3.0SC 1980 Engine build
 

Hi guys, I´m about to rebuild my 1980 SC engine.
I´ve dissembled it all, so time to start cleaning and inspecting all the components.

So after cleaning the aluminum cases :) : http://forums.pelicanparts.com/uploa...1589915698.JPG

http://forums.pelicanparts.com/uploa...1589915698.JPG

http://forums.pelicanparts.com/uploa...1589915698.jpg

http://forums.pelicanparts.com/uploa...1589915698.jpg

http://forums.pelicanparts.com/uploa...1589915698.JPG

This is an US version 3.0sc which means is a small port engine, so I was wondering if replacing the heads with 3.2 heads would be a good idea. Nothing wrong with my heads but :confused:

This build is going to be for a mostly street driving car maybe an ocasional track day.

I´ll be installing SSI for sure, maybe cams and I don´t know what to do with the CIS.

If anybody can help me here?
Thank you in advance!

I´ll keep you updated.

Something i would consider doing when my time comes.

https://forums.pelicanparts.com/porsche-911-used-parts-sale-wanted/1030224-remanufactured-911sc-3-1l-pistons-cylinders.html

Hi Pete, thank you for your answer!
Being my car a 930/07 it is allready 9.3 CR so is it worthy to spend over 3000$ just for 0.2CR increase and 100cc?

If I´m going to increase maybe I can go even higher, I live in Europe and here I can buy 98 Octane unloaded fuel with no problem.

I´m also somehow intriged about how the Row 3.0sc was able to get 200hp with almost the same engine I´ve got. The main difference I think should be intake ports, that´s why I was thinking to swap my head with the 3.2 ones.

The 3.2 heads are a different height on the intake as the 3.2 used a spacer between the head and manifold. Early big port SC heads might fit better depending on what you use for intake. You could port your existing heads as well. You really need to think thru the whole engine and match. Matching the cams, compression, intake and exhaust as a system will get you the best results.

john

It is not a huge undertaking to enlarge your ports. The valve size is the same as with the large port heads. The difference is, the smaller ports decrease in size towards the intake manifold. You would only need to enlarge the port to match what ever new intake system you are planning on running.

So basically, what new intake system are you planning to run?

If you don't feel confident using a die grinder, or similar tool, there are a number of outfits that specialize in porting heads.

The basic question, is why do you think you need to do this?

I would like to get the same hp and torque of the Row 3.0 motors.
I don´t have to pass any emission test so I would like to by pass all the compromise decissions porsche made to get throw emisions on the US small port Sc´s.
Early big port heads are not easy to find anymore.

From what I know so far intake ports, CIS and distributor curve were the main differences. My car is 930/07 code so 9.3CR so I´m not so far from 9.5.

I can port my heads but apparently Carrera 3.2 heads combustion chamber dessign is better and both port are already enlarged.

I do have to keep CIS (classic car restriction here) but i can try to find a Row fuel distributor and spark distributor, my car was already upgraded to MSD when i bought it.

Exhaust I can go to early type or SSI

My car is a 1975 911s, I´ve found a magnesium case 2,7 i can exchange for my 3.0
I´m not millionaire so budget is also something to do not completely forget...

What would you do guys?

This is my first 911 so I´m all ears.

Keep in mind that the large port 3,0s had larger runners in their CIS. Unless you do something to enhance your intake, porting alone will not make a noticeable difference. If you search there are some comparisons of large port and small port motors HP numbers.

Back dating your exhaust and retuning your CIS, plus tweaking your cam timing and ignition will give you some good gains.

BTW, I have a large port CIS gathering dust. Make me an offer if you want to go that route.

Trackrash sure I will contact you!

2.7 VS 3.0 is an old topic but difficult to extract conclusions as everybody keeps defending what they have. If I understand well 2.7 is more revi and more expensive to upgrade vs 3.0 has more torque, stronger aluminum case and higher initial hp.

What I want is a fun car to drive, reliable, it has to be CIS and not too expensive to build.

What would you do?

I have a ‘76 with a relatively healthy 2.7 with CIS. I have purchased a 3 litre for long term reliability as I really don’t want the hassle of rebuilding a mag case engine down the track. If I were you I would keep the 3 litre and port the heads to suit the large runner CIS.

And how can you be sure you port all the heads the same amount? Of course you can port them using a 5axis CNC machine...

This is why I liked the idea of swapping them with the 3.2 heads. Valve size are the same so only difference are the ports. I don’t think the manifold spacers would be a big issue.

I would like to use 964 cams as well.

Max Moritz
 

I have been collecting parts for my pending 3.0 (‘82) build for several years. After I read through countless threads on 3.0 performance, I ended up going the old school route with a combination of engine and transmission enhancements.

My plan is a classic short stroke with MM P&C’s, early 3.0 large port heads & CIS, 964 cams, turbo oil pump, and SSI’s with an M&K exhaust (I have all of these parts).

I also have a short geared (2nd thrust 5th) 915 built with a Wavetrac, Wevo gateshift, one piece bearing retainer, reinforced side cover with 930 bearing and a lightweight flywheel & aluminum PP sitting in my garage.

I spread out the costs over many years to limit the budget shock (the $10k+ gearbox was a big enough shock). I am still saving up for my engine build, but at least I already have most of the the big & hard to find items. I am really tired of my stock SC falling off cam at little more than 5,000 rpms. I hope to raise my redline by at least 1500 rpms with decent low end torque (assisted by my lower geared 915).

Good Luck, parts and labor are very expensive these days - I’ve got more “invested” in my 915 than I paid for my good running and driving SC a few years ago...

If you haven’t stumbled on it yet, this is worth a read to double check components of 1980-1983 RoW v US Spec.

http://forums.pelicanparts.com/porsche-911-technical-forum/85905-difference-3-0-vs-3-0-euro.html

And I’d say this is worth a read for a simplified blueprint: https://www.pelicanparts.com/techarticles/911_engine_rebuild/911_engine_rebuild2.htm

While I’m at it: http://forums.pelicanparts.com/porsche-911-technical-forum/701117-9-8-1-c-r-pistons-late-cis-2.html

How do I have all these at my fingertips? My 1980sc engine just told a mechanic to tell me it needs a rebuild also.

Good luck with your project.

OP has more ambitious power gains but perhaps this is a somewhat related.

Has anyone got a sense for power gains from 9.8:1 compression in an otherwise stock US 930/07 911sc (9.3:1 compression)? Ie, no commensurate changes to porting, intake runners, distributor curve etc.

Presume breathing/fuel supply too anemic but curious whether this is overcome by higher pressures from smaller port (with some tuning to US distributor)? My understanding is bigger runners would only deliver power at higher RPMs.

Is consensus still that this is too much static compression for these engines?

Roughly, 1 point of CR will provide about 4% power.
So, 9.8 from 9.3 will provide about 2% power gain. Also, you have pump gas considerations.

Also, OP, what size heads do you have,,,early or late SC? Porting is not as easily done as it is made out to sound.

That is my concern, taking a dremmel and opening is not difficult but having all of them equally made sounds like mission impossible to me.

This is why I really like the idea of using the head of the 3.2. Valve size remains the same and it´s just port size that is bigger. The only thing that stops me from doing it is the cc of the 3.2.
Is it the same as the 3.0?
Are my 1980 9.3cr pistons ok for the 3.2 head? Am I going to still have 9.3 cr?

A lot of questions that blocks me right now...

I can´t believe nobody has tried to swap the 3.2 heads?

It looks like a great idea in my head..

Check the link in my sig below.
Squeeze it through an online transator and you'll understand the curves/diagrams further below in that workshop.

A friend of mine who bought a cpu controlled ECU for his 930/07 engine from me, used new P&C with 9.8:1 from te 930/10, SSIs when doing the rebuild and uses an initial ignition timing of 10-12 BTDC at 900 rpm and the engine ... also pulls really strong. In my case I have the same setup with SSIs and same timing, same small ports but still the 9.3:1 CR and I fell "almost" no difference, well, not that significant as someone would expect.

PM william knight, he'll tell you if bigger ports will make a difference for the other mods you're proposing.

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Thank you Pelicans!!

AndrewCologne kein problem, ich verstehe ein bisschen ;)