Cams??

Dark_Horse said:

Does anyone have the VT stage 2's? I'm wondering about them because they have a pretty agressive idle but the description says it's a good all around street/strip cam. They sound damn mean. I see that the valve lift is 560 and 575, I wonder if they have clearance issues

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Midnight2V said:

I have had the Comp xe270ah in my car for about 4 years now in both NA and supercharged form, so I can speak of their performance. I will not speak on any other cam except to compare it to the PI set I had before. The reason I have had it for four years is because I have yet to find a better cam for MY particular setup.

I have a built, stock displacement, ported SVO heads/Intake combo and these cams really woke it up. They make more power over the PI set in every part of my dynograph (2500-7000rpm). The power did not peak until 6300 in naturally aspirated form. I was getting 325rwhp, and 345 peak torque at around 4600rpm. I had all the other assorted bolt-ons. Torque was well over 300 from 2400 rpm until well past 5500. I would shift at around 6700. If i remember right, i was running around 19-21 degrees of total ignition timing on 91 octane gas.

As you can see, these cams make fantastic peak torque. In fact they make more peaktorque than either the xe262ah and the xe278ah by Comp Cams own admission. You may gain some significant power by going to the 278ah if you go past 7000. I don't know.

These cams do even better in supercharged form. This is due to the larger LSA and the longer duration on the exhaust valve compared to the intake. In NA, a little more duration on both intake and exhaust combined with a smaller LSA would probably yield a little better power, but at the expense of torque.

Designing a cam is a game of give and take. Ask yourself this, what do you want the car to do? Have a peak power number you can impress all your friends with , or a nice wide powerband you can develop a great big smile with while you move through it. Sure you can find a cam that is going to make more peak power, but at what cost? I don't want to run around having to run 4800-7000 just to make power on a cam....especially in NA form.

Instead of looking for peak power, you may want to look for power under the curve. Whether or not the HItech stage 2 meets this description is unknown to me because I went PA before they were ever released, and so I never got to race a HiTech equipped car, let alone on equal footing. A great example of power under the curve vs peak power is the 2001 cobra rated at 320 hp compared to the 2003 Mach 1 rated at 305 hp. The mach 1 made more power under the curve despite a lower peak value. This has been proved many times on the dyno, and more importantly, at the track.

As far as lift is concerned, It seems that all the 2V heads do not make significant flow increases beyond .550", ported or not. Comp realized this and that is why they stressed ramp rates instead of peak lift in their design. Their design allows the valve to be at a much larger average lift accross the cycle compared to many designs. What good is a peak lift if you are only at it for .025 degrees of your crank cycle when the piston is at bdc and hardly moving? Remember, the valve that opens to .600" also has to close .600". That means more energy losses in the valve train for minimal gain.

I hope this helps you with your decision. I only throw my 2 bits out there because I have seen lots of guys with better peak numbers than my own who are infuriated when I outperformed them. I just do not see the merit of gaining a few HP in a very narrow area at the expense of a lot of torque over a wide part of the RPM range. Remember it is your rig. You do what you want and never mind what anyone (including me) tries to tell you. Find out for yourself.

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