Best Cam Profile For A Stock SC?

[dd74]

Tom: does this help?

[rdane]

GREAT job!

Dave what year is your SC?

Jim/superman has a back dated OEM exhaust, not SSIs.

This is a stock '81 with SSIs again done on the same day and dyno.
http://standingwave.org/albums/porsche/als.jpg

[emcon5]

Originally posted by dd74
Tom: does this help?

No, that is the one I already have. Even blown up, I can't really see the scale lines on the sides. Do you have a higher resolution version?

If you have a better version, or a hard copy, maybe you could just pull the numbers out for me.

Dane, cool, I can work with that one.

Tom

[dd74]

Dane: mine's an '83 SC engine - bone stock w/backdated exhaust and a Triad dual-in-dual-out muffler.

Tom: that's the best I can do for now. The hardcopy's at home...somewhere...

Jack Olsen completed the original scan, so he might have a hardcopy.

Jack? You around?

[emcon5]

Updated.



What I would really like to have is a graph for an otherwise stock early SC with backdated exhaust.

Tom
edit: fix chart

[rdane]

What I would really like to have is a graph for an otherwise stock early SC with backdated exhaust.

If not before we will be dynoing Mark Wilson's '79 with new SSIs in a few weeks along with my 3.4.

[kstylianos]

Hey guys, this is great stuff!!

Not to throw a monkey in here, but it would also be interesting to note other engine variables (i.e.: CR, ignition timing, cam timing lift, intake/exhaust port sizes, exhaust setup, etc) just so we can be better educated and start piecing together WHY a particular engine setup performs a certain way.

BTW: I still think Noah's Carrera 3.0 is a freak of nature. The reason Noah gets 200+ HP at the rears is because he's able to sustain a higher torque# in the high RPM's....that engine breaths very well. It would be nice to know where Noah timed his cams, his current exhaust setup, intake/exhaust port sizes, etc. We could use this other info. to start dissecting the finer points and (for example) see/understand why Noah's engine is able to sustain a high RPM torque#.

I'll Start:

CR: 9.7:1
Cam Timing: 2.0mm (range 1.8-2.0mm)
Ignition Timing @ Time of Dyno: 38 degrees @ full advance
Intake Ports and Runners: 36mm
Exhaust Ports: 35mm (stock)
Exhaust: SSI's/Dansk Sport
Misc: Sachs lightweight pressure plate/clutch

[rdane]

Tom any chance you could add some of the new dyno sheets being posted to your graph?

[echrisconnor]

Is there any concrete evidence as far as advancing or retarding cam timing for better performance? I read in BA's book that Porsche experimented with this, but in the end, it didn't make an enormous difference.

If one were running low CR but wanted to run the 964 cam would changing cam timing make this cam any more or less compatible?

[rpiper]

What a great thread! REAL DATA, not just hearsay. Way to go guys. I need to track down my dyno sheet so I can add to the 964 cam results. Cheers,

[aigel]

Originally posted by echrisconnor
Is there any concrete evidence as far as advancing or retarding cam timing for better performance? I read in BA's book that Porsche experimented with this, but in the end, it didn't make an enormous difference.

Jerry Woods claims that he experimented himself on the dyno and found little change in the 911 from moving the cam timing around. I think that the pushrod V8s are more sensitive to this than the 911, but don't ask me why.

If one were running low CR but wanted to run the 964 cam would changing cam timing make this cam any more or less compatible?

The problem is that compression is 'bled off' due to higher overlap on the 964 profile. If your dink around with the timing, there is no way that the overlap is reduced by any noticeable amount. Maybe someone that has a true clue about cams, like John (camgrinder), can chime in.

George

[aigel]

Originally posted by rpiper
What a great thread! REAL DATA, not just hearsay. Way to go guys. I need to track down my dyno sheet so I can add to the 964 cam results. Cheers,

Note that only the shapes of the curves are comparable. Not the total torque and hp. So, if you have a flat torque curve, that's great, but in a worst case scenario, the steeper one may actually start where the flat one sits over the entire band.

I also think the thread is mainly about driveability in town etc. If you are talking performance at a track, you don't care what's under 3500 or even 4000 rpm. So if you can buy some power in the high end and pay for it a bit at the bottom, it is good.

Just a few random thoughts!

George

[KNIGHTRACE]

The M1 cam we came up with would be worth trying for a comparison. WK

[KNIGHTRACE]

I have had the best results with the M1 cam made by webcam. I sell them if anyone would like to try them. Much better than 964 or 20/21 KNIGHTRACE@MAC.COM Thanks, William

[icarp]

I am not sure how to post this info , so here is the link to another Pelican thread
3.0 rebuild for performance advice

Good dyno curve and more info on page one
Ian