The comprehensive DOHC engine swap thread.

[i3uller]

Has anyone on here gotten there car smog legalized at a referee station in california? I have wanted to do the swap for a long time but this is the one thing that really holds me back. I know that all you have to do is have an engine that is newer than the car your putting it in and retain all the original smog equipment, then go get it certified. I want to do this really bad! What, as far as wiring, would i have to do different than all the non smog swaps on here??? I plan on a non vanos m50. Thanks for your time.

Well as long as you don't use track pipes or something I don't see how it wouldn't pass.

[permit]

Passing visual inspection is the tough part, if it doesn't look like the stock engine, they will send you to a referee that has to investigate the engine and exhaust shit.

I passed visual :) and barely passed the actual test, but that was before I got a full custom exhaust setup.

There are enough 24v swap e30s in Cali to assume you'll pass smog.

[Beej '86 325es]

I haven't had to do it in St. Louis yet, but I hear they don't even pop the hood. They just hook a tube up to the exhaust and that's it...which is nice, because I know once I do the swap I'll pass with flying colors. Emissions still sucks though.

[bimmers4life]

I haven't had to do it in St. Louis yet, but I hear they don't even pop the hood. They just hook a tube up to the exhaust and that's it...which is nice, because I know once I do the swap I'll pass with flying colors. Emissions still sucks though.

If only California was that easy. I was just wondering if anything as far as wiring would be different on a car that needed smog as opposed to one that it didnt matter on.

[Addissimo]

I know once I do the swap I'll pass with flying colors.

Don't be too sure about the flying colors part. M50s, if tuned, aren't that smog friendly. Make sure your cats are nice and hot.

[Beej '86 325es]

Don't be too sure about the flying colors part. M50s, if tuned, aren't that smog friendly. Make sure your cats are nice and hot.

That's true. One reason is because performance chips usually require higher octane gas. From what I understand, to pass emissions, you want about as low octane as you can find.

[bimmers4life]

That's true. One reason is because performance chips usually require higher octane gas. From what I understand, to pass emissions, you want about as low octane as you can find.

That makes sense cause the higher the octane the harder it is to ignite. So a low octane would burn more completely. I think that is how it would work. Someone who knows about this please chime in.

[kylebes1]

That makes sense cause the higher the octane the harder it is to ignite. So a low octane would burn more completely. I think that is how it would work. Someone who knows about this please chime in.

I took my '91 300e in with high octane and advanced timing. The guy that tested it said it passed with flying colors.

Everything I have read is taht the m50 is a very clean running engine.

As far as the affect of octane on emissions, I would have to say N/A. Just be sure to drive for at least an hour. Do a couple WOT redline runs at about the 30 minute mark. Then just drive normal to the test place, and don't shut her off until the guy takes the car from you to test it.

[hugh jass]

a few questions....

1. I'm planning on using an e36 tranny with my s52 conversion. I wanted to get a short shifter from Rogue Engineering to use with the tranny. Should I be able to just use the straight E36 short shift kit and shift rod with the e36 tranny and will everything line up? It seems to me like it will.

2. Does anyone have the pn for the wiring harness cover that goes along the firewall in the e30 chassis? I've seen a couple of swaps with this in place and it really cleans up the wiring.

3. Does anyone have the pn for the mounts for the ecu/dme above the glovebox? I recall something about them being 6 series mounts of something.

Thanks!

[325Projectz]

21 TRIM PANEL WIRE HARNES ENGINE 1 51711380392 $20.31
22 COVERING WIRE HARNES ENGINE 1 51711380391 $18.19
23 SUPPORT WIRE HARNES ENGINE 1 51711380390 $22.32
24 INSERT WIRE HARNES ENGINE 1 51711380888 $5.93

[hugh jass]

thanks guys
another question
when replacing the profile gaskets/valve cover gaskets on my 98 s52, does it matter if i use the pre-95 ones, or do i need to use the later ones? will the later ones be compatible with all of the changes needed to run obd1 on the motor? thanks again.

[kylebes1]

thanks guys
another question
when replacing the profile gaskets/valve cover gaskets on my 98 s52, does it matter if i use the pre-95 ones, or do i need to use the later ones? will the later ones be compatible with all of the changes needed to run obd1 on the motor? thanks again.

You should use teh one that corresponds to your vavle cover. You should be able to retain the s52 vavle cover with the OBD1 conversion...

[hugh jass]

Is this the only crankcase ventilation on the twin cam motors? where do the 2 outlets lead to (4 and 5 in the above diagram)? does one go to the charcoal cannister? thanks again.

[M50_325I_E30]

(that took some reading )

im starting my M50/E30 conversion in the next couple of day's, and i have a couple of q's : )
the engine mount's, is it the rubber mount's that have to be changed or the actual metal ones, or both?

and an e.c.u question, will it be ok using my chiped (173) 325i ecu or will i have to use the ecu that goes with the M50 engine? if i have to use the M50 ecu will it fit direct in to the the same conector as the 325i one?

i cant wait to get this done :)

[Brew]

(that took some reading )

im starting my M50/E30 conversion in the next couple of day's, and i have a couple of q's : )
the engine mount's, is it the rubber mount's that have to be changed or the actual metal ones, or both?

and an e.c.u question, will it be ok using my chiped (173) 325i ecu or will i have to use the ecu that goes with the M50 engine? if i have to use the M50 ecu will it fit direct in to the the same conector as the 325i one?

i cant wait to get this done :)

You might want to read that again...
E36 engine mount arms, E28 535 engine mounts.
You need the entire engine wiring harness from your M50, as well as the M50 DME.

Good luck.