The XFFI 273 H-14 is about the biggest cam you can run in a stock hemi. Without valve relief notches the factory hemis are limited to about .550" of lift and the 273 comes in at .547 Intake and .550 Exhaust. List price for the cam is $399.68
Hughes Engines can regrind your stock cam to similar specifications for $199.00 I've wondered about the durability of this, but considering this is a roller cam, I'm seriously choosing it for my build and saving $200.00 dollars.
http://www.hughesengines.com/Index/produ...mp;partid=24709A 6.1 Hemi + Cam + Long Tube Headers + Good Tune = 480 - 505 HP. Assuming the retention of the 6.1 Hemi intake and fuel injection. With a single plane intake and carb, you'd be about 20-30 HP down from this number and give up a fair amount of torque as all but one of the intakes for the modern hemi are single plane manifolds.
The only issue with the XFI 273 is that you're going to give up a bit of low end torque with this cam, as compared to the XFI 268. Given the weight of a Challenger of around 3900 Lbs. you might miss the low end torque depending upon the rear end gear you've chosen.
For example, if your rear gear is 3.90 - 4.10 I wouldn't hesitate to run the XFI 273 especially if you have a manual transmission or a converter with a slightly higher than stock stall speed, say 2200 - 2500 stall rather than the stock stall. If you are running a 3.23 - 3.55 rear gear and stock converter, I'd probably stick with the XFI 268 or something similar.
Here's an article from Popular Hot Rodding about all three Comp Cams for the Gen III Hemi. This was done on a relatively stock 5.7 Hemi, but the motors are similar enough that the basics should apply.
http://www.popularhotrodding.com/enginemasters/articles/smallblockshootout/0602phr_hemi/viewall.htmlRegards,
Joe Dokes
