get 2.8 running or 3.5 conversion?

1980bmw · Post by **1980bmw** » Sat Apr 18, 2009 10:58 pm

I have a 1980 528i that's been sitting for at least 2 years. Waterpump went, and the PO parked it for about two years, then I bought it for $200. I have a new waterpump, and fanclutch, and a couple spare radiators. But I'm not sure if the car overheated so the head might be cracked or warped. Also the car has 220,000 miles on it. It is a 5spd and its a OG CA blue plate car with no rust. So I'm looking to find out how much its gonna cost me to get this thing on the road. Should I get the old engine overhauled and running or would it be worth it to just to a 3.5l swap?

I'm looking to put at least 2k into the car (brakes, tires, etc) I'm just looking to start my budget and get parts together

Bob in San Jose · Post by **Bob in San Jose** » Sun Apr 19, 2009 3:45 pm

As you already have the parts for the cooling system, I would go ahead and replace them and see if the engine runs OK.
At 220+K miles it should still have many good miles left on it.
That being said, do you have milk shake in your oil? If you do you definately have at least a head gasket issue.
As the car has been sitting for a couple of years I'd replace the oil before starting it.
looks like a good find.
Where are you located?

Mike W. · Post by **Mike W.** » Tue Apr 21, 2009 10:24 pm

Like Bob said, check it out first. If it was me, I'd try to get the 2.8 running first, but if it showed signs of water in the oil or a cracked head, I'd pick up a 3.5 before I tore into it. Much more fun and probably less money in the long run. 2.8's are long lasting, but 3.5's just seem to go forever, they really got the engine build down with longer lasting rings and valve guide seals.

1980bmw · Post by **1980bmw** » Thu May 28, 2009 10:51 pm

Alright, this is kind of a bump, but I think I've decided to go with a 3.5l swap, but would it be cheaper to get a donor car, or to but the engine separate? What models should I be looking for for a donor? Also is it worth it for the motronic?

anthony · Post by **anthony** » Fri May 29, 2009 12:33 am

I went 3.5 motronic. I checked the pick n pulls when I found one that had all the stuff I pulled it, and then rebuilt it. It took me about a year to get all the stuff together. Check the FAQ and search the site and you will find all kinds of information. I found this whole process enjoyable. Once you have it all together it only takes a day or to to put in. Somewhere in there I remember Mike W. explaining the mixing of E12 and E28 also there is some debate as to whether or not you need to get a smaller brake vacuum booster if you use the E28 intake manifold. I did. I also got the e28 radiator. It is is a really sweet ride.

Karl in KS · Post by **Karl in KS** » Fri May 29, 2009 10:31 am

When my 2.8 started using oil, I figured that an engine overhaul would cost about as much as a replacement 3.5 engine. So given that the engine needed work, I didn't really feel the 3.5 swap cost much. I did the swap by getting a long block and installing the L-Jet system on it. If I had it to do over, I think I would get the whole Motronic conversion.

Check into the FAQ for 3.5 conversion. Somewhere around 1987 in the 7-series to 1989 in the 5-series the engines were upgraded to larger valves which improved engine performance. Also there were running changes to the oil pump and other things as the years piled up on the M30 engine.

Good luck with your find.

Adam W in MN · Post by **Adam W in MN** » Fri May 29, 2009 12:26 pm

1980bmw wrote:Alright, this is kind of a bump, but I think I've decided to go with a 3.5l swap, but would it be cheaper to get a donor car, or to but the engine separate? What models should I be looking for for a donor? Also is it worth it for the motronic?

This guy has an M90 3.5 liter for sale which should be an easy bolt-in for your car. The M30b34 or M30b35 is essentially a bolt-in, but there are a few tweaks needed that are explained in the FAQ on this site.

http://www.autobahnsport.com/

Mike W. · Post by **Mike W.** » Fri May 29, 2009 8:57 pm

Motronic is better, but not a huge improvement. Contrary to popular opinion, it will not get you more power, but it will get you a different torque curve, a smoother running engine and slightly better gas mileage. If it works out easy, great, but you need a motronic specific bellhousing and flywheel to do it. I expect to sometime, and I've got all the pieces, but when I did the install on mine, I just wanted to get it running for the time, so I didn't do that part. If you get a 3.5 and don't do a motronic, you need to remove the cam nut and install a conversion nut. Not a real big deal, but I'd want to do it before I put the engine in.