C4 tips for durability


Founding Member
Sep 18, 2000
Albertville Al.
We are building up a C4 (157T) for my friend's 86 Coupe with the equivalent of a GT40 crate engine. The car is a weekend driver with about 50/50 highway/track time. More engine modifications are in the car's future. Right now it runs high 13's@100 mph through the "freebie" C6.

What would like to know is what kind of modifications are needed or recommended to make the C4 a reliable transmission at the 300-400hp level?

For reference the C4 is a 1967 originally behind a 289 in a Mercury Cougar.

Thanks very much....
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