Is there a way to tune the software to engage the supercharger at only a certain engine speed or throttle position/engine load? I really don't need it at the low low rpms I drive with the kids in the car....But i want it for when its just myself in the car....

Is there a parameter in the ECU that can be modified?

Also, exactly when is the SC disengaged? And what conditions cause it to engage?

Ive owned SC'd project cars before, but they were all NA cars that were converted (and none of them had a SC clutch that was actuated by the engine management)...

Its just a little frivolous to have 20+ PSI at 1800 RPM when im just driving to the grocery store. I want to keep this as my daily driven car, but the fuel consumption at low RPM is just ridiculous

Any insight or ideas would be greatly appreciated

Thanks!!!

 

s/c is disengaged before 2800rpm if there is no heavy load on the throttle. (I'm a little iffy on the rpm. some say 1500rpm, but I remember I read 2800rpm back in the days)

not sure if it's possible to turn it off at higher rpm it could be possible if you can cut off the power to the electric clutch.

 

i thought i read 2800-2900 RPM after i first bought this car. but i can hear the SC way below 2000 RPM (and that is even at 10% throttle).

 

you dont hit 20+psi at 1800 rpm if any psi at that rpm. you hit those higher levels of boost at the very top of 3rd and 4th gear.

 

i think that's because even at idle the pulley still spins the clutch a little.

 

I wasn't being serious when I said that LOL

I was just saying that it is very obvious that the SC is working below 2000 RPM. My M3 (pre turbo) had nowhere near the mountain of super-low-end torque of this car (even when I'm barely on it). The M3's 3.2l motor had an 11.5:1 compression ratio, and had no low end despite that. The C32 (with a relatively low 9.0:1 CR) has sooo much torque (available where the M3 would almost stall). So the SC is definitely working very low down.

A 3.2l motor with a 9.0:1 CR should feel pretty lethargic with the SC fully disengaged.

 

On this type of SC, it is the helical screws that make the whining noise.

 

yea, and what i meant is that even when the sc is not engaged it would still spins a little bit and there will still be a whining noise.

 

After installing a boost gauge I have noticed the supercharger will engage, and boost upwards of 10PSI with light throttle applied at lower speeds. The c32 will shift all the way up to 5th around 45MPH, so you're driving around in a gear that is meant for 140+MPH. Boost is required to accelerate in this condition... Best way to avoid boosting is using the manual automatic to hold the transmission in lower gears.

 

well the supercharger switch has been uninstalled. it won't work on any cars that come from MB with a supercharger. I was getting a code from the electromagnetic clutch plate constantly. i dont recall if it was a resistance incompatibility or something to do with the car reading a different amount of metered air or something. either way, the ECU is incompatible with it. everything is back to normal again

 

the supercharger needs to spin even at low speeds because if not it's a huge restriction for airflow.

 

So then, is there a way for say LET or Jerry or one of these people with intimate knowledge of this ecu to change the mapping that controls when, and under what conditions, the SC engages?

 

i honestly doubt it, regardless of what tuner you go to. i didn't exactly go to a slouch shop.....dynocomp with their renntech tuner

 

update. going back to the shop either tomorrow or friday. the owner has an idea that may make this work. i'll update when i can.

 

Doing a quick search of the forum should return results that show that the S/C on the C32 engages at about 2900 rpm OR about at 40% - 44% load. That is why the S/C can be working from a stand still or disengaged at 50 mph.

 

I have the 185MM tune through Eurocharged but through my current observations the supercharger will never engage to the point of boosting at any RPM. You must apply enough throttle, and in the case of Eurocharged tune it is certainly less than 40% throttle to boost. More around 10-20%. However, I could see the clutch engaging slightly to spin the rotors thus allowing more flow of air without boosting.