Throttle body blending advice needed

[Bill Chase]

There is a noticeable step/lip where the throttle body opening tapers into the bore where the throttle plate is, is it better to round and blend the transition like a short side radius? Or leave the sharp step in place?

For reference it is a first performance tpi throttle body 71mm (2.815")throttle plate, 102mm (4")outer diameter. Pics of side profile, and rear mounting surface included, it can be bore out, but will still have the huge step down in diameter. Goofy design, in many ways the 5.7 L31 vortec throttle body is a better fit, simple 1/2" plate spacer and it will bolt up, match the plenum opening better. Suggestions?

[midnightbluS10]

I'm sure it was designed that way on purpose. I don't think I'd just pick some arbitrary "smoothed out shape" just because I think it looks bad, and without any actual flow data to verify anything at all.

It's not like it's a stock GM tb built for economy. I'm sure that thing was designed with performance in mind from the beginning. So I wouldn't be so eager to just arbitrarily change it all up without at least some sort of data to quantify that what you're doing is actually helping.

Unless you just want to do it because you "feel like" it'll flow better. Then by all means. Go right ahead lol