C1 - B3 Alpina... I need some help

Post Tue May 23, 2006 8:39 am

Ok, I need some pictures of the Alpina B3 head and the C1 head... I'm askin is cause I'm pretty sure our 325iS Evo 1 came with an Alpina C1 head, and the Evo 2 had the B3 head...

So that is my predicament

Steve

Post Tue May 23, 2006 12:52 pm

What do you need to know?

To confirm whether it's an Alpina head, there should be four numbers stamped into the front/inlet side.

Post Tue May 23, 2006 2:08 pm

I want 2 compare them... cause we're having a bit of a dicussion about the different heads on the 325iS ... my one mate says that the cam shaft is the only Alpina thing on the head of the Evo 1, and the Evo 2 has a C1 head with camshaft...

Where I think the Evo 2 has a B3 head and the Evo 1 has a C1 head.

What r the differences between a standard 325i head, and the C1 and B3... that would probably help out.

Post Tue May 23, 2006 2:48 pm

Right... all that Evo stuff for the Sport must be specific to SA; over here, a Sport's a Sport.

I'm guessing that an Alpina head would have bigger valves, porting, and of course the cam would be different. The early C's were based on the 323i, which has a different casting number on the head (ends in 731) than the 325i (ends in 885).

E30 Alpinas were:

C1 2.3 - C1 2.5 - C2 2.5 - C2 2.7.

All except the 2.7 should have a "731" head.

There was also a "C2.5", which was a 325i with an Alpina cam (amongst other options)

As far as I'm aware, the B3 is the German designation for the UK C2 2.7, unless there was a different one for SA.

It's a dark art, though, ain't it?

Post Tue May 23, 2006 5:27 pm

a C1 is a modified 200 head off a 2.3 M20 and won't be fitted to your car.

So i believe the engine in the evo2 is the same as our alpina C2 2.7 engines in europe. This is a modified 885 head off the 2.5 M20

how old is your car?

Post Wed May 24, 2006 7:28 am

So far what I know about the 325iS Evo 1 , is that it's valves r the same size as a normal 325i ... but I'm not so sure about the ports, and the camshaft.

I know the Evo 2 has a bigger exhaust valve, its actually the same size as the intake valve. and a 272deg cam shaft.

Wish that BMW SA was more open with the specs, as well as Alpina who was partnered in building the 325is Evo's and 333i

Post Wed May 24, 2006 5:12 pm

so the evo 1 just had a tinkered with 2.5 head yes?

ah evo 2 had a better cam in them, we only got 268 in europe on C2's, both have bigger valves then.

did evo2's have a bigger throttle body too then?

Post Thu May 25, 2006 7:48 am

Theu both had a bigger throttle body... but it can still be made even bigger

Post Fri Jun 02, 2006 3:54 pm

Useful info... what's the source, Argos?

Alpina knowledge: The Da Vinci Code of the auto industry...

Post Fri Jun 02, 2006 4:04 pm

I had an Alpina cam - its had 266 engraved into it.

Post Wed Jun 07, 2006 8:19 pm

I currently have my Alpina B3 2.7 in pieces. I took the valves out of the head today (07 Jun 2006) and measured them - Intake = 42mm and Exhaust = 36mm which as far as I know are the same diameters as a standard 325.

A couple of years back I turned out the throttle body to its absolute maximum, but I do not remember that its size was different to any other throttle body (we had 325 Shadowline and 325 is Evo 1 bodies as well)

Post Thu Jun 08, 2006 8:56 pm

Argos wrote:Has the head got the four digit number stamped along the top edge (inlet side)?

The only numbers I see that might interest you are
13/01 (bottom edge)
and
1 705 885 (top edge)

Post Mon Jun 12, 2006 10:23 am

Thanks man.

the 325iS has a 272 Alpina Cam in it... that I do know I used 2 have one, and every tuner in South Africa knows this.

Post Mon Jun 12, 2006 10:27 am

Andreas wrote:I currently have my Alpina B3 2.7 in pieces. I took the valves out of the head today (07 Jun 2006) and measured them - Intake = 42mm and Exhaust = 36mm which as far as I know are the same diameters as a standard 325.

A couple of years back I turned out the throttle body to its absolute maximum, but I do not remember that its size was different to any other throttle body (we had 325 Shadowline and 325 is Evo 1 bodies as well)

Thought the Evo1 and 2 had the same TB. I thought the Shadowline had std TB, but with 9.8:1 CR pistsons ?

Post Mon Jun 12, 2006 6:20 pm

In my last response I tried to give the impression that I am not 100% sure about the throttle body sizes. Sorry, I should have been clearer. Asked my brother, who enlarged both his 325 Shadowline and 325 is Evo 1 throttle bodies and he also cannot remember if there was any size difference.

To be honest I doubt that there were different sizes available, you can phone BMW spares and ask if they have different part numbers for the throttle bodies of the different cars.

My TB was turned out to 65.8mm in front and tapers down to 64.65mm at the back where it meets the intake manifold which has a hole of 64.5mm (average, not completely round).

The TB was turned out a bit too much though; after a while the whole spring mechanism broke off because of too little wall thickness. Had it welded back on and packed it with some hard glue and never had another problem with it again.

Post Wed Jun 14, 2006 2:52 pm

Ahh, ok...

Cause I do know that the 325iS had a bigger throttle body over the std 325i .

I must check, but 2 find a 325iS evo that isn't modified... thats another story

Post Wed Jun 14, 2006 9:04 pm

Stevin wrote:Ok, I need some pictures of the Alpina B3 head and the C1 head... I'm askin is cause I'm pretty sure our 325iS Evo 1 came with an Alpina C1 head, and the Evo 2 had the B3 head...

So that is my predicament

Steve

Steve, bear in mind that BMW SA tried to cut down on costs to keep the Alpina B3 affordable when they built those 15 cars. One of the sad facts is that they started off with a standard 325i and converted it to the B3 spec.

M20 engine blocks have some numbers punched in on the intake side down next to the engine mounting arm. The first two digits indicate the cubic capacity of the engine when they assemble it. Now my engine block's number starts off like this "25 6E 2", indicating a 2.5 liter ( I guess the 6 represents the cylinders and maybe the 2 is for 2-valve). On my brother's 325is Evo 1 block this number starts with "27 ..." indicating 2.7 liters.

My car even has standard 325i brakes without ABS. There are NO aluminium control arms and NO solid rubbers for the control arms. The hubs are standard 4-stud NOT the 325is 5-stud with bigger wheel bearings.

The B3 does have thicker sway bars than a 325is, Bilstein shocks, the special Alpina offset rubber mount for the front struts, Alpina steering wheel and gear knob, 3.91 diff and a 2.5/2.7 head.

My point is this, even though I have an original (have the Alpina metal car no. 12 identifier tag somewhere) Alpina B3, it is a BMW SA edition and any specs, codes and identifiers I provide on this forum may surprise our European friends who know the original B3 from Germany.

Alpina B3 2.7 Racecar under construction.