beauphus

Hello all. I know this pulley topic has been exhausted by I need some expert opinions. I havent really finished the CLS ever since I bought the CL TT and had a baby earlier this year. Im rady to complete this project car. Jeremy is coming to town shortly and I am debating going back to a 180 pulley. As it currently stands I have a 190. Most would argue this is far too big but due to the amount of mods and types of mods I have it may not be. Here is my current list of mods:

190 pulley
ported and polished heads
ported supercharger
meth injection
kleemann cams
long tube headers
CF airbox
82 TB
TTM fuel rail with high flow injectors
MBH intercooler (huge)
rear mount reservoir with dual mziere pumps

Based on above cooling is not a particular issue for me. I have been told that due to some of my mods I am not creating as much boost which is why I went with the 190 pulley. I am trying to decide whether I should drop down to a 180 or stick wih the 190. Any thoughts here from those in the know?

shardul

iTrader: (1)

lets talk in terms of boost. what boost are you seeing with the 190?
Since you have heads headers etc etc. the boost generated with a 190 may not be that much. Hell a stock car with a 180 may generate more boost.

beauphus

mid 13's

shardul

iTrader: (1)

i dont think so that is high at all. that is roughly 2 psi over stock. Now since you said cooling is not a issue you should stick with the 190mm

Exotic-metal55

Stay with the 190mm all day long. Your mods need them and your boost is low.

I would go 195mm and get tuned for that!!!

Yacht Master

+1 all the mods that serve to allow the engine breathe better, Porting, LT headers etc, can cause a drop in boost. If anything you are on the low side.
I agree with Exotic, a 195 would make more sense considering your current mods.

cfi_luz

At what point (RPM) is the supercharger out of its efficiency range?

beauphus

thanks all for the input. Aside from boost would it be possible to create MORE power from the 180 on less boost or is there a direct relationship between boost and power?

Bruce at TTM concurred with all the opinions above and being that he is the resident genius I shouldve listened

KLR CLS

Technically it's not about boost at all, but CFM. The more CFM of cool dense air the more power you make. PSI is affected by head flow characteriscs, exhaust scavenging, TB sizing etc. More pressure generally means more heat for a given size pulley. IE less pressure in the intake tract surely lowers compressor outlet temps.

Bottom line is a bigger pulley makes more revolutions/ more compressor flow in CFM. Thats why the bigger pulleys always make waaay more torque down low. Heat management is what keeps it making power through the whole run.

cfi_luz

Agreed, more CFM is what you need to worry about, not what the boost gauge says. Just like doing head work will effectively lower the boost pressure, you are still moving the same amount of air, but since you now have a larger volume the air is compressed less, hence a lower boost reading. You will make more power as you increase CFM of the supercharger until you either spin past its efficient rpm range or you heat the charge so much the car pulls timing/detonates.

stevebez

Has anyone analysed what the parasytic losses on the S/C are for diff pulley sizes and at diff rpms?

BRABUS786

Hey

190mm. And dont look back

Acid

Ali_E55

go for 190mm, you won't regret it.