2.2 E mods

[0687]

Kenik

saw on the ratios thread you're going to 2.3 also - what are you ending up with on CR, cams, induction and ignition?

thx

Chip

[kenikh]

Since this is your thread, I will digress. I am glad you asked!

It took A LOT of research for me to finally come up with a configuration (and especially cam) that was going to be perfect for me. I actually ended up having John Dougherty make me a custom set of cams. The cams I ended up buying are DC44 cams, but on 102 lobe centers. For reference: http://www.drcamshafts.com/911profiles.htm
This cam gets bigger lift than a 906 or RSR cam (almost the same as the DC62), but with less duration, using the same lobe center specs as the E, L and Mod-S cams.

This results in a cam that breathes HUGE air. Since air volume makes power and air volume is a function of lift x diameter x duration (way oversimplified), I went for more lift and less duration to get the same air volume into my motor as an older, longer duration cam like the 906. The good thing is that this cam doesn't have terrible reversion characteristics, like a big overlap/duration cams.

The cam makes rising power to 7800 RPM at zero degrees timing, with only 3 - 4 HP fall off at 8000 RPM. As described by John, the cam makes more power everywhere in the power band when compared to a stock S cam; actually torque production is more in line with an E cam than an S. So my description of the cam is "makes 906 power with E torque".

The tradeoffs: If you want to get real revs (over 7400 RPM), you need race springs and lightened retainers, since these cams open and close the valves FAST. Since that is where the top end power really lights off, it is a good investment. One caveat on my advice as well: everything I have just told you is academic. This top end is still on a rolling rack at Supertec, waiting for pistons to be supplied from JE. Once the parts get shipped back to me they will be installed by my local mechanic.

Regardless, I have had enough input from experts like John and Henry Schmidt to trust that this configuration is going to be a shocking revelation for my car, especially with the big cams, a displacement bump to 2.3 liters and the AFKQV gearbox I just had built! As you may know, the displacement is achieved by using the obligatory 85mm JEs on stock spec '69S heads at a CR of 9.5:1, in bored 84mm Biral cylinders. I didn't really feel that twin plugs were gaining me much more than a hole in my wallet, so the dizzy will remain stock S. MFI is to be installed, as well. Best guesses are that this should all result in 205 - 210 crank HP at 7800 RPM and a torque curve more reminiscent of an E cam than an 'S' or 906. 2.7RSs should live in fear.

One last thought: If I didn't want to spend money on springs and retainers, the DC40s are almost as good.

I hope this helps.