copper head gaskets for 745i (archive)

The complete automotive resource for buyers, sellers, and owners like you.

Copper gasket is usually recommended whenever the power increases over 100 hp/l.In case of a 745i that limit is 343 hp. However, the head gasket usually blows because of lean mixture. When you increase the power you will be safe when at the same time you increase the fuel supply with a rising rate regulator.
Copper head gaskets are great because those do not blow. In case of trouble something else will blow, if the gasket withstands the stress. However, the gasket is usually the weakest link in the engine. If you have a copper head gasket that is no more the weakest link. In case of trouble something else may break, but that needs a lot more power to happend. That is why copper gaskets are used in racing cars. If you go to the internet and search for copper head gaskets you will find a lot of companies offering those to racing teams and hobbyists. Anyway I still think that when you build a ultimate driving machine copper gasket is the right choice.
I know that e.g. John Stein and many other 745i owners with our upgrage kit feel that copper head gasket is not needed, because all these cars have run well a long time at power levels over 100 hp/l. They have a point there. With all that torque you accelerate so fast that in typical street conditions you are never able to use the turbo for more than few seconds at a time.
But if you want to push the car very hard for a longer period of time, the situation changes. I have driven some longer periods at 250-290 km/h and then the key point is long term reliability at high stress conditions. What I just try to say is that a copper gasket gives you some extra long term reliability to your car.It's like in F1 cars, where you always try to find the best solution.

Sorry about this long message, but I also want to include my installation instructions for a copper head gasket so that you would better understand what I am talking about.
I still have some 745i copper gaskets in stock, eventhough have not offered those to anyone for about a year. I can make some more if you are interested. To make it cost effective ( as I would have to buy big raw copper plates) I would need some 10 orders. Note also that you can with copper head gasket remove the head several times with the same gasket!

With turbo engines (especially high boost BMW 745's) we recommend to use
glue-based sealing materials. Eventhough the sprays are known to work OK in any
engine, we have been reported on one incident, when copper gasket in 745 engine
started to leak at higher boost when copper spray sealant was used.
We have used without any problems e.g. the Hylomar Blue glue-based sealant with
high boost 745 turbo engines. Glue-based sealants are also more "forgiving" than
the sprays in case the head/block surfaces are not in perfect condition.

Best performance and reliability is achieved when the surfaces are as smooth as
possible. If necessary, have those milled before installation. Remember that milling
reduces the valve/piston clearance so you may want/need to use thicker gasket to
compensate the milling.

Clean the copper gasket with solvent and carefully brush to remove any residue. E.g.
Scotch Bright pad is good for brushing. Use flat, hard and clean surface (table) to avoid bending the gasket.

Anneal (soften) the gasket. Annealing means heating it evenly to 400-600 � C using
flame heat. Use good size torch, but be careful with oxygen/acetylene torches. Those may give too much heat.

Correct temperature is reached when it turns just dark red. Let it air cool (about ten
minutes) and brush it again to remove the post annealing residue.

Depending on how many times you open the engine and how you handle the gasket it will become work hardened. Then reannealing is necessary.

You can reanneal the copper gasket several times until it does not turn soft anymore.

Copper includes small fraction of oxygen. Each annealing (flames) burns parts of that
oxygen. At some point the oxygen content decreases to a level where the copper
becomes somewhat brittle and then it can not be used anymore.

Use gasket-sealing material on both sides of the gasket. Use materials that you are
familiar with or any of the following that we have used or have heard been used
successfully:

Install head and torque it to nominal value. If you have time torque it first to
80% , wait few hours or over night and torque then to the nominal value.
There is no reason to overtorque the head, it just applies extra stress to the
weaker parts (less metal around the bolts) and may twist the head/block
surfaces. Remember that copper gaskets are not flexible!

At least Loctite manufacturers a copper spray (Permatex), which is very easy and handy to use. Just spray few coats (e.g. 5 ) on both sides of the gasket some 10-20 minutes before installation. Let it air dry.

As these are not "real" gaskets there may be some coolant leakage in some engines.
Therefore we recommend to add some coolant additive, which prevents leakage.

No re-torquing is needed. If you do it, then use only 1-2 Nm higher torque (engine must
be cool).

Questions, comments, or problems, please visit the Roadfly help desk.