Fel-Pro 9627PT unusual failure - potential causes and limits of the HG

[Jacob5se]

Hey guys,
I believe I experienced quite an unusual failure to my Fel-Pro 9627PT headgasket. Long story short car significantly overboosted (from normal 14.5 psi it was tuned for to 21.5 psi), white smoke came out of exhaust, when slowed down it died and didn't want to start. Towed it home and finally got around to disassembling the engine. All nuts on ARP headstuds were tightened the same, not one was loose. After taking the head off this is what we saw. The cylinder bores on the headgasket are not round, they have become oval-shaped, especially on the intake side. We haven't found any marks of detonation on pistons (Arias 8.8:1 made out of 2618 alloy), there's some small pitting on the head though we don't think it's detonation marks and we're not sure if it was present before when we assembled the engine. Coolant was present in cylinders 2, 3 and 4 (number 4 looks clean because we wiped it while searching for detonation marks, it looked the same as 2 and 3). Any ideas what could cause this type of HG failure? This is first time we see something like this.

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Another question is what would you say is the limitations for 9627PT with regular 7 bolt ARP headstuds? I've read many posts from people running it with way more power than I'll ever be, but I've seen they're commonly used with L19 studs. Are regular ARP headstuds my problem? I plan on running around 22 psi from my TD05H-20G in the future, so there should be plenty of room for this even with regular ARP headstuds right?

 

[Jacob5se]

Forgot to add head pitting photos.

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[bastarddsm]

Have to see the plugs, but I see that when I let it rattle. What fuel, AFR and Timing? Intercooler?

Also check the surface finish and flatness of the cylinder head.

What were you torquing the head studs too? IIRC ARP reccomends some comically low number like 75 for the 6 bolts. I go like 105 on a 6bolt with 12mm studs, and that's good enough with a 9627pt for a 3000+lb car to go 145mph in the 1/4.

Shooting from the hip I'd go like 85 or 90 on your setup, but proceed with caution. Maybe some of the other 7bolt guys have a better idea.

 

[Jacob5se]

This is what plugs look like. Unfortunately I do not remember what I were torquing head studs to. I bought a new set and I've read that people torque them to 85 with ARP lube. ARP recommends 80 for 7 bolt.
I'm on 93 octane, won't tell you my AFR and timing since I'm not the one who tuned the car, though it was tuned by a reputable tuner.

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[We're on Boost]

Sounds like you don't have a way of logging knock - or logging anything for that matter?

Is your engine the same as shown on your Vehicle Specs page? (Except for the head gasket, which is shown as a Cometic in your Specs).

Car looks really nice BTW!

 

[jdxnc]

Too me it looks like not enough clamping force.

You said it was tuned to 14 psi, shot up to 21.5 psi, I'd say there's a good chance that it went a little on the lean side for the fuel, coupled with possibly a little low torque on the studs as Kurt alluded to, the gasket relies on clamping forced and a good flat surface to do the job, as the saying goes, lean is mean. I've pushed that gasket to over 40 psi and it holds up if the conditions are right.

Make sure to use ARP ultra lube on the studs and the underside of the nut, to around 90ft-lbs with the 7 bolt studs, verify the head and deck are clean, dry and oil free when assembling and it should be more than enough on regular ARP's for 30 psi.

 

[jesse12345]

From my personal experience, I had my studs torqued to 80ft lbs. I started getting bubbles in the cooling system and my car was overheating on the highway. I decided to torque to 90ft lbs and cross my fingers, since then the issues have been gone. This was on a 7 bolt. I feel like 75 to 80 ft lbs is to low.

 

[awd4g63turbo]

Don't believe it was a head gasket issue. We run the same head gasket with L19s @ 34psi now, on a 6466. Plan on turning it up a little more before we swap the motor. I believe we were having a issue with regular arps @ 32 psi lifting the head slightly before putting in the L19s.

 

[diambo4life]

How exactly did you install the head? Were the surfaces inspected for straightness?

 

[Jacob5se]

Sounds like you don't have a way of logging knock - or logging anything for that matter?

Yes, unfortunately I don't have any way of doing that. I'm saving up for standalone next year to be able to do that on the fly.

Is your engine the same as shown on your Vehicle Specs page? (Except for the head gasket, which is shown as a Cometic in your Specs).

Yes, engine specs is the same except HG, forgot to update it after we built the engine second time using 9627PT hg.

Car looks really nice BTW!

Thank you!

Make sure to use ARP ultra lube on the studs and the underside of the nut, to around 90ft-lbs with the 7 bolt studs, verify the head and deck are clean, dry and oil free when assembling and it should be more than enough on regular ARP's for 30 psi.

Yessir, will do that.

From my personal experience, I had my studs torqued to 80ft lbs. I started getting bubbles in the cooling system and my car was overheating on the highway. I decided to torque to 90ft lbs and cross my fingers, since then the issues have been gone. This was on a 7 bolt. I feel like 75 to 80 ft lbs is to low.

Seems like the 90 is the way to got then, thanks!

Don't believe it was a head gasket issue. We run the same head gasket with L19s @ 34psi now, on a 6466. Plan on turning it up a little more before we swap the motor. I believe we were having a issue with regular arps @ 32 psi lifting the head slightly before putting in the L19s.

Thanks for the info, good to be sure it's not the hg problem. Seems like too little clamping force combined with lean on fuel. I will put it back together and torque nuts to 90 this time.

How exactly did you install the head? Were the surfaces inspected for straightness?

Unfortunately I don't remember to what number we torqued them last time (it was 5 years ago), but I'm pretty sure it was 80 as the ARP says. Surfaces were clean and inspected. Of course I will do that as well this time around.

 

[We're on Boost]

Yes, unfortunately I don't have any way of doing that. I'm saving up for standalone next year to be able to do that on the fly.

Ahh ok.
Have you thought about using EvoScan to log it the way you have it set up already (with the Ceddy Mods and tune that was already done by somebody)? Check this out - since I don't know diddly about EvoScan I asked some questions about it (in google ai). Might be some things not accurate in here but it's probably a good place to start for checking into it. 4 questions in Bold 14 font, 4 pages, Word docx:

 

[Jacob5se]

Ahh ok.
Have you thought about using EvoScan to log it the way you have it set up already (with the Ceddy Mods and tune that was already done by somebody)? Check this out - since I don't know diddly about EvoScan I asked some questions about it (in google ai). Might be some things not accurate in here but it's probably a good place to start for checking into it. 4 questions in Bold 14 font, 4 pages, Word docx:

I have a knockoff Tactrix 2.0 and a real Mitsubishi adapter, but it had some problems with connection stability, and with the price of a real one uncluding shipping, taxes and tariffs I'm better off putting that money onto a proper standalone that is supported by almost every tuner here where I am.

 

[We're on Boost]

I have a knockoff Tactrix 2.0 and a real Mitsubishi adapter, but it had some problems with connection stability, and with the price of a real one uncluding shipping, taxes and tariffs I'm better off putting that money onto a proper standalone that is supported by almost every tuner here where I am.

Yeah I think you are right. I just went shopping for a Tactrix Openport 2.0 and it seems like you can't even buy them anymore. So forget it .

 

[Jacob5se]

Yeah I think you are right. I just went shopping for a Tactrix Openport 2.0 and it seems like you can't even buy them anymore. So forget it .

Yeah and even when it was still available it was 169$, it would probably end up being something between 250$ and 300$. For ~800$ or even less I can have brand new full standalone with adapter and ditch that old and problematic stock setup.

 

[Jacob5se]

While at it what would you do with the block surface guys? I don't feel like taking whole engine out to take it to machine shop. Just clean it with razor blade and check with straight edge and feeler gauge?

 

[jdxnc]

While at it what would you do with the block surface guys? I don't feel like taking whole engine out to take it to machine shop. Just clean it with razor blade and check with straight edge and feeler gauge?

Razor blade and acetone then check for flatness.

 

[pauleyman]

While at it what would you do with the block surface guys? I don't feel like taking whole engine out to take it to machine shop. Just clean it with razor blade and check with straight edge and feeler gauge?

Block surface i prefer carbide scrapers over razor blades.