Do SC engines drive like S engines?
 

I have an '82 SC with the typical stock 3.0 engine. It doesn't really "come on the cam" until about 3000 rpm and peters out around 5000 rpm.
I have read that the 2.4 engine with S cams has to be driven in the upper rev range to be fully enjoyed.
Aside from the lack of sharp throttle response inherent in the CIS cars, is the 3.0 similar in behavior to the S powerplant?

Not really- the early S engine is far 'peakier'. The SC engine has extremely mild cams that the CIS injection requires.

SC engine has relatively high torque at low revs... not the case with the S. SC is in the peak of its powerband from 3000-5000 where it peters off a little. With the S you really need to get above 4000 or 4500 for some 'kick' then you're good until redline.

Ive been quite impressed with the feel of cis SC3.0's. Ive been underwhelmed by the carreras lack of feel off the line

My SC engine pulls hard from 3000 all the way to 7000 and doesn't fall off at all, and all I did was bolt on a minor intake and exhaust modification ;)

Seriously, an SC engine is much easier to drive on the street because of the torque, an early S engine has been described as almost too peaky.

the 3.0 l plant can be made more usable with the ssi install. night and day difference.

I'll bet an Early S ( stock ) would have is hands full with an SC ( stock) especially in the corners were torque would be more beneficial.

Anybody have any experience racing the two ?

The 2.0 - 2.4 S doesn't even wake up till 5000. It is far peakier.

The smaller displacement motors are the peakiest. The later 2.4 have a slightly broader torque curve.

The SC motor is much easier to drive in the corners, but the S has greater potential if driven properly.

I've driven my 2.0E (not quite an S) and a 3.2 Carrera. They're absolutely nothing alike! In absolute terms -- sure the 3.2 or 3.0 are a little faster. But as far as feel, my E comes alive at 4000 while the CIS cars come on-cam a good 1000 RPM earlier. My car's HP curve also peaks at a higher engine speed. It has to do with the cam design.

Given that without exception the "Early S's" are smaller then the 3.0's and 3.2's, they will have less torque at a given RPM -- it has to do with the engine size. In order for the "Early S's" to get comparable HP numbers to a 3.0, they need to spin faster. For the sake of discussion, a 2.4 will need to spin about 25% faster then a 3.0 in order to make the same HP. In fact the factor is actually a little less then this since the S's can take advantage of the engine tuning and cam overlap to make a higher BMEP (~torque per liter) at those higher RPM's, so in fact a 2.4S makes it's 190 PS at 6500 RPM while a 3.0SC make's it's 180 HP at 5500 RPM. So the S needs to spin 18% faster to make about 5.5% more HP.

Alternatively, the US 3.2 Carrera makes 207 HP at 5900 RPM versus a 2.7RS (basically a 2.7S engine) which spins to 6300 RPM to make 210 HP (6.8% faster engine speed to make up for an 18.5% larger engine in Carrera 3.2).

So the "Early S's" make up in engine speed what they lack in capacity. As a result the driving experience is completely different.

I got both engines and my 2.4S is far more fun on the track in the upper rpms. The 3.0 is more fun as a daily driver and economical on the street. If gas was cheap ever again, I would be driving my S MFI far more, just for the sound and feel. Flightly and nasty sounding with its sport muffler. Oh and my 2.7S CIS racecar motor, is like a neutered 3.0 but its race headers help and in the process are making me deaf even with earplugs YMMV.

That was my assessment as well. I went from a 2.4 S to a C3 to a 3.6 C3 to a 3.8Rs C3 the last one has it all.

a 3.0 or 3.2 w/ S cams or better is also a ball

I have owned both, autocrossed both, and tracked both and in my experience the S is far superior. Your argument however can only be answered with "it depends on the track".

An SC might have an advantage on a tight course with lots of slow turns and short straights because of the better torque down low in the power band. Given a little room though, a 2.4 S will out run an SC all day long.

On the track it boils down to power to weight ratio. A 2.4 S with 190 HP in a 2200lb car yeilds 0.086 hp/lb.. An SC with 180 HP in a 2700 lb car yeilds 0.066 hp/lb. While that does not sound like much in that context, it is huge on a fast track.

Most of my track driving has been done at Sebring which has fairly long straights and medium speed corners. Stock 2.4Ss smoke SCs there. They are faster down the straights, faster in the corners, and stop shorter all beacuse of the better power to weight ratio. My stock SC brakes were very tired after only a few laps and the S just kept asking for more.

To answer 911nut's question, no SCs drive nothing like an early S.
SCs are actually more fun on the street in my opinion because we feel torque in the seat of the pants more than power. Get an S on the track though where you can use the power and they are a lot more fun IMHO.

Don

Good answer, Don

I don't think the weight difference is really as extreme as 600lbs if you are comparing stock cars. 600lbs is basically 3 or 4 passengers! :eek:

These are Car & Driver road test weights. I'm not sure what their methodology is (i.e. full tank? tools & spare? etc.) but assume it is consistent with each car.
72 911S with sunroof- 2,455 lbs.
72 911E Targa -2,475.
78 911SC Targa 2,630 lbs. (I don't have a C & D SC coupe test handy)

This would suggest it is closer to 200lbs than 600.

my euro 78 sc= 2150 lbs *(just weighted),
cheers, James

2150lbs?!!!!!!!
How much have you stripped out of it? My 81 Euro SC came in at 2650 lbs.

911 Nut---Is your engine running right? My 3.0 pulls like a freight train from 3000 to 7000 as well. The only mod I have is a FlowPro muffler. Mine is a Euro so it started out at 204 hp/268 ft.lb from the factory. Maybe you need to add a premuffler and a better muffler....or SSI's and Ben's muffler....or install a 3.6. Ok, I'll stop now.00
If you are up to it, the Rally Sport Region is having their color tour on Oct. 16, starting in Fenton. http://rsp.pca.org
It might be a good chance to see how other simliar cars run.
EDIT: Oops,I guess I already invited you, didn't I?

Comparing an S to an SC or Carrera is tough, mostly, IMHO, because the cars themselves are so different. My E can be more fun than the Targa, but only because it's so light and nimble, and the peaky little 2L coming on at 5K all the way to 7 is an excellent match to the car's natural balance and tossability.

And the same can be said for the Targa, the motor (SteveW, test pipe, MB911 muffler) is matched well to the heavy body, stiff 22/29 suspension and big, heavy 17s, even though the car is on a serious diet. I drove from Boston to Burlington, VT and back last night (7 hours total) and at 120 MPH coming back through VT, the car felt as strong and stable as my E at 90, which any faster feels whispy and light.

Different motors, different cars.

So.... What about a 3.0 with JE pistons, Mod S cams, and Webers? Would that get you back to an early S feel in terms of peakiness?

AM

Nothing that a nice set of SSIs and a 964 cam upgrade won't fix.

a bit hotter than S cams would be needed

some will say that a larger displ. engine can never feel exactly like a 2.2 or 2.4 S engine... I guess the issue is how you define exactly

I originally built my RS replica with a 2.2S, later I put in a euro 3.2 with SSI's and 964 cams.

The car is faster and more reliable now but it's missing some of the fun.

It's a lot of work to keep that little motor on the cam but the rush from 4500 rpm on up is very, very cool.

Maybe clouding the issue, but:
Really, what would be the difference between say a 2.7 RS spec engine and a 3.0L with Early S cams (and appropriate pistons / carbs)?

Basically it's only 10% larger displacement and has the same stroke:
Is that really enough to call the 3.0 torquey and not as peaky?
Was the step from 2.0/2.2S to 2.7 RS also a big decrease in peakiness with an increase in torque?

AM

Andrew, the difference is in the crank. The SC 3.0 Crank is heavier enough to make the car slower revving, and not as "alive" feeling. A Carrera 3.0 uses the 2.7 crank and thus can retain that early, lively, free revving feeling. This is all from what I read on the forum, and my own logic. I've never driven an SC or C3. I guess it's Carrera 3.0 or earlier for making an early feeling engine.

Could this be partially offset by using a lightweight flywheel?

Lightweight flywheel, rods, and pistons can all contribute to a rev happy motor. I don't see why you couldn't make a 3.0SC based motor at least as rev happy as a stock 2.4 or 2.7RS.

I don't have pound vs. pound #'s, but I'm guessing an Al pressure plate will net more weight savings than a lightened flywheel.

The 2 together, that's sure to make a difference.

Early S cars like to run where the air is thin. Around town I rarely get into 4th gear. The cams come on crazy at about 4400 rpm and it starts to make the sweetest sound you have ever heard all the way to 7200 rpm, pulling hard all the way. They are really crabby when you hold them back. They have two speeds..idle, and Holy ****e! By comparison the SC is very gentlemanly, and civilized.

I have GOT to drive some more 911s!!

I've got a 78 SC; 3.0L; CIS. I know it has SSI header/exchangers, and has been re-cammed. But that is all I really know about the work the PO did to it. Let me say, it screams compared to almost everything else I have owned.

Now, reading this thread, I want to drive some others to get a real comparison!!

there's several things involved
- more displacement = more low end grunt
the peakyness of the cams is less obvious on larger displacement engines

- MFI throttle response

2.2S to 2.7 RS is definately a big decrease of peakyness

even 2.4 to 2.7 differs a great deal :
http://forums.pelicanparts.com/uploa...1128525009.jpg

I've driven an S - and I have to say that my 3.4 drives much more like an S than my 3.2 carrera used to.

almost a stumble down low - but boy when the 993 ss cams come on line there is a rush towards redline - unfortunately kept below 5000 rpms at break in - but you can tell she is coming into her own at 5000 rpms. Can't wait to take the training wheels off.

what gearbox do you have, Tod?

Did camgrinder suggest the 993ss cams? Can you elaborate on "almost a stumble down low"?

TIA

That is a very cool illustartive graph. The difference between my 98 pound weakling 2.4T and a 2.7RS is astonishing. No wonder that was such a popular configuration.

Don

Just like the "S" where it sort of collects itself - not really a stumble - more like a "i'm starting to accelerate" ... difficult to put in words - it's not really a fault - just a driving characteristic - just like the "S" that I drove (only driven one btw)

No camgrinder did not recommend them (the cams) He was great to work with - measured everything for me, made recommendations on rockers and such, in fact I just went to John and said, this is what I want... I got the recommendation for the 993 ss cams if I would do the exhaust too from several sources, especially not having to be emmission compliant.

My current trans is a 7:31 mag case 915, no LSD. With the 2.2S I used a 901 (911) also no LSD.