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Head Stud Torque, Pushing Coolant @ 600Hp

James_03

By James_03,
in Engines & Forced Induction

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James_03 Mentor

James_03

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Hey Guys,

Quick run down, rb26/30 built engine running e85. Currently running rb25det ARP head studs (202-4301). Recently made 624hp@all 4 at 26psi, but then started pushing coolant on the dyno.

Engine is running a factory nissan rb26 head gasket with rb25det ARP 202-4301 head studs. Now I am going to attempt to re-torque the head down before I pull it off again to go a MLS gasket. Currently the ARP rb25 (202-4301) recommended 108nm or 80ft/lbs of torque. The rb26dett ARP head bolts recommended 105ft/lbs.

Realistically I should have re-drilled the block and gone 26 ARP head studs with a MLS gasket, but I did the wrong thing and shortcut it which I admit.

What do people think of going 90ft/lbs on the 25 studs? Or should I just go to the recommended 80? I don't know if it's the gasket itself or just lifting the head, I also don't know if I can go a little more torque on the head studs then the recommended or if that's too dangerous to attempt.

Any help would be great.

Cheers.

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Ben C34
Ben C34

Royce is running 760 hp through an unopened neo with arp studs (swapped with head still on, 2nd last page of rb25 dyno results) Maybe PM him for advice?

GTRNUR
GTRNUR

It won't be the gasket that caused the initial leak of combustion gasses into the cooling system. The combination of cylinder pressure and not enough clamping pressure on the head studs will have bee

GTRPSI
GTRPSI

Ripps is running 1300Hp on RB25 studs, they only went to RB26 when chasing 1400hp, no oringing the blocks either. Use the ARP lube or else your torque will be way off and use a multi layer steel Head

nicksamaniac Collaborator

nicksamaniac

Posted
Posted

With lube on the thread you will get higher thread pressures than if it was dry, thread paste (loctite silver grade) will give much higher clamping pressure then oil @ the same torque settings.

Ben C34 Grand Master

Ben C34

Posted
Posted

should have gone MLS head gasket before you put it together. the factory head gasket can only handle so much

Royce is running 760 hp through an unopened neo with arp studs (swapped with head still on, 2nd last page of rb25 dyno results)

Maybe PM him for advice?

  • Like 1
GTRNUR Grand Master

GTRNUR

Posted
Posted

It won't be the gasket that caused the initial leak of combustion gasses into the cooling system. The combination of cylinder pressure and not enough clamping pressure on the head studs will have been the initial issue.

Just be prepared for the possibility that you may have already burnt the seal ring on the head gasket, and it may never seal regardless of how much clamp pressure you manage to crank it down with the ARP's.

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LTHLRB Grand Master

LTHLRB

Posted
Posted

Royce is running 760 hp through an unopened neo with arp studs (swapped with head still on, 2nd last page of rb25 dyno results)

Maybe PM him for advice?

I dont doubt the neo pushing that much for a second. But they only last so long. Id you're building a motor youd be crazy not to go a metal gasket.

Its definitely under torqued.

James_03 Mentor

James_03

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Thanks for the help guys. It was also running a 52mm ebay radiator that the end tanks were all warped on when I took it out, when we felt the front after a few power runs it was barely warm, so could have also contributed. I have replaced it with a Z series 53mm koyo now, and re-torqued the head last night to 130nm. Failing that then I'll probably rip the head off again, re-drill for 26 studs and tomei MLS gasket.

Hopefully I haven't burnt the seal ring as you state GTRNUR. When I checked them after first getting the cams out, they were all 80ft/lb still, and I remember taking my time when I did it and getting it spot on. So I think it is just a case of not enough clamping pressure overall.

Has not had an issue with pushing coolant until this last tune on e85/26psi. Prior to that was running 20psi with toluene mix and never had a problem.

r33_racer Grand Master

r33_racer

Posted
Posted

I have suffered this problem before too. In my experience extra torque wont be enough to stop it from lifting the head again. It is going to keep doing it unless your lucky and the gasket is still ok and you turn the power down back to roughly where it was on the old tune. Somewhere between your old power level and new power level there is too much cylinder pressure for the setup to handle. Otherwise you will just need to bite the bullet and rip head off, fit bigger head studs and MLS gasket and be done with it.

GTRPSI Mentor

GTRPSI

Posted
Posted

Ripps is running 1300Hp on RB25 studs, they only went to RB26 when chasing 1400hp, no oringing the blocks either.

Use the ARP lube or else your torque will be way off and use a multi layer steel Head gasket.

Watch this, may explain to why not to use oil and why to use the right stuff....

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James_03 Mentor

James_03

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Just thought I would report back guys.

Re-torqued the head to 142nm, just used lucas assy lub under the nut surface and on stud thread, installed a koyo 53mm rad with shroud.

Now running fine again, pushed it hard on the weekend and didn't see anything over 70C, coolant levels in the reservoir tank still perfect after topping it up. Still on 26 pound.

Might have got lucky.

Anyway cheers for all the help.

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  • 7 months later...
James_03 Mentor

James_03

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Hey guys,

Thought I would bump this thread as I seem to be in trouble again. Ended up taking the head off as it started to push coolant yet again.

I chucked the 202-4301's in the corner, and went the 202-4309 studs. Replaced with a tomei 1.2mm metal HG. Everything was fine for a while, went to a track day last weekend, got home, and the coolant reservoir had puked a little bit. I noticed as well that it appeared to be breaking down right at the top of limiter (7500). This could also be spark related, but I would bet that it's coolant causing the issue.

So question is, where too from here? I was thinking about re-tapping for L19's. I would like to go back for a re-tune for 30psi, but it's just not possible until I sort out this shit.

Has anyone had any similar experiences and how did you resolve?

How have people re-tapped the block in car? I imagine a drill guide is used like this possibly:

http://www.carbatec.com.au/portable-drill-guide_c21832

I would really love to hear what boost people are running with what studs. It may be possible that I have another issue like warped head/block instead, and I am barking up the wrong tree by going larger studs.

Cheers.

KiwiRS4T Grand Master

KiwiRS4T

Posted
Posted

If Rips can do 1300 hp (boost is irrelevant at this point) on 25 studs then studs (if they are properly torqued down) are probably not your problem. Maybe your gasket is a problem or maybe the head and / or block need to be trued.

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James_03 Mentor

James_03

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It all started when I went to e85, and probably increased cylinder pressures along with it. Was fine at 500awhp when it had the 98/toluene tune. Has never been overheated either and had the head skimmed when I fitted the gasket.

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