In Reply to: Here is the real deal!! LooooonG posted by Peter on February 07, 2000 at 14:44:49:
: There seems to be a misconception about the differences of the 3.0L motor and the 3.2L motor.
: after reviewing some paper work and checking out some dynojet runs of both 3.0s and 3.2s before and after SC'ing l found what l originally thought was the case.....l will try to scan them in and post them but for now here are the numbers and descriptions of the runs.... all runs are at the wheel figures.
: For the 3.0L @ 69 deg.F
: Stock HP = 205.3 HP @ a range from 5500 to 6500
: Stock TRQ = 208.6 lbs @ 4300
: For the 3.2L @ 84 deg.F
: Stock HP = 200.4 HP @ 6150
: Stock TRQ = 211.6 lbs. @ 4000
: Now for the Supercharged figures
: For the 3.0L @ 65 deg.F
: SC'd HP = 304.7 hp @ 6500
: SC'd TRQ = 255.7 lbs. @ 4800
: For the 3.2L @ 50 deg.F
: SC'd HP = 289.4 @ 6500
: SC'd TRQ = 256.6 @ 3900
: All dynojet pulls were done at ERT in Delaware. Looking at the numbers you can see why the claimed to fame power advatage of a 3.2 over a 3.0 is not only non-existent but its actually the other way aroung....in the stock pulls the 3.0 had the cooler temp advatage, so given the same temp..the 3.2 would probably pull similar HP numbers but the 3.0 still puts out peak HP for a 1000rpm range while the 3.2 peaks for a moment and then drops....and torque figures are surprisingly close. advantage goes the the 3.0s top end pull...(which is what counts)
: In supercharged format the the temperature advantage goes to the 3.2L and the 3.0L still pulls 15hp more and only loosed out on torque by less than one pound. By looking at the curves, the 3.2L power curve looks like a rollercoaster up top in SC'd form...not smooth at all...probably due to the restrictive manifold is having a hard time dealing with the all the extra air coming in. The 3.0Ls free flowing int.manifold flows smoothly all the way to the top and this is the reason for the difference in power. So to sum it up....SC'd 3.2 is not faster than 3.0.....other way around if anything!!!!! Hope this sheds some light on the subject
I'm sure this is what you found...But I'm also sure its not universally found this way...Why do 2/10 litre of size do nothing for the torque figure on your pulls, when in stock trim, BMW and others report an 11 ft lb advantage, owing directly to this extra stroke? Also, I've heard others attribute this 'rollercoaster' apperance of the curve, at least if it is a very 'quick' and 'jagged' rollercoater appearance to the Vanos doing its thing...This is how it usually appears on a pull...It usually hits at about 4k rpms for a portion of the curve, before it smooths out again. I'm not disagreeing with you...I just find it strange why BMW ups their power figures with the bigger (slightly ) engine, but your pulls dont seem to show it.
BTW, is your SC working at 6 psi? Is it a Powerdyne? Thanks.