Transplanting 3.2 + 915 into a 911SC

GT2BH · 05-05-2015, 04:54 AM

I've searched but there are so many different combinations of conversions that I didn't get the right answer.

I have a donor car, a 1985 3.2 in perfect working condition. I want to transplant the engine + transmission into my 911SC. Is this as basic as I imagine it to be or is there some work that needs to be done other than the fuel lines?

MJHanna · 05-05-2015, 05:21 AM

Well, both had a 915 trans, so it will bolt straight up. The wiring will be the main issue…

sc_rufctr · 05-05-2015, 05:26 AM

I've never done it but I can't imagine it being very hard at all.

It would mostly be about the electrics to run the EFI. The CIS fuel pump runs at a higher pressure than the later EFI so that's something you should think about.
The clutch and most mechanical bits would be much the same although I don't know about the gearbox and axle flanges.

I'm sure some people will chime in who have actually done this.

GT2BH · 05-05-2015, 05:30 AM

I have the donor car, so I can use the fuel pump from that, or any other parts.

On the wiring, I can get Dennis to make me a custom harness if necessary.

On the fuel lines, I can go to Len.

Dealt with both these guys are they are a pleasure to deal with.

uwanna · 05-05-2015, 06:17 AM

I first put a 3.2 into my '80SC, piece of cake! I then upgraded to a 3.6 964, much more challenging!
The 3.2 swap is just a matter of the actual motor and tranny bolt in/ install, then electrical "stuff". With the donor car, you have all the parts, pieces that you will need.
You can leave your SC fuel pump in place, works great with 3.2, or 3.6 for that matter!
You will need to swap some wiring in the 14 pin connector in the left rear engine compartment. You will of course need the 3.2 engine/DME wiring harness as well as the DME /DME relay that mounts under a front seat. You may have to cut a hole in the rear body bulkhead to run the large DME cable head thru. There is also a cable in your 3.2 car that runs from the DME area (under seat) harness to the fuse panel up front for DME relay power and also to the gauges for tach signal.
No need for new fuel lines or custom wiring harnesses!
Here's the 14 pin connector swap info (not my chart, found on forum)

gtc · gtc's Garage

If your donor car is from late '85, the 915's axle flanges will be larger than the ones on the SC - 108 vs 100mm.

GT2BH · 05-05-2015, 08:13 AM

Quote:

Originally Posted by gtc

If your donor car is from late '85, the 915's axle flanges will be larger than the ones on the SC - 108 vs 100mm.

So what would the solution be in this case?

gtc · gtc's Garage

I believe you can remove the 100mm stub axle from the SC rear wheel hub and slide in the 108mm axle (which has the stub axle attached). Haven't done this myself, so best to verify with someone who has...

Flat6pac · 05-05-2015, 09:15 AM

Both axles will fit. You might switch sides to give the balls new surface.
Bruce

uwanna · 05-05-2015, 10:19 AM

By all means, swap the BIG '86 axles and 108mm tranny output flanges with your transplant into your earlier car. The 108mm flanges use 10mm bolts instead of the marginal 8mm bolts on the 100mm flanges. No loose axle flange bolts anymore, ever!
One caution, the axle shaft self locking nut (at the wheel hub) for the large Carrera axles is torqued to about 339 ft/lbs as opposed to the castellated nut w/cotter pin (on the SC)
that is torqued to 231 ft/lbs. The big axle nut is a b**ch to remove, you'll need 3/4" drive
socket with a long breaker bar and a 3-4ft pipe extension slide over the breaker bar to break it loose. Best way to lock the wheel while removing the nut, is tranny nuetral, emergency brake full on, a lug wrench wedged between two wheel lugs and contacting the ground. Then use your full weight, and grunt it out!

KTL · 05-05-2015, 10:27 AM

Quote:

Originally Posted by uwanna

I first put a 3.2 into my '80SC, piece of cake! I then upgraded to a 3.6 964, much more challenging!
The 3.2 swap is just a matter of the actual motor and tranny bolt in/ install, then electrical "stuff". With the donor car, you have all the parts, pieces that you will need.
You can leave your SC fuel pump in place, works great with 3.2, or 3.6 for that matter!
You will need to swap some wiring in the 14 pin connector in the left rear engine compartment. You will of course need the 3.2 engine/DME wiring harness as well as the DME /DME relay that mounts under a front seat. You may have to cut a hole in the rear body bulkhead to run the large DME cable head thru. There is also a cable in your 3.2 car that runs from the DME area (under seat) harness to the fuse panel up front for DME relay power and also to the gauges for tach signal.
No need for new fuel lines or custom wiring harnesses!
Here's the 14 pin connector swap info (not my chart, found on forum)

That is a very helpful post right there, for both the wiring diagram and the very important sentence I highlighted in bold. Because if you don't do this? The incorrect wiring will "backfeed" the current and you will see wires release magic smoke when you connect the battery and key on the ignition. Ask me how I know............

Matt Monson · 05-05-2015, 10:32 AM

That chart is awesome.

GT2BH · 05-05-2015, 09:06 PM

Thanks all for your replies. It seems like this is doable.

So the to do list is basically get the new fuel lines?

My 3.0 engine will take a while to be put back together - perhaps I can then plant that into an earlier 911.

timmy2 · timmy2's Garage

3.2 harness may not reach the SC's male 14 pin rear fuse panel plug in it's normal location.
I have seen posts where people relocate it with wire extensions to the rear lighting 6 pin plug.
I also know someone who builds longer engine harnesses .

(3.2 engine harness is fairly simple and less cost than a CIS harness)

GT2BH · 05-05-2015, 10:26 PM

You know that I'm definitely going with a Dennis Harness

GT2BH · 05-07-2015, 01:15 AM

Ideally, if you had a donor car, what would you move to the new car other than the obvious? Would it make sense to move the fusebox? all the wiring?

The donor car has the 930 calipers on it, which I'm definitely moving as well

0396 · 05-07-2015, 02:28 AM

Quote:

Originally Posted by uwanna

I first put a 3.2 into my '80SC, piece of cake! I then upgraded to a 3.6 964, much more challenging!
The 3.2 swap is just a matter of the actual motor and tranny bolt in/ install, then electrical "stuff". With the donor car, you have all the parts, pieces that you will need.
You can leave your SC fuel pump in place, works great with 3.2, or 3.6 for that matter!
You will need to swap some wiring in the 14 pin connector in the left rear engine compartment. You will of course need the 3.2 engine/DME wiring harness as well as the DME /DME relay that mounts under a front seat. You may have to cut a hole in the rear body bulkhead to run the large DME cable head thru. There is also a cable in your 3.2 car that runs from the DME area (under seat) harness to the fuse panel up front for DME relay power and also to the gauges for tach signal.
No need for new fuel lines or custom wiring harnesses!
Here's the 14 pin connector swap info (not my chart, found on forum)

Nice! Thank you

uwanna · 05-07-2015, 05:58 AM

Quote:

Originally Posted by GT2BH

Ideally, if you had a donor car, what would you move to the new car other than the obvious? Would it make sense to move the fusebox? all the wiring?

The donor car has the 930 calipers on it, which I'm definitely moving as well

Good Lord NO, no need to swap fuse box and wiring. Way overkill! The SC and Carrera
fuseboxes are VERY similar, with some exceptions being DME and fuel pump power.
Just requires judicious study of both wiring diagrams to figure the changes needed.
I did it back in '92, long before any great resources like PP were available, and believe me "I ain't no genius"!

uwanna · 05-07-2015, 06:30 AM

GT2BH,
Found a couple of threads that may be helpful.
Install 3.2 into 911 SC

Index for Marc's 2.7 to 3.2 Conversion

RedCoupe · 05-07-2015, 06:44 AM

Quote:

Originally Posted by uwanna

By all means, swap the BIG '86 axles and 108mm tranny output flanges with your transplant into your earlier car. The 108mm flanges use 10mm bolts instead of the marginal 8mm bolts on the 100mm flanges. No loose axle flange bolts anymore, ever!
One caution, the axle shaft self locking nut (at the wheel hub) for the large Carrera axles is torqued to about 339 ft/lbs as opposed to the castellated nut w/cotter pin (on the SC)
that is torqued to 231 ft/lbs. The big axle nut is a b**ch to remove, you'll need 3/4" drive
socket with a long breaker bar and a 3-4ft pipe extension slide over the breaker bar to break it loose. Best way to lock the wheel while removing the nut, is tranny nuetral, emergency brake full on, a lug wrench wedged between two wheel lugs and contacting the ground. Then use your full weight, and grunt it out!

When I had to remove those big outer axle shaft nuts, I found it much easier to use my impact gun with the pressure turned way up than a long breaker bar with a length of pipe. It hammered away for a while, but got 'em off.