Power difference

[crystalworks]

Originally Posted by Raul_X5

I clean the air filter a month ago, is K&N filter, and change the oil and filter a month ago to.

Change back to an OEM style filter, unless you don't mind cleaning your MAF or replacing it if the oil kills the filament. If you over-oil the K&N it can have detrimental effects to the MAF.

Edit: Also, I agree with the others. The wheels are definitely part of your acceleration difference. Switch the wheels temporarily and see how big of a difference if you are really curious.

[O3X5]

I think he's talking about the engine oil.

[PropellerHead]

Originally Posted by g300d

The bigger wheels are heavier and give you a bit of a sluggish feel all by themselves.

That may be the difference you are feeling.

+1

I had the exact same experience swapping between OEM 20" and OEM 18" on my '04 3.0. The same thing happened on the '04 4.8is with non-OE 20" (heavier) and OE 20".

[Raul_X5]

Originally Posted by crystalworks

Change back to an OEM style filter, unless you don't mind cleaning your MAF or replacing it if the oil kills the filament. If you over-oil the K&N it can have detrimental effects to the MAF.

Edit: Also, I agree with the others. The wheels are definitely part of your acceleration difference. Switch the wheels temporarily and see how big of a difference if you are really curious.

Good point about the K&N filter, but i clean the maf sensor like one time in the month

[Raul_X5]

Originally Posted by PropellerHead

+1

I had the exact same experience swapping between OEM 20" and OEM 18" on my '04 3.0. The same thing happened on the '04 4.8is with non-OE 20" (heavier) and OE 20".

I have 20" no oem,

[lo_jack]

Originally Posted by X53Jay4.8is

Does your mothers X5 have a tune on it? Are the final drive ratios of the 2002 the same as the 2005. Oh wait doesn't the 2002 have a 5 speed tranny vs the 2005 running a 6 speed? Gearing ratios make a difference in performance feel.

All E53 3.0 final drives are 4.10s. That changes with engines (eg 4.4l is 3.94 and so on). So those two vehicles should both have 4.10s.

I would guess its unsprung weight. 17s to 20s without changing outer diameter could be 20lbs per wheel, unless the 20s are made of magnesium.

[O3X5]

with tires inflated it's easily 100-150lbs added and with every hundred pounds of weight added, it's a tenth slower which is a couple car lengths difference.