super 90 or SC?

356 Porsche-related discussions and questions.
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C J Murray
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#16 Post by C J Murray »

Vic- Both of my 1720cc S90 engines have touched up(very slight) ports and 30* chambers. Both run very well but one has single barrel '57 Super Solex carbs. Same stock cams and stock exhaust. Big difference in character due to carburation. I have compared the pure S90 to a SC 1720 with favorable results. Maybe most of the problems result from the 22* chamber? The following results are rear wheel not crankshaft.
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Freddy Rabbat
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#17 Post by Freddy Rabbat »

Tim Herman wrote: CJ, that is a different way but there are a few of us who have logged many a mile on those old '59 and earlier cars that just may not agree totally. What say you Freddy Rabbat?? Them S90's got you trembling?
I may place myself as a newbe among most of you in the ownership of 356s... even on Porsches I can say I started my ownership history back in 1986. My first 356 was purchased in 2000 and was a Carrera. I did not know a lot about them, but one lesson was clear for me among all Porsches.... you can drive them as hard as you like, you can pretend you race them everyday but DO respect all required maintenance... I am keeping my Carrera the same way I keep my 993 or my T2 Coupe... I have to agree that it is not easy to find good mechanics for the 4-cam engines... and it is easy to understand this difficulty on a car that was produced in such little volume. I believe the same happens with 959 engines or other small production pieces of engineering.

4-cam engines were expensive to be produced, required experienced mechanics and regular maintenance... roller bearing engines did not like low RPMs, but that is all.

I would love to understand the reasons why Porsche stopped regular sales of the 4-cam engines from model 1960 till model 1962.. but I am positive to confirm (no offense to any 356er please) that a S90 or SC engine performance cannot be compared to any of the 4-cams as long as they are properly maintained. 1.6 liter engines were tunned at that time to produce 180 reliable hps being driven up to 9.000 rpms with no problems. These engines can be abused, they are not made out of crystal. All you need is to keep them tuned. I love driving my T2 Coupe pushrod, but the experience is completely different when I drive the 4-cam. I can understand Tim's comment when a pushrod engine is compared to a 4-cam. Who remembers what was the best balance for a 904 when launched? Those with the flat 6 engines or with the 4-cam engines? OK I am going too far now :wink:

I do not drive my 4-cam 4.600 miles on vacations, but I would feel comfortable to do it now if needed... and I can tell you it will get the job done with no issues.

KTF folks!! They are all Porsches!!

Freddy
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allan johnson
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#18 Post by allan johnson »

Well,

Thanks for all the replies. I want the disc brakes. I'm getting a little impatient and I saw a 63 S90 that looks pretty good. I think deep down, I still want a C or SC - it is what I had 20 years ago right after I got out of college.

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C J Murray
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#19 Post by C J Murray »

Allan- Remember that if you find a car with a beautiful body, with drum brakes, that you can convert to disc brakes easily if you are not a stickler for originality. Of course, nice C cars are plentiful. Good luck and thanks for starting this thread.

S90 vs. 1600 4-cam. I understand why the pros generally don't post power graphs but it sure would be interesting to see the graphs of the two engines laid on top of each other. I suspect that the high rpm 4-cam produces less power in the under 4000rpm range where street drivers spend a lot of time. Just like a Normal or Super has advantages over a S90. Does anyone want to post a dyno comparison? Maybe with the numbers covered up so the sharks won't attack with stories of how they get 400hp from their engines?

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Steve Terrien
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#20 Post by Steve Terrien »

Stick with the s90's
Steve Terrien

chris romney
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#21 Post by chris romney »

Years of experience and technology advances have made it possible to get 4 cam type power out of a pushrod motor with few of the 4 cam's drivability issues by using twin plugs and twin distributors. I have a twin plug motor in my Drauz roadster and the difference is night and day. I can't quote you exact dyno numbers as the motor isn't fully broken in yet, but my "seat of the pants" dyno tells me there is a lot more power and a very flat torque curve. As always, the power increase isn't free as twin plug motors are more expensive tha plain pushrod motors, but they're a lot less expensive and a lot easier to work on than 4 cams.

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#22 Post by Norm Miller »

My twin plug 2002 L engine pulled 142 HP and 141 Lbs torque on the dyno.

This is more than any Carrera engine and similar to a 911 2.0 L.

It really is a ball to drive.

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#23 Post by Guest »

Both of the motors have a simmular output, the S90 was 90 Din @ 5500 and the SC was 95 @5800. The big difference was the construction of the motors. The SC was basically the same construction as the C and other motors other than the items need to make more HP. The S90 had a few mechanical details that are unique to that motor. The #1 main bearing was larger in diameter to handle the higher output and crank stress revs. The flywheel was lighter and had a shallow recess for the crank which made special flywheel shims necessary. The heads had bigger intake valves but retained the small exhaust valve. After a few years of use Porsche found all of this unnecessary and went back to the standard configuration. The unique parts of the S90 are cool but when you go to rebuild them you find no main bearings and when you do they are mucho $$$. What I have done is grind the #1 main to 356C/SC and 912 specs, heat treat and nitride the crank, trim the flywheel and then the rest is normal. Don't get me wrong I have also done for customers true S90 rebuilds but its harder and more $$ for no gains in performance.

Alan

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C J Murray
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#24 Post by C J Murray »

Norm- Post your dyno sheets and detailed specs.

Robert G Letourneau
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Re: super 90 or SC?

#25 Post by Robert G Letourneau »

I have a Factory {?} Blackened Head with the following numbers and letters on it.... 616.104.301.02 , KOK.2 , a stamped circle with "H" in the middle,also a Rectangle box with "P" stamped on it, Reinforcing wedges in Valve Train area, "58" stamped on mating surface, intake valve is larger than exhaust. Is it a 90,C,SC,912 ? any help would be appreciated,Robb

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Vic Skirmants
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Re: super 90 or SC?

#26 Post by Vic Skirmants »

S-90 and some C and SC heads were black. 912 never were.
I don't have my cylinder head casting number list handy, but if the intake valves are 40mm and the exhaust are 34, then it's a S-90.
The "58", if the original factory stamping for the combustion chamber ccs, would indicate a S-90. The later heads were usually 60-62cc.
And welcome to the Forum.

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Re: super 90 or SC?

#27 Post by Doug McDonnell »

Allan What kind of driving are you going to do? If you are "Vintage age" or approaching it and plan on street driving with most of you time spent under 4500 RPM then a C with a big bore kit will satisfy your needs and be a lot cheaper than an SC. And if you have a budget a C with a 912 engine will get you near SC performance at a fraction of the price. Buy the best body you can as that is where big bucks are spent to make things right. My 2 cents of advice as a "Vintage" person with more love of 356s than money.
1965 356C 2000 BMW 740i Sport 1967 Honda CL77 There is never enough time to do it right, but always enough time to do it over.

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Re: super 90 or SC?

#28 Post by Vic Skirmants »

Allan posted in 2010; think he's still looking?

John Laettner
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Re: super 90 or SC?

#29 Post by John Laettner »

I have been lucky to have owned both and each one is a great car. I liked the suspension from the SC better than the S-90--it is different than the S-90 with different torsion bars, just rides better to me, and is hard to beat. My S-90 had a very enjoyable motor, with the lightened flywheel and bigger intake valves. Both brakes worked well, though I prefer the discs. The dash is a little better looking to my eye on the C. I tilt the scale to the SC, but i would be proud to own a S-90 again, too. Wonderful dilemma you are in. John Laettner
 

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Re: super 90 or SC?

#30 Post by Erik Thomas »

I think a fine combination is a T-5 coupe with a well tuned SC engine. Light chassis, most powerful 356 engine. Here is a chassis dyno sheet of the first test run of the rebuilt engine. This engine was done by Jim Burns at KTR European Motorsports. It is stock displacement, with a pretty much stock wide lobe cam, Solex 40's with stock super 90 air cleaners. Crank is SKAT, Carillo rods, JE pistons with about 9.5/1 CR.
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356 SC engine chassis dyno.jpeg

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