bigbri: the only thing that causes that is excessive cooling system pressure. Either overheating, boiling, or cylinder pressure leakage (headgaskets).

 

Thanks bro...looks like I have some work to do....

 

Yes it can definitely be boiling, but if that's the case, it will suck the coolant back in, since the pressure will fall teremendously asfter the temp goes down from 230 degrees down to room temp. But if there is a leak, then that pressure differential is relieved simply by sucking the air in from the combustion chamber (through the leaking gasket).

Oil analysis can rule IN a headgasket failure with essentially 100% certainty, while ruling it out might be tougher in this early stage.

 

your heads are lifting - this is a common problem with the stock head gasket and stock size studs.

The only solution that I heard people having good results with is going with 1/2" head studs. I'm building my block up right now with a set and will probably be using a Cometic head gasket - although I've heard that once you use the 1/2" studs, the stock head gasket works too... The other big question is how much do you torque them down...

This solution requires mods to the block and your heads...

 

you are correct if the gasket was actually failing. the prob is cylinder pressures get so high, they push some of the combustion out into the water jacket. right after that it seals back up and no probs. normal driving it would be fine cause cylinder pressures are relatively low, and not making it into the water jacket.
the trick is going to be to strengthen the cylinder tops and creating a solid deck, increase clamping force, and possibly a solid gasket, as the stock one is multi layer creating many paths between the layers.
heres a pic to show what i mean. look at the bolt layout. the center bolts are pulling double duty. this type of problem and the deck design makes it so the water would never make it to an oil passage to be present in the oil. (well unless you had some serious issues, lol)

 

the torque specs should be the same as arp recommends for any 1/2" bolt

 

What are the torque specs on the stock size ARP bolts?" 78?

 

sorry, i don't remember exactly what it is right now. one cycle of 17lbs, second to 35lbs, then last cycle of a 90degree turn on them all. think thats close to it. i tested what the final torque average was though, and mid 70's sounds close. don't qoute me on any of this, the only thing i am sure of is the torque procedure.

 

Wow this sucks. I never run above 7.5 psi of boost and my coolant shoots out of the small hole on the lid. I have spray on my hood and on the intake pipe that connects to the TB. If you guys find the answer let me know, because this is what is holding off the build.

 

This doesn't mean the heads are lifting or the head gasket is runined..when you drive hard consistantly the coolant can move around and splash out also...So if you car isn't overheating you should be fine...

 

what about the 1/2" ARP studs sold by nizpro. I take it you gotta mod the block & heads to accept the larger studs, but they boast no need to tear down the valvetrain for re-torque (kinda sounds like it would pay for itself when it came time to verify/retorque). Wonder how much work that would be to just get the 1/2" studs to fit.

 

unfortuneately, my machinist is on vacation till tomorrow so i was unable to meet with him today. i just got off the phone with team performance motorsport though. they said they made it too 900hp on the motor before they would literally blow the radiator cap off the radiator, like 5 times or something. but they had already upgraded to 1/2" head studs by that point.
they would not answer how they are keeping the pro car together though, which they said has now crested to 1900hp now !!!!!
i think my first plan is to recheck the torque on the head studs and see if that helps it at my power level.

 

So does it seem like 1/2 head studs would fix this problem, since i plan on running around 16-18psi I am worried about this issue, especially the way i drive and im in so cal. Keep us posted. Thanks Scott!

-George

 

I am starting my buildup very soon so this is of concern to me since I want to get this done right the first time. Would sleeving the block and getting 1/2 bolts take car of this problem more than likely?

 

Is anyone offering off the shelf 1/2 studs?
and could we start like a file on the lift issue , like

what headgasket?
studs?
compression?
sleeves?
boost?
exhaust?
Hp?
rev limit?
retorqued? yes or no
cams?

on the cars that have had the problem?

 

They will have to be machined in the block and ARP has alot of studs in 1/2 inch.

 

performance told me they have always had good luck with the factory head gaskets. but it seems to me if they actually blew the cap off the radiator, there was a problem way before that point. they said at first they just used a stronger spring in the cap, but that sounds like a band aid for the actual problem.
i am first going to try and retorque the original arp head studs. if i still get it, then machine out for o-rings and a single layer copper head gasket. if it still happens, upgrade to 1/2" studs plus the previous. if it still is a problem, then all of the above plus some serious cylinder reiforcements will be made.

 

i have only seen the 1/2 kit for the vq35 sold in one place. it is $1020, or $1600 for the top of the line bolt (like best of the best type stuff) on performance motorsports site. this is before machining work. now i have to suspect there to be a cheaper way of doing this, but maybe performance had the studs custom made by arp making the cost sore through the roof. i will investigate more.
since you will have to be cutting the threads in the block, the lower and upper thread pitch or spacing would not matter, only height will be the difference. which could bring alot more possibilities to light.

 

I have the carbon flakes in my breather tank and had the same theory of the heads lifting. I spill coolant out of the hose coming from the breather tank at high boost levels. Gurgen had a post that talked about the ARP studs actually tearing up the headgasket.

Can anyone with sleeves, high boost (over 14psi) and at least 3K miles on the motor verify they are not having issues? I think the sleeves are holding only due to the increased surface area for the headgasket to bond to. If we could find a way to create a tight bond without sleeves, I think this would be a good alternative for alot of us.

I do not think the larger ARP studs are going to help. I think the cooling channels are creating the issue, not the studs. Just an opinion though.

 

we need someone with a blown head to cough it up and do a cut away with it to see how the coolant passages are in the heads to look for possible weak spots. i do'nt remember if they are identifiable by looking at the bottom of the head.