Muscle Mustangs & Fast Fords
Yo Ken! - Tech Q&A - April 2014
Answering Your Technical Questions
I have a '14 Shelby GT500. It's used on the street, road course, and dragstrip. I'm currently planning my spring 2014 "Stage 1" mods. I have already acquired Kook's 17/8-inch long-tube headers; Kook's 3-inch, catted, H-style mid-pipe; Stainless Works after-cat; VMP 2.4-inch pulley and 90mm idler pulley; FRPP twin-65mm throttle body; JLT 127mm CAI; and 3.73 gears. I intend to do a one-time baseline dyno, install all parts, and then do a final dyno tune.
At the same time, I would like to change the cams to achieve a "hot rod" idle. I am comfortable with a rough idle or very rough idle, I have done it previously on my ‘96 SVT Cobra. Which cams would you recommend? I have looked at numerous cam companies, but can't decide which cams to go with.
With these mods in mind, should I do any fuel system upgrades, such as a Kenne Bell Boost-a-Pump?
Kevin, aggressive cam profiles that give you a noticeable-to-rough idle and have that old school hot-rod sound are not the best for supercharged applications. These cams are designed for high-rpm horsepower in NA applications. What happens in a supercharged application is you loose cylinder pressure because of the shorter overlap and larger duration cam profiles, causing you to lose boost.
If your heart is set on hot-rod-sounding cams, I suggest any reputable cam company. Choose the cam that is specifically recommended for supercharged 5.4Ls, and don't forget to get a tune for your cam choice.
A fuel system upgrade is not necessary, but your datalogs should give you more of clue if you're running out of fuel after the tuning is done.
I am doing a Cobra conversion with my '01 GT. I want to swap to either a '99-'01 Cobra instrument cluster, or an '03-'04 (since it does have a Vortech, and the '03-'04 has a boost gauge built in). What, if any, issues will I have with this swap? I have heard the car will go into fail-safe mode and will need to have the PATS reprogrammed. Is this true? If so, can I use an aftermarket programmer to take care of this issue?
John, you will have issues. The reason is that PATS uses the PCM to enable or disable the engine. The instrument cluster communicates with the PCM to enable engine operation. The instrument cluster and PCM work together to prevent theft. They both share security data to make them a matched pair and will not function in other Mustangs. A dealer or locksmith with the tools (Integrated Diagnostic System, a very expensive tool) can pair them for you. Another option is a tune that disables PATS will also work.
I've got a blown bottom end on my Mustang. I found a cheap 4.6L engine from an '01 F-150. Can I use the bottom end from this engine in a '00 GT with a five-speed?
Via the Internet
Steve, yes you can. The 4.6 short-block from the F-150 is the same as your Mustang short-block. All parts will bolt right up. Make sure you use all accessories from your Mustang 4.6. There are many differences when it comes to a complete F-150 4.6 and the Mustang 4.6, but the short-block is identical.
I just recently had a motor built after my stock motor crapped out. My new motor is a 5.0-liter stroker with Sean Hyland Stage 2 cams. I also added Mac long-tubes and off-road X-style mid-pipe, Dynomax 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?
Via the Internet
Mike, the horsepower number seems to be close; the torque is a little low, but not by much. That said, there are many variables when you're on the dyno—weather conditions, type of dyno, and the tune, of course. The tune may be on the conservative side, limiting your torque numbers. You might try a different dyno on a cool day and/or a different tune.
Most important is how the car feels when driving. Dyno numbers can be off, and peak numbers mean very little. I'm sure the torque curve is higher and flatter now.
MAF The Story
In the Dec. '13 issue, you featured "Radical Rebuild," a red '86 Mustang GT. I noticed it has the MAF sensor located just before the throttle body, which is after the discharge (pressure) side of the supercharger. I was always under the assumption that it should be on the inlet side (before the supercharger). Why is it set up like this? Tuning capabilities? Aftercooler? I have my MAF before the supercharger, but I have no aftercooler. Any help would be wonderful.
Morgan Hill, California
Scott, there are two types of MAFs, draw through and blow through. The Radical Rebuild Mustang is using a blow through. Tuning is easier when using a blow through, but is affected more by pipe size and bends, where as the draw through is less affected. The keys to make the blow through work is keeping the pipe diameter the same size as the MAF, and have as little bends as possible near the MAF.