im new here and i was wondering if anyone can help me out. i have a 2004 mach 1 and there is a loud knocking sound coming from the back of the engine (sounds if it is coming from the intake). also when u turn off the ignition you can here the compression leak back through the intake. what could be the problem

 

All stock or have you done any exhaust mods or anything?

 

engine is all stock. catback is unbolted.its got a 6-spd tranny swap, short throw, and stage three clutch. i had a machanic look at it today and he said it sound like a rod because it has that ratta-tat-tat sound. ive spun a rod bearing in my 01 cobra b4 and its not fun. are these 4v notorious for this or is it just the way i drive. it seems these internals are too weak for these cars

 

You obviously abuse the crap out of your car. You got to pay to play...

 

The Mach and Cobra short blocks are pretty reliable unless you really beat on them...

 

^^ Yes indeed, sounds like too many rpms too many times

 

i dont launch the car too much or do a whole lot of down shifting. for future reference would it be better to shift at 6500 r's istead at red line (for my internals sake). i beleave the power starts to drop somewhere around 6200 rpm anyways. right?

 

could be a lifter

 

it could also be an exaust leak

 

nah man just shift at 7800 and let her fly! lol Once the power stops building of course it's time to shift otherwise you're going slower than you could be.