New L15 Head Stud Options!

[Austin@Wunderladen Racing]

Hey folks, so we've been talking with a fastener supplier for a few weeks now about offering some head studs for the L15 that fit properly, which would engage all the threads in the block and not require a spacer on the head like is being done with existing ARP based options.

At the moment it is seeming like we have the choice of 3 different grade steels they can be made from. The base grade would hold power similar to the ARP 2000 based options, the middle grade is about 10% stronger than the base grade, and the high grade is about 25% stronger than the middle grade.

We have access to an industrial grade tensile test stand and we've already tested a couple factory head bolts to see how strong they are. They exceeded our expectations which was awesome to see but they are weaker than all 3 grades mentioned above (according to the numbers the supplier gave us). When we have some studs in hand we will test them as well and share our findings with graphs and a thorough break down of where things stand.

But in the mean time, we are looking to gauge interest because to start it won't be feasible for us to offer all 3 grades (although if demand is high enough that may be possible in the future) so we want to start off offering whatever is desired most by the community. So what are your guys' thoughts and desires for head studs??

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[ValkenDnB]

I've seen people with ARP headstuds still lift their heads with e blended tunes. I would say high to prevent it from happening more. If it really is 25% stronger than the ARP headstuds there will be people that will pay. a premium for that extra reassurance of their head never lifting or having way less of a chance of lifting. As it is, the L15 headstuds are thin compared to stock type r headstuds. We're talking thumb diameter to pinky finger diameter when you put them side by side. Pretty excited to see these come out and get tested by people with ethanol blends.

 

[Austin@Wunderladen Racing]

I've seen people with ARP headstuds still lift their heads with e blended tunes. I would say high to prevent it from happening more. If it really is 25% stronger than the ARP headstuds there will be people that will pay. a premium for that extra reassurance of their head never lifting or having way less of a chance of lifting. As it is, the L15 headstuds are thin compared to stock type r headstuds. We're talking thumb diameter to pinky finger diameter when you put them side by side. Pretty excited to see these come out and get tested by people with ethanol blends.

Thanks for this feedback! I wasn't aware that people were having failures with the ARP options.

For what it's worth, based on what we found with our tensile strength tests, the base grade (same as ARP) would only be a 10-15% improvement in strength over stock, but that's just theoretical numbers. We won't know for sure until we can get our hands on some studs to test.

 

[ValkenDnB]

Thanks for this feedback! I wasn't aware that people were having failures with the ARP options.

For what it's worth, based on what we found with our tensile strength tests, the base grade (same as ARP) would only be a 10-15% improvement in strength over stock, but that's just theoretical numbers. We won't know for sure until we can get our hands on some studs to test.

They just released arp headstuds that are finally the exact size and thread that the L15 yesterday. So no more stacked washers or anything, maybe that might fix the issue with headlift once and for all.

 

[tacthecat]

Other than cost of material (10%, 25%, x10)? what are the drawbacks to going "big"? What are projected final cost adjustments - +10%, +50%?

 

[bbeem]

What steels are you considering. Did you see the details on the new arp2000 head studs tsp is offering? I'm currently running arp 8740 busa studs with 440c spacers holding up great. The two sets of factory head bolts obviously didn't hold.

https://www.civicx.com/forum/threads/arp-head-studs.62694/post-1135538

 

[Austin@Wunderladen Racing]

Other than cost of material (10%, 25%, x10)? what are the drawbacks to going "big"? What are projected final cost adjustments - +10%, +50%?

We haven't talked numbers yet other than our minimum buy in cost, which is not small, hence why we are curious to see if the interest in such a product is worth it for us to pursue it.

What steels are you considering. Did you see the details on the new arp2000 head studs tsp is offering? I'm currently running arp 8740 busa studs with 440c spacers holding up great. The two sets of factory head bolts obviously didn't hold.

https://www.civicx.com/forum/threads/arp-head-studs.62694/post-1135538

The 3 grades are similar to alloys that ARP offers. The base is 8740 based like ARP 2000. middle grade is a low alloy steel similar to L19 and the high grade is a custom age tool steel comparable in strength to CA625+.

I saw the TSP studs earlier today, I'm happy to see someone else has stepped up to the plate! I've talked with my partners a fair bit about studs and based on the poll results here it is seeming more like we will be offering the middle or high grade to start. Price will be higher than the TSP kit, these higher end alloys aren't as easy to produce which makes them more costly.

 

[tacthecat]

Thanks.
How close to the yield strength of the block or head will the new materials be (could over-torquing damage either)? Other than the L19 corrosion issues, are there other precautions that the end-user should be aware of?

 

[bbeem]

Thanks.
How close to the yield strength of the block or head will the new materials be (could over-torquing damage either)? Other than the L19 corrosion issues, are there other precautions that the end-user should be aware of?

Over tightening could definitely warp the aluminum head. The factory head bolts are 60lbs. The ARP head studs spec 70lbs with their arp lube. I went 75lbs. I wouldn't go above that personally. I also went up in torque quite a few sequences. After I hit all ten to 70lbs I went to 75lbs in proper sequence.

 

[Austin@Wunderladen Racing]

Thanks.
How close to the yield strength of the block or head will the new materials be (could over-torquing damage either)? Other than the L19 corrosion issues, are there other precautions that the end-user should be aware of?

Generally speaking, you won't yield the threads in a block by torqueing nuts on the other end of a stud. It's been a couple weeks since I measured the dimensions but I recall the block having something around 6D thread length (the diameter of the fastener multiplied 6 times), in most cases anything above 4D in aluminum won't have issues. With high grade tool steels like CA625+ the torque specs get close to 100ft-lbs and the resulting clamp load can cause the nut and washer to sink into the head which results in a loss of clamping force, but as long as the force is distributed over a larger enough area that's not an issue. We'll for sure be using as large of a washer as we can fit with either mid or high grade studs.

Great question about L19 and corrosion! I've yet to ask them particulars about the mid grade alloy's properties. L19 and a few similar alloys are known to be susceptible to stress corrosion, where basically any amount of corrosion on the fastener will result in a stress riser and eventually a crack will form and grow until there is a failure. While it is possible, those cases are very rare. As long as those alloys are kept oiled and out of moist environments it's not an issue. I doubt they'll tell us alloying metal amounts but they should be willing to disclose if it is susceptible to this or not. Custom age tool steels do not have this concern so it wouldn't be a worry with the high grade.

Over tightening could definitely warp the aluminum head. The factory head bolts are 60lbs. The ARP head studs spec 70lbs with their arp lube. I went 75lbs. I wouldn't go above that personally. I also went up in torque quite a few sequences. After I hit all ten to 70lbs I went to 75lbs in proper sequence.

There's no concern with warping the head with a stronger fastener but following the proper torque sequence is paramount with any studs. Doing them in graduated steps and in the correct order can have a large impact on how evenly the clamping force is applied to the fire rings in the head gasket.

 

[bbeem]

Having a stronger fastener is always a good idea. At 70ft lbs or a little higher you're still not at the studs limits. A stronger stud just ensures it won't stretch. I would be more concerned with dimpeling or warping or cracking the aluminum head, not stretching the stud. Honestly all these options should be strong enough. My 8740s have held.

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