Opnion on new cam profile for 2.7 rebuild
 

Has anyone used a SC profile for the cams on a 2.7 motor. I spoke with both Elgin and webcam and they suggested an SC profile would be the best for my setup. Anybody have this experience and how do you like it?

PROFILES:

74-77 911S CIS Lift In .410 Dur In 220 deg. LC In 118 deg.
Lift Ex .348 Dur Ex 200 deg LC Ex 103 deg.

911 SC / CARRERA Lift In .450 Dur In 232 deg. LC In 112 deg.
Lift Ex .400 Dur Ex 222 deg. LC Ex 113 deg.


Why is there such a big price difference between Webbcam ($670)and Elgin ($275)? Is Webcam worth it?

I am in the middle of a complete engine rebuild on 2.7 from my 75 Carrera (USA). Most things will be left stock including the CIS except:

-SSI's
-Dansk Sport muffler
-11 blade fan
-Carrera tensioners
-New Mahle RS pistons
-Sachs sport clutc.
-External front oil cooler

Thanks
Eric

it's starting to sound like this is going to be the year of the 2.7.

there are a couple of threads bouncing around on this subject.

are the rs pistons 8.5:1? if so the sc grind is also what I've heard to be the best fit too.

if you were looking at bumping compression, i've heard you can go a little wilder with the cam.

Hey Big Al,

Yes, they are 8:5:1 RS pistons.

I just read your post and see you have been researching also. Everone told me that the SC profile is a great match for the CIS.

Have you figured out the price difference between Elgin and Webbcam?

Also, I understand you have to buy new rocker arms as well...

Eric

Hi Eric,
I've posted several fact-finding threads on this subject lately. The rockers don't necessarily have to be replaced, although it's recommended for a smoother fit with no worn/rubbing areas. This is what I've been told.

Did Elgin happen to mention any other 'radical' alternatives? We're exloring 9.5:1 compression pistons and something analagous to the 20/21 or c-2 grind used in the 3.0. Wish I knew if anyone on this board has gone more radical with the 2.7 CIS with dyno results to back it up.
Ryan

Hi Eric,
Just noticed you're in Miami. I lived there for about 10 years through the nineties...loved it. Lived in Coral Gables, Hialeah, Miami Gardens, the Beach...whale of a good time and buttloads of memories. You been there long?
Ryan

Ryan, yes been here since 1987 went to UM and stayed. I live in Coconut Grove. Alot of good times, but ready to move out of this Bannana Republic.

Tom I will have to read the article again. I think you are correct about the JE pistons. I wonder why they said it was a mistake??

I am confused about something.

Assuming the 2.7S and the SC are similar engines (approx same compression and injection system), the 2.7S has slightly more power per litre - it implies the cams are a very similar or slightly more performance oriented grind. To me, an SC grind (rather than 964 or 20/21 or whatever) is a backward step.

Have I missed something?

here is a thread from rennlist about telling the difference between nikasil and aluisil from the outside. it's long and still leaves me wondering.

http://forums.rennlist.com/rennforums/showthread.php?threadid=4341&highlight=nikasil+alu sil+tell+the+difference

Good god...talk about having to split hairs! Hard to find a consensus...and some argue one is no better than the other. :(

Ryan

Definitely sounds like the fuel delivery could be an issue with higher compression, 2.7 already on the lean side. SC fuel distributor and WUR recommended...$$$....hmmm. But sounds doable...
Ryan

Another reply from Steve on the subject. Starting to sound grim for this idea:

Steve,
> Excellent reply! Not exactly what I'd hoped to hear, but what you report is
> logical.
> Fuel delivery would be a problem...certainly don't want any leaner mixture.
> Agreed.
> SC fuel distributor and WUR could be done? That might work nicely, but up
> goes
> the cost. SC cams...what about pistons with this setup? Could you or would
> you
> go as high as 9.5:1?
>

The only way you get 9.5:1 with a 2.7 is with custom JE pistons. You cannot run
those in an Alusil bore so one would need to either bore and replate with
Nikasil, use perfect used 90mm Nikasil cylinders, or bore to 92mm and use a
custom set of 92mm JE's. We've done al of these,....

>
> I certainly wouldn't hold you to this estimate, but what would be your
> ballpark
> for this engine, sc fuel distr/WUR, sc cams, higher compression
> pistons/rings,
> new rockers? I've got the 8:1 150 hp at the crank stock 2.7 now. Really want
> to keep the CIS, it's a daily driver, not a track car (this is Arkansas - no
> track :( ).
> Only am really exploring options that keep the CIS in the picture.
> Thanks!
> Ryan
>

With the 150 HP 2.7, the benefits of SC cams are nil, unless you equip your
engine with all of the 175 HP pieces: heads, intake manifold, airbox, etc. This
is now getting spendy and IMHO, just not worth it. Its FAR more cost-effective
to install a good SC motor and bolt on your SSI's an a good sport muffler.

I've done this exercise so many times over the past 20+ years and the results
are always the same. One can either make a 2.7 RS clone of some kind, or install
a 3.0 SC or 3.2 Carrera for great drivability and longevity (with good oil
cooling).
--
Steve Weiner
Rennsport Systems
Portland, Oregon
503.244.0990
E-mail: porsche@rennsportsystems.com

For Porsche High-Performance Solutions, Racing Components and
Performance-related Information
Visit Rennsport Systems on the Internet at:
http://www.rennsportsystems.com

For cost justification (ha)...I need to know if I've got alusil cylinders. How much is it to bore and replate with nik for those custom JE 9.5's? Next, how much for an sc's fuel distributor and wur? Probably more variance on these two items.

Question remains posed to Steve about intake manifold, airbox, etc. I don't even have the same ones that the 2.7 that cam with the 's' cams have I don't believe.
Ryan

I made some calls when I was starting my rebuild earlier this year, and EBS quoted me ~$1900 to replate my Alusil jugs with Nikasil, with JE pistons to fit.

That Rennlist article aside, I don't think there is any way to tell alusil/nikasil from outside. There seem to be exceptions to each "rule" described (number of fins, rib)

Tom

Aren't the Nikasil cylinders somewhat magnetic? I read about that somewhere in one of these threads.

Tom,
That sounds right. I've heard the pistons alone quoted for ~$1400 at JE...must make the bore/plating ~$500.

DD74,
I think I've read that as well, but I've heard arguments that neither is better than the other...so to me, whether or not this step is necessary is apparently still open to debate (by those more knowledgable than myself ;) ).

Here's Steve's final reply on the subject. It applies particularly to the 2.7 L with the 8:1 pistons, etc. The model with 'S' cams need not apply. Apparently the former doesn't draw enough air for the setup in Steve's opinion:



> Spendy for sure, I suppose. My original question was predicated on using the
> custom JE pistons, doing the bore and nik plating. Your last point has my
> attention: with this albeit pricey setup, would my 8:1 engine still need all
> those 175 hp pieces...intake manifold, airbox, etc.? Price being no object,
> just wonder if it could work. Last question I promise and thanks again for
> your time and prompt replies!

Well sir,.......engines are air pumps and if it cannot bring in more air, it
cannot generate more power. There is no point, and in fact a waste of time &
money to install different cams unless you increase the engine's abilities to
breathe. If you cannot change the heads and induction system to the "S" spec
ones of those years, then I would stick to a displacement increase and a modest
increase in compression.

Price being no object, yes but not as well as a good SC engine with a proper
exhaust.

--
Steve Weiner
Rennsport Systems
Portland, Oregon
503.244.0990
E-mail: porsche@rennsportsystems.com

For Porsche High-Performance Solutions, Racing Components and
Performance-related Information
Visit Rennsport Systems on the Internet at:
http://www.rennsportsystems.com

Ryan: I've been giving some thought to your situation. If you have a well running 2.7, even with 150 hp, it is still a well running 2.7 that is quite fast regardless of what other Porsches have in the way of horsepower.

To improve these engines is so tremendously expensive, that I've often wondered if they merit improving. In other words, if what Steve and others have said about the 2.7 being at the top level of its engineering, is it worth it to pour thousands of dollars into something that won't, as you thought, net you 200 horsepower, but might get you 15 more horsepower?

My thought is that you should wait until it needs rebuilding to do any improvements. By how you explain things, it seems the engine may last a while, which will enable you to save up some money before you need to address a rebuild. By then, you might consider a larger engine or a different car entirely.

As it is, Tyson Schmidt once told me that at Willow Springs Raceway, a 2.7 is able to post very respectable times, meaning to me that if not in straight-line out-and-out powerful, with a combination of lightness and driver ability, it is still a capable and competitive car.

Heck, maybe your engine will last to the point where if an RSR motor becomes available, you won't bat an eye at dropping $10K for it.

DD74,
Very well said. I'm beginning to face reality, I believe. What you say is true...my car is very quick right now and running very well. I'm in agreement that I wouldn't realistically consider doing this until rebuild time and I don't know how long away that is.

Unless someone comes up with a miracle suggestion, I'm probably better leaving things alone. This one is so pristine, that I think it's becoming more of a rarity every day. My goal before this talk was always to make it look like it did when it left the showroom, but not a garage queen, but rather a daily driver that fools the average person into thinking it's much, much newer.

I don't doubt that with the right driver and suspension mods, it would post respectable numbers at the track. If I learn anything more I'll ceratinly post, but for now, like you, I'm unconvinced it's practical for my car...we'll see.
Ryan

i would stay with cis or move to the after market computer driven fual inj. s.d.s. or electromotive or who ever b4 subjecting myself to mfi or carburation for more pwr. cis and 964 is a good option