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Anything that involves removing a finite amount of material that can't be replaced means there is a possibility of permanent damage. When it comes to porting heads at least, lots of practice and flow bench testing is involved. I'm sure the TB is a little easier since it's just a single circular passage. I'd love to see a writeup.
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'02 MCS, Sport, Premium, Webb Sportbox RAF, 15% pulley, Milltek cat back, H-Sport comp rear swaybar, Powerflex engine and gearbox inserts, Stewart Warner boost and oil temp gauges in E-Pod, Optima Red Top 35, Whalen knob, M7 front grill, Hella FF200 fog lights on Out Motoring brackets, MCAW
Writeup! Please. I would give this a try if it seems like something I could manage.
__________________ People seem to like me because I am polite and I am rarely late. I like to eat ice cream and I really enjoy a nice pair of slacks. Years later, a doctor will tell me that I have an I.Q. of 48 and am what some people call mentally retarded.
I'm also VERY curious - as the self-appointed NAM grand-poobah of whistling throttles...
a) did this car exhibit any throttle whistle at slight open throttle before the mod, and
b) if so, did that change at all?
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I'm Paul, The car is Blimey--- BlimeyCabrio's Blog--- 2006 MCSCa w/lotsa mods and Union Jacks
Ten-time Dragon Veteran - Occasional Trackrat - Extreme Twisty Addict - Rhymers Ferry Road Fanatic
Anything that involves removing a finite amount of material that can't be replaced means there is a possibility of permanent damage. When it comes to porting heads at least, lots of practice and flow bench testing is involved. I'm sure the TB is a little easier since it's just a single circular passage. I'd love to see a writeup.
you are correct. there is a a critical part when grinding close to the butterfly valve. If you got to far, then you basically open the space around it more and create idle problems.
I'm also VERY curious - as the self-appointed NAM grand-poobah of whistling throttles...
a) did this car exhibit any throttle whistle at slight open throttle before the mod, and
b) if so, did that change at all?
I didn't notice any whistle. I am running a 19% pulley, Alta drop in filter, DT BPV.
I did notice I get more blower whine now and low rpm.
There are three styles of throttle body modifications, full bore with enlarged plate, double venturi, and venturi at entrance, Stephen’s appears to be a semi-double venturi. But, the flow path downstream of the TB is to be considered if you think modifications of this type have much worth beyond self gratification, if you’re not making other wholesale changes. The entrance to the supercharger intake duct is 62.6mm ID, 4.6mm larger than the TB bore, discussions about protuberance created by the plate post can support either pro or con argument of effect but we’ll keep this simple and use ID or fluid diameter for comparison, so were ok for the first .75 inch, then the effective diameter/fluid diameter narrows a little more, still ok until a few inches later it drops to less than 56mm. The fluid diameter of the section on the left in this photo is smaller than stock bore.
A segmented supercharger intake duct reveals a variety of fluid diameters which don’t exceed 62mm until an inch before the outlet side and there is a ramp at the end (removed in this example) which effectively narrows it again.
Forced induction will overcome variances in the upstream/downstream flow path that are detrimental in naturally aspirated applications, but upstream can only flow as good as its narrowest section. It’s hard to let go (I’m big time guilty) of NA notions if that’s what you’re experienced with. Our intake tracts (including TB) have proven to be good for lots of output.
Way to take a DIY initiative! It's all about the butt dyno because when it comes down to it, it's you driving the car! Not a dyno.
'05 HB/B MCS. 
People seem to like me because I am polite and I am rarely late. I like to eat ice cream and I really enjoy a nice pair of slacks. Years later, a doctor will tell me that I have an I.Q. of 48 and am what some people call mentally retarded.
