Supercharging a Shelby GT

You should be safe upto about 450 rwhp. I have 412 rwhp on my wifes daily driver (06 Mustang GT with a pullied and custon tuned Roushcharger) and no problems so far. The 4.6 has cast pistons, crank and powdered metal rods that do not always hold up under alot of boost.

 

Supercharging a Shelby GT - Take a look at these sites

The Ford site gives you the H/P levels for the 4.6 @ non-I/C and I/C using their S/C kits. Click on the popup on the right that is titled Superchargers, then click on the individual S/C kit numbers that come up in the popup that comes up for more info.

http://www.fordracingparts.com/home/home.asp

Kenne Bell has some pretty good data and also could prove to be a good resource.

http://www.kennebell.net/

FAQ on K/B site:

"Will the supercharger hurt my engine? We bought our red 1990 Mustang convertible new. It has 110,000 miles on it and 3620 dyno runs on the 100% original engine. The heads have never been off and it's driven daily. Boost does not overstress the rods, crank, block, bearings etc. like rpm does. Engine inertia loads increase with the square of rpm. A 10% increase adds 40% more inertia loading. A 25% increase = 100%! A Kenne Bell supercharger doesn't require higher than stock engine rpm to make more HP and torque. We do it with boost. Remember, a Twin Screw doesn't have to depend on engine rpm to generate boost. The most common engine problems emanate from 1. over revving, 2. detonation (inadequate fuel octane, excessive ignition timing, lack of fuel etc.), 3. running more boost than the kit was designed for and 4. "other" engine changes and modifications such as heads and pistons (too high a compression ratio), injectors (wrong size), mass air meter (wrong calibration), headers (leaks), ignitions (non-compatible), regulators and pumps (excess or insufficient fuel pressure), underhood filters that suck in hot air etc. We could go on and on. We've seen it all."



Doc

 

You really have 2 options on SC's from Shelby. The Paxton and Whipple in either HO or normal configurations. With the Paxton expect approx. 450-465 rwhp with a good, safe tune. The Whipple is somewhat higher but reaching the max for the bottom end. But the key is the tune. It is worth a few $ to have the car tuned on the dyno.

With the Paxton you do get the Shelby history with a Shelby serial numbered tag mounted on the SC. That's if you purchased through Shelby autos. It is avalible in either a matte aluminum finish or polished. The Whipples do not have the Shelby Name on them. They are right from Ford Racing and have their logo along with Whipple. They are avalible in Black Matte finish or Polished. And about $700-$900 more expensive. With the Whipple install you also loose the strut tower brace. Hope this helps. Here is a shot of my Black Whipple on the SGT.

 

I think it's safe to say for all of us that no matter how much power we have it is never enough, and undeniably, supercharging your car is a very effective way of dramatically improving your vehicle's performance. While there are a number of safe applications beware that you would but supercharging a car that has about 10:1 compression. Generally something along the lines of 8.6:1 would be ideal. I personally feel that if you were going to add a blower to your ride, you're far better off building it from the ground up and lowering your compression and putting all forged internals. I few years ago I had a '98 supercharged 4.6 Cobra that I bought off a gentleman who blew up his bottom end, as he had just thrown the blower on and the motor couldn't tolerate all the boost he was running. He soon thereafter tore the motor apart and did it the right way, forged internals and all. I realize that time and money set limits but there is a right and a wrong way of doing things, and I think you'd be much happier with the results you get from building your motor from the ground up, not to mention that you can run way more boost and make more power that way too.

 

Agreed 100%. A forged bottm end with lower compression is the right way to do it. Also how you abuse, read use, the car plays a key role in deciding.