Hey guys!

With the Ecotec project I'm doing https://www.fiero.nl/forum/F.../HTML/045570-13.html I need to get flywheel bolts that are longer than stock, but here's the thing. I found a place that has the size I need in grade 10 steel, BUT I also found a place that has the size I need in titanium.

To make a long story short, my whole bottom end is about shedding weight to increase throttle response, and considering titanium is lighter than aluminum, but almost as strong as steel, is it worth it, and would they hold up well enough? All told, with what's been added, and taken away, the crank/flywheel setup is 15 lbs lighter than stock. Should I even bother with the extra pound I could shed by going with titanium bolts?

I figure also, if I'm getting flywheel to crankshaft bolts that are titanium, I may as well get flywheel to pressure plate bolts that are as well.

What sprung this idea was the guys who do titanium lug nuts and lug studs on their wheel hubs. The idea came to mind "Hey, I could shed even more rotating mass at the crank!"

Tell me what you guys think. I dub this as a forum poll.

Grade 10 Steel or Titanium?

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Petty Officer Michael C Casaceli
Aircraft Electronics Technician Second Class
Patrol Squadron Ten
United States Navy

Hey, I say go for titanium. Much like you, when I start my Ecotec 2.0 SC swap, one of my main goals is to reduce rotating mass and every little bit helps.
By the way, I'd like to say that I've been reading your build thread with great interest. You've answered MANY questions that I've had about Ecotec's in Fiero's so for that, thank you! Looking forward to its completion!

Cesar.

I use a private supplier for my bolts and they offer alot of things in "bitanium" which is a alum/titanium alloy. they are great bolts and are holding most of my swap projects together.

First off, the steel metrics you're referring to are likely 10.9 grade, not 10. Stay with those and forget the fancy stuff. You need to know much more about the ti fasteners before just getting some and putting them on. I'll guarantee you would not notice any difference anyway. You'll have to do much more. The weight you're eliminating is close to the center, it won't change moment of inertia enough. Going to a lighter flywheel is better. Some people who make aftermarket ones pay attention to trimming the weight off the outside as much as possible. A light chromemoly one is the safest to recommend. Skip the ti bolts. Loosing a flywheel is like having a buzzsaw come thru the firewall.

quote Originally posted by MikeW: First off, the steel metrics you're referring to are likely 10.9 grade, not 10. Stay with those and forget the fancy stuff. You need to know much more about the ti fasteners before just getting some and putting them on. I'll guarantee you would not notice any difference anyway. You'll have to do much more. The weight you're eliminating is close to the center, it won't change moment of inertia enough. Going to a lighter flywheel is better. Some people who make aftermarket ones pay attention to trimming the weight off the outside as much as possible. A light chromemoly one is the safest to recommend. Skip the ti bolts. Loosing a flywheel is like having a buzzsaw come thru the firewall.

agreed.

Titanium is as strong as steel how? Tensile strength? Shear? Have you seen commercial titanium flywheel bolts?

quote Originally posted by ryan.hess: Titanium is as strong as steel how? Tensile strength? Shear? Have you seen commercial titanium flywheel bolts?

I didn't say it was as strong as steel. I said it was ALMOST as strong. It's available up to grade 9 as far as I know.

And yes Mike, I know it's 10.9 grade bolts, not 10. I just like to keep things simple for small forum threads like this and go by "Grade 8, grade 5, grade 10".

You have a point with the fact that because the weight is in the middle, it won't make a difference. I already have a lightweight flywheel, and I took 6 lbs off the crank, but I wanted to see if I could squeeze out another pound or two effectively.

But I guess not. Oh well. Steel it is.

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Petty Officer Michael C Casaceli
Aircraft Electronics Technician Second Class
Patrol Squadron Ten
United States Navy

[This message has been edited by fieroturbo (edited 05-10-2007).]

Okay, I do not know much about metullargy, Heck, i do not even know how to pronounce "Billet" properly...

But, you guys are talking about shaving off a couple of pounds by swapping out the flywheel bolts???

I currently have a set of flywheel bolts sitting around, from the Fiero 2.8. These are the stock, so i presume steel, bolts. All 6 of them weigh a combined total of 3.5 ounces, per my postal scale.


Or am I completely missing something???

quote Originally posted by KlingonFiero: Okay, I do not know much about metullargy, Heck, i do not even know how to pronounce "Billet" properly... But, you guys are talking about shaving off a couple of pounds by swapping out the flywheel bolts??? I currently have a set of flywheel bolts sitting around, from the Fiero 2.8. These are the stock, so i presume steel, bolts. All 6 of them weigh a combined total of 3.5 ounces, per my postal scale. Or am I completely missing something???

I was talking about both the flywheel to crank, and flywheel to pressure plate bolts combined. The ones I need are more than twice as long as you have.

the pressure plate to flywheel ones would be worth it as you are farther out there, but going to a tripple disc clutch would work much better. Its not how much weight you lose, its how far the weight is from the moment of the crank.

I would not bother for the amount of weight you save. I'd rather know that the flywheel is going to stay securely in place. Also titanium is not lighter than aluminum.

Wow, according to wikipedia... we're all wrong:
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Physical Characteristics

A metallic element, titanium is recognized for its high strength-to-weight ratio.[6] It is a light, strong metal with low density that, when pure, is quite ductile (especially in an oxygen-free environment),[18] lustrous, and metallic-white in color. The relatively high melting point (over 1,649 °C or 3,000 °F) makes it useful as a refractory metal.

Commercial (99.2% pure) grades of titanium have ultimate tensile strengths of about 63,000 psi, equal to that of steels alloys, but are 45% lighter.[5] Titanium is 60% heavier than aluminium, but more than twice as strong[5] as the most commonly used 6061-T6 aluminium alloy. Certain titanium alloys (e.g., Beta C) achieve tensile strengths of over 200,000 psi (1.4 GPa). [19] However, titanium loses strength when heated above 430 °C (800 °F)[5]

It is fairly hard (although by no means as hard as some grades of heat-treated steel) and can be tricky to machine due to the fact that it will gall if sharp tools and proper cooling methods are not used. Like those made from steel, titanium structures have a fatigue limit which guarantees longevity in some applications.[20]

I know for a fact that the bolts I have are a variation of a aluminum alloy, and I would imagine that they are not any different that what somone would advertise as an aluminum bolt.

I suppose the biggest question would be if something is technicly 100% pure titanium.

you didn't mention, are the titanium bolts rated 10.9? that rating has nothing to do with material, only the hardness. if they do not meet that spec then the answer is a simple no. you also have to consider other things like coefficient of expansion, if they barely expand compared to steel, you may pop them when things get hot, or worse, pull the threads on the crank.
the thicker the materials are, the more important expansion becomes too.

if you can get the correct hardness, the pressure plate bolts would be a more acceptable and usefull place.
you;re only talking ounces even at the crank end, and since I really don;t think you want to see what happens to a car without a scatter shield on the flywheel looks like if the flywheel comes off, I think you are better off with the proper rated steel crank bolts

"titanium is lighter than aluminum" ? Not-! At least, an item of titanium, weighs about 60% more than its identical aluminum counterpart. Still surprises me how often people casually say "of course, titanium is stronger than steel, and lighter than aluminum." I don't bother to correct them anymore.

I s'pose you could say things like this... but only if we're talking different volumes. You could also say "bricks are lighter than feathers" - assuming we're comparing five pounds of bricks, versus a ton of feathers!

I have to agree with those who recommend staying with steel fasteners. Best to stick with what you know works. It costs less, and you won't reduce the rotational inertia an appreciable amount by switching to titanium bolts. The flywheel + pressure plate assembly are likely the biggest contributors.

But-! If it turns you on to be able to say you've got titanium flywheel bolts, well, whatever turns your crank. Or, flywheel

[This message has been edited by StuGood (edited 05-11-2007).]

I suggest those who think that there are ti bolts with 10.9 markings, look a little harder. It can be alloyed to give a very high tensile strength. But it's apples and oranges. It won't meet 10.9 specs in every regard. It likely would have it's own markings. It would have a different surface hardness, different core hardness, different modulus and and everthing else. You can get tensile strength that is very high. But there's more to it. I personally would only buy from an aerospace fastener manufacturer but learn more first. There's a lot of ti fasteners being made in ti, but there's different grades and alloys. Then the heat treating needs to be understood. Even the threads and the radius under the head is significant. Use the ti bolts somewhere less critical than a flywheel, unless you know what you're doing. It's a wonderful but expensive metal. My friend has ti brake rotors for a Formula Atlantic. And a 3 1/2 lb. ti flywheel. And a Tilton carbon/carbon clutch. He used steel ARP flywheel bolts, if that tells you anything. He has a degree in metalurgy and welding science. We talk about metal once a week. He has money for exotic stuff, we still consider the application and reject things constantly to go with heavier metals to do the job safely. Again, you won't notice the weight savings wherever the bolts are on the flywheel. I have a Lotus exige that I track. It gets shifted at 8500. I went to a Toda lightweight flywheel. I weighed the pressure plate, disc and was very concerned. I dropped maybe 3 lbs. I really couldn't tell any difference. My speed at the end of a long straight was the same. My wallet felt amazing lighter however.

Considering the risk and reward. What's happens if a flywheel comes loose at high rpm vs a gain that will be hard to detect.

I raced bicycles back in the 80's when all the carbon fiber, titanium and weight stuff was first starting to come in. The adage was "steel is real".

[This message has been edited by sanderson (edited 05-11-2007).]