2.7L to 3.0L Engine Conversion / Swap
 

After quite a bit of thought (and searching), I've purchased an 81 3.0L engine to mate to my 1976 915 transmission. I've searched and searched and tried to gather as much info as possible for the conversion. However, even so, I still have many questions/concerns.

Felixcontour posted a week or so ago . . . and received some good responses. But since there are no definitive threads on this conversion, I thought I'd start one and document with pics and all.

With the engine comes the SC Tachometer, Flywheel, Computer/Lambda, Ignition, Harness. All updates have been done and compression and leak-down look great.

Here are my questions - I pick up the engine next weekend and trying to get all necessary parts beforehand:

(1) I'm unsure whether to buy the appropriate 81 3.0L fuel pump or to retain/use my 2.7L pump. Folks seem to go either way.
(2) Fuel line adaptation -- After looking at the fuel lines from my model car and with the engine I'm going to put in, does anyone know (a) what specific lines I need to purchase, and (b) if there are any other fittings I need to purchase to make this work?
(3) Oil line adaptation -- My understanding is that I may have to adapt the oil lines. I do not have a front-center or passenger wheel well mounted oil cooler. Do I need to do this right away? Are there any other lines/adaptations I need?
(4) Adapting lambda/computer is a daunting task. Any suggestions or help is greatly appreciated.
(5) My understanding is that the clutch from my 76 915 will mate to the 81 flywheel . . . am I correct?
(6) Anything I missed?

Thanks in advance gents. I really appreciate all the help I've received here thus far. Here's a picture of the subject in question and captures how scared of engine fires (yes, past experience) I was after we fired her up after a 6+ year sleep.

http://lh3.ggpht.com/_n5urvaFtLDg/SY...0/DSC00513.JPG

subscribed

Update on Conversion Questions
 

Update:
Okay guys, I've arranged for a pickup truck and for a hoist so I can put the engine in. I've also made some great headway with the help of a few other Pelicans (Felixcontour, avt007, KR8) in creating a parts list and answering the questions I had earlier. My big concern is getting all of the parts I need, and understanding how to mesh the electronics from the 3.0 with my '76 chassis. Here is a list of parts that I think I will need:

Parts List:
(1) SC Fuel Pump
(2) Fuel line adaptation from Fuel Pump to Accumulator (changes from 2 port - '76 to 3 port - '81)
(3) clutch (will reuse my '76 Sachs, but need new hardware - see below)

(4) Resurface '81 flywheel
(5) new flywheel bolts
(6) new clutch pilot bearing
(7) new crankshaft seal behind flywheel
(8) tools for the clutch/flywheel: flywheel lock, clutch alignment tool, flywheel bolt tool, breaker bar

Do I need any other parts?

With respect to my questions above:
1- I think I'll opt for the SC fuel pump

2- I need to change the lines to/from the fuel accumulator. Someone mentioned that I can just plug the 3rd port. Is this correct? Or can I adapt another line?

3-I want to try and reuse the clutch pack and pressure plate. What parts should I inspect or replace?

4- Thanks to Rob (avt007), I believe I have a template for understanding what the terminals in the big 14-pin connector coming out of the back of the SC motor will be. I do need to figure out how to adapt this to work with the '76 chassis. He listed the plug pin locations as follows for his '80 SC (Looking at the back of the plug, with the wires coming out the bottom, the numbering of the pins is from the top left (#1), then top right (#2), working down to the bottom right hand pin (#14)). Here are the pin numbers, colours, and purpose of the wire, for my ‘80Sc 3.0:

Pin # Colour Purpose
1. yellow starter solenoid
2. no wire connected
3. grn/blk oil temperature sensor
4. grn/red oil pressure sensor (for oil pressure indicator)
5. grn/yel Backup light switch
6. grey Backup light switch
7. no wire connected.
8. no wire connected
9. grn/wht oil pressure switch (for idiot light)
10. red/wht power for WUR, temperature valve, supplementary air valve
11. blu (x2) from” D+” terminals on regulator and generator
12. blk/vio from ignition box, to tach (tach signal)
13. yel/blk heater fan motor power
14. red generator output.

http://forums.pelicanparts.com/uploa...1233012636.jpg



How can I find out what the pins on my corresponding chassis harness connection mean? And how can I adapt this to work?


5- Discussed under 3-8 above.

I could really use some help on this one. Thanks in advance guys.

Rick - did you ever figure out how to convert from your 3-pin CDI to the 6-pin CDI? I don't understand the wiring diagrams enough to figure it out.

I don't know if maybe someone else can explain how to do it, in really simple terms.

(Yes, I understand that MSD is better, but I'm on a budget!)

you have to use the 6 pin with the 3.0 dizzy. you may want to just go with the MSD.

If memory serves me right... you will have to change the purple tach wire. The 76 body doesn't have the purple wire to the 14 pin connector. Rest of colors/wires match up. Get a wiring diagram for both cars.

I used the existing fuel pump. Still need to add a relay so pump doesn't run all the time.

Using 6 pin box.

Same car...76 body, 81 3.0.

Jim

I thought at in 76 the fuel pump relay was added as an extra safety measure (so that if the engine stopped and the key was in the "on position" so that it wouldn't continue to feed fuel to the engine).

This thread seems to confirm:
http://forums.pelicanparts.com/showthread.php?t=105831&highlight=adding+fuel+pump +relay

Help?

Rick,

You are correct on the "safety measure" of the pump not running without the engine.

My car was more of a basket case and was most likely missing the relay. What I meant to say was "my" car still needs the relay. Sorry for the confusion.

Jim

lamda
 

rick, adapating the lamda system is very easy. the ecm and harness is all self contained package. you just have to drill a 24mm hole in the rear lower seat area for the harness to go through, and run the two power wires to the front fuse box. i highly recomened using it. it make for a much more smoother and powerful car, plus, make for a lot of afr adjustment while in open loop (richen it up) and still get excellent fuel milage while idling and part throttle.

plug
 

and jim is correct. the only wire different in the plug is the tach. (its not there)

The comments on the plugs matching up confirms my research using wiring diagrams. If you're concerned, open up the car side connector and compare wire colours.

this has been really helpful! thanks for the replies guys, and thanks rick for starting the post.

Update 2
 

Some progress to report. I collected the 3.0L engine from San Jose and brought it back to Sacramento. It looked great and everything went smooth (thanks to a hoist when both loading and unloading and a nice porsche hoist adapter and a good friend).

http://forums.pelicanparts.com/uploa...1233605207.jpg

A couple of points in my favor with the engine I bought.

We pulled off the clutch, pressure plate, and flywheel. The clutch plate measured a 8mm thickness. I know there are many who say that you should replace the clutch "while you're in there". But from my research an 8mm thickness indicates the clutch is close to new and therefore does not need replacement.

The flywheel looks good (no scoring or scratching) and therefore does not need to be resurfaced or replaced.

The seller included with the engine everything I need for an extremely simple conversion. (a) computer, (b) wiring harness, (c) ignition box - replacing the Permatune box, (d) SC tachometer, and (e) accumulator.

The engine drips a bit of oil. Before installing into my 1976, I think it'd be wise to address some of these issues. From this picture you see that I suspect the oil breather hose/gasket. The dirt and guck collecting in this area is why I suspect this.

http://forums.pelicanparts.com/uploa...1233605237.jpg

Also the hose in the back of the air boot for the CIS shows cracking and should probably be replaced.

Plan:

At this point I think I've come up with a pretty good plan to address all the issues and install the engine. I'm hoping this whole process takes a month or two at most.

Purchase these parts:
- Lithium Grease (for all electrical connections)
- 12-guage? wire for tachometer
- Throw out bearing ($140.50)
- Pilot bearing ($26.00)
- 9 flywheel bolts ($4 X 9 = $36)?
- Flywheel seal ($15.25)
- Clutch alignment tool ($9)
- Oil Breather Hose
- Oil Breather Gasket
- Breather Cover Gasket ($2.25)
- Oil


(1) ELECTRONICS: I need to install the computer brain under the passenger seat. To do this -- and connect the wiring between the brain and the engine -- I will drill a 25mm hole from the engine bay to the cabin and run the necessary wires to go to the computer brain and the extra line that will run to the updated SC tachometer.

The only thing I'm not certain about this one is how best to wire the power source for both the computer & to the engine bay.

(2) CLUTCH/FLYWHEEL: Re-install clutch. Since the clutch disc looks like it has minimal wear and the flywheel shows no signs of needing to be resurfaced, I'm going to replace all the parts that are advised, save the clutch disc. From what I've researched, I'm still uncertain as to whether or not to reuse the flywheel bolts. I know on the 6-bolt pre-78 flywheels (1972-1976, I believe) the flywheels are only to be used once. But I've heard you should replace the flywheel bolts on 78-83 cars -- but I've also heard that you can reuse. Because of the uncertainty I will error on the side of caution and replace these.

(3) OIL/FUEL: Everything appears to mate up beautifully . . . especially with the accumulator the prior engine owner provided.

Rick,

would you mind putting up a picture of the flywheel?
I am looking at a slightly used flywheel right now, and would like to have some comparison.

Thanks.
Christian - your prior engine owner ;-)

Sure thing Christian. I'll take a picture tonight when I get home this evening.

Thanks again for the engine. It looks great.

wiring
 

rick, on the wiring, the two that go to the front can be connected to the fuse box on a source thats hot with key in "run" position only not the accessory position or your frequency valve will be buzzing while listning to the radio. and the rear one can go to your rear fuse panal, its to power up the porsche diognostic tool

Rick, Have a look at your clutch throwout arm (fork), they have a tendency to crack.

3.0 Flywheel Pictures
 

Here you go Christian. Tell me if you need a different angle shot. Tried to include part numbers on the flywheel.

Flywheel shot
http://forums.pelicanparts.com/uploa...1233638901.jpg

9 bolt (not 6 bolt like on pre-78 flywheels)
http://forums.pelicanparts.com/uploa...1233638989.jpg

Shots of part numbers on 81 flywheel:
http://forums.pelicanparts.com/uploa...1233639062.jpg

http://forums.pelicanparts.com/uploa...1233639119.jpg

Hope these help.

As just a quick update, I took off the steering wheel tonight to figure out how to connect up the SC tachometer.

The electrical female electrical/bulb fittings are the same on both tachs. Here's how I've numbered it:
http://forums.pelicanparts.com/uploa...1233639370.jpg
These are the bulbs, etc. for 1-5 that goes on the top row.
http://forums.pelicanparts.com/uploa...1233639660.jpg
These are the bottom spade connections. I believe the purple stripped wire (the one on the top) that goes into "1a" is what is connection I need change/adapt for the SC.
http://forums.pelicanparts.com/uploa...1233639533.jpg

In the next couple of days I'm going to figure out how to drill hole to the cabin, bolt down lambda/ecu/computer brain and the other wiring.

Special thanks to Alex (foreground) and Fernando (background) for their help this past Saturday.

http://forums.pelicanparts.com/uploa...1233639990.jpg

Tach Wiring
 

Can someone/anyone help on the tach conversion?

There are three parts of the conversion that I'm confused with.

(1) I have the updated tach itself. The back connections look identical to my 76 tach. The top 5 connections are slots for the little lights. There are 3 spade connections on the bottom. The purple/black wire, I believe, is the one that needs to be updated (or is it all three) to the purple wire?

(2) Where does the wiring for the tach come from on the engine itself? I couldn't find a purple wire on any of the plugs or wires on the "new" engine.

(3) Did you run the wire between the tach and the engine directly? Or did it pass through a fuse or some other device?

Thanks.

Harness wiring hole
 

Here is a pic of the hole for the DME harness.
The rope shows where the wire went.

Christian

http://forums.pelicanparts.com/uploa...1233775604.jpg

This is absolutely perfect. Thanks.

Tach wiring
 

From the wiring diagram I get that the black/violet cable from your speedo
is connected to the Electronic ignition unit.

From there - and now I am guessing - it goes through the 14pin connector
to the front.

http://www.pelicanparts.com/911/911_Parts/Electrical/911_electrical_82SC_Part1-2.jpg

Christian

Update: I can confirm that it goes through the 14pin connector at terminal 12!
Late Update: In a SC, probably not in your car :-(

tach
 

rick, on the tach, find the b/p wire in the main harness (in engine comp) coming from the fire wall. its there, but not in the engine harness. others might chime in and say this is wrong, but ive always hooked it up to the hot side of the coil. mine and others ive done this way worked fine with thousands of miles with no probs.

Is this what you mean Don? (see this other thread)

http://forums.pelicanparts.com/porsche-911-technical-forum/455763-tach-wiring.html

Wiring diagram..........
 

Rick,

The 14-pin connectors for '76 & '77 are the same as those in the SC's. The black/violet wire from the tach goes to pin #12. Your wire harness (engine side) should have the black/violet in #12 too.

The two-port fuel accumulator will work well for both SC's and '76-'77 cars. No need to change unless you want to spend and buy a three-port FA. The 3.0 liter motor you bought will have a return line for the fuel accumulator. Plug it for 2-port FA or use it for a 3-port FA.

If you are using the 6-pin CDI, it will be a simple plug in work. Not familiar with the MSD 6AL ignition set-up. Keep us posted.

Tony

Black/purple wire..........
 

Don,

Connecting black/purple wire from the tach directly to the hot wire of the coil will work for '76 & '77 cars because they have points (distributor) and use 3-pin CDI. On the other hand, the SC's are using 6-pin CDI and wired differently. The wiring diagrams for the '76 & '77 and the SC's are completely different for the ignition system.

I'm interested to know if you have done this on an SC engine with 6-pin CDI. As you said it, this was done by others too and would like to learn something new. BTW, the wire in pin #12 (engine side) should be black/purple and will plug in directly.

Tony

I would not use Lithium grease for electrical connectors. Get a tube of DIELECTRIC GREASE which is made specifically for this purpose. It is thicker and will not tend to run.

ECU drilling hole / Small Update
 

I just received the rest of the parts to finish up the clutch and think I know enough about the tach wiring to try a couple things and see what works best. I still hope to hear from Don on where he wired the harness to the front fuse panel.

Thanks HarryD, I did mean dielectric grease, not lithium grease. So thanks for giving me the added reminder.

I ended up drilling the hold for the ECU a little low (advice for further people drilling this hole). To make sure you don't do this, just don't drill the hole in the bottom right hand corner (passenger side). Go a little higher, at least halfway or more up. (sorry about the bad pics)

http://forums.pelicanparts.com/uploa...1234240476.jpg

As a result I had to wire the harness over the transmission.

http://forums.pelicanparts.com/uploa...1234240639.jpg

I'm going to take a closer look to see if I can simply make the hole a little bigger to negotiate a more direct route.

Thursday I have a day off and I am going to do several things including some of the "common oil leaks" Wayne suggests in his book. I'll probably mount the ECU unit under the passenger seat also.

Re-install clutch, plug in related wires, new fuel filter, re-mount engine, plug in all the lines (oil/fuel), new oil/gas and turn the key (hopefully this next Monday).

Update & Question
 

I made some progress with mating the engine and getting it to a position where it could be installed. http://forums.pelicanparts.com/porsche-911-technical-forum/457868-engine-doesnt-want-go-engine-install.html?highlight=conversion+swap

Now I'm to the point where I need to tie off some lose ends in order to finish the conversion/swap. And, as such, I now need help from the electrical gods.

Felixcontour helped out by posting a picture here http://forums.pelicanparts.com/porsche-911-technical-forum/454978-81-cis-ecu-wiring-question.html?perpage=20 of the '81 wiring deliema. Tony (Boyt911sc) helped out by answering the questions directly but I'm in a situation where I'm trying to figure out what fuse ('76 chassis) goes to what wire ('81 engine harness/dme).

As I understand it the three wires in question on an 81sc -- The Diagnostic connection (red) and the 2 wires (red & red/white) that come directly from the ECU.

It appears the Test connection/diagnostic wire goes to rear fuse #22 (25a). It also appears the ECU red wire goes to Fuse 18 (5a) and ECU red/white goes to Fuse 30 (Fuel pump relay). I can make sense of where the red/white wire form the ECU goes but not the other two (diagnostic red wire and ECU red wire).

The question becomes this: what are the corresponding fuses from an '81 to a '76 for the diagnostic port Fuse 22 (25a) and for the ECU red wire Fuse 18 (5a)?

Update:
 

Okay, well it's time for an update. Made a lot of progress but have
started several additional threads because there were some specific
questions I had that wern't answered here.

With the help of Tony, (http://forums.pelicanparts.com/porsche-911-technical-forum/459414-ecu-wiring.html) we figured out the proper wiring to help my '76
evolve into something with a "brain" (an ECU/DME harness from the
'81). Thanks to his guidance, I wired the red/white line from the ECU
went to terminal 30 on the FP relay, the red line form the ECU went to
my fuel pump fuse (#18). The rear diagnostic line I wired to the rear
middle fuse and grounded to the chassis. I hate wiring or electrical
stuff . . . so Tony's help was very very appreciated. Hopefully the
vampire clipping will work until I have more time re-do my fuse box .
. . which I hope to complete somewhere down the line.

Putting the engine in was a PITA. Based on the help of others, I
think this was due to inproperly disconnecting the shift coupler
(stupid me . . . since that's one of the easier parts of the engine
install). Anyway, I pulled the trans out, replaced the shift coupler
seal and the main driveshaft seal (thanks to the suggestions of others
and only minimal pain to my wallet) and slapped the two in. Well,
maybe not slapped . . . since it took hours and hours or figuring out
the right way to do it with the engine on an ATV jack and the trans
on. but anyway, it's in.

my fuel pump (FP) had been leaking before due to using an aftermarket
Walbro pump (since I couldn't afford the original 76 pump from PP).
The banjo fuel line from the pump to the rear pressing down on one end of the fuel pump, putting pressure on the fitting . . . thus creating a leak. After cutting the line shorter, refitting the banjo, and connecting everything up . . . it now works
without leaking. Whew . . . thank god.

There are several remaining issues, the biggest of which is the oil
line from the crossover oil pipe on the '81 connecting to my '76 oil
tank (see post http://forums.pelicanparts.com/porsche-911-technical-forum/460049-crossover-tube-help-needed-2-7-3-0-a.html). It's hard to explain in words . . but the crossover pipe in a
'76 comes under closer to the front of the car. The '81 crossover oil
pipe runs closer to the back of the car. The upshot is that the line
from the oil tank just can't be adapted without pinching the line. So
I need to find the appropriate line for the intermediary solution . .
. or find the rest of the lines for front cooling (i have all lines
except those that goes from the engine/tank to thermostat).

The second issue is the return fuel line. They're different sizes on
the 76 chassis and 81 engine side. I've a temporary solution . . .
but will have to figure something more permanent or long term.

There's one plug that I can't figure out. But I don't think it's
mission critical. It has a different plug than all the others.

I replaced the breather hose on the '81 with the one from the '76 since
the breather hose on the '81 was cracked. When putting in the engine,
the hose was pinched between the engine and the chassis. I got it
loose, but now it's not properly routed and it doesn't exactly reach
to the oil tank. I'll have to wiggle that thing around until I get
enough slack.

I still need to do the tach wiring, but plan to do this soon. I'm
simply going to extend the purple/black line in the rear of the
engine. If that doesn't work, then I'll run the wire all the way
through (from tach to engine compartment and to pin #12 on the 14
pin).

Aside from all this, I'll need to pay more attention to the inside.
But that's not critical to the swap / conversion. So I'll update
after the engine starts and I confirm everything works.

Update
 

A few years have passed but I'm back to where I ended up. I pulled out the 3.0 and did a top end rebuild after a couple of years and need to hook back up the electrical wires in the back.

I forgot to take pictures of where I had connected all of the wires and I'm trying to work with the mechanic who is putting back in the engine (in Emeryville) to get it all going. Shig (my mechanic) has been doing a great job, but he and I are both ready to be done.

There are a few wires that we need to sort out. For those of you that haven't read the entire thread, I am updating my 1976 chassis with a 1981 3.0L engine.

There are two groups of wires. (see photo)http://forums.pelicanparts.com/uploa...1383706164.jpg

The wires with the red box around them I've isolated first. The black/violet wire goes to the tach (pin 12 on the 14 pin connector). I think you can jump the connection over, as I recall (see photo for pin top second from the left).

http://forums.pelicanparts.com/uploa...1383706283.jpg

The other two red wires in the red box, I'm unsure about. My memory says they go to the other wire that is in the first picture above (left of the red box...the wire with the masking tape around it). BUT, I also remember that I jumped from the top fuse between the red box and the other wire. I cannot remember where!!

If I look at the 81 ECU diagram (see below), I WANT to say that the line from the ECU brain that I installed under the passenger seat jumped into the wire to the right of the top fuse. I am having a hard time remembering the outcome of this post: http://forums.pelicanparts.com/porsche-911-technical-forum/454978-81-cis-ecu-wiring-question.html?perpage=20

http://forums.pelicanparts.com/uploa...1383706526.jpg

Can anyone help? Last step until my mechanic in Emeryville and I celebrate this very very long project.

Thanks....

When I converted my 75 914 to an 83sc 3.0L I found it easier to understand the plug from the chassis and knowing which wires you will be able to use and which ones you wont! I was able to switch the pins on the motor plug to match the ones that were a direct conversion on the chassis plug. The ones that are left from the motor plug that didn't match anything from the chassis were pulled out and run externaly or the unused pins from the chassis plug used and the chassis end connected to the proper item...ie:Oil Pressure sender that the 914 didn't have!

I don't know if any of this is helpful but when I was done the motor fired on the first click for me so it worked! As for the brain power I just connected it to an ign source that was hot after the motor started under the dash and grounded it under the seat!

http://forums.pelicanparts.com/uploa...1383710123.jpg

Brown with black stripes wire that is taped is the wire for your fuel safety switch. It needs to be jumpered to the white plug on the engine harness brown/red wire. I don't know what else Tony had you do so i cant advise.

I would have had you wire up the tach signal to the male 14 pin connector on the fuse panel and leave the engine harness alone.... Along with 2 other chassis harness wiring changes to make it completely plug and play.
There are only really 3 wiring changes that need to be made to mod the '76 &'77 cars to accept the '78 to '83 harnesses for plug and play.

Move the purple tach wire to the 14 pin male connector terminal 12, move the brown/black wire to the white T connector and one other that I can't remember off the top of my head....

Edit, brain kicked in, it was moving switched power to the white T connector as well. (Both changes to the chassis/male side of T connector)
Doing it this way allows for the 6 pin CDI to work properly and have a clean plug and play installation.
No messy jumpers or wires hanging around. :)

Thanks Timmy/Jeffs.

The wiring is all sorted in the front fuse box and the ECU is installed and everything worked before. I'm trying to remember how I did it in the back.

Jeffs, which wire are you referring to as the white T connector? Is there anyway you can help me think through what the third connection is?

I'm so close!

I believe you can take switched power from the top fuse of the 3 fuses on the rear panel if unused.
See edit to my earlier post.

Timmy was the one talking about the white T!

Are you still working on the main engine harness or the FI harness? The FI harness is just constant power, Switched power ground, 02 sensor and temp sensor (depending on year)!

http://forums.pelicanparts.com/uploa...1383757088.jpg

Thanks Jeff/Timmy...

So, looking at the ECU wiring harness (yes, I've installed this under passenger seat and wired to front), I am trying to determine the connection points in the back. After you wire it through the firewall to the back there (1) pin connector -- this is easy mate up, (2) the O2 sensor -- hangs off, (3) ground, (4) and loose wire. Everything except for 4 makes sense. I think, per Timmy I jump this into the right side (front of car) between two top fuses (rear engine compartment drivers side).

Timmy -- thank you for the update. I'm just not grasping the edit "it was moving switched power to the white T connector as well. (Both changes to the chassis/male side of T connector) Doing it this way allows for the 6 pin CDI to work properly and have a clean plug and play installation. No messy jumpers or wires hanging around."

I jumped wires before...and I'm trying remember even that.

Do you have any pictures from your original install?
I was reading your earlier posts and they jump all over so I'm not sure what you did originally.
Pictures of your current engine harnesses would help as well.
This is a prime example of why we need to document our mods, laminate them and keep them somewhere safe!

The edit was referring to the one other change I couldn't remember when I first posted.
I could direct you in how to do the wiring changes starting from scratch easier than trying to guess what you have done before.
I'll have to look at my schematics at home tonight before saying anything else.

I don't have the two wires hooked to anything! The red one and the brown one with the small ground loop are just wire tied to the 02 sensor wire! When I did my conversion I was told by a Bosch Injection Specialist that they are not needed! He did tell me what they are for but I can remember!

Are you talking about the injector harness?