What do I want off an Australian b35 for my b34?

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635911
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Joined: Wed Jun 15, 2016 12:33 pm
Location: Sydney, Australia

What do I want off an Australian b35 for my b34?

Post by 635911 »

Hi All,

I have searched, but can't get clear information on this. Please help.

I have a very nice 1986 635 CSi Australian delivered shark, with a very tidy original m30b34.

I just bought a decent looking Australian delivered e34 with a (supposedly) very low km m30b35.

I know I want the head, inlet manifold, harness, crank pulley, 1.3 ECU and oil level sender in order to get the better breathing head etc onto my b34.

Here is the question.....is there any point in getting the pistons? All that I have read says putting the b35 head on a b34 block will drop compression.

Is this true for Australian delivered cars?

Will using the b35 pistons be of any use?

Also, conflicting info about the cams. Some say the b35 is hotter than b34. Others say the Australian (ie not North American) b34 got the hotter cam anyway.

If not, what is the recommended/tested route for the conversion. Obviously interested in improving performance (but not turbo).

All comment/assistance appreciated.

Cheers,

Toby
1986 635 CSi Lapis Blau with Anthrazit buffalo
1988 911 3.2 231HP Grand Prix white (Sold - 13 years of Zuffenhausen fun))
1984 BMW R80 G/S Dunkel Blau
1982 Yamaha SR500 scrambler
baders
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Re: What do I want off an Australian b35 for my b34?

Post by baders »

My honest opinion is that that's a lot of work to do for a little gain. Are you doing this yourself or paying a shop ? Probably OK if you're DIYing it.

What I decided to do was find a good S38B36 and drop it in my 1986 635csi. A lot of work (and still not finished), but a lot of gain over the M30.

Trying to judge what spec an Australian car engine is pretty much guess work. We generally got lower spec engines (though not as pollution control swamped as US cars).The only way to be sure is a tear down and measurement.
1986 635csi LOCUTUS / Arktis Blau Metallic / Pearl Beige / S38B36/ Close ratio dogleg 5sp
2002 E46 M3 / Topaz Blau Metallic / Black Nappa / 6 speed SMG software tuned / Bilstein PSS10 Coilovers / CMP RACP reinforcement
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jps635
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Re: What do I want off an Australian b35 for my b34?

Post by jps635 »

The attached may be of some help if you haven't already read elsewhere. I copied a number of articles into a single file a while back when i was doing this research.

I've just rebuilt my M30B34, which I will detail once tuned and dyno'd, but essentially I stuck with the complete M30B34 set-up after a number of discussions with Korman in the States. Their logic, the smaller dia intake runners and smaller valves in the B34 head would produce more torque and therefore better for a street build, as opposed to an all out hunt for power at higher rpm.

Took a few years to amass all parts and spread the cost. Luckily, in searching parts I stumbled across a NOS head in the states, as on dismantling my engine, head was found to be toast - a number of deep corrosion pockets, with head gasket on its last legs. Mileage was 237K's. Engine was strong, with excellent compression and well serviced in the 9 years has been with me. Cam and valve guides were worn, which I knew beforehand, but was surprised to find a decent amount of oil contained in the lower bell housing pan.

I got the new head ported and polished, installed a schrick 284/280 cam, korman race rockers, all new valve train assy. Block was bored and honed to 2nd oversize, new mahle pistons, pauter rods, polished crank and rest new.

Engine completely balanced, final compression 10.6:1, full fritz exhaust, custom intake, link engine management and wasted spark setup.

The whole process took 5 months as I did a lot of other stuff at the same time. Has run enough to bed cam in, torque head down, adjust valves again etc, and ensure no leaks. Has plenty of go, but badly in need of a tune, due in a couple weeks, after which should be a strong reliable street engine.
Attachments
High Power M30.pdf
(140.36 KiB) Downloaded 220 times
'85 635csi JPS (RA2-66)
davem6
Posts: 81
Joined: Thu Aug 13, 2015 1:06 am

Re: What do I want off an Australian b35 for my b34?

Post by davem6 »

Don't open either engine. Pull your original engine and store it for later options for originality. Install the E34 engine complete (if it is in as good condition as you suggest), you will need engine mount adaptors like this.
http://www.bmw-stuff.com/proddetail.asp?prod=m30r
Complete install, engine Motronic etc.
Options for up grade:
1. headers/exhaust
2. standalone ECU including MAF delete
3. cam
All depends on budget which options you select.
Cheers
Dave
1987 M6
NSW Australia
GazM3
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Re: What do I want off an Australian b35 for my b34?

Post by GazM3 »

Toby.
Is your b34 a high comp (leaded) it low comp engine.

If it’s the low comp engine just drop the b35 in as it has more power and more importantly a lot more drivable engine under the curve.

Modifying any m30 engine is pretty responsive to a point but the intake manifold limits power developement peak to about 5300ish. Still I can build a pretty happy 260-280bhp m30 peaking at that rpm level.

The real fun begins when u use individual throttle bodies
BMW’s
84 E24 M635csi
90 E34 M5 3.6
94 E34 540i/6 SC E85
97 E36 M3 euro SC U/C
97 Z3 2.8 widebody

OTHERS
11 Audi S5 3.0 SC
19 VW Amarok V6
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