[Z06] Ti Connecting Rod problems?
04-07-2005, 08:45 AM
#1
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Ti Connecting Rod problems?
I read on another forum that the Z06 Ti rods might be having problems. It wasn't a Corvette forum, I run a Ti rod in my drag ATV and the manufacturing world for Ti rods is fairly small. After we heard that rumor, my motor builder is even more concerned about how much nitrous I want to throw at my Ti rod. Anyone else heard that rumor or have more details?
04-07-2005, 09:40 AM
#2
Burning Brakes
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Just surfing for Ti Rods:
...So where do titanium rods really shine? In any all-out racing effort where an approximate 15-percent reduction in ultimate tensile strength is an acceptable trade-off for an approximate 20-percent reduction in connecting rod weight. As for ultimate power capacity, know that they’re used in everything from 9,000-rpm NASCAR motors to a handful of 6,000hp Top Fuel motors (though most teams use aluminum). With the right communication between you and the manufacturer, they’ll handle anything you can throw at ’em. Just be sure not to scratch them! Titanium is very “notch sensitive.” Small surface imperfections caused by rough handling must be polished immediately, or they can grow quickly.
...Tit rods are streetable, but VERY pricey, and MUST be handled with kid gloves, TIT. is very prone to scuffing, and scratches or anything that blemishes the surface is lethal for them, you have to be REAL careful when installing/handling them.
...I've done more research and apparently they don't come into their own till they hit 7,000 RPM. They are found in engines like those in the NSX for this exact reason, since the NSX is often revved to 10,000+ RPM. They also have very long lives when they are properly hardened, often exceeding that of the steel ones.
...I've heard before that Ti rods transfer all the crap and abuse the pistons see right to the bearings and subsequently require frequent bearing replacement, though I'm unsure if this is a fact.(I think this is BS)
(Galling, think of this as mechanical welding.My words)
...The downside of titanium is that it is very prone to galling. Galling is, in simple terms, a cold welding event. Once two parts have galled, disassembly is difficult or impossible. Galling can be prevented by control of the surface roughness of the threads, use of correct lubricants, and the selection of a gall-resistant alloy.
Bottom line, 1)if you watch your engine being built and a guy drops a rod on the floor, bang on the glass and hold up a sign that reads "I don't want no stinking scratched rods in my motor" 2) Try to keep a little oil in the engine to prevent galling.
...So where do titanium rods really shine? In any all-out racing effort where an approximate 15-percent reduction in ultimate tensile strength is an acceptable trade-off for an approximate 20-percent reduction in connecting rod weight. As for ultimate power capacity, know that they’re used in everything from 9,000-rpm NASCAR motors to a handful of 6,000hp Top Fuel motors (though most teams use aluminum). With the right communication between you and the manufacturer, they’ll handle anything you can throw at ’em. Just be sure not to scratch them! Titanium is very “notch sensitive.” Small surface imperfections caused by rough handling must be polished immediately, or they can grow quickly.
...Tit rods are streetable, but VERY pricey, and MUST be handled with kid gloves, TIT. is very prone to scuffing, and scratches or anything that blemishes the surface is lethal for them, you have to be REAL careful when installing/handling them.
...I've done more research and apparently they don't come into their own till they hit 7,000 RPM. They are found in engines like those in the NSX for this exact reason, since the NSX is often revved to 10,000+ RPM. They also have very long lives when they are properly hardened, often exceeding that of the steel ones.
...I've heard before that Ti rods transfer all the crap and abuse the pistons see right to the bearings and subsequently require frequent bearing replacement, though I'm unsure if this is a fact.(I think this is BS)
(Galling, think of this as mechanical welding.My words)
...The downside of titanium is that it is very prone to galling. Galling is, in simple terms, a cold welding event. Once two parts have galled, disassembly is difficult or impossible. Galling can be prevented by control of the surface roughness of the threads, use of correct lubricants, and the selection of a gall-resistant alloy.
Bottom line, 1)if you watch your engine being built and a guy drops a rod on the floor, bang on the glass and hold up a sign that reads "I don't want no stinking scratched rods in my motor" 2) Try to keep a little oil in the engine to prevent galling.
Last edited by Patrick McDaniel; 04-07-2005 at 09:47 AM.
04-07-2005, 11:17 AM
#3
Le Mans Master
Just adding to the Ti rod thread::
There has been a minor issue with Ti rods in the Ferrari 360 challenge cars. It was traced back to the surface near the big-end bearings. Aparently there was not enough oil flow between the two rods on the common crankshaft journal and some galling occured at some high RPMs*. The fix was to machine three tiny oil relief groves in the sides of the rods (and then polish up the machining marks.)
[*] don't remember the RPM that this occured at (I suspect near red line (8500) )
I don't buy the story about Ti rods transfering any more force to the crank journals than any other steel rod. If anything, the fact that you are sacrificing ultimate strength for lightness would lead you to believe that the Ti rod would transfer less of the piston crap to the journals. My opinion.
There has been a minor issue with Ti rods in the Ferrari 360 challenge cars. It was traced back to the surface near the big-end bearings. Aparently there was not enough oil flow between the two rods on the common crankshaft journal and some galling occured at some high RPMs*. The fix was to machine three tiny oil relief groves in the sides of the rods (and then polish up the machining marks.)
[*] don't remember the RPM that this occured at (I suspect near red line (8500) )
I don't buy the story about Ti rods transfering any more force to the crank journals than any other steel rod. If anything, the fact that you are sacrificing ultimate strength for lightness would lead you to believe that the Ti rod would transfer less of the piston crap to the journals. My opinion.
04-07-2005, 12:36 PM
#4
Originally Posted by MitchAlsup
Just adding to the Ti rod thread::
I don't buy the story about Ti rods transfering any more force to the crank journals than any other steel rod. If anything, the fact that you are sacrificing ultimate strength for lightness would lead you to believe that the Ti rod would transfer less of the piston crap to the journals. My opinion.
I don't buy the story about Ti rods transfering any more force to the crank journals than any other steel rod. If anything, the fact that you are sacrificing ultimate strength for lightness would lead you to believe that the Ti rod would transfer less of the piston crap to the journals. My opinion.
one of the selling points on titainum hand guns is the reduced recoil.
04-07-2005, 02:04 PM
#5
Safety Car
Originally Posted by OWENMUSTANG
one of the selling points on titainum hand guns is the reduced recoil.
04-07-2005, 02:14 PM
#6
Get Some!
Originally Posted by bernrex
Explain to me how a lighter gun could have Less Recoil? ... given all else is equal ... ie. same muzzle porting of barrel, etc.
Ti rods weight less so forces on the crank and wrist pin will be less.
Back to recoil, there is real and felt, and some heavy pistols will feel like they have more because of momentum, I guess? I guess on some pistols having less mass accelerated by the recoil would make it feel like less recoil? Of course if the weapon is big enough like a .50 auto it will absorb most of the recoil with the internal bolt and springs.
04-07-2005, 02:42 PM
#7
Le Mans Master
Originally Posted by bernrex
Explain to me how a lighter gun could have Less Recoil? ... given all else is equal ... ie. same muzzle porting of barrel, etc.
The Ti rod is less stiff longitudinally than the steel rod, so that when the mixture combusts, the rod itslef is compressed a couple thousandths of an inch where the steel rod is only compressed a single thousandths of an inch. Thus the Ti rod acts more like a spring (here) than the steel rod.
With reasonable rod design, this springiness is all in the longitudinal direction and results in no bending of the rod.
{I could be dead wrong here}
04-07-2005, 02:52 PM
#8
Safety Car
Originally Posted by CPT Z06
I'm not a physicist, but I don't buy this either, the lighter .50 sniper rifles have to have a very good muzzle brake, because they are lighter; even if they are semi-auto and have a sliding bolt to absorb some force.
Ti rods weight less so forces on the crank and wrist pin will be less.
Back to recoil, there is real and felt, and some heavy pistols will feel like they have more because of momentum, I guess? I guess on some pistols having less mass accelerated by the recoil would make it feel like less recoil? Of course if the weapon is big enough like a .50 auto it will absorb most of the recoil with the internal bolt and springs.
Ti rods weight less so forces on the crank and wrist pin will be less.
Back to recoil, there is real and felt, and some heavy pistols will feel like they have more because of momentum, I guess? I guess on some pistols having less mass accelerated by the recoil would make it feel like less recoil? Of course if the weapon is big enough like a .50 auto it will absorb most of the recoil with the internal bolt and springs.
04-07-2005, 09:03 PM
#10
Drifting
Consevation Of Momentum 101
Originally Posted by bernrex
The formula ( Force = Mass X Acceleration ) should apply. If a pistol has a lighter Mass (from Titanium parts ? ), the Kick or Recoil (Acceleration) against the hands would be higher/stronger ...... for a given pistol load (Force) exiting the muzzle. Since, for every Force generated there is an equal and opposite Force present.
Light guns punish you more and heavy guns don't.
This subject has NOTHING TO DO WITH TI RODS!!!!!
BTW I am a licenced gun dealer/gunsmith and I consultant to firearms mfg, nra firearms instructor and a licenced proffesional engineer (M.E.)
The benifit of the TI rod is reduced bearing loads,Higher rpm limits due to reduced load and some dynamic compression ratio and stroke increase due to greater rod stretch/compression BUT THAT IS VERY SLIGHT. There could also be some very slight reduction in peak load during peak pressure in the combustion process.
Surface treatments and coatings can eliminate gauling problems.
TI rods are good , don't worry be happy...LOL
04-07-2005, 10:05 PM
#11
Race Director
Originally Posted by Patrick McDaniel
Just surfing for Ti Rods:
...I've done more research and apparently they don't come into their own till they hit 7,000 RPM. They are found in engines like those in the NSX for this exact reason, since the NSX is often revved to 10,000+ RPM. They also have very long lives when they are properly hardened, often exceeding that of the steel ones.
.
...I've done more research and apparently they don't come into their own till they hit 7,000 RPM. They are found in engines like those in the NSX for this exact reason, since the NSX is often revved to 10,000+ RPM. They also have very long lives when they are properly hardened, often exceeding that of the steel ones.
.
My logic goes something like this {reminder: this is only my opinion}
The Ti rod is less stiff longitudinally than the steel rod, so that when the mixture combusts, the rod itslef is compressed a couple thousandths of an inch where the steel rod is only compressed a single thousandths of an inch. Thus the Ti rod acts more like a spring (here) than the steel rod.
With reasonable rod design, this springiness is all in the longitudinal direction and results in no bending of the rod.
{I could be dead wrong here}
The Ti rod is less stiff longitudinally than the steel rod, so that when the mixture combusts, the rod itslef is compressed a couple thousandths of an inch where the steel rod is only compressed a single thousandths of an inch. Thus the Ti rod acts more like a spring (here) than the steel rod.
With reasonable rod design, this springiness is all in the longitudinal direction and results in no bending of the rod.
{I could be dead wrong here}
04-07-2005, 11:45 PM
#12
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The Ti rod in my Raptor is physically larger than the Chrome Moly alternatives. It weighs 100+ grams less than Chrome Moly. The rod has been cryo treated and friction coated. My ATV motor is 727 cc with a single 105mm piston and often sees 10K rpm.
I wasn't so much questioning the benefit of the Ti rod, just wondering if GM was having trouble with them in the Z06.
For the other thread buried in this one, the next pistol I buy will be a Taurus 7 shot Ti .357
I wasn't so much questioning the benefit of the Ti rod, just wondering if GM was having trouble with them in the Z06.
For the other thread buried in this one, the next pistol I buy will be a Taurus 7 shot Ti .357
04-08-2005, 09:27 AM
#13
Safety Car
Originally Posted by UBETRUN
For the other thread buried in this one, the next pistol I buy will be a Taurus 7 shot Ti .357
A nice piece ... once had a Raging Bull big bore 48 ... some SOB stole it out of my Vette's lowered window. I had to use the Vette to run him down and rub him out.
04-08-2005, 10:55 AM
#14
Le Mans Master
Originally Posted by rgregory
Saving rotation mass helps accelerations at any RPM.
That is, the accelerations are the same with high mass and low mass, but the forces associated are less with low mas components.
see my ex wife I throw up
04-08-2005, 12:08 PM
#16
Race Director
Originally Posted by MitchAlsup
I think you mean:: Saving rotation mass helps reduce the forces associated with acceleration at any RPM.
That is, the accelerations are the same with high mass and low mass, but the forces associated are less with low mas components.
That is, the accelerations are the same with high mass and low mass, but the forces associated are less with low mas components.
04-08-2005, 12:29 PM
#17
Originally Posted by UBETRUN
The Ti rod in my Raptor is physically larger than the Chrome Moly alternatives. It weighs 100+ grams less than Chrome Moly. The rod has been cryo treated and friction coated. My ATV motor is 727 cc with a single 105mm piston and often sees 10K rpm.
I wasn't so much questioning the benefit of the Ti rod, just wondering if GM was having trouble with them in the Z06.
For the other thread buried in this one, the next pistol I buy will be a Taurus 7 shot Ti .357
I wasn't so much questioning the benefit of the Ti rod, just wondering if GM was having trouble with them in the Z06.
For the other thread buried in this one, the next pistol I buy will be a Taurus 7 shot Ti .357
mine is the 4inch tracker. nice gun btw!
04-08-2005, 01:01 PM
#18
Le Mans Master
Originally Posted by rgregory
I was trying to convey that there are more advantages to the lighter rods besides what had been stated. I should have been clearer, I was speaking in terms of lightening any moving parts in an engine which allows the engine to rev faster. Which in turn provides more acceleration for the car given the same HP.
04-08-2005, 01:41 PM
#19
Burning Brakes
