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Ford Explorer Community - Maintenance - Modifications - Performance Upgrades - Problem Solving - Off-Road - Street
Explorer Forum Covers the Explorer ST, Explorer Sport, Explorer Sport Trac, Lincoln Aviator, Mercury Mountaineer, Mazda Navajo, Ford Ranger, Mazda Pickups, and the Ford Aerostar
The cam that runs stock in your Explorer is the F4TE-6250-BA. It is a hydraulic roller that runs .422 on the intake and .448 on exhaust. The GT40P heads that come stock on the truck can do better with a tad more lift but not much. Porting the heads and having larger intake and exhaust vavles would go a long...long way in improving the breathability of the engine.
A set of roller rockers right off the bat will provide you some extra HP so I would sign on to that idea right off the bat. The B303 (.480/.480) cam will help but I would probably push to the E303 (.498/.498) based on the flow patterns I have seen with the GT40P heads not really breathing till about .500 on both sides. The E will not destroy the idle of your vehicle either...which is nice if you have a wife who wants to sport the vehicle--not wanting to bound down the streets sounding like a Shelby Cobra. If you are going to put this kind of effort into the engine--my suggestion would be to have a larger set of valves put in the heads--there is room and either do a home port job or take them to a maching shop and do it. It only takes an extra nickle to go first class in this case.
This setup is what I am currently working on with my Explorer--yeh I know the my profile states 91 XL...been too lazy to change it to a 99 AWD. I am currently working on a home port job as I did not get as much out of the cam as I wanted. The GT40P heads are good / great in comparison to the stock 5.0L heads and the lower intake is almost identical/similiar to the lower and upper intake from the Mustang Cobra.
The reason for the port job is less for the intake than the exhaust (in with the good...out with the bad). Ford heads are not known for being good on the exhaust side of things. The GT 40 head has a 1.84 intake and a 1.54 exhaust. The GT40P has the same intake and a 1.45 exhaust so it does not flush as much of the spent fumes out before the next cycle takes place in the cylinder. I will be looking at the size of the valve seats to see if we can at least get the exhaust to 1.54 if not 1.6. I will continue to toy with this in between travel and get everything back to my wife's satisfaction--hopefully sooner thant later.
Did you ever complete the head work on your Expy?? I want to bump up my Explorer's power but I don't want to get into supercharging and all that. I was thinking an E303 cam, head work (based on your experience) , roller rockers (1.6 or 1.7??), and then a set of FMS headers. I figure this will get me up to ~260HP at the crank at least which should provide a nice little boost in power.
The GT40p headers are hard to come by. So start looking if you want to use them. if you bump up your lift, you may not want to increase the rocker height to 1.7 or the rpm power range may move higher than you want.
as heavy as the X is, i would go with 1.6's. the 1.7's will move your powerband up too high. and BTW, if anyone wants to know what an X really weighs, i weighed mine the other day. 96 xlt V8 2wd, 4120 lbs. with a full tank of gas and no driver.