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Wildcat96's Avatar
 
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Location: Fort Worth, Texas
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SC Cam Question

Hi All,

My 81 930 is currently at Imagine Auto for a new clutch, cross threaded spark plug fixed, and oil leaks taken care of. I was talking to a friend this morning that was telling me I should have SC cams installed in the car since the head was off. My car is completely stock and would appreciate your opinions about SC Cams.


1.) How would SC Cams affect the power delivery on a stock car?

2.) Would I need to change the exhaust, Etc to accomodate the SC Cams?

3.) Would SC Cams affect the long term longevity of the motor?

4.) What is the average cost of a cam replacement?

5.) Are there any drawbacks to replacing the cams on a stock car?


Thanks for your input!!!!
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Old 07-12-2008, 07:11 AM
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I was really close to doing this until the "while you are in there" list started to get too crazy so I stayed stock. If you are replacing the cams you should also increase the port size of the intake. Also you can mill the head and cut the cylinders for the fire ring. Once you start to figure all that stuff out it just makes everything crazy.
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Old 07-12-2008, 08:42 AM
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Cymru am Byth
 
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I had my stock cams reground to SC profile, off boost, engine is more responsive for better drivability and gain in HP. If you are going to change the cams, you should do the other upgrades, turbo, exhaust, headers etc, these are easy bolt ons, and you can do them as money is available.
You should talk to Stephen at Imagine, he's the man.
Glad I did it.
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1986 930 (Gone but not forgotten)
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Old 07-12-2008, 09:44 AM
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Julian, did you port the heads when you changed cams?
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Old 07-12-2008, 10:12 AM
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Crotchety Old Bastard
 
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All '81 930s are 300HP Euros. The stock exchangers are pretty good.

You don't need to remove the heads to change the cams. They are easier to change with the engine out of the car though.

SC cams are great. I have them in my engine with a K27-7200 and stock Euro exchangers like you have. Heads are stock as well, no need to port them unless going after big power.

You should consider a more modern turbo if yours is still stock. HUGE difference when combined with a cam swap.

How much? Pricing is subjective. If the engine is out of the car it is a couple hours work to R&R and dial them in. They should adjust the valves while at it.
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'78 911SC Widebody, 930 engine, 915 Tranny, K27, SC Cams, RL8 Headers & GT3 Muffler. 350whp @ 0.75bar
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Old 07-12-2008, 10:53 AM
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DSp Turtle,
Had the heads completely rebuilt, but did not port them, decided I was not going to try to make big HP, just good solid reliable HP, so left them stock.
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Old 07-12-2008, 02:22 PM
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Can anyone give a comparision of the differences of using either the SC or 964 cam specs in a stock (for now) 930. Also, any suggestions on who to use to regind the stock 930 cams to either SC or 964 specs.

I love this place...
Old 07-12-2008, 03:45 PM
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We were going to send mine to Web Cam before I chickened out on it. Apparently they are one of the best for the regrind.
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Old 07-12-2008, 03:50 PM
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Quote:
Originally Posted by Gregsgroup View Post
Can anyone give a comparision of the differences of using either the SC or 964 cam specs in a stock (for now) 930. Also, any suggestions on who to use to regind the stock 930 cams to either SC or 964 specs.

I love this place...
I considered the SC cams but finally went with 964s. John Dougherty is a real expert and posts often on this board. His site has the lifts and durations on virtually all of the cams we might use http://www.drcamshafts.com/911profiles.htm

The 964 cams are just a little bit more aggressive than the SC cams and still are very streetable in our engines.
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Old 07-12-2008, 05:26 PM
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SC for me. Per Stephen's recommendations along with opening up heads, Carrera intake, Motec, yada yada. Very nice off boost. 5k miles on rebuild and love it. Webcams did the grind, timed well on install.

YMMV
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Old 07-12-2008, 05:43 PM
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What's the typical cost for a regrind to SC specs?
Old 07-12-2008, 06:07 PM
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Here is a money saving tip on cams for street cars. Since these are forced induction systems and low compression ratios, you are not going to gain that much with different cams until you open up the rest of the system. In the mean time, do two things: advance the cams for improved low end response and then make sure the valve lash is dead on. You will notice a difference without replacing a thing. My favorite cams on my CIS car were 964's.
Old 07-12-2008, 06:09 PM
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So you don't think a 964 cam is overkill on a 3.3 with stock heads & CIS?
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Old 07-12-2008, 11:43 PM
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I used WebCam, IIRC, cost was about $700.
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Old 07-13-2008, 06:16 AM
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Cams are the heart of the motor. The motor is an air pump and the cams manage the air flow thru lift and duration of the valves. The stock, SC and 964 cams all do well on a reasonably stock motor given this is a forced induction motor. If you use your car for street use, I doubt you'll notice a difference if nothing else is changed. On a dyno, you'll see a difference. If I remember correctly, when I went from SC to 964 cams, I got about 20 hp on top. Then I started playing with the timing and found I could feel the difference on low-end off boost throttle. If I wanted top end I would have retarded the timing.

My point is, just changing the cams on these motors is not like changing cams on a naturally aspirated motor. There are better places to spend money - like like try a straight pipe or straight through muffler for a real kick on a stock motor (get rid of post-turbo back pressure).
Old 07-13-2008, 06:30 AM
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I completely agree with that, but he is thinking about the "while I'm in there" aspect of changing cams.
If he wants to change them at some point but doesn't plan to do it himself it should be less expensive to do it now while the engine is out and apart.
I'd get a quote for the added work to be sure.
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Last edited by RarlyL8; 07-13-2008 at 06:53 AM..
Old 07-13-2008, 06:46 AM
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Gregsgroup,
The two mentioned, John Dougherty & Webcam, charge IIRC $275 for a regrind. I am no expert, but in my reasearch if you use SC cams from an SC a "boss" is missing to run the scavenge pump? Now that you are looking at cams, you have to decide SC or 964? Here is interesting reading
euro 1982 turbo with 964 cams question
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Old 07-13-2008, 09:22 AM
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Thanks everyone for your input!!

I think I'll stay stock for now.....

Can't wait to get the car back as it's been at the shop almost a month and it's a beautiful day today. Guess I'll have to take the Camry for a drive instead.
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Old 07-13-2008, 10:04 AM
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Before you give up, check with Stephen @ Imagine Auto. he has a special grind that really works. I think he posted a dyno sheet showing exactly what they made. Very impressive. Fitting these and doing the other work suggested will give you a big kick in the pants.
Old 07-13-2008, 11:58 AM
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In the mean time, keep an eye out for a set of stock SC cams. I picked up a set of brand new ones on evil bay for $150 shipped. Then had John Doherty machine on the scavenge pump drive for another $150. $300 bucks, and didnt have to alter my stock cams (for when I put it all back to stock...if that ever happens)
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Old 07-13-2008, 01:18 PM
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