3.0 Heads

[Brookieslayer]

I have done some searching and I cannot see the information I seek, so I thought I would ask the brain trust here for an answer.

I have an '83 SC ROW with a 3.0 engine. Does anyone know if I have large port 3 liter heads, or small port 3 liter heads? I have found conflicting evidence of both.

I also would like to know if anyone knows what the difference between the two. I am starting to plan for my project engine build and would like to know ahead of time what I have for heads on the current motor.

Thanks in advance for the answers.

[Brookieslayer]

I had posted this incorrectly in the for sale side my apologies. Thanks for the answers over there!

[Glenfield]

Do you happen to know your engine number? Some RoW were from Canada, Japan etc and had engine code 930/16. These are small port engines. A RoW from Europe for the same years had a big port head (930/10 motor).

[boyt911sc]

Originally Posted by Brookieslayer

I have done some searching and I cannot see the information I seek, so I thought I would ask the brain trust here for an answer.

I have an '83 SC ROW with a 3.0 engine. Does anyone know if I have large port 3 liter heads, or small port 3 liter heads? I have found conflicting evidence of both.

I also would like to know if anyone knows what the difference between the two. I am starting to plan for my project engine build and would like to know ahead of time what I have for heads on the current motor.

Thanks in advance for the answers.

Brookie,

Posting the engine serial number would definitely identify your motor. But for a quick look, inspect the intake runners on the motor. They should have -2R (34-mm ID) or -4R (38-mm ID). You should have the -4R if your motor is indeed a large port engine. Keep us posted.

Tony

[Bill Douglas]

An '83 ROW engine is a 930/10 and yes it's got the big valves and is the best SC engine they made. Likes to have SSIs too.

[porschyard]

Originally Posted by Bill Douglas

An '83 ROW engine is a 930/10 and yes it's got the big valves and is the best SC engine they made. Likes to have SSIs too.

All 3.0 valves are the same size, the main differences for the euro motors are the intake ports, compression ratio, fuel distr. and warm up regulator.

[911parts]

Beyond 79 all the SC's (not SCRS) intake ports went to 34mm, small runner. even the 930/10 series motor but it had the 9.8/1 compression pistons. That's a great motor to port to 39mm, use big runners, Webs 20/21 cam and SSIs

[Brookieslayer]

Originally Posted by boyt911sc

Brookie,

Posting the engine serial number would definitely identify your motor. But for a quick look, inspect the intake runners on the motor. They should have -2R (34-mm ID) or -4R (38-mm ID). You should have the -4R if your motor is indeed a large port engine. Keep us posted.

Tony

I will check the runners, and report back. Thank you

As a small aside what size are the ports on a small port engine? 34mm?

Thanks

Paul

[Brookieslayer]

Originally Posted by 911parts

Beyond 79 all the SC's (not SCRS) intake ports went to 34mm, small runner. even the 930/10 series motor but it had the 9.8/1 compression pistons. That's a great motor to port to 39mm, use big runners, Webs 20/21 cam and SSIs

The motor currently has SSI's and runs great.

The project is heading to 3.2 or 3.3 in size and MFI for induction.

The CIS will go by the wayside.

[Walt Fricke]

911 Parts: what you say is correct for US SCs. But not for the late Euro SCs - along with the higher compression pistons (9.8) they kept the large port heads and runners all the '78-9s had.

[Glenfield]

That’s what I’d thought Walt. Surprised if 0.5 compression bump and fueling explained 25 extra HP for the 930/10.

3.3 MFI is very cool. Why the MFI and not EFI out of interest OP? Those CIS components should be snatched up

[Brookieslayer]

Originally Posted by Glenfield

That’s what I’d thought Walt. Surprised if 0.5 compression bump and fueling explained 25 extra HP for the 930/10.

3.3 MFI is very cool. Why the MFI and not EFI out of interest OP? Those CIS components should be snatched up

I am looking forward to the 3.3 MFI as well! The coolness of MFI is the reason, I am looking to backdate the car to a 74 ish 2.7 Carrera, lightweight with a little extra in the back! I have driven MFI and it is so entertaining and responsive, I think it is the right way to go. especially for a 911.

Other parts will be easy to sell for sure. Thanks for the comments!

[Brookieslayer]

Originally Posted by boyt911sc

Brookie,

Posting the engine serial number would definitely identify your motor. But for a quick look, inspect the intake runners on the motor. They should have -2R (34-mm ID) or -4R (38-mm ID). You should have the -4R if your motor is indeed a large port engine. Keep us posted.

Tony

Thanks for the info. I finally got a chance to get the decklid opened and checked the runners (too much snow removal!!!). The runners are 4R, so a large port engine.

Does anyone know what the port size is of the small port heads?

Thanks in advance.

[Glenfield]

34mm for small port motors.

Definitely post details on the build. Sounds unique and good inspiration for SC owners looking into the back catalogue. Great pick with the Carrera MFI

[Brookieslayer]

Originally Posted by Glenfield

34mm for small port motors.

Definitely post details on the build. Sounds unique and good inspiration for SC owners looking into the back catalogue. Great pick with the Carrera MFI

Thank you for the information. Looking forward to getting into the build as well.

The factory did build a nice IB hotrod in the 2.7 Carrera!

[fred cook]

When I built the 3.3 short stroke engine for my '80 SC I used twin plug Carrera heads that had been ported for use on a track engine. I also swapped the small port air box for an early large port air box. I modified the CIS to be more like the 73 1/2 system but kept the AAV to serve as a choke system. I also set up the cold start valve to open at full throttle to add extra fuel to avoid having a lean running condition. Pistons are 100mm Mahle 11:1, cylinders came from LN Engineering. Cams are 964 Porsche units. I used the XDi system to fire the twin plugs and mounted the control box in the cabin behind the passenger seat. Exhaust is SSI. You are probably questioning keeping the CIS system. Mainly I just wanted to see what kind of power I could get from it. Turns out This Frankenmotor will pull hard all the way up to 7500 rpms and would probably go higher! The only "issue" that this engine exhibits is that it really does not like to run hard until it is fully warmed up. I added an air/fuel meter to aid with tuning. At the moment I have the system set to idle at about 14.5:1 (almost stochiometric) but at full throttle it will go to about 13:1 (richer). When you look in the engine compartment, the only thing that looks strange is that there is no distributor! The coils are mounted on the little shelf behind the fuel injection box and are pretty much out of sight. I haven't had an opportunity to put this on a dyno but the car feels like it has maybe 100 more hp than stock! Good luck with your engine and don't let anyone tell you that you can't do something! Listen to advice but don't be afraid to wander over into unknown territory from time to time!

PS: I think the intake ports on this engine are 42mm and the exhausts 41mm. I tapered the inside of the intake runners to match the heads and did essentially the same thing to make the flow smooth (laminar) going into the exhaust. I'm sure this engine would make more hp with properly sized headers but I used what I had on hand.

[AlKidd]

My 83 ROW has the larger tubes at the airbox but the head to tube gasket is the same size as the small intake tubes. Is this normal? I would have thought the size of the intake tube would be consistently larger engine to air box.

[911hutch]

should be as stated earlier.... intake runner ending in 4R and 38 mm inner diameter which matches the 38 mm inner diameter of the intake port in the head

[AlKidd]

My question related to the intake manifold gasket. Its the same part # for all years including the years when the runners were larger.

Originally Posted by 911hutch

should be as stated earlier.... intake runner ending in 4R and 38 mm inner diameter which matches the 38 mm inner diameter of the intake port in the head

[Jonny042]

Originally Posted by Glenfield

That’s what I’d thought Walt. Surprised if 0.5 compression bump and fueling explained 25 extra HP for the 930/10.

3.3 MFI is very cool. Why the MFI and not EFI out of interest OP? Those CIS components should be snatched up

He drove Project Heavy Metal and hasn't been the same since