Engloid

You can get two flat planes bolted together flat with 5ft-lbs. We torque most bolts to achieve two other things:

1) Flatten the gasket to the point is seals correctly around the cylinders (and elsewhere).

2) Achieve proper stretch of the bolt. Stretch is of utmost importance. If you stretch it too far, it can exceed its maximum yield strength and it will not go back to the same length. This reduces its tensile strength. If you don't stretch it enough, the stresses of combustion can cause "head lift" and/or stretch the bolt over and over, eventually causing a fatigue failure.

I think what happens in a lot of cases is that a person has a failure and blames something that really isn't the cause. If a shop doesn't properly torque the head studs, and they fatigue and break, they're going to say you should have bought better studs. They aren't going to tell you they don't have or didn't use a torque wrench.


ARP essentially said that the L19 is overkill, not necessary, but appeals to the people that want the best, even when the best isn't necessary. I have to believe they are the manufacturers and the experts on how their bolts/studs perform, how strong they are, yield strength, proper torque specs, etc.

thatv35guy

iTrader: (1)

No, no, no, L19's are not overkill on turbo VQ's, that is completely false. Enough people in the VQ community have had issues (head lift) with ARP 2000's that they shouldn't even be considered for a VQ making anything north of 500whp. I lifted my heads around 550-600whp on ARP 2000 head studs.

Ask Dynosty for their input, they've built more high horsepower VQ's than anyone.

Also, how much whp where you able to make on your car with ARP 2000 head studs?

Engloid

I made 425tq and 439hp at the wheels on oem head and rod bolts. As we know, rods are the weakest link. You really think the standard arp is only good for 100hp or less over oem?

thatv35guy

iTrader: (1)

Its been proven, ARP 2000 head studs just don't hold up on this application. It's just a matter of time before they fail and you suffer head lift. L19's are a must. I'd actually run Juke head bolts over ARP 2000's too.

35reilly

True I meant bore. Lol. I was doing multiple things in my phone when I said that. Hehehe

ThatZGuy

Alright so after doing some research, talking with my mechanic and a few others i know exactly what im getting for my build. Also you do want to use a torque plate when boring and honing your block it provides a better seal to give you proper gains and safety. As for the build im getting Darton cylinder sleeve kit, Eagle Rods, Wiseco Pistons, ACL Race Bearing kit, APR Main Bolts, APR L19 STud Bolts, HKS Gasket Kit, Rev-up Oil Pump, Timing Chain. On top of the Stage 3 Southbend CLutch & FLywheel combo im getting with a SS-X Extream Clutch Disk(800HP) With the turbo Kit im putting in 600CC Fule Injectors and Walbro 255 Fuel pump. Trying to decide if i wanna go 1 step farther and just get JWT OR BC Cams and some Heavy Duty valve springs or just save that for next summer Which i may have to do because ive already got about 9k going into this car this winter.

Engloid

The total cross-sectional area of the 8 head studs is .8836". The bolts we are referring to, I'm not sure are considered the "2000" series. They're part number 202-4701. They have a tensile strength of 200,000psi.

I have rounded some of these here, but made a crud spreadsheet that carried out several decimals. This is looking at one head (8 studs, 3 cylinders).

A little quick math says that the 8 bolts would hold 176,715 total pounds (NOT psi). The three cylinders have 33sq-in of total area on the head.
If combustion pressure was 400psi, that's 13,323total pounds of tensile pull on the head bolts that will hold the above 176,714 pounds of tensile stress.

Long story short, we would have to reach a pressure of 5100 psi in the combustion chambers to reach the limits of these 8 head studs.

Correct me if you see a mistake or I've overlooked something, but based on this, it appears the these studs are far above what is actually needed.

NOTE...in the spreadsheet, it rounded the stud cross section down to zero. It's actually .110477 sq in per stud. This is measured at the smaller neck section, not the threads. I fixed this rounding of this section and others, and will post below.

Engloid

see attachment

35reilly

Sleeves?? For what??? You only want to hit the 5s no need for sleeves!!!!!

ThatZGuy

What do you mean i only want to hit 5s? And why shouldn't i get sleeves it makes it safer to push it beyond its limits. If anybody else thinks i dont need sleeves let me know. I was 50/50 on it but its almost like a safety precaution im putting this much money into the car why not make sure its stronger. I Mean i plan to build it up more and add more power after these installs next year.

35reilly

No need buddy!! Plus you know the cost to do the work for that??? No need for them at all. There guys pushing 700 plus and no sleeves

35reilly

I was mid 6s no sleeves and no problems. I should be in the 7s now and not running sleeves

thatv35guy

iTrader: (1)

Yeah, sleeves are completely unnecessary and are only going to add another potential point of failure to the engine... and for one last time, ARP 2000's will not hold anywhere near 600whp on a VQ. If you're keen on throwing your money away, go for it.

ThatZGuy

I'm getting the L19 Head studs and APR main studs package. Ok so I will not sleeve the VQ but I am boring and honing it with a torque plate.

Resmarted

iTrader: (2)

Torque to yeild is vastly inferior to stud design. Then on the next level arp2000's have failed countless times.

Resmarted

iTrader: (2)

Right because shops that successfully pioneered this platform and engine, that have run their engines to over 1000whp safely, successfully, and with as much reliability as possible, have been too incompetent to correctly torque down heads.

Tool steel is overkill for most applications. But on the vq engine it is not. I believe I have heard similar instances for other engines, simply requiring stronger "overkill" head studs.

l19's are a great alternative to 1/2" which would also suffice, because they don't require modification.

Sound Performance, is one of the best shops in the country, they have told me personally about head lift issues etc because of headstud choice. Dynosty same thing (I don't know if they had them). Both of these shops held records consecutively for quickest and fastest 350z's, and both have run the most power I know of on an oem block, non oringed vq. At least on this side of the pond.

I'm glad you read the instruction manual on how to properly torque spec. But you're on your own believing arp2000's are a good solution.

Resmarted

iTrader: (2)

Yeah. Head lift is a *****.

Considering the l19's are roughly $200 more, you'd be a dumbass not to run them.

midz350

iTrader: (4)

If I can go back in time, I would get a built short block from Sound Performance or Dynosty even if it meant extra or even double the cost. The only shops I would trust with a VQ.


That's coming from a guy who bought/built 4 VQ engines before.

Resmarted

iTrader: (2)

Except over time several members running 500whp range (sub 600whp) have lifted heads on arp2000's.

The numbers are only a simulation, in a perfect world. The real world results speak for themselves.

If you wan to run the 2000's for sub 500whp that's fine. In that 500whp range it's a gamble. I would just use the l19's regardless. No reason not to. You aren't going to hurt anything by buying stronger head studs.