To ARP or not to ARP

fmorelli

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Alright so looking for some feedback.

For my ported N54 head, I have a Cometic head gasket and of course a new set of factory head bolts. I'm looking at a 20psi or so motor on ethanol, maybe 600whp ish ... can I just run the Cometic with factory head bolts? Or do I need to call up Tony @ VAC and get his ARP stud kit? I understand one needs to Time-sert the block for this install - one more thing I'm not really interested in dealing with, especially with the motor in the car.

Unless there is a fairly good argument in my context, I'd like to run new factory head bolts. Thanks for your thoughts in advance!
 

JohnDaviz

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Jan 6, 2019
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I head the same thought process. Going for a Cutring Head Gasket and chose the ARP std Studs because the bolts are the weak point ultimately.
My car was running about german 600-620 horses and my head lifted.
I also bet my ass that you won´t get scientific relevant data from probably everyone but just personal opinion.

I had a few emails with Calvin from VAC and he said that i most likely will not need Studs up to 700hp ore even a bit more.
He also said that i will be fine with the standard studs which contain the 9mm studs. So no modification on the engine needed.
 
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pysical

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Jun 16, 2017
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Why do you need to time sert the block?

I have a OEM headgasket with the 11m studs on my built motor which hits 36psi on a 6466 and no issues. No time sert.
 

SLOWESTN54

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Why do you need to time sert the block?

I have a OEM headgasket with the 11m studs on my built motor which hits 36psi on a 6466 and no issues. No time sert.
What was the process for going to 9mm studs to 11mm studs?
 

fmorelli

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pysical

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"Aluminum Block Engines Use Raceware Head Stud Kits and must be time-serted for proper installation. Inquire about our Time-Sert kit or our in house proprietary time-serting service."

(from https://store.vacmotorsports.com/arp-performance-head-stud-kit-bmw-n54-p4972.aspx)
Hmm sounds like a VAC gimmick. Not sure why their ARP head studs would be any different than ADE or anyone else who sells/sold them. I have only read like 2 people ever using time serts in the n54 but a lot more with arp studs.
 

Torgus

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I vote the 11mm arp studs. Pain in the ass to do or to bring it somewhere but people have lifted the head at 600whp before or so I have read.

But plenty of people use the stock studs and are fine. Really your call on the hassle/expense/time.

You should just buy a block and have it built. It's just money! You can always make more ;)
 

Torgus

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It's this kind of logic that got me in the mess I'm in.

Every time I look at my spare head I think just send it to vac and have stage 4 done. But then I should get cams...~5500 later is what keeps me back...and knowing I really then need to build the block.

If my wife knew the money I put into this thing for how little I drive it I think she would murder me.

Also, Fuck Covid and for me having almost no reason to drive.
 
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fmorelli

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Every time I look at my spare head I think just send it to vac and have stage 4 done. But then I should get cams...~5500 later is what keeps me back...and knowing I really then need to build the block.

If my wife knew the money I put into this thing for how little I drive it I think she would murder me.

Also, Fuck Covid and for me having almost no reason to drive.
Last "black friday" VAC ran a deal on the CNC work. Pony up.
 
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fmorelli

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I vote the 11mm arp studs. Pain in the ass to do or to bring it somewhere but people have lifted the head at 600whp before or so I have read.

But plenty of people use the stock studs and are fine. Really your call on the hassle/expense/time.

You should just buy a block and have it built. It's just money! You can always make more ;)

I have a block down at Barry's that I could use but that's just really pointless given where I'm headed. My bottom end should be fine, so long as it is not idiot tuned.

Ok that said ... not sure I read your "pain in the ass to do" comment right. Is it a pain in the ass? Anything special about installing the ARP head stud kit?
 

RuskiRacer

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Standard size thread right in
IMG_20211020_231451_982.jpg
 

doublespaces

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Wait, I thought there was a lot of hoopla about the studs not being threaded deep enough or something?
 

RuskiRacer

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Yeah not sure what the big hoopla is. Same engagement as stock headbolts would be. 9mm are slightly shorter just as the stock 9mm headbolts are
 

pysical

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Someone, I can't remember, was selling some Chrysler studs that were to short and pulling threads. A few people (VAC, ADE, BMB, etc) have the correct studs which have longer threads.
 
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Jern54

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Oct 18, 2019
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You need at least 35mm thread on the studs (block side).
The Chrystler studs only have 20 ish mm thread and is a no-go.
For my ported head project I have ordered 11 + 9 mm ARP studs at VAC which have the correct thread length.

Going Full M11 is overkill for my application (+/-700 on Hydra HP800 turbo's)
 
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