experimenting (just some ideas)

hytorksc

Registered User
i've been reading on these posts and other places that the less parasitic drag you place on the SC motor, the more power will get to the wheels.

well... just for the heck of it, i removed my 5% overdrive SC pulley and put the stock one back on. i compared the power drain (turning the rotors) the eaton m90 presents on the motor- 70hp with the 5% vs 40hp with the stock. how did this translate in terms of seat of the pants feel? well...

my current mods include custom porting everything (intake thru exhaust header), MAF, TB, raised top, intercooler fan, underdrive pulleys. what i noticed was that the car felt 200-300lbs lighter in how it responded performance-wise. i mean wheelspin really came back harder (low end) and high end acceleration was easier coming. Overall i felt no deterioration of performance like i expected. i don't know- maybe what really happened was the 5% pulley took the fuel system beyond it's limits creating a lean condition.

so then i optimized and adjusted what i could to maximize acceleration with the stock pulley and i find myself happy with the way the car feels. boost was originally peaking out at 16lbs with the 5% OD pulley, but to my surprise i'm still peaking out at 14.5 to 15lbs boost with the stock pulley. i think i made the m90 very efficient with my custom porting job. now i'm figuring that just adding a 70mm TB would actually increase boost by another 1lb bringing the boost level back to near 16lbs (original level with 5% pulley). i must have shifted more HP and Torque to the wheels across the full rpm range by doing the pulley swap reducing parasitic drag.

at this point it may be that the OD pulleys really don't give a broad increase in power, it just helps in certain areas of the power band. at some point at higher rpms the drag will overcome the benefit unless you're working with a very deep breathing 3.8 (nowhere near stock).

any thoughts or ideas on how to make further low cost improvements on this is appreciated- ie, plugs, lighter driveline components, etc.

thanks-
 
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