Muscle Mustangs & Fast FordsHow To Tech Qa
Yo Ken! Tech Q&A - December 2014
Answering your technical questions
Go, Then No Go
I have an '06 Mustang GT with an automatic. It has been modified with a cold-air intake, SCT tune for 91-octane, and cat-back side-exit exhaust. When I hit the gas the car will stall then take off. It's like it is starving for fuel, but I know cars with superchargers that have stock fuel setups and don't have this problem. Is it a tune problem or the throttle body? It did do it a few times before I put the TB and tune in.
You may have a fuel pump going bad. There was a TSB (Technical Service Bulletin) on the 2006 Mustang GT. It seems as if some Mustangs may have air bubbles forming around the fuel pump when cruising, which could be occurring in your 'Stang and causing this problem. Ford suggests you have the fuel pump and pickup assembly replaced. I would also suggest a custom tune to dial in your combination. This is important to get the most out of your combo.
I have an '06 Mustang with a 4.6L. It had a few mods when I bought it. They include JLT cold-air intake, Steeda pulleys, BBK long-tube headers and X-style midpipe, Ford Stinger mufflers, and a custom tune for 93 octane. According to the person I bought it from, dyno pulls showed 367 hp and 375 lb-ft of torque at the crank. My goal is 410 hp and to stay naturally aspirated. I talked to someone at a speed shop who first said that the mods I want to add (Comp Cams Stage II NSR, C&L intake manifold, and Ford Racing throttle body) would give me 350 rwhp. With a 15 percent loss at the rear, it calculates to 411 hp at the crank. Today, I visited the shop and was told from someone else at the same shop that the C&L manifold and throttle body were not the way to go and I should do the cams and a supercharger. I really want to stay naturally aspirated and keep cost at or below $3,000. Muscle Mustangs & Fast Fords taunts the C&L manifold replacement to 34 rwhp with a different throttle body, so I'm confused what to do.
Via the Internet
The C&L intake will increase power, but at a high rpm, I'd recommend the Ford Racing intake. It makes great power. Maybe your shop feels that it is not worth it because of the power coming in at such a high rpm. Your mods are right on track to reach your goal of 400-plus horsepower. High-rpm horsepower is not a bad thing. Ideally you want power to come in fast, but that can lead to traction issues. The 4.6 Three-Valve makes good torque for a small engine, and having that extra power at the upper rpm ranges keeps your Mustang pulling hard through the entire rpm range. So if you want to stay naturally aspirated and reach 400-plus horsepower, go for the mods you are planning.
More Muscle Needed
I plan on putting some go into my ride, and though it's not a Mustang, its power/drivetrain is identical (4.6L, 4R70W, and 8.8-inch rearend). My ride is an '01 F-150. She has served me well but needs some more go. From reading, I've learned that the 4.6 responds well to boost, so I'm pretty sure that a kit from Hellion will get the job done. The 4.6 will grow to a full 5.0 (via Livernois stroker kit) and it'll breath through a stock Cobra top end. The gearbox will be done by TCI. This will pretty much round off the drivetrain.
My question is in regards to the axle. I know it's been proven to hold up under some pretty punishing conditions, but can it hold together under the truck once the torque gets into the 650-700 lb-ft range? Keep in mind that the truck weighs around 1,100 pounds more than a 'Stang. Is it reasonable to ask so much of the 8.8, with something simple like a differential cover/girdle, or should I swap it for a 9.75? Also, I'd like to use Detroit TruTrac, but I've heard from various people that these will blow up under a load. Would it make a difference as far as the differential is concerned whether I use the 8.8 or a 9.75?
There are a lot of aftermarket parts for the 8.8, and we've seen them in 7-second race cars. I would think because of the weight of your F-150 that the axles are your weakest link. The 9.75 does have larger axles, but depending on the condition of the 9.75 you may have to upgrade the internals. If you build up the 8.8 with all the good stuff, axles, differential, and gears, along with a girdle, you will probably spend about the same as the 9.75, and the 8.8 will do OK under your F-150. TruTrac is an excellent differential, but for your power level I would go with a Detroit Locker. I like the idea of the larger housing and internal components of the 9.75 for your combo.
Exploring the Unknown
I have a 2WD '99 Ford Explorer Sport (the two-door) with an aging V-6 and a need for more power. I already have the short-block, EFI components, trans, and a ton of other parts from a wrecked '00 5.0 Mountaineer. My plan goes like so: rebuild short-block as a 306 with forged pistons, TFS Stage 1 cam, 1.6 roller rockers, FRPP GT-40X heads (58cc chamber, going for 9:1 compression), stock Explorer intake (not sure if I want to have the lower ported), Torque Monster headers, rebuild and J-mod the 4R70W, a TCI Saturday Night Special converter, and to have it tuned by Henson Performance (a Ranger/Explorer specialist). The rear axle is already in order: 8.8, 31-spline Traction Lok with 3.73s. I intend to turbocharge it in the future; that's why I'm going with the forged pistons and conservative compression. This truck is my daily driver, but I also plan to take it to the track every so often. With that in mind, I want the shift point to be 6,000 rpm at the most, while keeping a fairly healthy amount of torque.
That being said, what kind of power can I expect from this setup? Do you have any suggestions that will squeeze more power out of this mill? What size injectors should I use? I would have to modify an aftermarket throttle body to work with the Explorer throttle setup; is it worth the hassle?
Via the Internet
Without the turbocharger, your 306 with the right tune should make 340-plus horsepower (300 rwhp), and it sounds like your combo will have great tip-in throttle response and power. I expect torque to be equal to the horsepower. With the turbo, and depending on boost level and size of the turbo, 450 to 500 hp should not be a problem. I suggest you go with 24-lb/hr fuel injectors without the turbo and at least 42-lb/hr fuel injectors with the boosted combo, but it may require more depending on desired power level. Henson Performance will more likely have a better idea what your combo needs when you get it tuned. I would stick with the Mountaineer throttle body; it will move more than enough air for your combo.
If you want to stay naturally aspirated and reach 400-plus horsepower, go for the mods you are planning.
To Space or Not?
First, I enjoy the magazine and the ideas I pick up to increase the power of my '10 Mustang GT. I just put on Baer GT Plus front brakes. I have 20x8.5 rims in the front and 20x9.5 rims in the rear with 40mm offset. In order to put the Baer 14-inch two-piece rear rotors on, I had to use lug-centric 8mm wheel spacers. Are the spacers safe to use or could they cause damage to the hubs, bearings, and so on?
I do not see any issues using the 8mm wheel spacers on the rear. What's important is that the wheel studs be at least three-quarters or more through your lugs. If that's the case, you should be OK. The rule of thumb is for the wheel stud to be at least six threads deep into your lugs. Longer aftermarket wheel studs are available if needed.
Lookin' for Power
I just recently had a motor built because my stock motor crapped out. My new motor is a 5.0L stroker with Sean Hyland Stage 2 cams. I also added Mac long tubes and off-road X-pipe, Dynamax mufflers, JLT ram-air intake, and 4.10 gears. After the car was dyno tuned it made peak numbers of 334 hp and 310 lb-ft of torque. I know numbers are not everything, but is this right? Shouldn't a stroker be able to make more torque than a stock motor with the same bolt-ons? I went with this combination because I felt it could get me a solid 370 rwhp and 350 lb-ft of torque.
Via the Internet
I am assuming you are talking about a 4.6 Two-Valve. The numbers for your 5.0 stroker are right about where they should be for the mods you have. The 310 lb-ft of torque may not be what you want, but for a Two-Valve mod motor it's were the torque comes in and how flat it stays throughout the powerband. To get 370 rwhp out of a naturally aspirated Two-Valve engine requires extensive headwork and very aggressive cams, which will make for a not-so-friendly ride. I would be happy with those numbers; they are more than Project Silver Stealth 'Stang, which ran 12.70s with an auto.