I am in the process of an engine rebuild, and since I do have some cam pitting and am always looking for chances to boost performance, I am planning on a cam upgrade. Leaning heavily towards a 993SS profile. But I have a few questions I can't seem to find solid answers for.

1) Can the 964 stock camshaft be properly reground to meet the 993SS specs? I have found one shop that says yes and another says no.
2) Is it possible to identify characteristics of a cam profile which support low/mid torque development versus top end hp? Or am I off in newbie-land because it's a lot more complex than that? I am not a racer but instead looking for street and AX/DX performance improvements.

Thanks for any knowledge and direct experience you might have to offer. These are anxious times for me since my rebuild was somewhat suddenly forced on me due to increasing oil leaks - left me scrambling to figure out how to efficiently investigate and incorporate any enhancements.

 

Steve,

1) Yessir, your cams can be welded and reground (this prevents going down beyond the base circle), however new billets are recommended.

2) There are VERY few cam profiles that work with the stock OEM single-throttle intake system so your real-world choices are limited to stock (perhaps tweaking the cam timing a tad) or the 993SS ones. These latter ones shift the effective RPM range up a bit without compromising bottom-end torque very much at all. We usually go to the trouble to install larger intake valves to take full advantage of the cam upgrade,....

Hope this helps,

 

Thanks, Steve. I ended up talking with Webcam today and they confirmed that regrind of a stock 964 cam to a 993SS profile cannot be properly done without a weld buildup. Turns out the new cams are not much more than the welded and ground ones, so it looks like I will go the new billet route you suggest. Another source lists three profiles and their characteristics. Any chance you can educate me (and other novices) on the effect of the differences (albeit slight) in these three profiles?

-993 Super Cup (modified): duration-248/234, lift-.490"/.455", lobe center-114 degrees
-Sport 964: duration-248/238, lift-.490"/.470", lobe center-112 degrees
-Web Cam 993SS: duration-260/240, lift-.490"/.446", lobe center-112/110 degrees

Thanks for your time and expertise!

 

Try also talking to Jim at Dougherty cams. Very pleasant chap.
They do a DC21 camshaft which works well with stock 964 engines and is one step up from a supercup camshaft. I am advised they work well with intake and exhaust upgrades and will also work with an aftermarket chip.
I have been told that with all else stock, they see around 25-30RWHP which by my very rough calculations should be around 25kw at the crank.

ie: 25-30hp x @1.32 (for drivetrain loss) gives 33-40hp crank. Which is 24-29kw at the crank.
They are very well priced for new billets.

Mine are going in next week so I can let you know how they go.....

 

Jim please do report on the cams when they are installed. Thanks!

 

I had my cams reground by Elgin Cams in Santa Rosa, CA ... Dema told me that the 993 cams are a bit too much for 964s ... He's been doing cams for quite a long time and anyone I talk to around here states that he knows what he is doing.

So far so good, I've had a pretty good experience with them. Plus, it didn't cost me a fortune to get them done.

(no affiliation with Elgin Cams. I'm simply a customer)

 

Thanks, Jim. I have emailed John at Dougherty, and he replied that they could regrind my 964 cams to their 993SS specs. Not sure if that is a good idea? At the price quoted there couldn't be any welding involved. I have also gotten a recommendation from another distributor that their DC21 camshaft is a good possibility. The DC21 appears to be similar to the 3.8 supercup, but has a bit more exhaust duration and lift. Thanks for your advice, and I look foward to hearing about your results.

I have not contacted Elgin directly, but in reviewing their website I do not see a any 993 labeled cam, so perhaps that jives with what you are saying. They do list three profiles for the C2 which appear to be pretty high performance (maybe too much for me). I will have to call them directly. Thanks for the tip.

 

Dema will recommend that you go with his mildest grid. Something as aggressive as a 993 grind can lead to drivability issues or will lead to a need for a high idle. Overall, and don't quote me on this, as i remember the mild regrind for a stock 964 will yield an overall 5% power increase through out the power band. Anything more aggressive and you will need to up your intake capability.

Don't judge this guy from his website. I met him face to face, and he is truly old school. He has much more experience with cams than he does with keeping his site up to date.

 

These common-plenum, single-throttle intake systems are quite sensitive about intake reversion which means one pays very close attention to lobe centers. This prevents drivability issues.

I won't tell you which cam to use, but I will tell you that cams with 112 deg LC's will cause you grief (idling, surging, etc) so whatever you decide on, I'd suggest maintaining the stock 114 deg LC's and you'll be quite pleased.

JMHO, but I think Dema Elgin is THE best cam person out there.

 

Paulie, thanks for your comments. I am concerned about adding too much cam upgrade and ending up with drivability issues, so your point is well taken. I want to be careful not to bite off more than the stock intake can take advantage of. I appreciate your perspective.

Thanks, Steve. Your comments make sense and line up with Paulie. That is an interesting point about the lobe separation angle since I do not want to get into issues with street drivability. Question though - isn't the stock spec for this 113 deg? You have convinced me to contact Dema Elgin Monday and see if he can get me settled down on a new profile that matches my interests.

Thanks very much!

 

I seem to be finding slight variations in the specs for the stock 964 cam profile. Can anyone positively confirm or correct these numbers?

240 deg Intake duration (@1 mm basis)
230 deg Exhaust duration (@1 mm basis)

.470" Intake lift
.430" Exhaust lift

113 deg lobe angle

1.26 mm overlap

In looking for a higher performance cam profile I want to make sure I am comparing it to the correct stock data.

Thanks!

 

Talked to Dema Elgin today, as a couple of you have wisely recommended. He answered the call himself. His first name is pronounced “deema” in case anyone was wondering. Very easy to talk to and quite helpful. Based on a brief description of my situation (in the middle of a “while you’re in there” engine rebuild) and goals (to pick up some low-mid range power & torque for street and A/X driving, but without risking drive-ability, reliability, and “issues“), Dema said the best candidate is his Super C-2 camshaft - what he terms a mild regrind of the stock cam. It is noted on the website as “one step up” for the 911 C2. The spec’s for the stock 964 (I think I have it right, but please correct/add as needed) and the Elgin Super C-2 are:

cam table.png

You can see that there is not much difference between all parameters except for overlap. Steve W, I took your comment to heart about the lobe center angle as you can see it is identical to stock. Dema obviously agrees with you. Despite trying to find out more about overlap and the effect of its variation, I must confess I am not sure why Elgin chose to nearly double it for his Super C-2 versus the stock cam. I didn’t notice the difference until after our telcon. Any thoughts or concerns?

In case you’re wondering why I am only marginally upping the performance of my camshafts, my reasons are (FWIW) - the regrind is reasonably economical and quick, I am already upping my displacement to 3.8L, and I am getting more cautious because of worry about the risk of making too much of a change. I am also having Steve Wong make me a custom chip, so I think that will get me where I want to be without being too greedy.

BTW, Dema will also polish the rocker arms and QC the bushings.

So, that is where I am heading. As always, any comments are of interest to me. Cheers.

 

Anyone using this cam in their 964? Care to share your experience with it?

Thanks.

 

FWIW, I have been advised that the Dougherty DC21 camshaft is done on a 113 lobe centre and will probably give better gains than a Supercup camshaft. I will have mine in and dynoed hopefully by next Friday so I'll be able to provide details on gains then. I can't verify this personally as i have no personal experience with the Supercup camshaft. I have had several associates here install the DC21 in 964 and 993 engines and they are very happy with the results.

 

Thanks, Jim.

According to the Dougherty website, the DC21 has a 112 deg lobe angle. Their DC 20 is called Super C2 and looks to be essentially the same as the Elgin Super C2.

I look forward to hearing how things turn out for you - hope it goes well and gives you what you were looking for.

Amazing how the complex nature of cam profiles and their effect on performance, when combined with personal tastes, can make it so hard to decide!