I consider my M30B35 to be a wonderful engine. I'd rather have my not-so-economical 39-year old technology behind 18-year old construction than a lot of what's being designed and made today. The torque, smoothness, and overall reliability are still competitive, even among brand-new cars. And then there's the sound...:drool:

So how's it compare to the older engine - the M30B34 that many of you have? Is there any reason to prefer it over the B35, even something minor like the sound? Is there more of whatever quality makes the last of the M30's what it is?

i was going to make a similar post tonight too! but mine will be turbo'd by late spring. sorry to take it off topic bro.

The B35 is simply a better engine in every way. It has a higher CR stock, but not too high such that it will ping on regular. The heads flow much better. It is smoother, has a hotter cam, better intake manifold, and uses the Motronic 1.3 system, rather than the decidedly more clunky 1.0 system.

Now, M90 versus M30B35, that is a hard question.

bump

M90? :confused

Was ist das?

How hard is it to swap a B35 for a B34? If, say, I wanted an E24 that moved and sounded like Irina?

M90? :confused

Was ist das?

How hard is it to swap a B35 for a B34? If, say, I wanted an E24 that moved and sounded like Irina?

The M90 is pretty much a M88 block with a M30 head. So, it is a very oversquare M30. This means it is very easy, using stock parts, to get a displacement up to 3.7L using widely availble parts. Also, it revs much more freely than the M30B34 or B35. The "ultimate" stock combination for the M30 is a M90 with a B35 head, as that gives a 3.65L engine with a CR of ~10:1 CR. Should put out ~220 rwhp 240 rwtq.

The M90 was used in the E12 M535, and the E12-based E24 635csi, if I remember right.

In terms of switching to a B35, there are a couple of changes. The B35 motor mounts are slightly different, such that it requires an adapter plate to get all the bolts to match. That said, three of them do, so it isn't that critical. Also, to get the most out of the B35, you need to switch to Motronic 1.3, which also requires using the later engine's wiring harness, DME, and harmonic damper. The trans and everything should still match. You'd want to use the old flywheel though, as it weighs a lot less than the B35's dual mass flywheel.

This M88 block/B35 head - what does it take to work? Does everything just bolt up, or is there some custom work/tuning involved? I can't imagine M88 blocks are easy to find.

This M88 block/B35 head - what does it take to work? Does everything just bolt up, or is there some custom work/tuning involved? I can't imagine M88 blocks are easy to find.

Not really, the better option is to try and find a M90 block, then use a B35 head. You have to switch some of the timing covers, but other that that, it is apparently a bolt-on affair. I have yet to do it, but it is on my list. If I can't find a S38 for a good price, this is the second best thing.

As for a tune, yeah, that is needed to get the full power out of the engine. Honestly for that though, I'd just go MegaSquirt. The M30 is about as simple as an engine can get, in terms of operation. No VANOS, no COP, just a dizzy and a cam. If going that route, I'd also ditch the AFM for a MAP or a MAF. That way, you can tune it yourself.

If you are trying to make the "ultimate" M30, I'd go with a worked head, (from someone like BavEngine or Metric Mechanic) a 288 cam, (little lumpy at idle, but not too bad) aftermarket pistons and rods, (not to change the CR, but to reduce the reciprocating mass, makes it rev faster) and a slightly overbored M90 block. (Gets you to 3.7L even with plenty of meat left between the walls if you want to go FI later.) Couple that with a MS system, and you're likely laying out ~250rwhp. Of course, this engine would cost you ~5.5-7k just for the parts. You'd have a completely rebuilt engine, though, second only to the S38.

ok now you have me thinking and thats always a problem. anyway what year did the b34 stop and the b35 begin? and in what models? I have an 87 L6 and a 91 535 and the engines are totally different in feel and sound.Are these the two you refer to. Because I was thinking how cool it would be to have the e34 setup in my 6. Also I have an e12 based 6 and it was built in september 81 and wonder about that engine also cause it pulls almost as fast as the e34 but I atribbuted that to the 5 speed.

The B35 is simply a better engine in every way. It has a higher CR stock, but not too high such that it will ping on regular. The heads flow much better. It is smoother, has a hotter cam, better intake manifold, and uses the Motronic 1.3 system, rather than the decidedly more clunky 1.0 system.

Now, M90 versus M30B35, that is a hard question.
Agree, My old M90 in the 80 Euro pulled just as well as my S38 in the M6 until above 5500 to 6000 RPM where the S38 starts to really make power.:)

does an 1985 635csi have the motronic 1.3 system? and how easy would it be to make the 'ultimate m30 combo' in my car?

does an 1985 635csi have the motronic 1.3 system? and how easy would it be to make the 'ultimate m30 combo' in my car?

Motronic 1.3 started with the E32 and E34. It was used on the M30B35 exclusively, as far as I am aware. All the M30B34s have Motronic 1.0. The easiest way to tell is to check the harmonic balancer. The 1.3 takes the crank position off the harmonic balancer, hence it is toothed, like a large gear. The 1.0 system gets this same information from the flywheel, which actually is a large gear. The sensors are attached to the bellhosuing to get the flywheel reading. The 1.3 systems also have their intake manifold stamped with just 3.5, versus the earlier 3.2/3.5.

For your car, it really depends on how far you want to take it. The ideal build, like I said earlier, would require a new block, new head, and switching to MegaSquirt or other source for tuning. So you'll end up replacing the whole sheebang anyway, not exactly an easy task.

ok now you have me thinking and thats always a problem. anyway what year did the b34 stop and the b35 begin? and in what models? I have an 87 L6 and a 91 535 and the engines are totally different in feel and sound.Are these the two you refer to. Because I was thinking how cool it would be to have the e34 setup in my 6. Also I have an e12 based 6 and it was built in september 81 and wonder about that engine also cause it pulls almost as fast as the e34 but I atribbuted that to the 5 speed.

If thinking causes a problem, I'd hate to see you doing engineering! :stickoutt

The date of the B34/B35 switch is somewhat ambiguous. The best determinant is by model, rather than year. The E32 and E34 only got the B35 for sure, as well as Motronic 1.3. The B34 was on the E28, E23, and E24 from ~82 onward. Motronic 1.0 was also used on the B34, as before the L-Jet system was used, an older, analog system of electronic fuel control. Your E24 and E34 have totally different feels because one uses the B34/1.0 pair (the E24) and the other uses the B35/1.3 pair. (the E34) This gives ~40 more hp, based ont he BMW figures. This older E24, is it a 635? If it is, then it could very well have the M90.

Agree, My old M90 in the 80 Euro pulled just as well as my S38 in the M6 until above 5500 to 6000 RPM where the S38 starts to really make power.:)

That's what everybody says. I've wanted to do this build for a while, my life just isn't in the right place yet. I've even found a local supplier that could get me the major components (M90 short block and B35 head) for ~800$. So when the time is right, I may very well do it. It is more a matter of space than money.

Motronic 1.3 started with the E32 and E34. It was used on the M30B35 exclusively, as far as I am aware. All the M30B34s have Motronic 1.0. The easiest way to tell is to check the harmonic balancer. The 1.3 takes the crank position off the harmonic balancer, hence it is toothed, like a large gear. The 1.0 system gets this same information from the flywheel, which actually is a large gear. The sensors are attached to the bellhosuing to get the flywheel reading. The 1.3 systems also have their intake manifold stamped with just 3.5, versus the earlier 3.2/3.5.

For your car, it really depends on how far you want to take it. The ideal build, like I said earlier, would require a new block, new head, and switching to MegaSquirt or other source for tuning. So you'll end up replacing the whole sheebang anyway, not exactly an easy task.



If thinking causes a problem, I'd hate to see you doing engineering! :stickoutt

The date of the B34/B35 switch is somewhat ambiguous. The best determinant is by model, rather than year. The E32 and E34 only got the B35 for sure, as well as Motronic 1.3. The B34 was on the E28, E23, and E24 from ~82 onward. Motronic 1.0 was also used on the B34, as before the L-Jet system was used, an older, analog system of electronic fuel control. Your E24 and E34 have totally different feels because one uses the B34/1.0 pair (the E24) and the other uses the B35/1.3 pair. (the E34) This gives ~40 more hp, based ont he BMW figures. This older E24, is it a 635? If it is, then it could very well have the M90.



That's what everybody says. I've wanted to do this build for a while, my life just isn't in the right place yet. I've even found a local supplier that could get me the major components (M90 short block and B35 head) for ~800$. So when the time is right, I may very well do it. It is more a matter of space than money.

alright then. whats the easiest way beside chipping it(which i will probably do first)to add power and keep the motronic 1.0 system and not switching over? get a straight up euro tuned m30?

Just to add to the above, the '85 to '87 got the Motronic 1.0 Adaptive. Also don't use the presence of a sensor on the harmonic balancer as a test as to which system is on the car, many e24's and e28's had one in addition to the sensors on the bell housing but it was only wired to the diagnostic plug and not used by the Motronic.

Most important is the fact that the e24 did get the B35 with the Motronic 1.3 for the '88 (6/87) and '89 model years.

Bluesman, to see if you car has the M90, look for a white "L" panted on the side of the block under the intake manifold. Here is more information on the M90 engine and how to ID it. (http://bigcoupe.com/phpBB2/viewtopic.php?t=1296&highlight=m90+tell)

Sixseries, your info lists your car as a Euro 635 - 5 SP, It doesn't get much better then that. You should already be running 218 HP vs 185 HP and chipping won't help much.

Most important is the fact that the e24 did get the B35 with the Motronic 1.3 for the '88 (6/87) and '89 model years.


You know, I've always heard that, but when I've seen late (post 6/87) parts 6-ers, they always have a B34. I also know they supposedly did the same thing on the E23, giving the very late runners B35s, but I got such an engine for my E9, and it is a B34. To be absolutely sure, and to make sourcing the engine easier, I'd just go for an E32 or E34.

Oh yeah, another way to visually identify the B35 head is the complete abscence of a mechanical fuel pump hole of any sort on the head, at about the middle on the intake side. The B35 has a couple of stamped lines there instead.


Sixseries, your info lists your car as a Euro 635 - 5 SP, It doesn't get much better then that. You should already be running 218 HP vs 185 HP and chipping won't help much.

Plus, you'd need to use a Euro chip, as the Euro DME is setup differently, since it doesn't (if I recall correctly) have cats or O2 sensors. The CR is also higher, so using a US chip would be counterproductive.

Just to add to the above, the '85 to '87 got the Motronic 1.0 Adaptive. Also don't use the presence of a sensor on the harmonic balancer as a test as to which system is on the car, many e24's and e28's had one in addition to the sensors on the bell housing but it was only wired to the diagnostic plug and not used by the Motronic.

Most important is the fact that the e24 did get the B35 with the Motronic 1.3 for the '88 (6/87) and '89 model years.

Bluesman, to see if you car has the M90, look for a white "L" panted on the side of the block under the intake manifold. Here is more information on the M90 engine and how to ID it. (http://bigcoupe.com/phpBB2/viewtopic.php?t=1296&highlight=m90+tell)

Sixseries, your info lists your car as a Euro 635 - 5 SP, It doesn't get much better then that. You should already be running 218 HP vs 185 HP and chipping won't help much.

yeah its a euro sixer. unfortunately even though being built in europe and having the better looking euro body, it came stock with a cat so the engine is a powerful as a US 635. thats why im intersted in chipping it.

yeah its a euro sixer. unfortunately even though being built in europe and having the better looking euro body, it came stock with a cat so the engine is a powerful as a US 635. thats why im intersted in chipping it.

So you've got a Euro Kat version? That's pretty uncommon. Since this is a pretty different sounding car, upgrades must be considered very carefully. I would first check to see what sort of DME you have, as that will determine if you can use the american chips or are limited to the Euro chips.

Alternatively, you could just switch the whole car over to MegaSquirt. It would be quite a job, though, and make repairs a one-man show with you as the star. No shop would want to touch it.

And just having a Cat doesn't mean the HP is as low as the U.S. model, a well designed Cat shouldn't knock much HP off. It is the compression ratio that is going to have the biggest impact on the HP, the question is, what was the compression ratio for the market where the car was originally sent to?

And just having a Cat doesn't mean the HP is as low as the U.S. model, a well designed Cat shouldn't knock much HP off. It is the compression ratio that is going to have the biggest impact on the HP, the question is, what was the compression ratio for the market where the car was originally sent to? True, but the factory Cat cars made for Europe and other parts of the world are the same as the NA cars engine wise. There were even a few Euro delivered S38 engines in the M-cars instead of M88 engines.

True, but the factory Cat cars made for Europe and other parts of the world are the same as the NA cars engine wise. There were even a few Euro delivered S38 engines in the M-cars instead of M88 engines.

Exactly, I thought they all had the same CR if they had a cat, making them pretty much a US car, in terms of the engine.

Too Bad! But it sounds like it will respond to a regular chip. ( I'd check with the chip maker, of course).

And just having a Cat doesn't mean the HP is as low as the U.S. model, a well designed Cat shouldn't knock much HP off. It is the compression ratio that is going to have the biggest impact on the HP, the question is, what was the compression ratio for the market where the car was originally sent to?

yeah i was disappointed when i checked the VIN #. its got the 8.0:1 CR. is Dinan or Conforti the better one? and i have to keep the upgrades simple cuz im a 16 yr student with virtually no time on my hands and little money.

yeah i was disappointed when i checked the VIN #. its got the 8.0:1 CR. is Dinan or Conforti the better one? and i have to keep the upgrades simple cuz im a 16 yr student with virtually no time on my hands and little money.

Then check a few things first:
1. O2 sensors. They croak, car runs too rich, kills power and mileage. Bad all around.
2. Coil, plugs, and wires. Bad coil can cause driveability issues. Weak coil causes lack of power.
3. TPS. Miscalibrated TPS will cause lack of power.
4. Cat. They go bad over time. Yours, given the age of the vehicle and likely miles, could very well be kaput. If so, easiest thing to do is straight pipe it. Should cost~40$ from an exhaust shop.
5. Change ALL the fluids. Coolant, diff, manual trans oil, regular oil, brake fluid, the works. Put in high-quality fluids, and the car will almost certainly run better.
6. Steel brake lines and some better pads. Gives much more linear brake feel. Before you go faster, make sure you can stop better. Stock rotors are fine. If the stock brakes with these simple mods aren't enough, you need to slow down.
7. Suspension. The E24 was a touring car. If you want to feel like you are going fast, (and you probably will be) springs, shocks, and sways are an excellent way to go, especially if the stock ones are shot.
8. Limited Slip Diff. Stick with the stock ratio, the LSD will help keep you in control if things start to get hairy. Otherwise, you'll end up a one-tire-fryer. Can be had from pick-n-pulls for ~200$.

9. Driving classes. I cannot stress this enough. Not those defensive driving classes, but the performance classes, like Skip Barber and such. They will teach you to be more alert, more attentive, and how to handle tricky situations like hydroplaning through a curve. Plus, they teach you how to drive more efficiently, saving gas and allowing you to use the car to more of its original potential. Improve what's behind the wheel before adding power.

9. Better than a chip, I'd switch from the AFM to a MAF. Gives better driveability, responsiveness, power, and mileage, as well as all the bonuses of a chip. On a B35, showed 20rwhp gain by itself. I suggest Miller. Given your somewhat unique application, though, I'd give them a call first.

That will all be plenty to both teach you about the car, and keep you from killing yourself. Heed my words, I was just there, not too long ago. (I'm 23) I saw too many of my friends end up a road pizza because they did stupid crap while driving.