Swapping B20 to B25

[BackinBlack]

Finally got all the bits and pieces together for the swap....but...

Was looking at the two engines (B20 still in car, B25 on the floor), and spotted a difference.

On the throttle body of the B20 there are two vacuum(?) pipes coming from the right hand side which lead to the brake servo. On the top pipe there is a link to the big air line into the throttle body and then into the top of some valve that the bottom pipe attaches to before the pipe goes off to the servo.



On the B25, there appears to be no join for the top vacuum pipe to join the air pipe?

Is this not required for the B25, is it OK to replace the top hose with a single piece like the bottom hose?

Any guidance would be very helpful.

[BackinBlack]

Erm photo didn't come out, will try again.....

[BackinBlack]

[clarko74]

I had had this issue when I upgraded to Motronic 1.3. The short answer is yes, the branch into the large intake isn't required and can be omitted. You can replace the top hose with a single piece or remove the bit with the branch in it, trim the bottom hose down and just fix the two into one bit into this. This is what I did and it tidies up the engine bay too:



Here is my original thread fyi:

http://www.e30zone.net/modules.php?name ... c&t=183011

[Brianmoooore]

First pic. is the set up used on early E30 M20s, second pick is a hybrid bodge using the big air hose from a later M20, and the throttle body and part of the non return valve from the earlier version.
The late version should have a throttle body with a single connection on the right hand side, going to a simple angled non return valve, of the type used on M40 engined E30s, and later BMWs, and from there, a hose going to the brake servo. The brake servo on these later E30s is also rotated through 180 degrees, to bring the hose connector nearer to the engine.
It's a bodge I haven't seen before, but it should work fine.

[BackinBlack]

Brilliant, thank you for the feedbacks

Full steam ahead for the conversion.

Patrick