906 Cams

[rfn026]

I have a set of 906 cams I'm thinking about putting in my 1973 911. I have the S pistons and Webers. Does anyone have any experience driving an early 911 with these cams?

I can deal with a little loss of mid range torque but I don't want a high rpm screamer. This is a street car.

Richard

[JGalt]

From 6 to 9 it is "dearly beloved we are gathered here, ..."

Below 6, it's wake me when it's over.

[jluetjen]

If you don't want a high RPM screamer, don't get 906 cams. They've got little if anything below 4000 RPM (which is why Porsche didn't even start their dyno runs on carb'd 906 engines until 4500 RPM)*, and really don't come "on-cam" until 5500 RPM and pull strongly until amost 8000 RPM. Now if you haven't ported your engine's heads, and they're not S heads, you'll wind up with an engine that pulls strongly from 5000 - 6500 RPM and then runs out of breath.

Pick a 2000 RPM rev range where you want your engine to be strongest, and then you can start to talk about what cam will be right for you.

* Note: Engines with 906 cams can be driven at less then 4500 RPM, but only at part throttle. Even then they'll still be tempermental. MFI helps this quite a bit compared to carbs.

[gumba]

My 2.8 twin plug had 906 cams w/46mm Webers. They weren't happy until I hit 4500 + rpm. Great for the track, less than ideal for the street.

[kenikh]

Here's a thread I started over on the S board asking a very similar question:

http://www.early911sregistry.org/forum/showthread.php?t=10662

[jluetjen]

Here's a chart that I did a while back based on the factory dyno charts for the different 2 liter engine configurations. The bold red print shows where that particular configuration is best. I've also plotted the results out graphically.