What is academic is suggesting they are somehow unsuitable. Steel and aluminum are susceptible to the effects of corrosion too.

OEMs have researched this sufficiently to use them with confidence in pricey engines over the better part of 20 years, some of which carry impressive (e.g. 100k mile) warranties. The proof their research is accurate is self-evident (no statistical pattern of failure, no apparent recalls or production changes).

 

Yeah... How much research for the automotive companies is done is schools vs. in their labs. The companies pay for it, but students are much cheaper then researchers.

Comparing corrosion resistance of titanium to that of steel, I think we both know is laughable.

Doesn't mater though, we are on the same page about if the rods are coated, they like would not have issues.

Again though, who's going to put $2500 rods in their econobox racer?

 

So to dumb it down for me, the coatings are whats preventing embrittlement issues as well as the actual alloy in use?

 

Most likely.

Good info you posted up and is VERY relevant to using titanium in just about anything.

Titanium is a great material, but it comes with its fair share of downfalls (not just cost).

 

Not primarily. The coating is mainly to prevent galling of dissimilar metals (mainly friction or deformation induced). I would presume that the amount of Hydrogen present inside an internal combustion engine to be negligible as far as design constraints are concerned.

 

Please shoot me in the face if I stray to far here. I think it might have been Ted B (don't quote me) that mentioned something about lighter weight, blah blah blah and rotating mass, blah blah blah, creating less load and therefore wasn't beneficial for a F.I. car? I think the initial statement was based on lighter weight drive shafts. ... Would the Ti rods fall into this category?

 

Lighter rotating parts are always better for acceleration.

Less energy absorbed by the part, more to the ground.

Not the case for driveability though.

 

It is unless one is dealing with a hydrogen fuel cell. I don't think a combustion engine crankcase is regarded as a 'hydrogen charged environment'. And not to mention, those conditions also affect steel, but that doesn't seem to be a problem. Ti aluminide turbine wheels employ a different alloy to retard the occurrence of that phenomenon, but there is a big difference in temp between a turbine wheel and connecting rod. And of course, with a tough CrN coating, it should be a non-issue for the rods regardless. The largest drawback for the rods is simply the price tag.

IF I said that, it wasn't taken in quite context I intended. The greater load placed upon the engine, the greater the exhaust gas heat, and the quicker the turbo is spooled. Whether that is beneficial, or not, depends upon a variety of factors.

 

Cool beans, thanks for the clarification. Back on Topic...

 

That last part being the key, and toward the top of the list of concern for anyone wanting to build a daily driver...

03whitegsr,

I'm the kind of "idiot" that might use Ti rods in a daily driver (Evo). It's a matter of balance though. In the grand scale of things, the Ti rods might "off set" the weight of another component that I may want to use in the complete drivetrain. Having your cake and eating it too sometimes requires unusual, or unorthodox methods where the ends justify the means. How does it go? Fast, Reliable, Cheap... pick two. Well, I've always been a "bang for the buck" guy. Not going to be able to do that with what I want to do next... Fast, utterly reliable daily driver. I'm searching for the right combo, and I think "right" set of Ti rods may get me back where I want to be. Drivability, yet still less rotational mass... we'll see.

With the alloy used, and the coating to boot, I really don't see anything other than cost being a downside over steel. However, we've yet to be proven right or wrong in my opinion.

 

Agreed.

I think each surviving original Acura NSX makes a statement for the case that perceived drawbacks are minimal to non existent in actuality.

 

I agree that I don't "believe" there would be a problem, yet are we sure of what alloys where used in these other applications? Was it not the Z06 that you were referring to the 6AL-4V, or was that an aftermarket company? There are always pros and cons to any alloy used. I'm just not sure who's using what. 6AL-4V is the most common Ti alloy to my knowledge... by a far piece. Which would also make it the ringer for most rod makers to use. Kinda like the Stainless used in almost ALL 3" aftermarket exhausts... but I digress. Just cause it's what is the most common, and most used, does not make it what everyone is using (yet more likely). Guess a phone call to the companies might shed some light on that.

Sorry for the circles... my mind is doing warp 9 with this and the other 12 things I got going. For anyone confused on the alloy in question, here is a breakdown that I found with a quick search for those who don't know what we are talking about with 6AL-4V.

http://cartech.ides.com/datasheet.aspx?i=101&E=269

Because it is the most common Ti alloy, there is of course buttloads of info out there with god and everyone's opinion on it... so take some of what you find with a grain of salt.

 

I didn't run into God's opinion (where did you find that?), but the 6AL4V alloy is so common because it is apparently an all-purpose standard for many different applications. The fact that it also works well for connecting rods is a good thing, as that keeps the price down. AFAIK, that is the only alloy I know of used for connecting rods. Using another alloy would almost certainly be even more expensive.

 

LOL! We have been on the same page... I've just not looked into whether anyone's using anything else... because someone always is in some limited application or another. I was drilling holes in this alloy back when it was pretty much only an aerospace material (RB211 & V2500 lines). As we said before, can't see why it would not fit the bill.

I got into this thread because if someone is making them, someone usually needed/ordered/used them. Therefore creating a market for them (however small). So I'm interested in those people's experiences. Where ever they are, and if ever they will even talk about it.

 

Haha, I'm kind of a sick individual, you're talking to the wrong person.

On my daily driver, that sees 15-20k a year...

Quarter Master Clutch
No B-shafts
-300 pounds of AC, sound deadening, airbags, factory carpet, etc. (if it's non essential, it's not on the car)
12kg/mm coil overs
ported head, intake, turbo, blah blah blah
AMS moustache bar eliminator
Shep rear diff (tighter lock up)
Lightweight driveshaft

I literally hate my car for all but the 5 seconds of joy I get from freeway on ramps or unobstructed corners... Scaring the **** out of my wife with a 2nd gear power slide is always fun too.

And those 5 seconds make it all worth it to me.