Do I Need Head Bolt Upgrade?

[sweetr33]

hey, ive just spoken to the guy who built my engine and he tells me that running over 400hp i will need to drill out original head stud hole in block and increase size from standard 10mm to 12mm....i have an ARP 10mm headstud kit already in it but apparently its no better than stock cos the setup isnt a torque to yeild design, what are your views??? i WONT pull it apart and do this as u need to strip engine down to bare block and get holes drilled by vertical mill(from what im told) so i'd rather get a different engine made but was going to order my 35/40, splitfire coils and ebc tomorrow but wont till i know that he's just scaring me............ i got o-ringed block with an o-ring recess in the head and 1.6mm copper gasket and arp headstud kit...please let me know if you've heard the same???

[Spoolup]

Well mine makes 480rwhp with the 10mm studs, and will make alot more.

He's just scaring you or doesnt know any better.

[sweetr33]

ok, he built a 33 afew years back that made 490hp at treads n had head lifting off block issues...

[R31Nismoid]

Depends how much boost he was running, probably quite a bit to have the head lift off.

Or on the Nitrous possibly.

Gotta look at surrounding circumstances aswell sometimes

[Spoolup]

indeed.

There are plenty of big power cars getting around with std head bolts, let alone ARP studs. Look at all the SOHC RB30's making spastic power. I think he's getting head gasket issues confused with lifting head issues.

Like Nismoid said - unless he was running super low comp with massive boost previously.

[sweetr33]

indeed.

There are plenty of big power cars getting around with std head bolts, let alone ARP studs. Look at all the SOHC RB30's making spastic power. I think he's getting head gasket issues confused with lifting head issues.

Like Nismoid said - unless he was running super low comp with massive boost previously.

ok, thats kinda relieving......the last thing i want is to pop a head gasket again... wat a bastard.. guess i'll just see how it goes, been running for about a 1000k since last gasket was changed so might retention it maybe to be safe..........

[Guilt-Toy]

when i built my engine i just ordered brand new head studs from nissan (standard ones) and chucked the old ones out. I got 487rwhp. One of the guys in melbourne i talked to when buying some VL turbo go fast bits for my mates car said that anything around 33psi of boost and then you will lift the head on the standard setup.

[proengines]

Standard 25 or 30 head bolts are 11mm. You shouldn't have a problem at that size but I'd check the length of the bolts against each other and replace them if there is more than .5mm or so difference in the underhead length.

[mokompri]

when i built my engine i just ordered brand new head studs from nissan (standard ones) and chucked the old ones out. I got 487rwhp. One of the guys in melbourne i talked to when buying some VL turbo go fast bits for my mates car said that anything around 33psi of boost and then you will lift the head on the standard setup.

33psi ey, interesting... the highest cylinder pressures occur during the combustion stroke which is more related to airflow/power made rather then outright psi.

more power, more bang, higher cylinder pressures. clear cut 33psi sounds like hes experienced it once at that level and believes it applies to all.