Before you read my ravings, read this write up by Jim Comforti on the subject of software, et al (posted at RoadFly E46 M3 Forum 5/31/03) - If you don't know who Comforti is in regard to tuning BMW's you really should find out.
Folks, I've said it once.. I'll say it again.. there is very little cheap horsepower (read: from software) to be gained from the E46 M3.
I'll bet that I've spent more butt time and dyno time combined than anyone else in America (outside of factory folk) with the S54B32 motor in both of it's forms. In 2 different M3's (my wife's and Josh MacMurray's) and my M Roadster.
In the M3 form, there are SIX legitimate RWHP to be gained.
That's it.
Software and HEADERS/CATS yeild about 8RWHP, but a significant gain in torque midrange (about 10 lb-ft RWT).
See, there are esssentially 5 things you can tune at wide open throttle on the M3. I doubt if most tuners even mess with the third one below.. but it does exist.
You can tune the fuel.
You can tune the ignition timing
You can tune the actual opening of the throttle plates (as opposed to pressing the pedal.. 100% of pedal does NOT mean 100% of throttle)
You can tune the timing/sync of the intake cam VANOS
You can tune the timing/sync of the exhaust cam VANOS
You can do all 5 of those in some happy combinations.
You can spend too many hours on a dyno until you are cuckoo from the CO and HC fumes you're breathing.
You will gain SIX REAL HP.
Same Day, Same Car, Same Dyno, Same FUEL, everything.
That's it.. SIX.
We've done it.. software is being released THIS week.
(It's real easy to play dyno games with this motor by changing fuels and then running the ignition timing up to create GOBS of power with say 110 octane race fuel.. the same timing with 91-94 octane street fuels will destroy the motor before you can say "Oh sh*t there goes my motor!)
To gain more you need to change HARDWARE.
To go from the 270something range.. 272-278 or so. to the 295-300 range you need to change:
Headers (and necessarily the CATS), then you need to open up the motor and using $1000+ of special tools and a LOT of finesse and patience you need to change the cams.
If you use BIG cams.. say 280 or greater.. you have NO error in the position/sync of the cams statically. If you screw it up, you WILL bend valves before the word "GO".
We've done the cam installs.. (No, we didn't bend valves
To gain about 10% in power you will spend around $6,000 in parts alone
(Yes, OWWWCH!.. and just think, we have to buy all this stuff just to test it.. then pull it off and most times JUNK it because it didn't work like we wanted.. at least we get to keep the "good" stuff tho)
Note, I didn't include any software costs, and software is absolutely NEEDED if you goto headers/cams. Those who don't believe me can try it and report back with the melted motors. (Hint: in one test of cams without software the vehicle hit the "lean stop" and set a MIL within a few hours) that ONE test was the last w/o software as we found the fueling to be significantly leaner than even the "lean stop".
With tuned software, you can get about +8-10 with headers/cats alone and anywhere from 14-30 with headers/cats/cams.
For those who want to argue.. let me offer you this.. there are quite a few in this country successfully running cams/headers/etc. They got their software from a source outside the contintental US. They know who they are and who I am talking about in a warm climate with very good Pina Coladas. I developed that software and have been "secretly" working on this stuff for WELL over 2 years now.
The funny thing is that the numbers they are all getting (300+rwhp) are coming from experimental software (not finished) of mine.. the final software gives no more HP really, but you can run cams and not stall.
Jim C.
PS: Now everyone can pipe in how "someone" got 300rwhp from some magic intake and software.. it's not real people. trust me it isn't.
Ask any REAL tuner out there and they'll tell you.'
If you feel the need to waste money, I'd suggest you find a worthy church, charity, or even a local watering hole and blow your money their instead of wasting it on smoke and mirrors.
Source:
http://m3.madrussian.net/modnotmod.shtml