TwinTurbo.NET: Nissan 300ZX forum - One last time
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Subject One last time
Posted by Kyle(Houston) on September 15, 2017 at 10:47 PM
  This message has been viewed 46 times.
In Reply To Re: Re: Re: Re: Re: Lets set a few things straight posted by Scott ZShack Taylor on September 15, 2017 at 04:02 PM
Message :Sigh, You are clearly having some reading comprehension issues.
:I have too many water logged Z's to fix and engines to build to keep explaining the same thing again and again.
:I am going to explain it one last time for you without all the stupid copy and pasting.

Nope. I can read and comprehend just fine.

:I am not some noob Z guy. I have been doing this for 20 years too. I just can't stand this pages format so I stick to FB.

Ahhhh. Sorry since you didn't know the kits that have been sold for the last 18-19 years were ARP8740 kits, I assumed you were new on the scene. The actual arp2000 kit has only been available for less than 4 years and your post on your website was just from this year. So I assume you installed the 8740 kits before 2014 and just didn't realize it??

:Here are my replies
:I am well aware of the thread pitch. Apparently you think I don't know what I am talking about and that you know more than I.

I actually don't claim to know more then anyone else. I learn new things everyday

I do not need correcting on this subject. You are clearly not comprehending what I said in several instances!
:The pitch of 1.75mm is the block end. that means every one turn of the stud counterclockwise will raise the stud 1.75mm out of the block. Thus raising the threads at the top of the stud. The nut height is the same because the head didn't move. This is where the available threads get reduced. Again not something I would expect a shop to do, but those fellow z guys/gals, our customers in which you refer to as "idiots", have done or may do!

Gotcha. I was assuming the installer would seat the stud properly. I mean if someone backed a stud out 1.75-2mm out of the block then threads would be exposed. I honestly didn't think even the most inexperienced mechanic wouldn't notice that.

So if we assume that the studs are seated properly into the block, then no worries about running out of threads. I think I more than proved that with my pictures and measurements.

:I did not forget the headgasket at all. I purposely did not include it just to see if you were actually reading what I write and following the math. Glad you caught it. Just goes to show that you are only interested in nitpicking my post and not actually trying to understand it!

No I actually like a good debate. It helps not only myself but you also plus anyone else that reads this thread. Everyone learns and it makes people prove their points.

I have completely understood everything you have posted. I just don't agree with some of it. Hence the debate.

:As for the write up and tq specs go. I never said I personally go to 120. You may want to reread it. I said that since many big power guys are taking L19 to 120, then there is no reason why the 2000's can't go to that as well. 120 is less then both fasteners yield point. (but way higher than 8740)

Here is where I start to have major problems. You act like ARP2000's are the same as L19's and can be torqued as high.

Here are the facts:

ARP8740 = 200,000 psi = recommended torque = 90 ft/lbs

ARP2000 = 220,000 psi = recommended torque = 100 ft/lbs

ARP L19 = 260,000 psi = recommended torque = 120 ft/lbs

The yield points are:

ARP8740 = 112.50 ft/lbs

ARP2000 = 125 ft/lbs

ARP L19 = 150 ft/lbs

If you do the math that is 25% more than the recommended torque which is what ARP rates all their studs at.

Which is straight from ARP's website: "Recommended torque is equal to 75% of the fastener's yield strength"

On your own website you are telling people it is OK to torque the ARP2000 bolts to less than 5% of their total yield point(120 ft/lbs vs total yield at 125 ft/lbs). IMHO you should put a disclaimer on your site so the general mechanic without a calibrated torque wrench doesn't put the ARP2000 bolts at their total yield on accident.

:I know you think I am contradicting myself but I am not. There is a difference between what a bolt can handle and what the blocks threads can handle. BOTH are figured into the final TQ recommendations by ARP.

I agree 110%. That is why I have a problem with you saying the ARP2000 can be torqued to 120 ft/lbs on your site. Whether you do it or not. It is out in the public

In the case of the 8740's, according to ARP's engineer, the fastener itself is compromised at 83FtLbs. ARP2k and L19 are not.

OK..I will be perfectly honest here. I talked to ARP engineers years ago about the proper torque on the 12mm studs used in the 300zx ARP8740 kits, They said back then that 90 ft/lbs was the recommended torque(75% of the total yield of the studs).

On top of that, it was Mike Smith @ Jim Wolf Technology that actually used a stretch gauge to determine the correct torque for the ARP8740 studs. You can see it as a FAQ here:

LaZy Link

Also since you insisted, I called ARP today and gave them the part numbers for the studs for the 300zx ARP8740 kit. I was a great call and we talked for a good 45 minutes. He told me that the 12mm ARP Studs that we use for the 300zx kit can be torqued to 90 ft/lbs and that is what ARP recommends(75% of total yield). He was also good enough to tell me I can use this instruction sheet from the Mitsubishi since the studs are almost identical and the instruction sheet is general. I thought that was pretty cool.

Instruction sheet: LaZy Link

They can go higher than what ARP's engineer recommends the block can handle. It is why they say to TQ 2k's to only 100FtLbs and not the full 125 that they can handle! Sure there is a margin of safety there. how much? IDK.

Correct. ARP recommends 75% of total yield for their recommended torque values. That gives a ~20% margin of error in case someone is using a harbor freight "precision" tool. The ARP will be at full yield at 125 ft/lbs and would be junk at that point

I am sure their reasoning for this takes into consideration that block castings can be different. We have seen this in other areas of the block like coolant flash and cylinder wall thickness etc

Not necessarily. They set the torque values depending on the total yield point for the stud. I am sure they reduce it some for aluminum blocks but I have not seen any issues with the iron blocks

:What I was saying is that if these OTHER guys are taking L19 to 120, then you can take 2k to the same level. That is all. For that matter you can take 8740 there too if you want to disregard the yield point. The limiting issue then becomes if the block threads will handle it and will the head handle it etc. (But that is a whole other discussion)

Well the L19 studs at 260,000 psi do have a total yield point of 150 ft/lbs. So 120 ft/lbs is right at 75% of total yield.

ARP set the ARP2000 studs to have a recommended torque level of 100 ft/lbs because their total yield is 125 ft/lbs.

I have torqued down many L19 studs to 120 ft/lbs without any problems. So I don't know exactly what the yield point is of the 300zx block threads. Maybe that is something that will need to be tested before going to 625+ studs.

:As far as you saying the 8740 will go to 112 FtLbs? That directly contradicts what the engineer says they can go too. He was very adamant about that. And NO you have not provided any evidence from ARP that 8740 studs in the VG are recommended to 112Ft-Lbs!

I called ARP directly today and talked to an engineer who looked up the part numbers for the 300zx ARP8740 kit and he said 90 ft/lbs. Plus the fact that Mike Smith @ Jim Wolf technology did an actual stretch test years ago and stated that 90 ft/lbs was the correct torque for the studs.

Anyone who reads this can call ARP directly and ask what the proper torque level is for these two part numbers

AU4.900-1LUB <--- Short stud
AU5.400-1LUB <--- Long stud

I was quoted directly that both are good for 90 ft/lbs at 75% of total yield.

I personally torque them to 100-105 ft/lbs(~9% from yield) with a calibrated torque wrench but that is just me. I recommend sticking to the recommended 90 ft/lbs for the ARP8740 kit and 100 ft/lbs for the ARP2000 kit.

:So lets recap.
:As far as the studs metallurgy is concerned, You can take both 2k and L19 to 125.

Well if you torque the ARP2000 to 125 ft/lbs, you have basically torqued them to yield and made them paper weights.

The L19's could do 125 ft/lbs but it is recommended to torque them to 120 ft/lbs

This doesn't mean you should or that I am recommending it. If guys want to do so, they do so understanding the inherent risk involved. But that is what we do when we are pushing the envelope. Right? Lol

Well 125 is be too much for the ARP2000, but good to hear you do not recommend it

:Just like if they want to use L19, they assume the risk!

No risk in torquing them to 120-125 ft/lbs but I guess you think they have a risk of failure even though none have been reported in 10+ years of use.

With that said: The ARP engineer did say today that they do prefer 625+ head studs over the L19 but they also have not seen any problems with them as of yet

:As a shop owner, I will never recommend using a product against the manufacturers recommended use or specs unless a customer wants it done and paperwork is signed stating so. It would be foolish to do such a thing from a business perspective!

110% Agreed

:You are free to disagree with me on this. You can continue to do it your way and I will do it my way. Doesn't hurt me a bit.
:A simple phone call with your studs part number will net you an actual TQ value for the 8740. But you won't likely do it because you don't want to be wrong. That's human nature. lol
:Best of luck
: :-)

I have people that have done the actual stretch test on them(Mike Smith @ Jim Wolf), I personally called years ago and also confirmed today, and I recommend anyone with questions to call and confirm for themselves also.

Kyle "Grumpy Bear" Puckett
Import Parts Pro
Phone: 281-288-0700
AIM: KyleatIPP
Yahoo: KyleatIPP

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