Engine changes v rebuild

[Paul02]

Hello
I am relatively new on here and read about the various engine options that will fit an E9 with a bit of work.
What I am not sure of is the main reason for doing this ?
Is it that the old engines are unreliable (even after rebuild ) , slow , not enough power , harder to find spares ,thirsty , etc .
Please tell me why I want or should change my engine which I thought was alright ? Does anyone keep them stock or is a change the way forward. Also how does the performance compare with say a 3.5 litre with motronic against my 3.0 cs. Is it worth all the exercise if I am content with performance.
Paul .

 

[x_atlas0]

You hit the nail on the head: performance. The 3.5 has more torque and more power, especially when combined with the Motronic 1.3. The parts for a M30 rebuild run ~2-3k, to say nothing of the labor. Tossing in a used 3.5 is a good bit less than that, and you get all the benefits of fuel injection.

 

[Paul02]

Thanks Fella

You explained it straight away .
I always wanted to upgrade just needed to know why I was doing it apart from change for the sake of it.
I appreciate your answer.

Cheers Paul

 

[psychrunner]

leads to another Question....

Would I be able to keep my 4 speed tran. if I add the 3.5 liter m30b35 engine? I talked to bavarian engine exchange today and the sales guy indicated that a change to the 5 speed would be necessary. I don't think that is accurate, though it is for sure a desireable change.
Thanks

 

[velocewest]

What transmission you use is entirely your choice. The engines are all the same bolt pattern, same tail on the crank, essentially all the same block. The only issue is if the engine had a manual or automatic behind it originally, as you might have to install a pilot bearing -- 2 minutes and under $10.

Bavarian Engine Exchange is not the most well regarded source of parts or advice in the BMW community.

 

[BarryG]

If you are looking for a great motor give Steve Haygood a call.He has a 1989 635csi motor,Harness,& ECU...
www.stevehaygood.com
This deal came about 3 weeks to late for me or I would have grabed it up.It is the, I think 218 HP motor.The harness is also the long one that will go all the way back to your glove comparment...
Steve is the Man when it come to getting parts,Best deals and very Fast.
He has also done the swap. Maybe he could do it for you?

 

[dave v. in nc]

thirstier?...

I am aware of the benefits of the the 3.5 except Paul's question about thirst. How does the 3.5 compare to the 3.0 on fuel efficiency; apples to apples (ie., if both had same 5 speed tranny..) Dave V. in NC

 

[x_atlas0]

Re: thirstier?...

I am aware of the benefits of the the 3.5 except Paul's question about thirst. How does the 3.5 compare to the 3.0 on fuel efficiency; apples to apples (ie., if both had same 5 speed tranny..) Dave V. in NC

So far in mine, I've been getting mid 20s, mostly suburban driving.

 

[Honolulu]

Mileage

The consensus of what I've seen is that the Motronic engines give "some" increase in gas mileage, like 2-3 mpg. But a coupe may only get 13-15 to start with, overall, so you won't win any miles/gallon contests. Ever.

 

[x_atlas0]

Re: Mileage

The consensus of what I've seen is that the Motronic engines give "some" increase in gas mileage, like 2-3 mpg. But a coupe may only get 13-15 to start with, overall, so you won't win any miles/gallon contests. Ever.

13-15? Man, that is low. An E34 535 will do at least 17 all city, and easily do mid-high 20s on the highway, and that car weighs an extra 800lbs. The drivetrain is exactly the same, if you do a 3.5B35/265 swap, as the E34 had a 3.45 diff, as well.

Are your carbs in good shape? What about the fuel filter? Plugs? Heck, the magazines at the time got 17+ in the 3.0CS.

 

[velocewest]

In normal day to day driving, I got ~18mpg in town and ~28 on the highway in my e12, running a 10:1 comp 3.5 with a Schrick 282 and chipped Motronic. It was capable of much worse...