[s-cars] cracked head

[Kirby Smith]

Higher octane fuel has a higher temperature/pressure at which it will
detonate, thereby minimizing detonation.  What property of higher octane
leads you to believe it was related to the effects you saw?

kirby


Bobby Richter wrote:
>
> Just a bit of input here.....
> At 140,000km my '94 S4 manual developed a crack between the the No.5
> intake valves and was leaking coolant into the combustion chamber. The
> car would miss for about 30 secs in the morning and then run fine.
> Coolant loss was minimal.
>
> Probably my fault. As a keen pilot I always filled my car with AVGAS
> (100 Octane, leaded) after a flight and enjoyed the extra performance it
> gave.
>
> FYI - the EM also developed many cracks and the K24 turbo housing as
> well as the turbine outlet was damaged with cracks. The moral of the
> story is that higher octane is great but get a chip to deal with it. The
> EG temps were obviously far too high.
>
> Now running a new RS2 turbo, new head and gasket with one of Mihnea's
> programs and a full flow exhaust and all is well.
>
> Cheers,
> Bobby
>
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