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08-16-2005 04:22 PM #1
08-16-2005 11:11 PM #2
Big Valve Engines (M30B35)...
1987-1992 E32 7 Series
1988-1993 E34 5 Series
1988, 1989 E24 6 Series
Those are all U.S. model years, build dates can be different. For example E32 model year 1987 production began in August, 1986. Model year 1988 6 Series production began in June, 1987. In addition to bigger valves, these engines have higher compression ratio, resulting in 208 hp in the U.S models. Most, except for the very early 7 Series and the 6 Series engines, require an adapter for the right engine mount.
These engines can be identified by the toothed harmonic balancer and the intake manifold being braced underneath instead of being braced to the valve cover.
08-17-2005 03:22 PM #3
08-17-2005 08:45 PM #4
You can get an adapter from Carl Nelson's shop, La Jolla Independent, 800 466-8184. It's a custom built item, so it'll take a bit of lead time.
If you're going with the Motronic, the engine is better since you won't need the motronic bell housing, since the sensors are on the front of the engine. If you're going with carbs, the engine is better because it breathes better than the M30B34 engine.
08-17-2005 11:30 PM #5
08-17-2005 11:32 PM #6
08-18-2005 12:24 AM #7
Getrag 265/6 Overdrive...
First, the 265/5 is the "dogleg" 5 speed which has a 1:1 final ratio. You don't want that one unless you're planning to do the Pike's Peak Hill Climb. And according to Carl, it's a POS. The 265/6 was in various early '80s 5, 6, and 7 Series, as well as the 1985 5, 6 and few 7 series and also the E30 M3. The 1985 transmissions require the addition of the speedo gears, since those cars had electronic speedometers.
Don't bother with the Getrag 260 series, the early ones (pre 1985) suffered from poor layshaft lubrication, the later (post 1985) ones aren't much better. The reason BMW went back to the 265 in 1985 was that the 260 wasn't hacking the program. The 260s have an integrated bellhousing and the 265s have separate bellhousings.
The 262 4 speed is a great transmission, but if you want a 5 speed, the engine swap is the obvious time to do it. Carl can fix you up. His children will appreciate the college educations we are all providing for them.
08-24-2005 06:07 PM #8
Dont get excited about the valves
The only change in the m30 valves is for the b35, as mentioned. The thing is that it only grew 1mm. Every other m30 head has 46/38 valves. Nothing to get excited about there. Pistons can be used to bring up compression, so all the b35 really has is displacement. Its not as special as everyone thinks it it.
08-25-2005 02:11 AM #9
And the difference between 182 hp and 208 hp is inconsequential. That could have been easily accomplished with just an increase in displacement and compression ratio? I'm guessing not, otherwise BMW would not have invested all that time and money changing the valves (and the head, and the intake manifold) in the first place.
But I'm no fluid dynamics engineer, maybe someone has a flow analysis that can show why they wasted all that effort.
08-29-2005 05:14 PM #10
08-30-2005 03:51 PM #11
LOL! I need to open a palm reading place...
I knew you were going to bring that up.
No, if you will read my post carefully, I asked if you thought that just an increase in compression ratio and displacement would be sufficient to raise the power that much. By implication, they do have an effect. Motronic 1.1 has some nice driveablity improvements, such as controlling cold starting from the ECU rather than using a cold start injector, but that doesn't increase power. Try putting Motronic 1.1 on a B34 engine. Will it produce any more power? No, 1.1 doesn't cause the extra power and torque, its mapping allows the B35 engine to take advantage of the increased compression ratio and cam duration. Motronic 1.1 has greater spark advance, which is needed to take advantage of the higher compression ratio, which in turn requires premium fuel. But you can do those things using carbs and a distributor, as well. 1.1 just does it in a very elegant manner. As I mentioned in the very first post, the bigger valves allow the engine to breathe better. The bigger valves let even more air in during that longer duration intake cycle. Maybe 1 mm doesn't seem like much but evidently it's enough. Again, tell me why BMW would bother if all the other changes were enough.
09-01-2005 08:36 PM #12
- Rio Rancho, NM, United StatesMember No: 124000
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- Apr 2005
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11-27-2009 12:44 AM #13
- Perris, CA, United StatesMember No: 129993
- Join Date
- Aug 2005
- Rep Power
Carl had done a friends 3.0 CS a few years ago
It's not that big a deal, when looking at both heads side by side, the B35 head is a more "open chamber" design, which would result in lower compression on an earlier engine. The intake ports are wider and the stock intake manifold barely seals on the sides. It produces a "step" going from the intake to the head, not a smooth transition. I am going to install an M90 (same bore and stroke as the M88/S38) in my '74 Euro 3.0CS. It is the engine used in the '79-'81 M535 and Euro '79-'81 635 and 735 - 218 HP. In california a '74 or earlier CS will not need to wory about smog issues, so I may upgrade with a Schneider cam, headers and B35 head with L-Jet manifold with motronic 1.1. A friend installed a new B35 that had been in his 633 into a '89 635 and he said the newer electronics "woke it up". The motronic bellhousings for the 265 trannys are very hard to come by, Carl just got one a week or 2 ago.
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