Join Date: Jan 2010
Location: Fraser Valley B.C.
Just doing some parts searching for a 351W rebuild for a 1990-93 Mustang LX 5.0L.
This will be my third time doing such a swap in Fox bodies, but its been some time since the last time. Anyway Im wondering about compression ratios and cam choice. I decided on a custom grind cam from Comp Cams with a 212/220 duration at .050 and 533/544 lift. This will be a retrofit roller cam using lifter parts from Comp. Anyway using pistons from Probe Industries, they have two choices. One is a dished 351W piston with a 15.9cc dish, while the other is a flat top with valve reliefs. Being the cam I will be using is for low to mid range performance with a lower duration, and this car is running EFI fuel injection with EECIV, what is the highest compression ratio EECIV can run with with a lower range cam? Is it in the 9s or can you go up to 10.3? I know a lot of motors today run close to 11s, but Im not sure how well EEC 4 can handle that, especially if the cam is rather mild. Any thoughts? Im trying to keep streetability with mileage as a concern, since my last 351W I was only getting 200km on a tank of gas with a midrange cam and flat-tops.
One last question. Do you have to use the 351W EFI fuel injector rails from the truck motor or can one use the ones off a 5.0L? And if I do use a 351W EFI fuel rail, will the ones off a 90s truck motor connect up to the existing feed line in 90-93 5.0L Mustangs? Im just concerned the fuel connector will be in a different position on the truck motors then the Mustang.