boulderado said:
Im interested in this as well. Beyond the 500 to 600 bucks youll pay for the cams I have heard you will pay 5-6 hours of labor at your local shop, unless you can put them in yourselves. My questions are:
1. aftermarket cams pass emissions?
2. reliablility issues with cams?
3. horsepower gains?
4. you gain power at certain RPMs and lose it elsewhere?
5. recommended aftermarket cam set up on a stock 02/03 GT?
To answer your questions:
1. Probably not. This has been asked on here and Modular Depot and the general consensus is "no". I even think one of the VT Engines guys chimed in on a response at Mod Depot and said the same thing.
2. No reliability issues other than if you don't change the valve springs and break one. VT Stage 1 cams don't require a spring change, but their Stage 2 cams and all the Comp Cams "recommend" new springs. This is one of those areas where it is "better safe than sorry". The 4.6L is an intereference motor and if you break a spring and the valve drops open even partially, there is a high chance of bending that valve and/or damaging the piston. A friend of mine and I changed my valve springs last week. The passenger side took about 4 hours. Then after we learned the process, the driver's side took 1.5 hours. Its not hard, its just tedious work.
3. Off the top of my head, the only ones I can think of with posted gains before/after are Mustang92's VT Stage I cams where he gained 22hp. Also, VT Engines posted a dyno graph on Modular Depot of a near stock (only mods were weld-in Flowmasters) '99-up Mustang that gained 29hp with their Stage 2 grind.
4. To a certain extent, yes. Most will gain more hp up top, but are still very streetable uless you get crazy.
5. For a daily driven car, I would suggest the VT Stage I cams or the Comp Cams XE262AH cams. If you can live with a rougher idle in your daily driver, then try the VT Stage II or Comp Cams XE270AH cams (thats what I have). Anything stouter than that, and you'll need ported heads. SHM has some good grinds, but I really don't know any of the specifics so you might want to look into them, too.
My other suggestions would be that if you are changing them yourself, allow yourself plenty of time to do the swap. It took us a whole week, but we just worked from 8 or 8:30 to 10pm each night. We had a total of about 12 hours doing the springs and cams.