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Discussion Starter · #1 ·
I hope someone with experience can help me out here..i am posting to help a buddy with a 87 Supra turbo. His internet is down. He blew a head gasket on the dyno after 5-6 runs. He says he has heard the MKIII's have a bad habit of blowing headgaskets. Anyways with 8-9 lbs of boost he managed to make 275 at the wheels but he threw a MBC off my talon on it and increased it to 12(it spiked and dropped to 10 thru the last run) the headgasket gave up. My question is what is the reason the Headgasket gives up so soon on these cars?? The Wideband showed it at 12:1 and 8 to 9 even 12 lbs of boost really isnt that much or is it for these cars?? What would some of you guys recommend to keep from blowing a another headgasket besides lowering the boost? Aftermarket gasket? Upgraded fuel system?? I apologize for leaving any info out but i was not there for the dyno session. Any help or advice would be appreciated. Thanks
 
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Discussion Starter · #3 ·
7m blows stock hg so easily because the factory didn't torque it enough...i think they used 54ft-lbs which causes the hg to go pretty easily. mine was shot at 62k miles or so.

the best thing to do would probably get an HKS metal head gasket with ARP head studs, get the head and block machined to the spec required for mhg use, and go with that.

The stock gasket will most likely go without any detonation but w/ detonation i think it'd be blown extremely quickly...with the proper torque, i've heard of someone running 25psi on a stock gasket...

melloboy
 
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Discussion Starter · #4 ·
So the torque spec from the factory is too low?? He rebuilt the motor but used the factory torque specs. He is thinking of a HKS gasket and studs like you recommend. What should the head be torqued to then??
 

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on vacation
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3,062 Posts
the biggest weaknest behind the 7m is the headgasket, which is easily enough fixed, then it usually leaves the owner as the next biggest weakness.
 
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Discussion Starter · #7 ·
not sure of the metal head gasket, but there is some debate going around as to retorquing the stock HG to higher torques actually causes the stock HG to blow easier. That's how mine blew. compression was testing fine so i retorqued the gasket higher and it blew a week down the road...tho it might have been because my radiator exploded.

the arp studs should have come with a manual saying 75ft-lb if the moly lube supplied with the studs were used and 85ft-lb if regular engine oil was used as lubricant.

melloboy
 

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boost freak
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10,042 Posts
eh. other than the low factory tq spec, its detonation that kills ANY HG. control detonation, you won't have any HG troubles...

the 7M does NOT like to be run low on oil, you'll spin rod bearings if you do. keep it full!
 

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329 Posts
When I had the ancorM I never had a problem with the head gasket. It was torqued down to 72ft/lbs early in its life and never had a problem with it. The old girl died of old age.
 
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