3.2 Conversion into '72
 

I'll start by apologizing for starting another thread on a 3.2 conversion into an early car. I know there are several very good threads already out there providing a wealth of info on this topic. Unfortunately, as we find out all too often, everyone's situation is usually slightly different. As a result, I find myself with questions that can't seem to be answered perfectly by most of the existing threads. Or, when I search, I just can't seem to find the right threads. Naturally, if anyone can direct me to threads that they think will be of any help, please feel free.

So, now the questions start:

Electrical panel in the engine bay. Can anyone point me towards any info that describes what needs to be done to move from a '72 panel to one that will be compatible with the '84 engine? I read the "Marc's 2.7 to 3.2" thread, but that doesn't seem to be the same as my '72. I know the female 14 pin plug from the engine plugs into the male on the panel, but there are quite a few additional components (relays, regulators, etc) on the '72 panel that do not appear to be on the '84.

Thanks.
Roger

he 14 prong connection on the engine is engine info, oil temp, pressure, key ignition for the starter, back up lights.
The engine is run by the harness for the DME, which gives you coil, tach, everything to run the engine so realize there is 2 systems at work to run the car.
Bruce

Keep your numbers parts!
 

IMHO Keep your 72 numbers parts to preserve the value of the vehicle. Get the matching EFI brain & EFI wiring to the brain from the donor car. EFI tends to be a little be happier with the matching brain. I went with 3.0 CIS (carbs work well too) in my 73 because it was the least amount of changes. The 3.2 will bolt up but the trans/ring & pinion will be a concern if you like to hot rod the car. Some people have not had issues but others have sheared 7:31 gear teeth because of the increased torque (not peak HP). A 8:31 915 will handle the torque but will probably require a speedo change. The suspension & tire size will also need to be considered if you want to hot rod around. Is it is a matching numbers car? Is it just better to get a later model Carrera for the 3.2 power? Not passing judgment, just saying. Make yourself happy.:)

Roger- Look up the threads and posts by E Sully. I think that his 14 pin plug discussion is the best. You have got to understand where each wire goes and its function, and if you need that particular wire at all. So-get a 72 wiring diagram, an 84 engine bay diagram and an 84 DME engine harness diagram and dig in. Then-draw your own diagram. I bought a set of 14 pin male and female plugs and made a foot long 14 pin extension cord, and was able to make the 14 pin connections that I needed within that cord. You will not need the regulator or the CD box, but you will need the coil.

I wish I could find a quick reference that explains the difference between the two different control panels. The 72 appears to have several more components on it that the 84 does not. I want to determine if I can just leave these connections open, if they are not needed for the 84.

I've seen several threads showing the "before and after", but I can't find any explaining a step by step of what get's connected where.

Thanks.
Roger

Thanks. I have seen his name on a few. I'll look for more. Yes, I know I need to compare the wiring diagrams (I hate electrical work!). I have factory manuals for the 72 and a Bentley for an 84, so I should have what I need (I guess I'm being lazy).

Roger,

I did this swap several years ago in my 73 and it's not as difficult as you might think.

PM me if you have any questions, I'd be more than happy to help you.

All the original stuff is long gone (not a concern for me). I do have the matching DME, harness, and everything else from the donor car, including the 8:31 915 w/LSD. Yes, I changed the speedo to an electric as well. Suspension is good at 21/27 torsions, 19/19 sways, tires are 205/55 and 225/50 on 16" Boxster rims, bunch of other usual suspension mods for DE, bigger brakes, etc. I should be fine in this respect. I just wanted more power with better everyday drive-ability, without draining my kid's college fund!

Roger

I have a 73 with an 86 3.2L and have been doing some work in the engine compartment. Here are some pictures. I will be happy to try to give you more specific answers and track down wiring etc.

These are not great pictures but... more specifics are possible.

http://forums.pelicanparts.com/uploa...1363561375.jpg
http://forums.pelicanparts.com/uploa...1363561595.jpg

Very nice. It looks like you're using the original panel, is that correct? What are the two silver boxes for on the panel? I was planning to convert over to a 84 panel (I have), but maybe I should just use my 72?

Roger

OK, I found an explanation in the Haynes manual with respect to what is on the '72 control panel. It appears I have a Start Enrichment Relay, RPM Transducer, and a Two Stage Rear Window Defrost Relay.

I assume both the Start Enrichment and RPM Transducer would be related to the original MFI and would not be needed now. Any thoughts?

Roger

Your right Roger, motogman's panel looks just like my setup so just leave the way it is for now.

According to the Hayne's manual, that round black relay is the Start Enrichment Relay. At least that is what was supposed to be there originally, unless it was replaced with a different relay?

I noticed the wiring harness from the 84 has a round relay socket in it, that I presume was originally mounted on the control panel. I have not determined what this is for yet.

Roger

Can you post a pic of that socket for me? I'm thinking it might be the O2 sensor connection.......

Yes, I'll post a pic later when I get home. This socket is the flat round type that snaps into one of the round holes on the base of the control panel, where you plug a relay into it (3 or 5 prong).

Roger

Roger-Be careful and check the diagrams-that might be the test plug.

In the pictures I posted the two Al boxes on the original panel are the RPM transducer and a rear window defrost relay. I am not 100% sure if they are used.

You were also asking about a flat 5 pin connector - maybe the one shown below by the dist cap. It is not used in my set up nor is a small round 3 pin connector.

http://forums.pelicanparts.com/uploa...1363658672.jpg


By the way... if you still have the engine out and have not yet done so, check the fuel lines. The 3.2L have three lines which are known weak points and are a PITA to replace with the engine in the car .... ask me how I know .:mad: (there is another recent thread where I have received several good reference threads on this issue.)

Here are some pics. First pic shows my original panel on the left, with RPM Transducer and Rear Defroster Relay still attached. The empty socket is for the Starter Enrichment Relay, which I don't need. I pulled out the harness, intending to install it into the 84 panel, on the right.
http://forums.pelicanparts.com/uploa...1363661897.jpg

This pic shows the end of the Motronic harness, which I believe attaches to the control panel. This socket is the one I'm curious about. I believe it is the same one in Motogman's photo as well. As inaminit noted, maybe this is the test plug, which would go into the round hole on the vertical panel of the 84 control panel?
http://forums.pelicanparts.com/uploa...1363662082.jpg

I should add that I already purchased the replacement O2 connector from a fellow Pelican (can't remember his name now).

Roger

I think you may have missed this above...

"Suspension is good at 21/27 torsions, 19/19 sways, tires are 205/55 and 225/50 on 16" Boxster rims, bunch of other usual suspension mods for DE, bigger brakes, etc."

This is more substantial than a stock 3.2 Carrera, and the car will weigh a few hundred pounds less.

Roger

OK, learning more. On the 84 panel, the relay next to the Rear Defrost relay is the Heater Fan Blower relay, below.

http://forums.pelicanparts.com/uploa...1363667345.jpg

Bad news is that this puppy costs $300 and my control panel harness is not equipped for it anyway. I do want to use the heater blower, so I need to figure something out.

I know the blower was intended to be activated by a switch attached to the heater lever between the seats. I don't have this now, but was planning to install some sort of switch. I guess my question is, do I really need the relay, or can I just wire a switch that activates the motor directly without a relay?

Roger

You don't need to use 'THAT' relay, but I strongly suggest using a relay - blower motors can draw a lot of current, and switching 10amps is something better left to a relay. A normal 20 or 30amp relay should work for this.

Chuck.H
'89 TurboLookTarga, 348k miles

"That" relay contains a bunch of circuitry designed to prove the engine compartment blower is running before switching on the auxiliary blowers in the footwells. You'll find a bunch more info on it if you search for threads on backdating heat in carreras. I think it might also serve some function for the multi-speedness of the blowers too but memory fails. Or not enough coffee yet.

Basically what I am saying is a basic old fashioned relay will work for the purpose. Best recommendation for the most user friendly setup would be to get heat levers with the switch built in that will start the blower when you need it.

Yes, I know there will be a fair amount of current running through it. I thought if I used an appropriate switch and heavy enough wire, it would be OK. But, maybe I should rig a relay into the circuit. The other thought with a separate switch (vs using the Carrera style levers with the switch) is to be able to open the heater control valves without always turning on the blower. I thought some heat would blow through the system without the blower.

Roger

The only existing relay you need is the rear defroster, and one fuse that feeds it. I used SSI's and backdated the heat to simplify and lighten the car. This is the wiring from my 1973.5 CIS, which differs a little from early 1973's and yours also, but much of the changes are the same. I made my own custom panel to eliminate the excess wiring and move the 14 pin connector forward on the panel to better line up with the '86 engine harness. Using the later electric fan should not be too difficult, but I have not looked into it yet.
http://forums.pelicanparts.com/uploa...1363899078.jpg
http://forums.pelicanparts.com/uploa...1363899171.jpg

Ed,

Fantastic! Thank you. I have never had heat in the car since I bought it back in '98 (the flapper boxes were rusted out). The car has been primarily a DE car since I bought it, so I didn't care. One of my reasons for converting to the 3.2 Motronic motor was to make it more drive-able in Chicago traffic. While it won't see snow or rain, it could see those clear cold early spring or late fall days. I think the auxiliary heater fan could be useful when sitting in bumper to bumper traffic.

Of course, this story sounds much better to my wife than, "I need the 3.2 to keep up with newer cars down the straights at Road America" :D

Thanks.
Roger

I'm also using SSI's and backdated the heating system just like E Sully mentioned, and believe me when I tell you that I get more (and instant) heat than I will ever need without having to use the auxiliary fan setup from the 3.2 motors.

And don't forget without a heating system you won't have any way to defrost your windows on those clear cold early spring or late fall days ;)

I hate to break it to you but the 3.2 L still won't keep up with the newer cars at RA - at least on those long straights. :( I have the original 915 with (I guess) stock gearing. Perhaps some top end speed could be gained with modified gearing - are you planning any gear box changes?

Keep in mind, newer for me is the 80s! I'm installing the stock 915 from the '84, which has slightly taller gearing than the '72 915. After running this car for 15 years with the 2.4 (140hp, then modified to about 160hp) and an open diff, 210hp and a LSD should be fun...especially at under 2400 lbs.

Roger

I don't have a 1972 to check for accuracy, but from the diagrams I highlighted in red what should be eliminated from wiring as compared to my 1973 CIS.
I would think that if you intend to keep the electric blower from the 3.2 you could mount a switch of some kind by the flapper box to activate one of the un-needed relays on the console with a feed from the spare fuse to feed it. It might be okay to just have it turn on whenever the engine is running, except for the wear and tear on the blower itself.
From what I read in the manual, the engine blower is activated by a servo controlled by the temperaature knob between the front seats of the Carrera, opening the ducts and activating the blower when heat is called for.
I don't know how it will work on your year, but I was able to hook the Bk/V from the DME directly to my original Tachometer and it worked well, it did not need the later Tachometer. Also the same with the oil pressure. If you decide to use the later instruments, the original Bk/V from the points to the tach could probably be used for the oil pressure light, which was not on the earlier gage.
1973 Porsche 911 - YouTube

http://forums.pelicanparts.com/uploa...1364047111.jpg


http://forums.pelicanparts.com/uploa...1364047215.jpg

my understanding is that the heater blower ALSO helps cool the engine and may be turned on by the DME

(I just finished putting 3.2 into my 914-6 & test drove it yesterday)

similar wiring conundrums as described above - had to test & verify every connection end-to-end - that also meant pulling everything
out of or down from the dash area - - it's a slow process

be aware that all yrs P don't all use the exact-same colors of wires (close, but...)

- and the gauges have different sender requirements so you have to match them - i.e., the 3.2 has 5-bar oil psi - your '72 probably has 10-bar

- I bo't a PMS adapter 3.2 to oem body harness - lots of the pins are not used so don't worry about them

- for DIY you CAN buy new 14-pin connectors - about $50 on eBay as i recall (I bo't an extra I don't need)

(my car is a "real GT" which had at 911R dual ign engine when it left Werks 1, - so it had a separate wiring bundle for the ign which bypassed the oem 914-6 harness - that complicated the conversion a bit)

- I removed that entire heater & blower setup since i have triad headers w/o heat, so it became irrelevant

( I do have the good-used relay, plate & blower setup FS) ;)

hunt around this site and also the 914World site - you will find complete diagrams of DME & wiring & the various connections - lots of us have been down this road already - it just takes a lot of time to wade thru and get it right

,



.

With respect to the fan, I think I will use a relay. I will see if I can rig a switch to activate the fan using the hand throttle lever. If this proves too difficult, I have an amber illuminated toggle that I can mount on the dash next to the hvac controls.

Here is my control panel. I opted to reuse the '72 panel. I cut a hole for the test plug (Note: Use a 1 1/8 drill. I used 1 1/4 and it's a little big.)
http://forums.pelicanparts.com/uploa...1364132502.jpg

My next task is wiring for the fuel pump. I'm using a Carerra pump in back where the MFI pump was located. The Carerra wiring harness has the rd/grn fuel pump wire going up front to the fuse block, then to the pump. I'm thinking I'll run this wire to the back, and possibly use one of the unused fuse positions on the control panel, then down to the pump. There is a grounding post on the bottom of the pump bracket (nut in picture), which I assume I can use.
http://forums.pelicanparts.com/uploa...1364133236.jpg

Does anyone know what the small black wire with the spade connector is? I know red/green is fuel pump and big black is coil, but I can't find a description for this wire. As you can see, it is grouped with the fuel pump and coil wires in the '84 wiring harness.

http://forums.pelicanparts.com/uploa...1364163233.jpg

That's for the factory ant-theft. It needs power in run and start, same as coil feed.

Why I hate electrical work...
 

OK, I installed a switch on the dash to activate a relay which will activate the heater blower. So far so good. Everything worked fine. Then I decide to check power to the three fuses in the engine compartment, since I want to use one of these to power the blower. I didn't seem to show power at the fuse for the rear defrost and rear wiper. So I turned on the rear wiper to check. Well, I forgot that the engine compartment was open. After a quick bit of nasty sounds, I shut off the ignition. The wiper motor was still making a buzzing sound, so I ran up front and disconnected the battery. Dumb.

So, the least of my issues is a slight chip in the paint on the engine lid from the ligature arm popping off the wiper motor and hitting it. The bigger problem is I believe I somehow damaged the turn signal relay, Hella TBB3 96P 2x21W-12V. When I turn on the ignition, this relay now buzzes, or makes a really fast tapping sound, kind of like an electric fuel pump. The rear wiper motor seems to work fine, but the stereo no longer works, which seems to make little sense When I hold my hand on this relay, I can feel it vibrating, so it would appear that it has something to do with the problem. I checked all the fuses, none blown. My heater switch still seems to work fine.

Does this make sense to anyone, that over stressing the rear wiper motor would damage the turn signal relay, which would in turn kill the stereo? Also, does anyone know where you can buy one of these? Our host does not appear to sell them.

Thanks.
Roger

I found the flasher relay
 

For future reference, the flasher relay can be bought at New-Part.com (again, our host does not offer it). I ordered one. We'll see if it solves the problem.

There is not a lot of information on the rear wiper, but I found this. Your wiring may vary and you would have to confirm what is in your car. I don't see how it would affect the flasher relay. It should have it's own fused feed from the front luggage compartment, with another feed fron the rear fuse panel that seems to be for parking the wiper after the dash switch is turned off. The power should be on when the ignition is in run/start position.
The radio is fed directly off terminal 30 on the ignition switch and does not go through the fuse panels, protection would have to be an inline fuse on the radio feed.
http://forums.pelicanparts.com/uploa...1364734119.jpg

Ed,

Thank you. This will be helpful. I suppose it is possible that the wiring has been changed over the years in some ways. There was an aftermarket stereo installed when I got it back in '98. I replaced the stereo last year, and I think I just tapped into what was already there. It's possible that other wiring changes could have occurred elsewhere. I'm going to pray that it is as simple as replacing the flasher relay, however illogical that may be. If that doesn't work, then it probably will involve some tedious tracing work.

Roger

Relay didn't fix it...
 

Unfortunately, the flasher relay didn't fix the problem. The flasher relay only buzzes when you use the flashers, hazzards, or the parking brake (which sort of makes sense). Also, when you turn on the ignition, there is a faint clicking sound from behind the gauges and the tach needle jumps up to around 2K. When I turn on my new heater switch, the needle moves up a little more, 2.2K. I guess I'll have retrace all the wiring under there and see what's happening.

The worst part is that I want to come home tonight and stuff myself with wings and beer. But I can't do that if I have to lay upside down under the dash checking wires!

Damn electrics!

Roger

Solved the flasher issue...
 

When I started looking around under the dash, I noticed the in-line 3A fuse had blown in the stereo power feed. I replaced this and everything works fine. This doesn't feel 100% right, but it works. The car had an aftermarket stereo installed when I got it 15 yrs ago. There may be some unorthodox wiring here, but it worked fine for 15 yrs, so I won't sweat it now.

On different note, is there a consensus as to the best way to connect spliced wires? Are twist caps and tape ok, spade lugs, soldering? I'm going to insert an inline fuse for the fuel pump.

Thanks.
Roger

High quality non insulated butt connectors are generally considered optimal and is what OEMs use.