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HELP! 87mm or 91mm metal head gasket


HB280ZT

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Hi All,

 

Well I blew my felpro head gasket on the back stretch of VIR yesterday. It is amazing what 15 psi, 6000 rpms in 3rd and 4th will do to a car. It was running really well then I got the white cloud of death!! I did manage to get off of the track without putting any fluid down. When I got home I pulled the plugs and found radiator fluid in cylinders 1 and 6.

 

But now the million dollar question is will the 91 mm head gasket work on a stock 82 turbo Z motor??

 

I know the stock bore is 87 mm but the head gasket at Courtesy Nissan is 91 mm and they are not sure if it will work or not.

 

So what to do??

 

I need to get this thing to my place by Friday so that I can have the car ready for another track day next weekend.

 

Thanks for the help.

 

HB280ZT

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Come on guys, anyone here using the 91 mm on there Turbo Z motor??

 

I am between a rock and a very hard place tring to get my car ready for a track day at VIR next weekend. I need to order a gasket today so that I can have it by friday. So any .02 is greatly appreciated!

 

Thanks

 

HB280ZT

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Are you sure that you are not having any detonation problems? I'm not a big fan of Felpro, but 15psi is probably pushing your luck with one. When did it blow, coming out of a turn? How much gas was in the tank? You may have leaned out under full boost when exiting a corner (been there, done that).

 

What Courtesy gasket are you talking about? OEM Nissan or NISMO metal?

 

First determine if in fact you were leaning out. If you were, fix the problem. Then run a NISMO metal gasket. It will work fine with an 87mm bore. If you want to drop your CR a bit, run the 2mm one (Felpro is 1mm).

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I actually just finished down shifting 5th to 4th and getting on the throttle going into turn 14 on VIR full. While in 5th I was not fully into the throttle but at about 4000 rpms at the time. I also was breaking at the time I down shifted so I was doing about 100mph or so, down from over 125. That is when I noticed the big white cloud of smoke. As for how much gas was in the tank about half a tank.

 

I just ordered the Nismo metal gasket and they only make a 2mm now so that is what I got. It should be hear on thursday I hope.

 

That is good to know that the only metal gasket now availible 91mm will work on a basically stock motor.

 

Thanks for the help. Now I just need to finish pulling the head and hope for the best.

 

HB280ZT

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Hi All,

 

Well I got the 91mm gasket installed and the car finally running, had some MS timing issues!

 

So the million dollar question is how long will I continue to get the white eshaust smoke out the tail pipe and the sweet smell??

 

I understand the whole exhaust has radiator fluid in it and will have to burn off but how long is to long or do I have another problem?

 

thanks for the help.

 

Harry

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Check to be sure that you don't have coolant in the oil (milky), then take it out on the highway to get all that coolant out of the exhaust. If aft a 15 highway rode, you still got steam, check your plugs and oil again.

 

Did you check the head for flatness? Did you clean the block and head surface? I use acetone, or brake cleaner. The gasket should be cleaned too. If you did all that, I'd be real surprised if the gasket is leaking.

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I changed the oil to start with and found some water in it. So when I got the car back together again I ran the car for 30 minutes to clean everything out and drain the oil again. Now I am waiting for the motor to cool then I will check the torque on all of the bolts to include, head, intake and exhaust bolts.

 

I did check the block and the head for straighteness and everything looked good. I did clean the head, block and new metal head gasket with brake cleaner before assembling everything.

 

Now it will be tomorrow morning before I can see if the car still smokes but with the temperature down in the 20's - 40's it maybe hard to tell if the car is smoking or just cold.

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  • 3 weeks later...
I changed the oil to start with and found some water in it. So when I got the car back together again I ran the car for 30 minutes to clean everything out and drain the oil again. Now I am waiting for the motor to cool then I will check the torque on all of the bolts to include, head, intake and exhaust bolts.

 

I did check the block and the head for straighteness and everything looked good. I did clean the head, block and new metal head gasket with brake cleaner before assembling everything.

 

Now it will be tomorrow morning before I can see if the car still smokes but with the temperature down in the 20's - 40's it maybe hard to tell if the car is smoking or just cold.

 

 

how did the headgasket work out ? i have a 91 mm bore 1mm hks gasket now but water is leaking a lil into my oil i think ima take off and reseal!!!

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Well all I have been running the car with the 91mm head gasket for about 2 weeks now, 500 miles or so and so far no water in the oil. Now during this time I did put it on the full course at VIR and hammered on it pretty good. You know full boost 15 psi and full rpms 6000 in the straights. So I am please with the fit and all so far, 91mm x 2mm metal gasket on a stock turbo bottom end .

 

As for the mfg not recommending it then ask them what to use and see what they say?? Because I looked and could not find anyone with an 87mm metal head gasket. Matter of fact when I checked my Felpro gasket it was right at 90mm. So not sure what to tell you other then to try it.

 

I will stick with 91mm metal head gasket and run the like crazy and we will see if I have any problems. Right now the car is running very rich so I need to get that problem fixed. Plus I had to pull the exhaust manifold the other day and send it back to Jet hot as I cooked off the coating they recommended and I am getting the next step up to try. We will see if it works or not.

 

Hope this helps.

 

HB280ZT

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  • 2 years later...

I wish I could have gotten to this post earlier.

The 2mm HG can be modified to the thinner head gasket. You will notice that the gasket is a makeup of multiple layers. You could have removed the eye-lits from the gasket and gotten the thickness you wanted.

The issue of a 91mm cylinder hole. First off the sealing ring is 90.5mm plenty of room to seal the water, oil and combustion chamber. Not a problem.

 

Second, 15psi of boost is alot of boost, so depending on your turbo charger it may be to much or ok. I was able to run on 15psi of boost on the MSA gasket. The felpro gasket died the first time I went to 15psi. The whole gasket, every cylinder let go, and tracked across 2&3. I run a gt35R turbo.

The metal gasket will do the job, but the thing to keep in mind now, is that the damage to the engine with detonation will be the piston skirts first (for stock pistons) and the rings next, then the bearings. So what I am saying is that the metal head gasket will not blow, but everything else will now.

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