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Over Driving the SC

GreyGhost

GreyGhost

New member
This site seems to base their information on pulley size, but I do not know

What the standard pulley size is and if it changed at all between years?

Every other site that I deal with on the SC's say what % a setup O.D. the SC.

Hence on my M90 it is actually 25% OD from the stock pulley size.

I don't expect anyone to convert to using this method, just stating what I am use to seeing and would like the stock size so that the calculations can be done so there can be an apples to apples comparison done.
 


I know it doesn't account for a whole lot but I would actually like to know what the difference is (% wise) going from say a stock 3.8 to 3.4 with the basic supporting mods of course.

Id really like to know what the CFM is (amount of air moved by the blower) between the different pulley sizes.

IF your doing all the calculations that is :th_winking:
 
Calculations?

Quite a bit.

Considering the GenV makes as much power as a GenIII with a 3.4" slapped on it whilst the GenV is still on a stock or close to stock pulley...there is no ramp up on the GenV...the rotors are better...and coated better for that matter...its also a little bit bigger of a blower as well...so since it is displacing more air, its of course going to make more power...and it can do it without pulling as much power FROM the motor to make it...unlike the GenIII...which needs hogging out...re-coated rotors, the entire inlet ramp smoothed so the air ramp up isn't all screwed like it is from the factory...and the outlet opened up quite a bit...its just a increase in technology really IMO.

Better overall design...but it is still a heaton...and the more you pulley down the pulley down, the more heat it makes and the more power it is going to TAKE to make more power.

I always had a nice little scale like this...

Both blowers will make about the same figures from the factory...while the GenV car will still make about 10-20 more horse and torque to the wheels than the GenIII car if they are tossed side by side with the same pulley.

3.8" GenV = 3.5"/3.4" GenIII

3.4" GenV = 3.2" area GenIII

3.2"/3.0" GenV = 2.8"/2.55" GenIII

That's how I always understood it...Steigmeier Performance...who is VERY well known for porting the M112 cases for the 03-04 Cobra's did a GenV M90 and said they gained nearly 20 crank horse from just their porting...I never saw any actual dyno charts...just their claims...but it was ported in a rain drop or tear shaped outlet...just like they do on the M112...something strange like this...

IMG_5668.jpg
 


Whats interesting to note is the speed.

stock balancer is 7.1" IIRC.

so that makes for a 1.87 overdrive ratio.

so 6000 RPM * 1.87 = 11 220 RPM stock.

with a 3.4 setup...

2.09 and 12 540 RPM.

3.0? 14 200 RPM.
 
01GTP said:
depends on the car, I hit 8-9 with my cam in 20* weather.
Click to expand...

That's with a cam so the car flows much better so it won't see as much pressure but still make a hell of a lot more power off the pressure it does see.

I'm on a 3.4" with stock cam and see around 9 to 10 with the occasional 11psi at redline.
 


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