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Reply to "Is 450 HP and/or 450 torque the limit for the zf?"

I'm not sure where that rating comes from? There have been a number of monster engines installed in these cars that are considerably heftier then the rating.

In the '70s there were some 427's installed by Dennis at Pantera Performance in Colorado. A box stock 427 medium riser is an honest 450hp on a dyno (stock) but it makes 550 lb-ft of torque at 1,500 rpm.

 

It isn't so much the horsepower as the torque that is the danger.

 

According to the "factory rating" the ZF's should have self destructed under such conditions and yet they are still around?

I know in the GT40 "program" Ford was not a big believer in the ZF. They were not run behind the Mk II's and Mk IV's at all. No one seems to know specifically where that rating came form but I wouldn't be surprised if it came from  Ford back then.

They were so convinced that the ZF was a problem that they thought one out of 3 would fail in warranty use on new Panteras?

 

Rule of thumb though always was 500/500 is the safe limit. Venture past at your own risk. A ZF is a VERY expensive item to have to rebuild these days.

 

It could also be that a big number engine is what causes the swagger to current owners and they either are afraid or don't know how to use the new power? I doubt that's the answer though?

 

Talk to some current vintage racers. They'll know the limit.

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