Never put that one on the dyno, but compared it to my 78SC & Carrera(both still mostly stock, it is much quicker, and both SC run 245s on 9X16 Fuchs:D The Euro system is pretty much the same as 78-79 and a little bit of head work, SSIs flow into a B&B muffler. Makes for a very fun cab:cool:

Hi Bob,

Greetings from down under.

I did this upgrade when I did a rebuild of my 204HP 83 SC. I had pitted cams so I decided to go with the change. Bearing in mind that I put in new rings, and had the heads freshened up also, so obviously the engine response is better anyhow, but I think the low to mid range is quite a bit better than before. The engine pull pretty strong from as low as 1800 rpm, when 3000 -4000 happens there is strong acceleration. My engine seems to run out of puff after say 5500 but I usually don't rev it that hard anyway. The SSIs would probably help up around 5000 for you.

Interestingly I found by experimentation that the car is happier running with the ignition timing advanced slightly. If I set the advance at 4000 to the mark on the fan belt pulley the engine at idle indicated 0 degrees advance ie. TDC. I advanced the mark at idle approx. 1/4" on gthe pulley. Straight away the engine pulled like a train. no pinging issues

By the way I run 98 octane as recommended by porsche.

From what I read about the STD v. 964 cams the concensus was that the change is minimal in but it is the max recommended due to issues with the CIS.

hope this helps.

Greg

I thought the 964 cam was the thing to do when you did the MAx Mortiz mod, 3.2 SS.

That is what I am running. I don't have any prebuild dyno data but the change is quite dramatic. There definately is an "on cam" sense with this combo at about 4000-4500 rpm. The dyno shows a very smooth torque increase to that point. Because of that "on cam" feeling, you do feel as if you are lacking low end torque but it is an unfair comparison to the stock setup without a pre and post dyno comparison.

Hate too tell you this but with 964 cams you will make power till 7000 rpms. Not in the low rpms.

Interesting timing (no pun intended ;)) I was just talking to my engine rebuilder about this today!

When I had my euro 3.0 SC '82 engine rebuilt I switched to 964 cams. CR was left standard at 9.8:1 After it was run it had a different character than before. Although it now revs to 6800rpm

http://i142.photobucket.com/albums/r...ril_7k_rev.jpg

and makes 232.1 bhp it lacks midrange torque compared to the 3.0 SC cams. This 'seat of the pants' 'butt dyno' is backed up by the figures from the real dyno runs.

Here is the 'before' dyno plot:

http://i142.photobucket.com/albums/r...7DynoPlot1.jpg

and now the 'after' one:

http://i142.photobucket.com/albums/r...8DynoPlot2.jpg

To save the bother of trying to compare them (they annoyingly have slightly different scales !) I've summarised the differences below.

SC cams: 964 cams: SC cams: 964 cams:
---------- ----------- ---------- -----------
RPM: BHP: BHP: Torque: Torque:
----- ----- ----- --------- --------

2500: 85 81 (-4) 177 164 (-13)
3000: 105 98 (-7) 185 172 (-13)
3500: 128 120 (-8) 191 179 (-12)
4000: 160 145 (-15!) 209 190 (-19!)
4500: 180 171 (-9) 210 199 (-11)
5000: 200 191 (-9) 208 200 (-8)
5500: 210 216 (+6) 200 202 (+2)
6000: 216.6 224 (+7.4) 190 196 (+6)
6300: 213 230 (+17) 178 190 (+12)
6500: ---- 232.1 186
6700: ---- 232 182

Both runs were done on the same dyno (moved from one premisis to another). It's well respected here in the UK (used by motorsport teams to test cars for racing series) and has proven to give repeatable results.

I've lost almost 10% power and torque in the midrange. I've spoken to John Dougherty (Camgrinder) about this (he didn't actually supply the 964 cams in the end as he was out of stock, but is just a very helpful, knowledgable guy) and he reckons this extent of torque/hp drop is not normal for 964 cams in a 3.0 204bhp SC engine.

We're going to check the cam timing. Was supposedly timed at stock 964 figures, ie 1.26 and will maybe experiment with advancing it to try and regain some of the midrange torque. John said he'd recommended values as high as 1.8 for low compression (read 8.5:1) motors to regain midrange grunt.

So, does anyone know what the safe (ie avoiding valve/piston clearance issues) range of cam timings is for 964 cams in a 3.0 SC engine. Porsche specs only give the single 1.26 figure for 964 cams, not a range of values like they do for the SC. I don't want to move outside of the safe range!

As an aside, I also had the heads mildly ported during the rebuild and was wondering if that may have had a negative affect on the midrange performance ?

Cheers - Gary

thanks Gary for your post... I too want to know thew answers to your questions to see the differences.
Bob

I think I read some stuff here on the forum, that some guys has set the timing at 1,6+.
So I guess you'll be fine, but youl'll have to check the piston/valve clearance anyway. -But won't you loose some of the top end power?

Will probably lose some top end, but having done 10 trackdays last year, including the Nurburgring and having her lug out of the low speed corners I'll willingly trade some top end to regain the mid-range torque. It's that whole 'area under the curve' thing that I'm really being to appreciate now. 'It's torque that wins races' isn't that the saying ;) ?

I put 964 cams in my Euro 81 SC and it is only a street car. There was a noticeable difference in power. I also put in SSI's at the same time so I am not sure how much each contributed to the power.
But I will say that every morning I have a very, very steep hill to drive up to get my coffee. In low RPM's the lack of power is very noticeable. You need to be at least 3000-3500 to be in a comfortable power range.
But on regular streets I love to drive this car. It is my daily driver.

Noone got any values for timing 964 cams in a 3.0 engine then? :confused:

Btw, here's a (rough) plot of the before and after dyno plots overlayed on the same graph showing the mid-range losses:

http://i142.photobucket.com/albums/r...8/DSCF1630.jpg

1.26mm

Currently set to that SP2, but as you can see from the graph I reckon there may be more midrange to be had by advancing it from 1.26?

That spec is from john dougherty. I'll look at my dyno reading tonight.

Thanks, I'd be interested to see a post of your dyno chart SP2 :)

WOw 6800. My car feels like it will pull till it explodes. IF you fall below 4000rpms there is no power at all. It makes it very difficult to stay in the power band. I'm a novice driver and I'm sure that is some of the reason. An experianced racer drove my car and he said he had to be in a lower gear then his stock car to have any type of power. He liked what I had done but said it would be hard for me to learn to drive as a beginer. My car feels like it is still making power at 7300rpms.

What have you had done to your car crashmy911 ?

I would like to hear the engine setup of crashmy911 as well.

I have the same situation as the thread creator had. New 964 cams sitting on the shelf for 7 years and now my 81 US spec engine is out and on the engine stand and I want to put them in.

I spoke with Mayo in Dallas today about the task. They are in the same class as Steve Weiner. Steve is a god from my viewpoint after he convinced me to buy the MSD 6AL ignition six years ago over the phone. Anyone need a couple of dead Permatunes?

Tom at Mayo noted that the springs should be upgraded to somewhat stiffer than stock as the ramp on the 964 cam is steeper than the SC and can provide an opportunity for valve float if you spin your engine above 7k. He also said that stock and mild performance 911/930's that had been run routinely at high rpm in their life may have small, invisible to the eye, stress cracks in the spring retainers. He suggested for insurance that you replace these as well.

Don at Engine Builder Supply did not see a big problem with using new original springs but said that you optimally should set the spring height to 964 specs. Mayo did not stress the 964 spring height adjustment and said that using the original SC shims was fine - given getting stiffer springs.

So new springs are recommended - original (and cheaper) style if you feel lucky. I believe Mayo said there was 60 pounds pressure on the stock springs (at "rest") and 90lbs on the springs he buys from Engine Builders Supply. Under full compression I believe I heard the pressure was 180 (original) vs 250 (upgrade) pounds.

Mayo also stressed the usual CIS false air checks with the engine out. Stressing the injector o-rings and the injector sleeve that is in the intake runner which holds the injector and it's o-ring. There is an o-ring on that as well that you cant see unless you remove it.

Race springs and TI retainers on my motor Bob (a bit of insurance against the occasional high rev ;))

so guys, do we have any general concensous about using the 964 cams in an other wise stock 3.0L and is it worth the effort??
The points I read ~ infer from the posters are:
#1. at <4k RPM the engine will be a dog... above 4k to beyond stk redline of ~6200 it will pull significantly harder vs. stk cam. I interpret this as a trade off & not a good one for street driving, especially, no matter how aggressive one drives as it would require to run the engine at 3500 + rpm MINIMUM to avoid the sluggish acceleration. On the track a different story as you are running close to or at full out to perform best at race.
#2. If the above is understood and accepted, one should do more than just installing the cams and thinking they are all done with it. Higher spring rate valve springs, cups, retainers, shimming possibly are all recommended as the 964 cam will want to be used by the driver = driving & enjoying 4k-7k? rpm travels and you Do Not want valve float on these engines to avoid valve/piston collisions.
#3. my overall conclusion on this subject, AND PLEASE INFORM ME IF I AM WRONG, is that like ALL modifications to the engine, they need to be considered in the 'big picture' of what one is trying to achieve here and how best to accomplish such remembering that the engine is a 'complete system' and needs to be thought of as such. So, if I were to install 964 cams I would think it best to also swap out the OE pistons to allow for a more aggressive camshaft. A cam shaft that would still be compatable running CIS injection which is the REAL LIMITING FACTOR HERE due to reversion occuring when too aggressive os a cam is used.

So. what is the most aggressive pistion and camshaft we can use, retaining the stk cylinders & stk CIS injection, AND, THE ALL IMPORTANT QUESTION, "will this piston/camshaft combo not have reversion issues, increase performance vs. stk 3.0 engine and not have the <3500 rpm doggie performance?? (my guess here is IF this will work as I am sure someone has done some combo here that the parts cost was $1-2k + tune~set up time all for 10~20 hp which to me is not worth it... might this be the adage, "there is no replacement for displacement?")

Thanks all for keeping this thread alive and lets see if there is a REAL benefit option here via swapping in & out parts with what costs & +/- performance results.
Bob