engines: 3.0i vs 3.0si

[xorbe]

Is the 3.0si stronger through the mid-range too, or is it just an intake change that results in a 40 crank hp advantage during the last ~1500 rpms?

Googled up a couple stock 3.0si dyno charts, but no luck on a stock 3.0i dyno chart. Just curious.

edit: Whoops - that was a silly question, as the 3.0si is rated +35 tq @ 2750 rpms... :embarrasm but I still wouldn't mind seeing a stock 3.0i dyno chart, as the max hp of the 3.0si is rated at 350 rpms more than the 3.0i engine.

[anpmech]

Is the 3.0si stronger through the mid-range too, or is it just an intake change that results in a 40 crank hp advantage during the last ~1500 rpms?

Googled up a couple stock 3.0si dyno charts, but no luck on a stock 3.0i dyno chart. Just curious.

edit: Whoops - that was a silly question, as the 3.0si is rated +35 tq @ 2750 rpms... :embarrasm but I still wouldn't mind seeing a stock 3.0i dyno chart, as the max hp of the 3.0si is rated at 350 rpms more than the 3.0i engine.

I test drove both and found the si faster of course, but not much. I got the 3.0i only because of what the dealer had on hand, (colors, features etc.), both engines are great. I think the si has a differnet tranny and a different intake as you said, as for the difference in HP, no clue. I'm not even sure the HP stated for both cars is correct. It seems my car has more than 215 to me.

[BimmerZealot]

Ya the Si shares the same transmission as the Z4M

[curley2]

255 hp for the Si

[Ztandem]

Ya the Si shares the same transmission as the Z4M
If that's the case, what tranny does the i have and where did you find out that the si and the M have the same tranny?

[epbrown]

The cars feel close because the 2006+ 3.0i has a 3.38 rear diff ratio while the 3.0si has a 3.07; the si got the lesser diff because with a 3.38 (or even better, 3.46) its 0-60 numbers would be too close to the Z4M. A 3.0i from 2003-2005 with a 3.46 diff would be quicker than a stock 3.0si with stock diff.

[Roffle Waffle]

ok, so whats the part number to turn my i into an is? :)

[bimmer_boyis]

ok, so whats the part number to turn my i into an is? :)



An N52 long block.....

[xorbe]

Changing the diff ratio changes the speedometer, right? Can that be recalibrated? (edit: I'm not planning on doing that, my friend and I were simply discussing the details.)


The cars feel close because the 2006+ 3.0i has a 3.38 rear diff ratio while the 3.0si has a 3.07;

But the i and si have different transmissions... confusing!


Ya the Si shares the same transmission as the Z4M

I read that the Z4M actually shares the 3.0Si transmission... :D

[epbrown]

Changing the diff ratio changes the speedometer, right?)

No, it doesn't.

[xorbe]

Do these engines have a multi-path intake, where it's effectively longer at lower rpms, and shorter at higher rpms?

[epbrown]

BMW calls their variable intake system VANOS, and yes, the Z4 has that. I think every BMW since 1999 does...

[xorbe]

http://en.wikipedia.org/wiki/VANOS

That's valve timing, not intake path length... I think we have (double?) VANOS + Valvetronic (in N52 anyways). I think the intake path must be constant. It sounds like the power is controlled strictly through the 0-10mm intake valve variance!