bigger displacement: what options?

G

GGR

Member
Messages
36
Reaction score
0
Location
Washington DC
Hi all,

as many 3.0 CSI owners, I have considered upgrading my car with 635 CSI parts: engine, 5 speed gearbox and LSD. But by browsing through the forum, I realized there were more advanced options, such as combining the B35 head with a M90 block using a B35 crank, which gives a 3.65L engine with bigger valves. My first question is to know if it wouldn't be simpler to bore a B35 block and fit M90 pistons to reach the same result. It would save the purchase of a M90 engine.

I went on browsing and found a link to Metric Mechanic. They develop a 4.0 litre engine. I tried to get the bore and stroke specs, but the only info I was able to find is that for a 3,9 litres the use a 90 mm stroke. Knowing that the 3.3 Li had only a 88.4 mm stroke, I wonder which crankshaft they are using...

Is there any experience on this board with the use of a Metric Mechanic 4.0 litre angine? What is it like?

Thanks in advance
 
I would be very wary of large (3.8L+) M30 or S38 derived engines, as they tend to have crank journal bearing issues due to the very large forces on the crank from pistons down the line. 3.7 seems to be the largest one can go without running into this issue. As it happens, I do know someone that is trying to get rid of a M90+B35 head engine, if you are interested.
 
I heard of a guy trying to stuff a V12 into a coupe...
That is about as extreme as it gets. Not sure if he succeeded but after that brakes and structural support would be an issue...
 
Ok, it seems I was mistaken. It is a stock M90, not a M90+B35 combo. However, you should be able to get a B35 head with a minimum of fuss.

The individual in question has a stock ~150k mile M90 for 500$.

This gentleman's name is Harold, and can be reached at:
[email protected]
 
Thank you for this. I was back in Europe for Christmas and did not follow up on the forum.

This gave me the pleasure to drive my CSI again, what a nice car. I co-own that car with a friend and for now he does not seem ready to go into upgrading it... So, I will have to wait a bit.

but just being curious: is it possible to to bore a B35 block and fit M90 pistons?
 
x_atlas0 said:
Ok, it seems I was mistaken. It is a stock M90, not a M90+B35 combo. However, you should be able to get a B35 head with a minimum of fuss.

The individual in question has a stock ~150k mile M90 for 500$.

This gentleman's name is Harold, and can be reached at:
[email protected]
Click to expand...

Is that the going rate for an M90 (Euro)? And would that include the ECU, etc? What about a "dogleg" close ratio 5 speed transmission (Euro 635csi) what do they go for as well?
 
chicane said:
Is that the going rate for an M90 (Euro)? And would that include the ECU, etc? What about a "dogleg" close ratio 5 speed transmission (Euro 635csi) what do they go for as well?
Click to expand...

I'd say the going rate varies considerably. After all, not many people, including some BMW breakers, don't know the difference between a M90 and any other M30, which frequently go for 500$ or less for a good long block.

Given the rarity of the cars that used the M90, I'd be willing to pay a bit more. Plus, it is substantially cheaper than the machine work on the regular M30 block to punch it out to the same bore.

In terms of the ECU and other bits, if I was trying to make a stroker/hot engine, I would use a standalone ECU, like MegaSquirt or any of the others. Since it is a very simple engine, you can use the simplest (and cheapest) sort. New wiring, a new ECU, and new injectors (from MegaSquirt, as an example) would run about 500$.

The CR 265 boxes also have a wide range of value. Similar to the M90, since it was used in so few cars, they can command a premium. However, given the weakness of the box, and how the OD ratios are spaced, there isn't much of a demand for them, either. 500$ would probably be a good starting point, unless it has been recently rebuilt.
 
I paid less than $500 a few years ago for an M90, but here's a current example of one along with a CR in Richmond, VA. This is not my ad, so please do not contact me about it:

I am parting out soon, a very rusty eurospec 635csi. The car has about 130K kilometers with a 218HP M90 motronic engine and a "dogleg" close ratio 5 speed transmission, which is VERY rare and never offered on US spec cars. This car was never "federalized", so all parts are pure unmolested european. The car is complete and drivable and was driven frequently until last fall.

Engine...$600.00 complete long block that is ready to drop in and drive with all necessary external parts for simple swap, such as ECU, external oil cooler etc. Transmission, 5 speed close ratio ...$800.00, interior in saddle brown with comfort, NOT sport seats {good leather} complete...$200.00,...factory sport steering wheel $35.00,... hood and trunklid $50.00 each. All glass in good shape and available. Please call or email about any other parts needed. This is an e12 based 6 series so any e28 based 5 or 6 series cars may require different parts.

Please call me at 314-xxxx or 266-xxxx with any questions. I would concider selling the whole car minus the LSD diff. and some small trim items I need for my 79 635csi. I would make the price VERY reasonable to save me the trouble and expense to take it apart. Lets talk if interested. I do not email pictures, so please do not ask. Thank you.
Click to expand...

Here's the original Craigslist ad:
http://richmond.craigslist.org/pts/989025892.html
 
You must log in or register to reply here.
Back
Top