Best Cam Profile For A Stock SC?

[smestas]

Greetings All,

I’m nearing the end of my engine rebuild and have a dilemma. I want to step up my stock cams but I’m not to sure which Elgin profile to choose from? They have two profiles to chose from for my engine (SportSC/330 or 964) but I wanted to hear from those of you who are running either cam with similar specs to my motor. My motor is a '78SC 8.5 compression ratio and the larger early SC intakes, boat tailed case, and a stock exhaust but is slated for headers and a dual in single out.

I did a search on the cams and have found good replies on both profiles. So which one would you recommend for a mostly street/canyon car with a few DE's a year.

[aigel]

If you searched the archives, I am sure you found John (camgrinder) clarifying Elgin's grinds. He clearly states that he wants to see higher than 8.5 compression for the 964 cams and that the 330 cam is what he recommends for the lower compression SC:

http://forums.pelicanparts.com/showthread.php?threadid=150334

Cheers, George

[oneblueyedog]

Since I have the stock Mahle P/C's (new) I used the SC/330 cam grind. I timed the cams in the middle of the specified range. Deck height was measured at 1.3-1.4 mm Power surges on at around 3500r.p.m. and pulls without flattening to 6000r.p.m. My engine prior to the rebuild was out of breath at around 5500. I'm also running a colder plug from stock.
I boat tailed the webs too.

I think Dave at Elgin and Dema both said that this cam gave about 10 more horse power to the wheels. It was nicknamed "The Cheater Cam".

I have yet to dyno the car. I don't know what I had before the rebuild. The next two mods I make will be a Euro pre muffler and modify one of my 2 mufflers to dual outlet. Then I'll dyno it.

I have lost 2 mpg in fuel efficiency.

I did not realize the acceleration difference until a friend of mine drove it and I sat in the passenger seat. I definately had to strain my neck and back when the cam came on. He felt it too.

In hindsight I have no regrets at all. It's much more fun and different to drive.

Lee 78 SC

[Superman]

I have a strong suggestion for you. Maybe a couple. First, I can tell you that those of us who are using the WebCam 20/21 grind are VERY happy. My car pulls strong and smooth at 1000 rpm, stronger at 3000 rpm. Peak torque levels out at 4000 rpm and stays there until after 5000 rpm where it falls off very slowly. horsepower curve flattens at 5000 rpm and stays that way until past 6. This car has a power curve like a V8 and is highly fun to drive, as a result.

But there is evidence that you need air volume and air velocity, to make them work best. With your fatter intake runners and low compression pistons, you will not get this velocity. Since your intake system is much more robust than mine, you have the convenient opportunity to just change pistons, or P&Cs to solve that problem. You can use somebody's used set of P&Cs (mine are Alusil and I re-ringed them with no problem whatsoever) which should be available very cheap. Go with a set of the later 9.3:1 pistons, or splurge and get some JE pistons with the more sensible dome shape in the high nines (9.8:1 or something). This, combined with a good set of cams (like the 20/21), will make your car a fire-breathing dragon. You'll have a faster SC than almost anyone else, with minimum cash outlay.

[911nut]

All,
What would be the total cash outlay to re-grind the cams, including all the stuff that has to be bought in addition to the cam regrind (20/21 is $750?)
Also, can cams be removed/re-installed via a partial engine drop?
Thanks.

[aigel]

For cams the engine has to be completely removed.

All you need is to regrind your cams and refurbish your rocker arms or buy new ones. Total bill for that is $750 if you include seals and buy new arms.

WebCams is real pricey since they reweld and reharden cams or even sell you new billet ones. I think that's overkill. You can have your cams reground to ANY spec at Elgin for much less.

George

[rdane]

From what I have seen on the dynos the 20/21 cam is a better tool for the 8.5:1 SC over the 964 cam. My USA '79SC was 185rwhp/215 at the crank with SSIs a sport muffler and 20/21s and 190K miles on the clock.

I used the same cam for a 3.4 CIS conversion and am very impressed this far (300 miles). Not always, but some times you actaully get what you pay for.

Seeing Superman's, mine and several 964 dynos I think the 20/21 is a better cam. I have not seen any of the Elgin dynos.

[aigel]

Originally posted by rdane

I used the same cam for a 3.4 CIS conversion and am very impressed this far (300 miles). Not always, but some times you actaully get what you pay for.

Seeing Superman's, mine and several 964 dynos I think the 20/21 is a better cam. I have not seen any of the Elgin dynos.

I am not going to argue grinds. I think at some point it is a wash. People swear by this and by that. There is only so much that mild cams like these can differ. There isn't the magic grind that will produce 10% more than the other.

The original question in the thread was if a 330 or a 964 cam should be used. You have not added much to that discussion by pushing the web cam at twice the moolah.

What I wanted to add is that there is nothing magic about that 20/21 grind. Any other good cam grinder can set you up with exactly that pattern. There is no patent or IP on it that will keep someone else from grinding it for you. So, why pay twice the money at web cam? I guess someone has to help them pay for their ads in magazines ? I sure would rather contact John (camgrinder) and ask him what he cand do for you. Ask someone that has done this for decades!

Sometimes I am sick and tired of the fact that we Porsche people get taken to the cleaners for services that would cost a third if it were performed for an American racecar. The cams are a good example. There is no reason that they should cost as much as web cams is charging. Especially for the DIYer, the parts cost is a big factor.

Cheers, George

[smestas]

Thanks for the feed back guys!

I was told by the seller that the 330 cam was the way to go but I just wanted to hear what the entire collective here thought since I have the choice right now between the two profiles. I guess if I had better compression then the 8.5 the choice for me to go 964 profile would be easier. I’ve already ordered the 330’s but the little voice in my head last night kept saying “are you sure you don’t want 964’s and a few more ponies”.

I was hoping to see if there were any members out there with 8.5 compression with 964 cam profiles to see how they like them.

[rdane]

Lots of thoughts on cams. My feed back isn't from cost comparisons or personal preferenece just what I have seen on dyno results.

Cam grinds are typically proprietary and developed on dyno results. (or should be any way) May be it is all a wash but that isn't what I have seen from actual dyno results. When it comes to CIS and cams I would say it isn't the case at all.

It is a false economy IMO to not spend a few extra bucks for the right stuff the first time when the engine is apart. Labor is the issue the majoriy of time not the cost of the parts. The DIY's time is worth every penny of the professional wrenches. I would hate to regret using the wrong cam.

George says I haven't added much to the conversation. I spent almost a year collecting info on CIS mods and hot rods and the dyno results that back up the results instead of the typical horsefeathers that get spewed on a BBS.

There is a differenece in cams for a CIS system. Take a look at the differences in torque curves and where the engines run out of HP
if you want to make a comparison.

Seeing Superman's, mine and several 964 dynos I think the 20/21 is a better cam. I have not seen any of the Elgin dynos.

I have enough info to recommend the 20/21 over the 964 for this aplication because it is the same as my engine originally. But like I said in the first post, I have not seen a Elgin dyno to make a comparison.

Easy enough to get some good info by what Elgin posted on the other thread in their 330 and 964 comparison. Take the comparison I have already made between 20/21s and 964s, apply Elgin's own comments, and the performance preference for me seems obvious.

Web cam is an improvement on the 964 for CIS by the dynos. Elgin says his 330 is a better offering for the low compression cars over the 964. I would like to see the dynos.

VMMV but at least Superman and I added another data point that may have been missed because of budget restraints.

[smestas]

Rdane,

There is a dyno report on this thread. Its from a SC with the SportSC/330 Elgin profile.

http://forums.pelicanparts.com/showthread.php?threadid=150334

[emcon5]

Charlie Stylianos has SC330 cams. His dyno sheet is here:



Not a low compression engine though.

Tom

[rdane]

The original question was "best cam profile for a stock SC?"

Which is the question I answered.

Here is a 20/21 and the 8.5 pistons on my '79. Check raise, duration and drop off as comparisons. Not a lot in CIS but I don't want to leave anything on the table either. I paid $670 for my 20/21s plus a new set of OEM rockers which were $30 each.




Superman's '83 rebuild (reringed @ 9.3?)




Add these comments from Charlie to the mix and I'll still recommend the 20/21 for CIS.

Originally posted by kstylianos
As another comparison, here is my recent dyno chart. 82SC 3.0 liter, 9.8:1 CR JE's, single plugged with Elgin SC330 cams, SSI's and Dansk sport exhaust. The early 80's intake ports and runners were opened up to 36mm. It's interesting to see the max torque numbers and curve are fairly identical and the HP curves are also VERY close. I think this is also an interesting comparison between 964 and SC330 cams.

[Superman]

When we gathered for beers at the close of the dyno run you see just above, our Group Engineer (and he knows who he is) stared at my dyno results. Absolutely stared. His assessment was quite favorable.

Now, after driving the car and looking at the results some more, I think I understand. It looks like a table top. No, the 20/21 cam is not a peaky race-cam. But if you want driveability and big fat loads of torque over a very wide rpm range, well....look at the above dyno results some more.

Other aspects of cars and engines lend themselves to mathematics better than the aspect of air flow through the heads. That's more like art/magic. And yes, little tiny curve differences, even between cams with the same lift and duration, can make a big difference. I have to agree that 20/21 cams are pricey. And effective.

And I still STRONGLY recommend some higher-compression pistons to go with them. THAT'S where you get power. Displacement and compression. Cams just adjust where the power occurs in the rpm range.

[smestas]

So would you guys say that the 20/21 grind is closer to the 330 or 964 profile?

[rdane]

Not what I would have quessed from the dynos as I would have thought the 330 and 20/21 were closer..but this from the guy who makes them. Web cam says the 20/21 is "Special performance grind for 911SC/ Carrera/ 964 engines." And they say a hotter cam for our use than the 964. I read that to be closer to the Super C from Elgin.

Originally posted by camgrinder
I hope this will clarify the grind names...

(Sport SC) is the same as 330 SC and is a one step up camshaft I recommend for 8.5-1 compression ratio engines. It also works well in Turbo engines.

(964 ) is the our version of the factory 964 C2 profile. Its a 2 step up over the SC stock grind and I like to see 9.3-1 or better with it.

(Super C2) is one step up for a 964 C2 and a big step up for an SC. I like to see at least 9.8-1 compression with it.

If you need more cam than the Super-C2 , there are other profiles available and we dont mind doing custom stuff and changing lobe centers.

Hope this helps,
John Dougherty
manager @ Elgin Cams

Gaining 500 rpm on either end of the curve in these cars does make a difference as does a really flat torgue curve. Both make the cars more fun to drive on the street. Here is Noah's dyno and his comments:

and a link to all our 3.0 dynos and specifics
http://69.55.224.199/quelle/phpBB2/viewforum.php?f=6&sid=ae93426101e73b8a4e6242d8375bc47b



Max HP: 203
Max torque: 176

"The straight line is the horsepower curve, and the peaky line is the torque curve, for those who were interested in seeing what the 964 cams look like on a dyno. "

[dd74]

Originally posted by aigel
...There is no patent or IP on it that will keep someone else from grinding it for you. So, why pay twice the money at web cam?

Actually, I've heard WebCam's grind is is protected, just in the same way Eastman-Kodak has exclusive righgts to the yellow coloring of their packaging. But I digress...

For all intense of purpose, which is to get the highest lift and fattest duration of a CIS-based cam, Superman and Dane not withstanding, every shop I've talked to recommends the 20/21 cams. The inherent problem with the cam entails smog testing, as a 3.0 equipped with such cams may not pass. The 330 or 964 might give a little more leeway with smog issues.

As for Jim's suggestion of a hybrid 3.0: if at all, and when the time comes, I'll probably break down my motor and build exactly that - late pistons, early induction, 20/21s and headers (if I can stand not having heat). I'm told the expected hp for such an engine would be 215-220 hp.

[smestas]

Why does that last dyno have the big dip in the middle of the torque curve as opposed to the nice table top shape mentioned previously?

[echrisconnor]

Lots of info here. Trust experience. Elgin knows what they're doing. Webcam has a great 20/21 grind, for which Elgin has their own interpretation (I believe it's the Super C2). Either case, match the cam to the rest of your engine.

My decision was made in my previous post. If you're staying with 8.5:1 CR, go with the Elgin 330. If you have the higher CR, then go for a more aggressive cam.

My engine will be coming back together in the next couple months. I have no frame of reference at this point, but I expect good results with the 330 and my 8.5:1 CR. Hard to say whether I would get more power with a different profile, but since I'm not changing pistons, I wouldn't expect better results with something else.

[rdane]

Originally posted by smestas
Why does that last dyno have the big dip in the middle of the torque curve as opposed to the nice table top shape mentioned previously?

My take is the 964 was a fluke...some one tried it in a CIS and went whahoooo! Then the cam guys decided to better the 964 for a specific purpose, CIS, ...and you have the 20/21 and the Elgin version. You could spend hours looking at the graphs and the different mods made to get the end results.

As Jim mentioned cams work with the rest of the engine. Plan well, do your own research, trust no one