regalman4925

my buddy is looking at a boat that has 7.4 LX MPI motors in it. it looks identical to a mag engine. the charts list 330hp for the lx motor but i am getting some sources showing the LX motor as the vortec 454 style engine. can anyone comfirm if the LX with the mag style intake is a 330hp and what the difference is between it and the mag? does it still have rectangle port heads and intake to match?

soldier4402

mag and MPI should be just the fuel/air induction method. I know my mags have 385.

GL@PBC

The LX is 330, the Mag is 385. Not sure on internals, but HP is accurate.

t500hps

I believe the MPI is 310 (not 330), MAG is definitely 385.

MPI's are cast internals and the MAGS are forged internals.

regalman4925

you are correct but this is a LX MPI, the MPI was 98 a newer if i am not mistaken. this LX model appears to be 96-97 from what i can tell. i cant post pics from work but if you google the 2 they are different intakes. the 98+ MPI is a L29 vortec engine with cast internals and oval port heads. the LX MPI has the mag intake which leads me to assume it has rectangle port heads? i have no clue on the internals of it, thats kinda what i am trying to figure out

GL@PBC

7.4mpi=310hp
7.4lx mpi= 330hp
454mag mpi=385hp

regalman4925

does anyone know what is differnt on this motor?? i cant find any info on the internals of it. is it cast? rectangle port heads?

bobl

The 7.4LX is an oval port (pre Vortec) 454 rated at 330 HP. Same engine as the old carbed 300 HP 454, except they added the EFI used on the magnum engines, so it looks like a 454/502 Mag. It has cast internals and small rods. They only made these for a year or so, then they switched to the 7.4 Vortec engines which were rated at 310 hp. Hope this helps clear things up.

Bob Lloyd
Full Throttle Marine

BUP

iTrader: (9)

carb was 300 hp
carb HO was 350
mpi 310
mpi LX 330
mpi HO Mag 385