Yeah, yeah, I searched…

So, my motor’s coming back from the machine shop this week, and I need to pickup a set of head bolts for this motor… previously, I was using HR head bolts, car made 466whp, didn’t have a single issue with them.

Now, since I’ve pulled the heads I’ve got to either buy a new set of HR head bolts (TTY), or purchase an aftermarket set… L19’s are on backorder and I was actually interested in H11’s, specifically the pieces sold by Cosworth, or I can get standard ARP or HR’s again… I’m shooting for approximately 525whp… Thanks for your input fellas!

 

i have a bnib set of L19's ill sell to you discounted off retail, bought them for a motor and decided not to use them so theyre sitting in my garage collecting dust

 

I read a thread about your first build. Can I ask what happened and why it was taken the machine shop?

 

It's a personal decision based exclusively on risk/reward. Since you already got away with HR's, I'd be tempted to only go one up for the ARP's or stick with HR's. L19's are just so extremely expensive. I have no doubt in their design, but it's a pile of money... And, so are head failures...
On a controversial side note, you would be shocked at how many times you can re-fasten a TtY bolt before it snaps.

 

The hr studs have proved themselves in the 5xx rwho area IIRC there are a few boosted hrs in the 500 range stock block and just recently a few stock block de's hit the 500rwho mark. Nothing wrong with throwin a few dollars at some arp's tho

 

I snaped 1 while unbolting the head. It had 4k miles on it.

 

not when u can buy a new set for 400!

 

go with L19's. eat out 1 less time per week and they will be paid for.

 

What's this got to do with eating out? If you have a give & take relationship with your gf, I don't think that's worth it! LoL!! Next, you'll be telling him to get fewer foot massages!
SamuelLJackson.jpg

 

how much does a set of HR bolts cost? 100$ or so?

I'd rather spend the extra 300$ and have head bolts that won't need replaced and if you blow your engine you can get money back out of them (worst case scenario).

HR head gaskets I think work great but I prefer studs over any type of bolt when it comes to head fasteners.

 

I think HR are around $60, ARP are around $200 and ARP L19 are over $400.

 

if you buy head and main studs togeather the head studs are much much cheaper. although i dont remember what i paid for mine wasnt quite $400 personally worth it imo considering what we pay for head gaskets might as well spend the extra.

 

how well built is your motor?
if it's done up all fancy then get the l19's
if you're not planning on pushing things save the coin.

it really depends on the build

for less than 600@ the wheels i see nothing wrong with a new set of tty bolts

but once you get close to 600whp i wouldn't run anything other than l19's

 

http://www.motoiq.com/magazine_artic...st-3-days.aspx
this engine uses HR bolts and is beat on all the time and still makes near 600hp with no issues in abudabi and so cal heat!!!

I have yet to see a "properly torqued" HR head bolt failure... seen lots of ARP failures though problem is the ARP bolt is too tough and doesn't allow for core shift (normal operation), and not expanding when the head and block heat up causing cracked heads, cracked blocks, blowed out head gaskets

and by "properly torqued" I mean using the FSM that some engineer gets paid $$$ to engineer, not just coming up with a different easier way to torque it...

 

^ What is the proper FSM method? Because on old VW diesels it was quite a PitA. You had to give it a "final" 1/4 turn and then drive the dam thing for a fair while before getting back in there and giving it ANOTHER HALF TURN!!

 

Arp says to do the same thing. Most head sealing solutions are like that. But nobody really does it from what I know.

I doubt the hr bolts are just going to fail. The heads need to lift for the bolt to fail (or they get over torqued). When you compare the tensile strength of tool steel (l19), especially in stud form, to that of well regular head bolts you start to understand.

Also the torque ratings don't translate between each other. Much of the torque used for bolts gets used up in overcoming the frictional forces of the threads.

The reason people use l19's is because we get to torque them down to 90+ lbs, and they won't stretch.

Thing is, you don't need that torque until you hit a certain level of power...

 

what is that level of power? This is not the first time I have heard this. Basically the stock head bolts stretch and contract with the heads and prevent other failures from occurring right?

I'm wondering because I have to decide when mine goes back together at a level of 600whp what I should run. I want to build for 700 and run 600.

 

TTY bolts are designed to stretch so the extra re-torque after the car has been driven is almost a must for proper function.

ARP on the other hand suggest that only to cover their asses. I've never re-torqued them and never had problems except when GRD ran my car at 14psi of boost 7 pulls in a row with 28* timing on pumpgas. That did my head gasket in due to severe detonation and had nothing to do with head bolts.

Will TTY work fine, ya probably. Sharif did quite a bit of testing with head gaskets and bolts and found that the most crucial component to our head gaskets failing is the bolts. With tty bolts and hks gaskets they were still seeing failure but with the HR gaskets (cheaper gaskets) they were seeing the head gaskets lasting due to the higher clamping force that the ARP allows.

Either way for 500hp you should be ok. I personally like using studs verses a bolt for install despite which one is stronger.

about needing 90ftlbs on the arps. I only torqued mine to 80ftlbs with cometic head gaskets and haven't had an issue at 650hp nor do i expect any issues when i push it further.

 

i don't have it in front of me but it is something like
before you start soak all head bolts in oil... I use ester oil cause it is easy to get
1. 70 lbs-ft
2. loosen to 0 lbs-ft
3. 30 lbs-ft
4. 103* tighten
5. 103* tighten
it is much tighter than 80 lbs-ft...

 

As far as I am aware, all head bolts/studs are designed to stretch. That is how they apply their clamping force. The deal with TtY's is that they stretch so much, that they are beyond the yield zone and have plastically deformed, meaning that they will no longer spring back to their original length.

Fail on my part for that picture being so big... Sorry!
Anyway, any metal can be bent or stretched within the level prior to its yield point and it will spring back to its initial shape every* time. (*Hundreds, thousands or millions/infinitely depending on its resistance to fatigue, which also plays a role, here.)
I believe that the reason TtY's call for additional ___° turns is that it eliminates the gap between torque corresponding imperfectly with clamping force, because really, torque is not a measure of clamping force at all. Like one of you mentioned, a lot of it can be eaten up in thread friction, which ARP does their best to deal with by including their magic lube, but at the end of the day, torque does not directly equal clamping. By saying "+ a 1/4 turn" you can essentially guarantee, based on the known thread pitch, that a certain clamping force and stretch has been applied.
The instructions I have for my regular ARP's (non L19) is "3 equal steps to 85 ft-lbs". There is no mention of extra turns after the final torque or after a certain #miles driven. Maybe the L19's call for additional tightening? I don't know.
On other nerdy thing I'd like to point out on that ludicrously over sized picture is that "tensile strength" is well beyond virtual destruction as far as a head bolt is concerned. It has already yielded (stretched permanently) completely beyond a length that it can perform its function. The line after that point is where it is literally coming apart in catastrophic failure. So, it isn't as valuable an indicator of what you really want in a bolt.