Risk of F40 Engine Modifications

Drew, lots of issues here, but probably the two main ones are the block (weak) and gearbox (potentially weak). The standard gearbox is basically the same as the GTO and is good to about 600HP to 650HP. After that, it's recommended you go with the non-synchro GTO/F40 gearbox. You can use one the newer transmissions (getrag, etc.) that can handle the output as well.

The F40 block, like the GTO, is a little weak for the output. The blocks are weak enough that mechanics sometimes piss and moan in frustration after a line bore because if you don't bolt everything back together in just the right manner, you're out of line before even putting the engine back in the car. Never mind what happens after a few spirited drives. Nothing to get too concerned about though. It's just the nature of the beast.

And none of this addresses how you're supposed to modify the software to handle the reduced backpressure when modifying a USA car. I've seen many a person just bolt on a tubistyle without taking into account the reduced backpressure. Then they wonder why the car isn't running quite right.

Been there, done that.

Guys like Craig Keeney, Steve Fremgen, Tony Palladino, etc. know how to do this right.

Take it to someone that knows what they are doing.

Steve Hill