stevieturbo

If the fastener is designed to stretch to maintain clamp loads as the metal expands/contracts with heat, then yes it could very well work better than a bolt that does not offer the same behaviour.

ARP's are not designed as stretch bolts in that manner....hence are fully re-usable.

Many OEM head bolts, flywheel bolts etc are not deemed re-usable, so there are clearly differences.

So it isnt static clamp force and one simple moment in time....it's how they behave under stress, heat, etc etc etc and of course cooling.

Forcefed86

iTrader: (4)

I wouldn't think TTY head bolts that have been reused multiple times would retain that same "stretchy clamping force". But the used headbolts seem to put up with the abuse on Denmah's build which was making ALOT more power than I was.

The ARP bolt does stretch, as does any fastener. The fact that it can be reused does not mean it's ridged. If that were the case, the ARP studs would suffer form the same lack of TTY style clamping force, no? Same with the china studs that are so popular these days?

I'm not saying I know, just discussing. Something let go for sure, and at this point I sure can't tell you what it was at this point.

stevieturbo

You're trying to compare totally different fasteners as the same though

TTY bolts are not supposed to be re-used.

A little google that maybe explains some better ? ( And I dont know all about it myself either, I just know that the fasteners are very different )

http://www.enginebuildermag.com/2005...head-bolt-use/

Forcefed86

iTrader: (4)

I’m aware they are supposed to be one time use bolts and appreciate the input. My point is Denmah did reuse stock TTY bolts and made over 1000whp doing so. Not only were they reused, but they are the same head bolts that had been reused multiple times on the same motor making 700-900whp many many times. My rational is if the OEM TTY head bolts that have already been stretched to their yield point many times can keep the heads down without issue, than an ARP bolt *should* be able to do the same job, if not better.

Maybe there’s some magic I’m not familiar with on the stock head bolts that makes them better. But my common sense tells me there isn’t. If a bolt stretches, it is loosening the clamp load placed on the gasket. I can think of no instance where a “stretchy” fastener would be better at keeping a head down. The ability of the gasket to flex/shift as the deck/head deforms is a different story, and can be a good thing.

speedtigger

iTrader: (16)

Fastener stretch is actually part of how they maintain their clamping load in different situations. A head bolt actually works a bit like a spring to hold the head down. If the bolt did not stretch at all, it would lose all of its clamping force with just temperature change. The best engine shops use "stretch" gauges to measure rod bolt stretch when assembling an engine. This is because a certain amount of stretch is ideal for a given fastener to maintain its clamping force.

Forcefed86

iTrader: (4)

That’s my point. The ARP bolt does stretch like any other head fastener. I’d think it would be able to maintain a higher clamping load in that stretch range than the factory bolt as well, making it a better part to use. Which is the whole purpose of running it over a factory bolt.

Tjabo

Matt would slap you right now for citing him as an example and then using ARP bolts!

stevieturbo

But it doesnt, it's made from different materials, different design, it does not behave the same. That's the point

Generally we use studs etc because they're stronger and we can tighten the **** out of things, and ignore any stretch aspect simply be pre-loading everything instead.

it's also like buying aftermarket gaskets because they should be better.....lets face it, few if any are better than the LS9 !

speedtigger

iTrader: (16)

You may have seen this already, but it is worth a read:
http://www.felpro-only.com/blog/prop...e-t-t-y-bolts/

People cite examples all the time of "getting away with" this or that. That is fine, but I not would exactly call that empirical evidence. A CFO that I used to work with had a saying that is both amusing and insightful. When people in the company would argue that they had not followed company procedure in the past and nothing blew up, he would say: "I have never been thrown through the windshield of a car, but I still wear my seatbelt". Always a show stopper.

Forcefed86

iTrader: (4)

The bolts are pretty cheap compared to the studs! I went with the $106 ARP bolts for the re-usability and better quality control over the china studs.

Seems to me like ARP is made from a better material for the job. Was an independent test awhile back where they tested the tensile stretch and failure loads of china studs, OEM bolts, and ARP 2000 studs. It showed that the china stud and OEM bolt were VERY similar and the ARP material was clearly better than both.

So the debate here is whether or not the OEM head bolt with less tensile strength is a better head fastener than the ARP? I know a stud is a better design, but comparing bolt to bolt here I don’t see how anyone could think the OEM bolt is more qualified in a performance application.

stevieturbo

At what level does something become a "performance" application though to warrant a different fastener design ?

None of us here have the ability to do all the testing needed and state which fastener is better or not. But if the OEM bolts work...then they work.

Which is a better material ? and for what job exactly ? Again, I doubt any of us could answer that one.

Head bolts etc are not clamped down to the point of fastener failure, so is that test valid ? Probably not.

Forcefed86

iTrader: (4)

They are talking about "typical bolts" snapping. The ARP fasteners are designed specifically to stretch and use on heads. They are not a typical hardened bolt. I've yet to hear of any ARP hardware snapping due to head expansion. If this were the case the "Pro's" would be using one time use TTY fasteners. Yet none do? I'm still not buying it guys. No stink'n way an OEM bolt is a better part for this application. Obviously they can work... that doesn't make them superior in any way to an ARP.

Forcefed86

iTrader: (4)

But we do know. Tests have been done if you just look around a bit. We are measuring tensile strength and clamping loads. ARP fasteners work better in both applications regardless of the success someone had with a factory bolt.

stevieturbo

Static cold tensile strength is not real world, working, expanding and contracting environment.

speedtigger

iTrader: (16)

I must have missed something in this thread. I am not sure who you are disagreeing with. I thought we were talking about whether it was wise to re-use TTY bolts because somebody "got away with it".

To me one big advantage of the ARP head bolts is that they can be re-used. When customers ask me if they are worth it, I tell them that they start to become worth it the minute you take your engine apart again. Then there is the additional clamping force that they are capable of if you need it.

Forcefed86

iTrader: (4)

Reaching a bit IMO. GM bolt is stretched to its yield point making it one time use. You can do the same with an ARP. But the ARP is only stretched to about 75% of its yield point so that it's reusable. Even at the 75% it’s clamping load is greater.

The examples are out there. Look at the L19, Custom Aged 625, and Aermet head fasteners ARP offers. The difference is in the tensile strength. More the better apparently?

Top fuel guys use the Aermet studs mainly because they are rated to 310,000psi tensile loads. Guys spend the big bucks on the aged stuff that’s rated at 280,000psi.

Pretty easy to see why you’d think the ARP 2000 bolts rated at 220,000psi would be better than a factory bolt. Here are the independent test results I was talking about.






I was simply mentioning that the TTY bolts that have been reused multiple times seem to hold up to big power. So in theory I think an ARP bolt would provide at least as much clamping force and be just as good as a factory bolt if not better.

speedtigger

iTrader: (16)

Somebody shared another LS headbolt test recently on Facebook. I looked for it to share, but did not find it. In their test, used TTY bolts actually had some favorable attributes over the Ebay studs. Where the used TTY bolts did poorly was their bolt to bolt consistently varied substantially more that the ARP or Ebay bolts. In fact, not only were their clamping force consistency all over the place, a couple used TTY bolts broke during the test. Conversely, the new TTY had extremely consistent clamping force.

RedRocketZ28

iTrader: (19)

Here's the screenshots of the thread on Facebook. Makes me worried that I am reusing my China studs on my new engine although I never had an issue with them for the almost 5 years my SBE LQ4 was in my car.

Pro Stock John

iTrader: (34)

How much timing advance do you typically run?

"I have never been thrown through the windshield of a car, but I still wear my seatbelt" that's pretty funny.

Forcefed86

iTrader: (4)

Had the injectors flowed. All within 2% of each other so that wasn’t the problem.

Checked the torqe on the head bolts before pulling and they all seemed to still be at 78 ft lb. Yanked the Pas side head off. #4 was blown huge. Head and deck seemed straight. No idea what/why this let loose. Plugs were oldish so I couldn’t get a great read, but there were no signs of detonation and the heat marks I could see on the strap looked conservative about half way down the strap. 10.8 AFR peaked around 5800 25lbs 13* of timing. This is with E85 7gph of water/meth (washer fluid) and 100* IAT’s.

Cylinder looked like it had a little galling. 90% sure none of the cylinders had any markings when I put the engine together. Rings gapped at 22/24 same as I’ve done on all my LS stuff. Figure I might have knocked the ring land out of that piston. Not sure what else would cause it, unless the ring was just cocked goofy.

Can’t pull the pan on this setup without removing the engine and I wasn’t ready to pull the motor yet. So I copper sprayed a used LS9 gasket and put the head back on. Torqued to 80ftlb. Cranking compression is the same as it was prior, so I threw everything back together. Started right up and seems ok. Cruised around quite a bit. The tune was reading really rich all of a sudden. Dropped a bunch of fuel out and it seems fine. Ordered a new WB02 sensor to be sure. I’ve had the same Bosch 4.2 sensor for 6-7 years now. I think it’s fine, but I want to be sure.