George D

We are adding a cam sensor if you think it's worthwhile. I don't want issues like the last run of damage. We are getting close to tuning the TEC, and I want your help. PM me if you like so this doesn't go OT.

Thanks Chris,

George

Chris White

If you did not stretch a fastener there would not be any clamping force! So even raceware studs have to stretch….just not very much!

There are 3 types of fastener stretch –
Elastic (the fastener returns to original length when relaxed) – this is how the stock studs work.
“Torque to yield” – the fastener is stretch to the point of yield (this is not breaking but a permanent stretch) – This is actually a common type of fastener for head studs or bolts with other manufactures.
And just plain failure….

Chris White

Give me a call on Monday...315-636-8716

Van

Glad you got it figured out!

333pg333

Well you win the prize Van.

Still, I wonder if we're dealing with a symptom rather than a cause. Changing to the ARPs may solve or may mask the basis of issue? Not sure. In some ways making the problem go away isn't the finish of the issue even though it's probably the bottom line. Finding the root source of the problem is almost as important.

George & Chris, I don't mind if you talk about TEC 3 stuff on my thread either. I'm not sensitive to O.T. and am guilty of it enough so don't mind me. Essentially as it pertains somewhat to the issue, I see relevance.

333pg333

We run a 2nd or reserve tank off the main expansion one George. So we see the fluid moving rapidly across to the 2nd tank and when it cools, it returns to the primary one. Last year when we had the h/g blow at the same track it was worse than in the photos that Sean has posted above. So the 2nd tank actually leaked coolant all down the side of the car and onto the rear LHS tyres. I couldn't figure out why my Hoosier A6s were skating around like a shopping trolley. I still drove that car home, so it says a lot for these Cometics.

As for detonation in your previous build, how did you track that if you didn't have the TEC3 all sussed out? Did you have obvious signs in the combustion chamber of that particular cylinder?

Van

I've been thinking about this - of course the purpose of an o-ring is to concentrate the clamping force in a specific area to withstand higher cylinder pressures. However, to do this job is also means that a certain part of the head gasket will bear more load - and it will be more likely to wear out.

I've seen that on my copper head gasket - the o-ring spot is where a little blow-by eventually developed.

evil 944t

IMHO, only half of this statement is true and even thats is not accurate statement. I don't know what you consider "high" boost or heavy detonation but, we have experienced "blow by" in applications over 550-600rwhp (roughly 22-23psi boost with 16v and 8v heads) with ZERO detonation (Knock is verified with digital knock sensing devices with full timing retard control).

The reason why I call it "blow by" and not "head lift" is because the leak is happening in the distance between the headstuds and not at or close to the headstuds.

The main problem I found with our block/head clamping is that there is not enough support around each cylinder. This has been proven with a special torque sensing material that is place between the head and block. It is torqued and then disassembled. Once disassembled, you read the material and it tells you where and how the head is clamped.

IMHO, aftermarket non stretch headstuds are good but not really needed. They are great if you want to reuse them for frequent inspections to the HG but again not needed for increased boost/performance. Both the stock and aftermarket studs require roughly the same torque values but to be honest, I havent fully tested stock studs much past 400rwhp.

The only way to increase even clamping forces is to close the gap between the studs. You can do this by adding larger diameter studs(not a huge help but better than nothing) or even better, adding more studs.

When changing headstuds, I would go larger to remove the old threads and get a better "bite" into fresh material. I would also consider different thread pitches to ensure proper torque values.(there is a lot to this)

Anyhow, thats my 2c.

George D

Patrck,

We saw signs of detonation. Beginning of some burn on the gasket. I thought the previous tuner had the TEC3 tuned properly. I never heard any detonation. We caught it early. The only reason I had the Nicom cylinders honed was because I only had 3K on the damn motor, and wanted it to be like new. The cylinder was ok, just not perfect.

We are at the end of getting things sorted and back together.

Tom M'Guinn

How do you work the pressures? Does the first tank blow into the second only after exceeding the original tank's pressure limit of 1.5bar? Either way, how does the fluid from the second tank get back into the original tank (since there is usually pressure in the original tank)? Just curious, thanks.

333pg333

It's just physics Tom....but don't ask me to explain them. What I mean by this is that I've seen it many times at the track when the coolant 'leaves' the primary tank and goes into the secondary one. After some time it returns back to the primary one. There must be a change of temp to produce a vacuum perhaps? I'm not sure. I guess it's something simple that I'm overlooking at this moment. It's 6.20am and no coffee yet.

Tom M'Guinn

So the coolant goes out and comes back in the original tank through the factory overflow hose?

333pg333

In regards to the discussion of headstuds and what's best, well firstly this motor is stock and the car is hopefully an interim one to get me through this season. I don't want to have to pull the motor and put in extra or larger studs, O rings, or deckplates. Not because they aren't improvements but because I shouldn't have to. We've put in some Raceware studs which probably won't be much different to using some new OEM ones, but perhaps the old OEM ones had seen better days? I just hope that this headgasket will last more than a few race meetings and perhaps I have to keep the boost below 1.5 to achieve that. Fingers crossed.

333pg333

Yes. Without making it sound more technical than it is, we put a 1.25 litre drink bottle into the front guard and use it for exactly that purpose. Seems to work pretty well. Last season when the h/g failed (but worse than the pics in this thread), the coolant went into the 2nd tank and popped the lid, hence spilling down the LH side of the car and onto the rear tyres. Not fun on a very cold day at the track!

fast951

Patrick, are you using a 951 head with the ceramic liners or a 944NA head?