1309 Ford Mustang Roush Stage 3 Front
Ken Miele
January 1, 2014

Danger Ranger

I have an '88 Ranger with the lowly four-cylinder. It's tired of climbing the 7-percent grade up to to my house, so I'm planning on a 5.0L swap. Are there any companies that make the conversion kit with the T5 trans? All the kits I've found use the C-4. I'm also planning on making 500 hp NA using an aftermarket EFI. For the engine, I'm thinking a 347 with TFS Twisted Wedge heads and Track Heat intake with a 90mm throttle body, but what cam? Any help would be amazing!

Guatay, California

Brian, Advance Adapters used to make the five-speed conversion kits. It still makes some of the components for the swap. There are no other companies offering five-speed conversions.

Getting 500 horsepower from a 347 might be a little tough if you're looking to have a daily driver. Your head selection and throttle body are good, but without an aggressive cam profile and some cylinder head work, you're most likely looking at 400-plus horsepower. I suggest a mild cam, such as the Ford Racing Performance Parts E303 or a cam with similar specs. It's a great all-around cam.

Mark It Up

I am the proud owner of a '99 GT that I've had since 2001. Like every enthusiast, the quest for more power is always there. I've modded the car over the years and now feel that it's time to make a big change. The goal is to swap out my current engine and drop in a Four-Valve Cobra motor.

From what I've read, there have been guys using Mark VIII motors, which seem to work and those engines are affordable. Will my computer run the engine? Are the Mark VIII motors strong enough internally? If you guys have any info regarding a swap like this, it would be greatly appreciated.

Tony Porcelli
Elyria, Ohio

Tony, the Mark VIII engine will work, but it does not make the same power as the Cobra. The swap can be done, as it is a bolt-in. You will have to use the corresponding computer and wiring harness from a Cobra Mustang. All accessories will work, as will the engine mounts. The trans and clutch will work also, but you will have to get a Cobra flywheel. It can be an expensive swap, with used Cobra engines running anywhere from $1,500 and up.

Just a Phase

I have a '12 Roush Mustang RS3 with the Stage 3 package (675 hp and 585 lb-ft of torque). The car is actually making only 550 rwhp on the dyno. I am looking to increase the horsepower output to 710 and torque to 690 lb-ft with bolt-ons and/or minor changes to the basic structure of the car. What would you suggest?

Alex Ros
Bentonville, Arkansas

Alex, the Roush RS3 comes stock with 540 horsepower and 465 lb-ft. The power you are making now is stout, and I assume you're using the Phase 3 Roush kit. Roush does make a tuner kit cable of 750-plus horsepower, but you will not get the warranty of the Phase 3 kit. If you want to stay with the Phase 3, a custom tune would be your best bet to get to 710 hp and 690 lb-ft. The power you are making now is pretty close to what I would say is safe for engine longevity, and anything more may be pushing its limits (see our DIY Roush blower series).

A Killer Combo

I have an '89 LX coupe and just finished re-wiring the entire car with a kit from Painless, and installed a FAST XFI 2.0 computer system. It has a stock engine with the exception of an electric fan, upgraded throttle body, underdrive pulleys, ARP head bolts, and 1011-2 head gaskets. I'm putting a set of ported GT40P heads on with an upgraded spring kit from Trick Flow that allows me to run a cam up to 0.512-inch of lift, as well as a Vortech Si supercharger. This blower is overkill for the current engine, but I got it new for a steal.

Which cam should I choose to go with the supercharger and the better flowing heads? Looking to go with a Ford Racing cam, the E303, B303, or F303. The car is driven half on the street and half at the dragstrip. The transmission is a Tremec 3550, and I have 4.10 gears installed in the rearend.

Clay Simpson
Edmonton, Alberta, Canada

Clay, I wouldn't say the blower is overkill, and it looks as if you have the right components to get the job done. I suggest the F303. It works great with supercharging, and with the 4.10 gears your 5.0L will just flat-out haul. Your combo will work well for a street and strip car.

Conversion Chart

I am converting my '99 V-6 auto to a V-8 five-speed. I have an '04 IRS and plan on using a 3650 from an '03/'04 GT. Since the 3650 was stock on the '01 Cobra, can I use a '01 Cobra driveshaft without the modifications I would have to do to a GT driveshaft? Are there any other issues?

Steve Rainey
Kingston, Tennessee

Steve, the Cobra driveshaft will bolt in without modifications. You will have to use the wiring harness and computer from the Cobra along with the Hydraboost to complete this swap.

The stock V-6 booster will not clear the valve covers. There are some minor issues, such as heater hoses and the throttle cable, but they are easy fixes. A Cobra throttle cable from Ford and a little trimming to the heater hoses, and you will be good to go.