mileage too high?

[fasthippo]

i have a npi motor with 135k miles on it, and i'm about to do a ported pi head swap with some other goodies. will my shortblock hold together or should i invest in a new one?

if someone has a modded npi of similar miles your input would be very helpful

 

[four six]

It will be fine. I would still save for a new short block though, and do better flowing heads.

 

[CobraRed_96_GT]

No need. I'm a good example. 120k miles. MMR Stg II ported heads, bronze guides, +1mm valves 10.3:1 compression with VT stage 1 cams and PI intake + bolt ons. Did a leak down test, piston rings held liquid/pb blaster indefinitely, compression test showed 5psi max difference between cylinders. All good to go. If i touched the bottom end it'd be left with all forged rods and pistons.

 

[fasthippo]

thanks alot, i had several people trying to convince me to just wait for a shortblock but i simply cant afford one right now.

 

[CobraRed_96_GT]

Never got that argument. Your replacing the top half of the engine with new stuff, how is that bad? More compression? If you run a compression test and it's good, and you run a good tune it should be running better than before.

 

[Dragstr05]

The 4.6 is no joke. Sure it doesnt make much for power in N/A form unless heavily modded, but it sure is reliable! 125k on my odo.

I've also seen an 03 cobra with 200k, stock bottom end. A while back someone here posted a link to a user on another forum with an NPI stang that had a supercharger installed around 100k, had 300k+ on it at the time (200k supercharged, 9-11psi). Also stock bottom end.

Dont abuse it, and maintain it with a good tune and you wont go wrong. There are more than enough people out there with a 4.6 to attest to how reliable they are.