gl bro and mine also has stock 243s and its just a 5.3

 

bigger isnt always better in some cases ...

 

You are very correct with that statement. Take your exhaust for an example, to big of pipe will loose compression and result in loss of power. E-mailed Comp cams today and they suggested i roll with the XFI™, 271PHR14
Extremely Strong from 4500 past 6700 RPM, Noticeable Idle So now i am tryin to find a shop that will put it in soon, before school starts up again.

 

Not a bad choice IMO. operating range is 1800-6900 and the graph that comp has looks good.

http://www.compcams.com/Technical/Ca.../pdf/page9.pdf


Edit: I wouldn't mind having it on a 109/110

 

I didn't realize that you had the VVT. You will need, in addition to better springs, the Phaser limiter kit as well, to limit VVT range to 20 degrees vs. the stock 50, to avoid the possibility of the valves kissing the pistons.
The graph on Comp's website actually shows the power increase from the larger 275 cam, but when GM High Tech Performance tested the 271 vs. the 275 on a 6.2L (L92), the bigger cam only made 13 more Hp and 8 ft lbs of torque over the 271. Bearing in mind that you have a slightly smaller motor, I would say that the difference would probably be even less between the two cams, so the 271 should work better for you.
Here is the link to the GM High Tech VVT cam install article:
http://www.gmhightechperformance.com...all/index.html

 

I'm thinking of losing the VVT. You can go with a bigger cam and gain more power. You can tune out the VVT functions and pretty much has a LS2 under the hood. I pretty sure all you need is a cam/lifters and timing cover. Mast motorsports has done these conversions and would know for sure what you would need.

 

really you think the bigger one would help more? yeah he gave me the p.n.'s to the phaser limiter kit and the springs,retainers, and hardened one piece pushrods. $920 for 13 hp?? I might not do it then. When you did your cam how much did it help?

 

I haven't done a cam yet, but I know one is in the future. I'll probably do 4.10gears first though.
What I meant was, the bigger 275 cam only made 13 hp more than the 271, which makes sense, because they are close on duration and lift anyways. You'll need the phaser kit with either cam. The bigger cam made 71 more HP AND gained low end torque (because of the VVT) over the stock cam in the GMHT test (and 69HP in Comp's test). Both cam made way more power than the stock cam all through the RPM range. Our motors can make around 500hp with just the big cam and headers (and tuning). That's very impressive, IMHO.

 

no, 13hp difference between the compcams 275 vs 271... so meaning the 275 made more power then one recommended to you, which was the 271. but 222 intake duration seems small to me, for a 6.0 engine... i would do at least 228 or 230 intake. maybe 240 or 242 exhaust, with a bigger lift as well. closer to the .600 range.

 

To go that big, he would definitely have to delete the VVT. We've had this debate before about the advantages/disadvantages of VVT. It depends on whether you want to make big high RPM gains at the expense of losing torque down low vs. good midrange and upper rpm power without any loss of torque down low. For my truck, I'm sticking with the VVT. If I want to hear a really lumpy idle, I can start my race car, which has a 565 CID w/ a solid roller w/ 294 degrees of duration @.050" and .823" lift and 16:1 compression. I love the sound, but I wouldn't want to drive that every day.
Also, when we go really big on camshaft in these motors, we have to recognize that there will be other things on our motors that are not optimized for high RPMs - like the long runner truck intake - which will become the limiting factors in high RPM HP gains. just my 2 cents...