I just picked up a 89 supra and am wanting to do some precautionary measures before I start making HP. I have been told by a few guys in my engineering class that I don't need to machine (Ground/Lapped) my head when replacing the head gasket. (Note: My headgasket is not blown, and I am assuming that it is not warped, I will check and make sure once it is off) These guys aren't the typical ricer type guys and know mostly what they are talking about but neither of them has owned a supra. Any help on this subject would be appreciated.
Head Gasket Question
- Thread starter Saltdog
- Start date
You absolutely need to do this - IF you are replacing your head gasket with a metal one. If you are going with another composite head gasket, then chances are you don't need to.
If you get all the gasket material off the mating surfaces of your motor without scratching the alloy head up you should be fine to run a new composite gasket. However, I'd recommend you get the head pressure tested and possibly do a valve job while you have it apart.
It really depends on how your motor is set up, how much boost you are running, and how hard you are driving your Supra that determines whether or not you absoloutely need a MHG. If you are running alot of boost you need a MHG. If you are driving the car hard much of the time you would also benefit from a MHG.
That being said, the truth is that anyone with a Turbo Supra is going to have greater reliability and the ability to run more boost with a MHG. The reason for this is that unlike a composite gasket which is not very strong and is subject to failure under high pressure (turbo boost) a metal gasket is essentially a 1 piece metal shimm that is far stonger and not very likely to yeild to extreme cylinder pressure.
The down side of a MHG is that it requires a very fine finish on the gasket mating surfaces (the bottom of the head and the top of the engine block) in order to create a good seal between the head and the block of the engine. The other down side is that kind of machine work costs as does the MHG itself. But it is absolutely the only way to have real peace of mind with a turbo'd motor especially a 7MGTE which are legendary for blowing head gaskets out (especially at elevated boost levels).
Lastly, the "experts" in your engineering class couldn't be more wrong about lapping the block and head in order to run a MHG! You will not get an adequate seal without lapping the block and head. I have seen people try on brand new heads and fail miserably.
Good luck and tell the propeller heads who told you that to stick to their slide rules.
It really depends on how your motor is set up, how much boost you are running, and how hard you are driving your Supra that determines whether or not you absoloutely need a MHG. If you are running alot of boost you need a MHG. If you are driving the car hard much of the time you would also benefit from a MHG.
That being said, the truth is that anyone with a Turbo Supra is going to have greater reliability and the ability to run more boost with a MHG. The reason for this is that unlike a composite gasket which is not very strong and is subject to failure under high pressure (turbo boost) a metal gasket is essentially a 1 piece metal shimm that is far stonger and not very likely to yeild to extreme cylinder pressure.
The down side of a MHG is that it requires a very fine finish on the gasket mating surfaces (the bottom of the head and the top of the engine block) in order to create a good seal between the head and the block of the engine. The other down side is that kind of machine work costs as does the MHG itself. But it is absolutely the only way to have real peace of mind with a turbo'd motor especially a 7MGTE which are legendary for blowing head gaskets out (especially at elevated boost levels).
Lastly, the "experts" in your engineering class couldn't be more wrong about lapping the block and head in order to run a MHG! You will not get an adequate seal without lapping the block and head. I have seen people try on brand new heads and fail miserably.
Good luck and tell the propeller heads who told you that to stick to their slide rules.
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A composite gasket is more forgiving, but won't hold as much horsepower.Saltdog said:
All the heads that I have seen were deformed on the mating surface from the original head gasket - it's torqued on there hard enough to mar the aluminum finish significantly.
Thanks Guys thats what I needed to know on that, one more question
Since I am on a school budget I will hold off on pumping up the boost, but as a precautionary measure I would like to retorque the head. I have the tools... know not to torque more then like 10-20 lbs at a time. My Question is: Would it be possible to take the head bolts out and replace them(ARP)? Is that something that is recomended?
Since I am on a school budget I will hold off on pumping up the boost, but as a precautionary measure I would like to retorque the head. I have the tools... know not to torque more then like 10-20 lbs at a time. My Question is: Would it be possible to take the head bolts out and replace them(ARP)? Is that something that is recomended?
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