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What do you guys think of doing a turbo on an 88 M20 Engine with a 325I head swap; any + or - ?

would appreciate advise

That's kind of the line I want to take with my 528e some time down the road. I think it's a great idea. Go for it.

I'm trying to decide between an S50 swap (lots of modification) or just better off with the turbo; not sure if it's California legal though

Keep the m20 in there...

Just beef up the internals a little with some pistons and rods and you will be good to go.


Let me back up...

How much power you looking to make?

Defiantly more than what I have not too extreme (that’s what my Porsche is for) however not too mellow; something right in between that “snaps” or is responsive when I apply throttle and still maintaining California emissions requirements. Any suggestions?

There really aren't any downsides to the 2.7i turbo. And it'll blast an s50/52 swap. Mine runs dead even with WS6 Trans Am's up until about 100, where it starts to pull away in 4th. Thats with a 3.46 open diff and 205/60 TRX snow tires. So it'd be a little stronger off the line without all the wheel spin. If you're close to sea level you wont need more than about 10 pounds of boost for about 300 HP. Dont worry so much about the bottom end. Just use head studs or stronger non stretch bolts to seal the head gasket and you should be fine. I'd trust that up to about 300 hp.

I’m at sea level (in the Bay Area). I’m running a 4.10 diff however do plan to swap out perhaps a 3.73 or even a 3.46. As far as the existing engine parts what do you recommend be upgraded? I currently have a 155K on the engine and it runs really strong but if the internals need to be replaced with something stronger or more suitable then I’ll go ahead and do that as well

The only thing I can think of would be the main bearings. If you've got the old double classification sheels in there, then you have a big oil groove cut into the bottom shell. BMW sells triple classification replacements, with a full face lower shell. I doubt that the old style bearings will ever cause problems, but the newer style shells would be better with thinner oils. You could probably get away with the stock head gasket if you upgraded the head bolts. If it blows, try an MLS gasket and head studs. Thats pretty much it though.

eze5601 wrote:

not sure if it's California legal though

The visual inspection will most likely get you on the far left coast.

I might be moving to Dallas; our corporporate offices are moving. I hate to leave SF but I'm ready for a change (I grew up here) what smog testing like in Texas?