Blu Bal was down and so I decided to port and polish the TB since it was off the car, and knife edge the butterfly valve.. Took about 2.5 hours total.

Realized I forgot to take final pics before installing.

I took enough pics in case I wanted to do a DIY write up.

 

Do you notice any difference?

 

I did. It seemed to rev easier and wants to move off the line faster. But what does the butt dyno know right?

 

Thats awesome! 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.

 

I'll do a write up and post it if people want me to.

 

YES!

 

 

Please do!

 

Is it easy to do? I mean, can you permanently damage your throttle body if you mess up? I might be intersted in the process.

 

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.

 

Writeup! Please. I would give this a try if it seems like something I could manage.

 

+1 here on seeing a DIY. That would rock.

 

+ a zillion.

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?

 

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 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.

 

Give me a few days to get this write up guys and I will post it up.

 

What measurements did you use for the modification? Write up, please!

 

measurements for?

 

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.