Just saw your post..... No, I ground off the sharp transitions on the inlet side only, and smoothed them. Did not polish, because the TM one was not. I figured if polishing helped, Tony would have done it. He's got alot of experience.

 

That's the problem with this entire hobby....what CAN'T you get used to?....LOL

I clearly remember about 15 years ago the first time at the track I sprayed an older Monte Carlo I had (with a 454 BB Chevy in it) and went mid 11's (crappy 60 foot) at 125 MPH or so and at the time I thought it cant get any better than this in a street car....BUT...If I could just achieve that "nirvana" normally aspirated I would forever be done. Two years later the same car with a 557 CID BBC and the first set of heads I ever ported went 131 N/A (4400 lb car btw) and after awhile I still wanted more (and got used to the pull of a 130+ MPH car)....then I sprayed the big motor and went 142 trap....LOL

Point of the story....you can get used to anything....its just a matter of how much time it takes. It is that fact that drives 99% of us to do more and look for more....for me personally if Im not just a little scared at WOT Im not having fun

 

Hence the saying "More Is Never Enough"

 

I was just talking about from a horsepower/torque gain perspective. I know you've seen great gains with a ported FAST 78 over a stock LS6, but the FAST 78 was only giving up 5-8hp or so over the 90? So that would leave me to believe that the TB isn't the main restriction and that the manifold design of the FAST is where the power is.

THEN, I see the other post of the guy with the TPIS modified LS6 with a stock LS2 throttle body and he gained about 20rwhp. So in that it would seem that replacing the 75mm TB with the 90mm is where the gains are? Sorta contradicting data so now I'm confused.

This is swapping an LS6 to a TPIS LS6 with LS2 90.

 

I boldfaced the statement above because all my dyno testing has confirmed that to be right on target....it is not the TB size which is a limiting factor (or should I say it plays a much smaller role). Its the manifold design itself which makes it alot better (plenum volume, intake runner cross section, approach to the runners with a better radiused bellmouth, etc., etc.)

When I originally did all the engine dyno testing of my 346 the first ported FAST intake I ever did (my 78mm version) made right at 20 more HP than an LS6 intake (ported 78 TB on both). When later on looking for a little more power I decided to try the 90 mm version and I only saw a 5 HP increase from the swap....however, the throttle response and SOTP gains from the larger TB made it felt like I picked up 4X that amount. The car was much more responsive and fun to drive....not to mention an extra 5 HP is an extra 5 HP....do that a few times and those single digit gains start to add up separating you from the rest of the pack.

Concerning the above graph with the 90mm snout in front of the LS6 manifold I naturally question how scientific the testing was (oil, water temps the same and things of that nature), and whether the before numbers were fully optimized (tuned). I have seen other tests comparing the various intakes and seen gains with the TPIS modified LS6 intakes, but in these tests even the stock unported FAST intakes usually look a little better in the upper portion of the curve. The modified LS6 intake does make more power on the bottom due to the smaller runners increasing the ramming effect but ultimately that same positive turns into a negative upstairs and the larger deeper breathing FAST design starts to take over. Past 6000 there is a significant difference between the two.

Hope this helps...

Tony