My VIN does start with "55" so that verifies that .
The number on the identification face by the starter of the "unknown" motor is 41243809. I have a "known" M30B34 with a number of 40073547. Give the same format of number except higher in the sequence of the unknown motor, I am fairly certain that this is just a B34 block with possibly the B28 intake manifold that would have been on the 528.
So now the question for me is whether I chase down an M90 or proceed with the Callaway Turbo M30B32 transplant?!?!
Thanks for all the input everyone. I love learning all these details!
So now the question for me is whether I chase down an M90 or proceed with the Callaway Turbo M30B32 transplant?!?!
Thanks for all the input everyone. I love learning all these details!
I just picked up a 9/80 635 (5590601) with the M90. I also have some pictures from the 11/79 M90 635 (5548918) I parted out last year. Let me know if you want any pictures/details to help with a FAQ.
Marc, that is awesome information, Chris, yours too. Although there seems to be a margin for confusion, the information above can be used as a process of elimination for those of us wondering if we have an M30 or M90, now, will someone please tell us why or if the M90 is "better" than the M30? or is it the other way around?
High compression!
Also, the bore and stroke are different. The M90's 93.4 x 84 allows it to rev easier than the standard M30. The M90 is the same short block as the M88.
The M90 feels much strong at lower rpms that the standard M30.
The M90 feels much strong at lower rpms that the standard M30.
Just when you thought this thread was done... here is a great article on the M90 and further addresses a discussion I have been taking part in on gearing. Interesting to read how the CR Dogleg with the 3.07 diff works with the M90...
http://www.motorsportmagazine.com/archive/article/april-1979/68/road-test-bmw-635csi
http://www.motorsportmagazine.com/archive/article/april-1979/68/road-test-bmw-635csi
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There's probably too many to list and they aren't all that meaningful. But one thing to note is that they are in the VIN, digits 5 through 8. E is the 5th letter of the alphabet, and C is the 3rd, so EC51 equals type code 5331. Later on I guess they quit coding the letters, the type codes are just "HE53" or "HK21" etc.
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It's the same bore and stroke, but you can't just interchange them. Most notably, the M88 has an oil drain back for the right rear of the head that an M90 does not have. The block is cast differently around this area.
I may have access to an '83 euro 635csi. Based on the info in the thread and below, the M90 was produced until late '81 or early '82. So which motor would be in an '83?
From what I gather, it looks like the only difference, according to Motorsport magazine, is that "The bore and stroke has been slightly revised in this latest coupe, the dimensions now being 92 mm. x 86 mm. for a total capacity of 3,430 c.c. (previously 93.4 mm. x 84.0 mm. for 3,453 c.c.). Quoted power outputs remain the same: 218 b.h.p. at 5,200 r.p.m." and "This smooth, taut power unit is further enhanced by the fitting of Bosch Motronic and fuel injection control system with the over-run fuel cut-out which was first offered by BMW on the 733i."
So is this still an M90 or did they revert to the M30 designation? And is the compression different or does it retain the high compression of the earlier M90?
Thank you.
From what I gather, it looks like the only difference, according to Motorsport magazine, is that "The bore and stroke has been slightly revised in this latest coupe, the dimensions now being 92 mm. x 86 mm. for a total capacity of 3,430 c.c. (previously 93.4 mm. x 84.0 mm. for 3,453 c.c.). Quoted power outputs remain the same: 218 b.h.p. at 5,200 r.p.m." and "This smooth, taut power unit is further enhanced by the fitting of Bosch Motronic and fuel injection control system with the over-run fuel cut-out which was first offered by BMW on the 733i."
So is this still an M90 or did they revert to the M30 designation? And is the compression different or does it retain the high compression of the earlier M90?
Thank you.
Bo, get the engine VIN ... that would be the first question that SFDon would ask. the next thing is to run a compression check to see what the engine reads ... around 210 is 10:1. barring the ability to do that, put a scope into the engine to see what the piston tops look like ... piano tops are good. a euro "dirty" b34 is a great engine to have ... as long as it hasn't been destroyed internally.
talk to Don
talk to Don
Thank you Layne and Scott. I'm trying to get the VIN.
If it is the 10:1 M30B34, can you still use US unleaded pump gas? At which point do you need to get your chemistry degree dusted off and start mixing special brews?
If it is the 10:1 M30B34, can you still use US unleaded pump gas? At which point do you need to get your chemistry degree dusted off and start mixing special brews?
Bo,
Even your stock m30 should have premium gas, show it some love!
Even your stock m30 should have premium gas, show it some love!
I just wanted to add another relatively easy thing to do if you have a laptop or android phone. This is a good option for curious folks like me that don't want to get their hands too dirty.
For $20, you can buy a USB inspection camera and drop it down the #1 spark plug hole. I've also run mine through my rockers and in the area near the A-Pillar windshield frame.
https://www.amazon.com/DBPOWER-Wate.../B01MT7OLIQ/ref=sr_1_2?ie=UTF8&qid=1490736580
With a camera, you can see the piston top, which is pretty distinctive for each motor.
Here is one of my 2800CS. Lots of fumbling with the insertion but it was my first time.
From: http://www.m535i.org/officers/ra/article.html
M90 piston (M30-family); 3453cc engine (found on E12 M535i, early E24 635CSi)
2002 High compression pistons. Dome form similar to B34 high compression dome
M30 B34, high compression pistons in engine (1st engine bay photo)
M30 B34, high compression pistons in engine (2nd engine bay photo)
M30 B34, low compression pistons 1 (these are M106 turbo pistons, but shape and compression are similar)
M30 B34, low compression pistons 2 (these are M106 turbo pistons, but shape and compression are similar)
M30 B35 pistons, photo 1
M30 B35 pistons, photo 2
M30 B35 pistons, photo 3
M30 B35 pistons, photo 4
For $20, you can buy a USB inspection camera and drop it down the #1 spark plug hole. I've also run mine through my rockers and in the area near the A-Pillar windshield frame.
https://www.amazon.com/DBPOWER-Wate.../B01MT7OLIQ/ref=sr_1_2?ie=UTF8&qid=1490736580
With a camera, you can see the piston top, which is pretty distinctive for each motor.
Here is one of my 2800CS. Lots of fumbling with the insertion but it was my first time.
From: http://www.m535i.org/officers/ra/article.html
M90 piston (M30-family); 3453cc engine (found on E12 M535i, early E24 635CSi)
2002 High compression pistons. Dome form similar to B34 high compression dome
M30 B34, high compression pistons in engine (1st engine bay photo)
M30 B34, high compression pistons in engine (2nd engine bay photo)
M30 B34, low compression pistons 1 (these are M106 turbo pistons, but shape and compression are similar)
M30 B34, low compression pistons 2 (these are M106 turbo pistons, but shape and compression are similar)
M30 B35 pistons, photo 1
M30 B35 pistons, photo 2
M30 B35 pistons, photo 3
M30 B35 pistons, photo 4
Yes of course. Premium is required. What I meant was does the 10:1 compression require additives to boost the octane past the 92 of premium gas?
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I have been doing that since the new head and rebuilt bottom was done on the E24.
Hey, rebuilt by Don, I am willing to fill the tank with Moet Chandon if he asks me to.
well ... premium in georgia and premium in california might be 2 different things. we have 93 octane premium around here. i'm not too worried about 10:1 ... my last 2002 had 10.5:1 and it ran great on premium
Here is the issue with "premium"... It is nothing more than a relative term. In the US, Premium is 92/93. In Europe (and Australia/Asia for that matter) premium is 98. In fact the lowest grade starts at 91/92 with mid-grade being 95. Further, in both Germany and Australia you can buy 102 at select stations. I think this has much to do with the difference in performance of cars over here versus other parts of the world and suspect that a couple/few decades ago it was even harder for engineers to make comparable power with the lower grade gas combined with the stricter emission regulations. For this reason, I would expect that an M90 here in stock form with timing adjusted to suit the lower RON would likely not make the 210HP of the 98RON fueled cars.
i am far from an expert on this subject, so i am happy to be set straight by somebody who actually knows and understands this more than i do. i think you are confusing RON (research octane number - europe) and AKI (anti knock index - US octane) - they are very different things. i have read on the porsche forums that 95 ron = 91 aki (california) and 98 ron = 93 aki (the rest of america)
aki = (ron + mon) / 2
mon is motor octane number
from wikipedia (so this could be wrong)
Research Octane Number (RON)
The most common type of octane rating worldwide is the Research Octane Number (RON). RON is determined by running the fuel in a test engine with a variable compression ratio under controlled conditions, and comparing the results with those for mixtures of iso-octane and n-heptane.
Motor Octane Number (MON)
Another type of octane rating, called Motor Octane Number (MON), is determined at 900 rpm engine speed instead of the 600 rpm for RON.[1] MON testing uses a similar test engine to that used in RON testing, but with a preheated fuel mixture, higher engine speed, and variable ignition timing to further stress the fuel's knock resistance. Depending on the composition of the fuel, the MON of a modern pump gasoline will be about 8 to 12 octane lower than the RON, but there is no direct link between RON and MON. Pump gasoline specifications typically require both a minimum RON and a minimum MON.[citation needed]
Anti-Knock Index (AKI) or (R+M)/2
In most countries, including Australia, New Zealand and all of those in Europe,[citation needed] the "headline" octane rating shown on the pump is the RON, but in Canada, the United States, Brazil, and some other countries, the headline number is the average of the RON and the MON, called the Anti-Knock Index (AKI), and often written on pumps as (R+M)/2. It may also sometimes be called the Posted Octane Number (PON).
Difference between RON, MON, and AKI
Because of the 8 to 12 octane number difference between RON and MON noted above, the AKI shown in Canada and the United States is 4 to 6 octane numbers lower than elsewhere in the world for the same fuel. This difference between RON and MON is known as the fuel's Sensitivity,[4] and is not typically published for those countries that use the Anti-Knock Index labelling system.
aki = (ron + mon) / 2
mon is motor octane number
from wikipedia (so this could be wrong)
Research Octane Number (RON)
The most common type of octane rating worldwide is the Research Octane Number (RON). RON is determined by running the fuel in a test engine with a variable compression ratio under controlled conditions, and comparing the results with those for mixtures of iso-octane and n-heptane.
Motor Octane Number (MON)
Another type of octane rating, called Motor Octane Number (MON), is determined at 900 rpm engine speed instead of the 600 rpm for RON.[1] MON testing uses a similar test engine to that used in RON testing, but with a preheated fuel mixture, higher engine speed, and variable ignition timing to further stress the fuel's knock resistance. Depending on the composition of the fuel, the MON of a modern pump gasoline will be about 8 to 12 octane lower than the RON, but there is no direct link between RON and MON. Pump gasoline specifications typically require both a minimum RON and a minimum MON.[citation needed]
Anti-Knock Index (AKI) or (R+M)/2
In most countries, including Australia, New Zealand and all of those in Europe,[citation needed] the "headline" octane rating shown on the pump is the RON, but in Canada, the United States, Brazil, and some other countries, the headline number is the average of the RON and the MON, called the Anti-Knock Index (AKI), and often written on pumps as (R+M)/2. It may also sometimes be called the Posted Octane Number (PON).
Difference between RON, MON, and AKI
Because of the 8 to 12 octane number difference between RON and MON noted above, the AKI shown in Canada and the United States is 4 to 6 octane numbers lower than elsewhere in the world for the same fuel. This difference between RON and MON is known as the fuel's Sensitivity,[4] and is not typically published for those countries that use the Anti-Knock Index labelling system.
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