M30 B35

[BAVARIANUT]

I agree, if I do it I'll certainly change the harness and the ECU. Eliminates the cold start injector, and all the later enhancements resulting in improved driveability.

AB

so would my 265 tranny in my 86 535i match up with the b35. which flywheel or clutch package do I use? Can I still use the lighter 533i flywheel with the e28 clutch kit mated to the b35 for some extra pep.

[BAVARIANUT]

what years where the e24's built with the m30b35? theres on by my house for sale, that I hope is right. It has like 120k on the odo.
It has a crap load of rust on the body, but that doesn't matter. it'll help me bargain.

[Brad D.]

Mid 87 to 89 models should have a b35. It will say 3.5 on the intake and it will have a toothed trigger wheel on the crank pulley. There are other visual clues but those are pretty obvious. Yes, your trans will work fine. If the 533i flywheel is a bolt on affair to the b34 then it will work fine on the b35. I used my b34 clutch and flywheel when doing my swap.

[BAVARIANUT]

sweet, sounds like a good project when the old m30 desides to quit.

[Mike W.]

Mid 87 to 89 models should have a b35.

Yes and no. Model years 88-89 only, but production for the model year started early for the 6'ers, as in June I think. So all 87 model year cars will still have a B34 engine.

[Brad D.]

Mid 87 to 89 models should have a b35.

Yes and no. Model years 88-89 only, but production for the model year started early for the 6'ers, as in June I think. So all 87 model year cars will still have a B34 engine.

I guess I should have been a bit more careful. June of 87 production date, which is what I meant as mid 87, would be considered an 88 MY car, so yes, you are correct that only 88 and 89 MY cars had the b35.

[Mike W.]

I ran the b35 off of the original Motronic 1.0(059 DME) and it was marginal at best. I say if you are going to do it, go all the way.

I know the benefits of using the later motronics, but what problems did you have using the early type? I would have thought you would still get a bump in power, but without the smoothness and increase in economy of the B35 electronics.

[Rich Euro M5]

I ran the b35 off of the original Motronic 1.0(059 DME) and it was marginal at best. I say if you are going to do it, go all the way.

I know the benefits of using the later motronics, but what problems did you have using the early type? I would have thought you would still get a bump in power, but without the smoothness and increase in economy of the B35 electronics.

I agree with you Mike. I think before I went through the hassles Russ C. encountered. I'd install the Miller MAF conversion with the optional tuning capability, the Split Second piggyback Martin in Bellevue is running, or a standalone.

Rich

[Jimmie G]

Rich mines not a swap so to speak my motor is a b35 with heavy port job on head and intake it effects low end torque some but pulls strong when it comes on.

The b35 heads intake ports are larger but the intake is smaller than the head ports. I think they did this to help low to midrange torque their is alot of room for port matching.

Jimmie

[Brad D.]

Performance-wise it was improved, but idle was actually rougher than a "typical" e28 and some holes in the power band. With the AC on the car would try to stall if steering into a parking spot or clutching and decelerating to a stop. The revs would dip and the IACV couldn't catch it. Without the AC on, it wasn't as big an issue, but still not perfect. Post b35 swap, all of those issues were remedied. I do agree though that some form of programmable MAF conversion would probably do the job and give you adjustability that the b35 electonics will never give you. Plus if you ever turbo you don't have to worry about the nightmare of the adaptive nature of Motronic 1.3.

[LA]

The head replacement should be a direct swap, however, both exhaust and intake mani ports will be undersize relative to the ports in the head.

Exhaust ports are the same. Swap to the b35 intake & the ports match and the newer intake has larger (more flow area) runners between the plenum & the head flange joint. There is a boss cast in place on the b35 intake that is easy to match drill for installation of the CS valve. The larger volume of the b35 cc is not a problem if you also install b35 pistons. They are not dished like the b34 pistons are. I bought my last used set from Vines for $90 including the rods & dropping the oil pan & swapping pistons w/o engine removal is no problem. The only harness issue is with the oil press sender on the back of the head -- just a different type of wire to sender plug, so just buy the E32 or E34 sender & you are good to go as far as harnesses are concerned.

Finally, take the flange off of the back of the b35 head & replace it with the coolant outlet from the b34 head...use the same hose that comes from the heater valve on your E28.

The larger intake valves, more aggressive cam, improved flow in both intake manifold and intake ports, increased compression combine to bump the 181 to 208HP and it is very noticeable in my opinion. Add an improved flow exhaust like MM sys 300 and a good chip & you will probably be pushing around 235HP or so. It takes a bit of time but with the exception of a diff swap this upgrade is the best bang for the buck I've experienced. I also take 0.012 to 0.015 off the head for a small CR bump and associated change in cam timing.

Everyone is different, but I would rather do this mod (leave block in car - just hone, add new rod bearings & cast iron rings) than to R/R an engine even if I had a bolt in b35. I've done it twice & will do it again if I have another M30 b34 enter my life.

[M635CSi]

Everyone is different, but I would rather do this mod (leave block in car - just hone, add new rod bearings & cast iron rings) than to R/R an engine even if I had a bolt in b35.

I agree the B35 head should be run with B35 pistons but from a reliability standpoint, a complete M30B35 engine is preferable to swapping B35 parts in/onto an existing M30B34 engine. For people that care, leaving the B34 block in the car and swapping in B35 pistons keeps the original engine #.

[LA]

Everyone is different, but I would rather do this mod (leave block in car - just hone, add new rod bearings & cast iron rings) than to R/R an engine even if I had a bolt in b35.

I agree the B35 head should be run with B35 pistons but from a reliability standpoint, a complete M30B35 engine is preferable to swapping B35 parts in/onto an existing M30B34 engine. For people that care, leaving the B34 block in the car and swapping in B35 pistons keeps the original engine #.

Come on now...how many M30 main bearing failures have you ever seen? Both times I checked (micrometer) the rod journals & they were round & in spec. Both times the bores were round w/in 1/2 a thou (I know -- a full tenth of a thou out) but my tolerance specs are a bit relaxed compared to BMW's. Besides, I don't expect more than 150K or so (above the prior 200K in one case and 140K in the other) from cast rings.

Of course I replaced the timing & oil pump gears & chains while I was in there & now I know what I have...this would not necessarily be the case w/ installing an M30b35 complete w/ unknown/documented history.

I do appreciate the point of keeping matching numbers, but honestly that was not a real decision driver in the cases I mentioned.

[M635CSi]

Everyone is different, but I would rather do this mod (leave block in car - just hone, add new rod bearings & cast iron rings) than to R/R an engine even if I had a bolt in b35.

I agree the B35 head should be run with B35 pistons but from a reliability standpoint, a complete M30B35 engine is preferable to swapping B35 parts in/onto an existing M30B34 engine. For people that care, leaving the B34 block in the car and swapping in B35 pistons keeps the original engine #.

Come on now...how many M30 main bearing failures have you ever seen? Both times I checked (micrometer) the rod journals & they were round & in spec. Both times the bores were round w/in 1/2 a thou (I know -- a full tenth of a thou out) but my tolerance specs are a bit relaxed compared to BMW's. Besides, I don't expect more than 150K or so (above the prior 200K in one case and 140K in the other) from cast rings.

Of course I replaced the timing & oil pump gears & chains while I was in there & now I know what I have...this would not necessarily be the case w/ installing an M30b35 complete w/ unknown/documented history.

I do appreciate the point of keeping matching numbers, but honestly that was not a real decision driver in the cases I mentioned.

I agree with you. The only downside (with using the B35 pistons in an existing engine is not having tools to machine the cylinders for an optimal fit and finish for use with the best parts. Running a hone up and down each cylinder a few times and Installing B35 pistons would be OK.

[Jimmie G]

Exhaust ports are the same but the b35 exhaust manifolds flow better also plus the rest of the exhaust with the dual cat design. It all adds up.

Jimmie

[LA]

Will the b35 exh manifolds bolt up to the b34 downpipes? If not, what is the best approach for adapting these?

Thanks!

[M635CSi]

The M30 B35 exhaust manifold outlets will bolt to the M30 B35 down pipes (what a surprise) and from there you can fabricate the exhaust system to suit. Another option is to find the exhaust manifolds and downpipes from an E28 equipped with the 218 hp M30 B34 engine.

[Jimmie G]

The b35 manifolds have two long studs and use a spring to take up space and put a load on the flange when the nut goes on and is tightened till it bottoms out. So they only work with b35 downpipes and the hardware.

Jimmie

[LA]

Thanks guys for the input on the exhaust! (I know, that was really bad, sorry - just couldn't help myself)

LA

[RobertRO]

I have installed M30B35 exhaust manifolds, when I converted to high compression M30B34, last year.
You can find some related information at the link below:
http://www.cardomain.com/ride/2418587/7