knowledge of metallurgy. i sat here reading it and wanting my desk references because it was so poorly worded and presented. i am actually a little offended by their catalog. they have crammed a whole bunch of engineering info into their catalog- its intimidating marketing. there is no need for all that gobledey gook in there. I actually wonder why anyone would manufacturer and market an alternator bolt that is 100x stronger than would seem necessary.
i find it curious that ARP only lists nuts not studs for the 6.0. maybe i am reading their catalog wrong.
reading the A1 Tech's catalog, its a more honest and better presented product. i don;t feel that they are trying to bully me into believing that their products are better and that i HAVE to buy their product.
anyhow, the fundamental difference between the H11 tools steel and the AISI 8247 is what those steels were designed for.
The H11 is a chromium hot work tool steel. the AISI is a high carbon steel. remember that these steel designations are 50-100 years old and their original intended uses are long gone. the tool steel in its nature is going to maintain its toughness at high temperatures and stresses, maintaining a sharp cutting edge. that is not to say it would work well as a stud.
the AISI steel is a general purpose high carbon steel with many different applications.
.................H11................AISI8740
Element......Weight %.........Weight %
C..............0.33-0.43.........0.38-0.43
Mn............0.20-0.50.........0.75-1.00
Si.............0.80-1.20.........0.15-0.30
Cr.............4.75-5.50.........0.40-0.60
Ni.............0.3..................0.40-0.70
Mo............1.10-1.60.........0.20-0.30
V..............0.30-0.60.........Not specified
Cu............0.25.................Not specified
P..............0.03.................0.035 (max)
S..............0.03.................0.04 (max)
Tensile Strength
(Mpa)........Not specified.......695.0, 25 annealed at 815°C more
Yield Strength
(Mpa)........Not specified.......415.8
Elongation
(%)..........Not specified.......22.2
Reduction
in Area (%).Not specified.......46.4
notice how the H11 does not quantify the Tensile, Yield or Elongation values? its because it is not needed for its intended application. this is not to say that EITHER is better. its only to show you how each alloying element is controlled and what properties are being tailored.
when you get to these levels of performance, either is going to be way stronger than stock.
but like i said before, be making the head studs stronger and almost stretch - proof, now you are going to be stressing the next weakest link in the system. thing is, what is that going to be? the gasket? the head? the threads in the block?
dennis