Current knowledge re putting in a 3.5 liter engine

Hogzip · Post by **Hogzip** » Mon Sep 16, 2013 12:10 pm

OK, after tinkering with various performance upgrades (320i intake runners, replacing fuel injectors, etc) I have finally decided to take the leap and put in the bigger Six into my 1981 528i.

I have read the FAQ on this (it's amazing how you guys devote so much effort on sharing information - THANK YOU).

What is the latest and best thinking about which year engine/model is the best source, L-Jet vs. Motronic, and the best process for putting it in? I do plan to have the work done by a Chicago area BMW restorer (The Werk Shop in the Chicago suburb of Libertyville, IL).

Thanks in advance for your thoughts. Also feel free to call me on my cell 262-672-0733.

Brian Younger
Kanasville, WI (by Lake Geneva)
Bri

Falkenberg · Post by **Falkenberg** » Tue Sep 17, 2013 2:47 am

It is relatively important to source an engine with the correct engine mounts. After '87 or so they changed the block a bit, and you will need custom engine mounts to fit such an engine. I found a 3.5 from an '87 E32 automatic, so I had to put the bearing for the manual gar box, swap the oil pump and oil pan, use the E32 oil filter assembly (with the E12 oil filter you will get not any oil pressure), make a small adaptation to go from acceleration rod to cable, and that was about it for the mechanics, as far as I recall.
Electrics were quite easy as well. Motronic needs a permanent 12V connection that my carburetted car did not have available at the engine plug, the RPM signal needs to be sourced from the coil, all the other stuff I got from the Motronic connector and connected to the E12 engine plug. The strictly necessary is available on the E12 engine connector so I did not hack in to the vehicles electrical sistem. Oh and I swapped the engines coolant sensor to something that matched the E12 gauge.
I did not have a fuel pump, but if your car has FI you'll have can r.e-use the existing one, and connect it to the motronic fuel relay (be sure to get an engine with wire harness on it).

Personally I would not use l-jet if I was going to swap engines anyway. Motronic has less mechanical components, is better integrated, handles both fuel and ignition. Once it works, you forget about it.

Hogzip · Post by **Hogzip** » Tue Sep 17, 2013 10:40 am

Thanks for taking the time to respond.

Are you happy with the performance of your bigger engine?

Where do you live? I'm in the greater Chicago area, and I'm trying to find a 3.5 liter e12 that I could see/test drive.

Thanks, Brian Younger

pappentl · Post by **pappentl** » Tue Sep 17, 2013 4:33 pm

I'm currently in my second 3.5 swap. For the first I used an M90 engine from a euro 635 rated at 218hp. With the stock L-jet it ran great, the increased power was noticeable, even through the 3.07 LSD. I took it to a driver's school running the full course at VIR and my instructor thought it pulled like a V8. My current project is another M90, but using Motronic 1.0 (it was available). I hope to have it up and running before it get's cold. I'm using the accelerator cable from a euro 520 setup so that's easy, but the brake booster is a bit trickier.

...tom

-----Original Message-----
From: Hogzip <byounger_5@msn.com>
To: tech_forum <tech_forum@firstfives.org>
Sent: Tue, Sep 17, 2013 11:40 am
Subject: Re: Current knowledge re putting in a 3.5 liter engine

#AOLMsgPart_1_bfe38205-da80-4ef7-9634-d4584abf5078 td{color: black;} Thanks for taking the time to respond.

Are you happy with the performance of your bigger engine?

Where do you live? I'm in the greater Chicago area, and I'm trying to find a 3.5 liter e12 that I could see/test drive.

Thanks, Brian Younger

Hound Dog

Post generated using Mail2Forum (http://www.mail2forum.com)

1st 5er · Post by **1st 5er** » Sun Sep 29, 2013 5:00 pm

Timely conversation.

I'm in process of the same swap.
I've got an '88 735, M30B35, sitting in my driveway. It's the donor.
I'll have one other step though after the motor swap, and that's adding a turbo. It is in transit.

Thus, I'm subscribed.

Falkenberg · Post by **Falkenberg** » Mon Sep 30, 2013 2:23 am

I'm somewhere in Europe, so I can't help you with a test drive. It would have been my pleasure.
The difference from the 2.8 zenith carburettor engine to the 3.5 motronic is very noticeable.

First there is the comfort factor. It just starts and goes. When it's +40 Celsius or when it is -15, turn the key and off you go. Idles below 1000rpm even on very cold start.

this
vs this

Then there is the torque. I have a 5-speed dog-leg and the original differential of 3.64:1 , and I can cruise in town in 5th gear. In 3rd gear it will loose traction (195/70R14 tires..) pretty easy, and when it rains care should be taken.

It is smoother.

Economy is a bit better in city driving (17-1 liters per 100km vs 20 on the 2.

. I never got to install the lambda feed-back, I suppose that that would improve mileage and make the engine even more smooth at low load/rpm where it feels a bit jerky sometimes. But I also have some slack in the drive train (I suspect the differential) that really amplifies any irregularity.

On the opposite side, I feel that the 2.8 was more rev happy.

braino · Post by **braino** » Mon Sep 30, 2013 4:44 pm

Funny. Having owned my 530i for a couple of years before doing the swap, I can imagine ever driving a stock car again. There's no comparison.

I just spent two days driving my '78 530i through the mountains mapping out a rally course here in the high Sierra of Central California. My friend Chris and I are organizing a two-day driving event that will central between LA and the Bay Area - ping me if you're interested in coming on the rally next October - it's going to be AMAZING.

for context, I'm really an Alfa Romeo guy and have rallied in Giulias of all varieties, a bored out Giulietta Spider, my Junior Zagato, various Spiders, a Berlina that I recently sold, etc.

My 530i(CSI) performed amazingly well. It cheerily tackled the climbs, descents, twisties and hairpin turns. The thermostat was steady throughout the entire trip, even in some pretty intense heat. It's definitely going to be my rally car moving forward. It's FAST, stable through tight corners and can handle terrain like nothing I've ever driven (we did some extensive off-road driving). The big-valve motor makes this car was it was intended to be (in the spirit of an M535i).

Having my new Recaro seats installed just added to the experience, as well. I pretty much avoided any crazy terrain knowing that I'd be sloshing around in my old comfort seats. There's nothing but gravity to hold you in one of those.

As far as the installation process, it's an interesting one and be prepared to spend money. Get a long block with all the goodies - all the fuel injection components, the FI harness, the computer, the engine harness, manifolds, etc.

As you've probably read, in '88 or so BMW moved the throttle position sensor to the front of the engine. This makes installation much easier. Definitely look for a later motor. Folks are right that the mounting bosses are a bit different, but all you need to do is get one of these:

http://www.koalamotorsport.com/proddeta ... 30r&cat=73

...and you're good to go.

The heating/cooling hoses are a bit tricky. It's better to keep the original radiator but use the later hoses. The top hose has no elbow, so you need to modify the plumbing on top of the radiator so that the hose goes straight in from the motor. It also has an integrated hose that passes coolant to the heater core. I'm not sure how you would integrate the original steel heater coolant pipe, nor would I want to.

I completely removed the AC so I know nothing about the complexity of marrying old with new here. Living in the Bay Area, you barely use it. In Wisconsin the situation is very different.

As I mentioned before, using a five speed, you'll need the right driveshaft and center cross-member. You'll also need the correct shifter linkage.

I was able to use the original power steering pump, but it would be pretty easy to have some custom pressure hoses made to adapt the newer pump to your car.

One more thing that I mentioned - make sure you have the shorter brake booster. The longer one will interfere with the intake manifold.

After I got my car running, I quickly moved on to increasing efficiency and performance. I installed a Miller MAF and chip and upgraded to 19# injectors. This made a huge difference. It was a bit tricky to get everything working correctly to get past smog, but when I did I passed with flying colors. I get really fantastic mileage if I keep the car under 3500rpm, too. 23-25mpg.

In a year or so I may start looking for an M6 motor to rebuild. Now that I'm all configured for a 3.5, it seems like it would be an easy swap. Anyone ever tried this?

cheers,
Brian

1st 5er · Post by **1st 5er** » Mon Sep 30, 2013 6:18 pm

braino wrote: http://www.koalamotorsport.com/proddeta ... 30r&cat=73

Brian

Just to clarify, this is the part you used in your E12?
It shows E24 and E28 fitment.

braino · Post by **braino** » Mon Sep 30, 2013 7:17 pm

Yep. It fit perfectly.

B

1st 5er · Post by **1st 5er** » Mon Sep 30, 2013 7:25 pm

braino wrote:Yep. It fit perfectly.

B

I figured so. Just wanted to be sure.

Firstfives.org