Power output

[steve853]

Just wondering, does anyone know the difference between the 2.5i setup, and the 2.5 Si?

As far as I can tell the engines are identical, but the Si has 40 odd Horses more than the i, and I was wondering if anyone knows how I can find them?

Steve

 

[grayboots]

A guess but it might be a restricted inlet manifold on the i variant. That was the difference between the E36 325i and the 323i, both 2.5 litres but the 325i was 192bhp and the 323i 170 bhp.

 

[Mr Whippy]

Is this an M54B25 2.5i vs an N52 2.5Si?

Or did the facelift E85's come with two different 2.5i engines, 2.5i and 2.5Si?


All I know is the 2.5Si is a 3.0 capacity engine, the same as the 3.0Si, but it has different cams and maybe head, and different ECU settings. In theory, the 2.5Si could have just been a remapped (down-throttled via valve lift) 3.0Si... in essence it is almost the same engine.

If there is a 2.5i (valvetronic version), then it could well be just a down-mapped 2.5Si, so very easy to remap to 2.5Si output (valve lift and et voila, more power)...

Or, the 2.5i you are talking about could be the old 2.5i M54, which is simply an older design engine to the Si unit, as well as actually being 500cc smaller in capacity too!

Dave