91 Lx Explorer Swap Questions.

Use the Explorer heads and intake. No larger injectors are needed.

The heads should visit the machine shop to have them magnafluxed, valves ground and springs replaced. The Explorer valve springs aren't well suited for the higher RPM that Mustangs hit when driven aggressively.

I recommend that you consider swapping the MAF for a larger one to take advantage of the extra airflow capabilities.

On a budget? do the junkyard upgrade...


94-95 Mustang GT MAF - $40-$100. It is 70 MM instead of the stock 55 MM on regular stangs built prior to 94. It uses a slip on duct on the side that goes to the throttle body and a 4 bolt flange on the other. You need a flange adapter to fit the stock slip on air ducting that goes to the air box. Wiring plugs right in with no changes. *1 *2

95-97 Ford Explorer intake manifold & throttle body $150-$300. The intake manifold flows 220 CFM +, much better than stock. Throttle body is 65 MM, bigger than the 60 MM on stock stangs. I got a 96 with EGR passages that match the stock setup, so my smog gear works just like factory. You’ll need a 65 MM EGR spacer & new gaskets for $65-$90 so you have a place to mount the EGR & throttle linkage.

Explorer GT40 or GT 40P cylinder heads. The GT40 heads have 3 bars cast at the end of the head. GT 40 's will work with any header setup, they are found on the earlier model Explorers from 95 - 97 I believe. The GT 40P's are found on 98-2001 model cars and have 4 bars cast into the end of the cylinder head.. They need aftermarket headers designed to clear the angled spark plugs.
Whatever you GT40 heads get, plan to replace the valve springs replaced with good quality aftermarket springs from someplace like Crane Cams or Competition Cams.

3G alternator from 94-95 Mustangs or other Ford. $20-$120. A must have to make the electrical system work like it should or if you have an electric fan. You’ll need a 4 gauge power wire and a 125-135 amp fuse to go with it about $15- $30.

Lincoln MK VIII electric fan -$40-$160. Free up some HP by not having to drive the stock fan. The 3G alternator upgrade is a must have prerequisite before you do the MK VIII fan. You won’t have enough electrical power if you don’t do the 3G upgrade.

Aluminum driveshaft: (courtesy of shawn13) It needs to be from a 92-93-94 Aerostar AWD. It measures 45 ½” center of the front U-joint to center of the rear U-joint. You will need the U-joint, part #PUJ353 from NAPA. The Canadian NAPA pat number is 1-0134BF. It should bolt right up after the U-joint swap.

Note: This driveshaft is not an exact duplicate of the Ford Racing part. It is 3” in diameter while the Ford Racing part is 3.5” in diameter. There is no guarantee that the balance will be any better than the stock part.

Use a piece of string and wrap it around the driveshaft. Make a mark on the string where the ends overlap. Measure the length of the string:
On the 3" AeroStar driveshaft the string will be 9.42" or about 9 7/16" long.
On the Ford Racing 3.5" driveshaft the string will be 10.99" or about 11" long

Gears - 87-88 T-Bird Turbo Coupe rear axle - disc brakes and 3.55 or 3.73 gears in one package for $125-$300. Add another $100-$200 or so to complete the brake upgrade.

*1.) Metal flange adapter http://www.kustomz.com/components.html Buy the TR70 for $40. Or spend some time on eBay looking for one that may fit.

*2.) MAF & sensor interchange
The 94-95 Mustang 5.0 MAF & sensor is also found on:
1995-94 Mustang 3.8L F2VF-12B579-A2A,
1994-92 Crown Victoria 4.6L F2VF-12B579-A2A,
1995-94 Mustang, Mustang Cobra 5.0L F2VF-12B579-A2A,
1994-92 Town Car 4.6L F2VF-12B579-A2A,
1994-92 Grand Marquis 4.6L F2VF-12B579-A2A,
Evidently the –A1A, -A2A, AA, etc. on the end of the part number is a minor variant that did not change the operating specs. You should be able to ignore it and have everything work good.

If you have a little more money and a need for speed, the right aftermarket heads will shame all of the gt40/Explorer heads. They will take advantage of the other upgraded parts, and you can order ones that keep both the AIR and EGR systems working.
The Explorer mostly used a different EGR system. But the intakes make for a great steer intake, especially if you have tmoss port the lower. So if emissions are important to you and local law, check the permanant posts on the intakes to see which years (1996?) and part numbers you are looking for to get the one with built in EGR.

The explorer top end is essentially the same as your Cobra. Swap the valve springs on the explorer heads to match your cam. You can reuse your stock injectors, rockers, pushrods. I would upgrade the TB and MAF as jrichker stated. Get the Felpro MS93334 intake gasket set and 1415 exhaust gaskets. For the Explorer intake, you will have to drill and tap the #5 intake boss for the IAT sensor, and if you want to retain the EGR coolant lines use the Explorer coolant tube or drill and tap the passenger rear pad for the return line.