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- - Brz throttle body issue (Grams 72mm) (https://www.ft86club.com/forums/showthread.php?t=141934)

Quote:

Originally Posted by PulsarBeeerz (Post 3359962)

Sorry but in real world practice with a +2mm over-bored OEM TB or 72mm TB AND port matching IM I saw a 2-3% increase in MAFv usage. If there is a bottle neck the pressure will just be dropped at the next neck down in line. There's an entire flange after the TB which no one every takes into account. I should add I have an extrude honed IM that neckes down to ~70mm before the plenum. Grams TB uses a reducer plate to go from 72mm down to the OEM 66.5/67mm opening. Yeah it obviously wont make a different as the IM port size hasn't changed.

Your example isn't applicable to an engine for many reasons the main one being the lack of a pressure differential before and after the "funnel" and the manner in which air flows in an intake system.

Did you tune for the TB? and/or rescale the maf?
What was your before/after MAFv usage? And conditions of testing?
Did you test TB and IM porting separately?

Grams is at least 70mm exit side i had to port match my 67mm TB spacer making it much larger to match up, but yeah without porting the entire manifold at least to the plenum you’ll always have that bottleneck which most people don’t do yet claim a “butt dyno” difference. And you’d probably need an equally sized intake pipe going to the TB, and a filter with enough flow to match.

Edit: my TB was not grams. It was blox 70mm, 70mm straight through even on exit side.

Quote:

Originally Posted by 86TOYO2k17 (Post 3359830)

This same effect can be achieved by changing the throttle mapping in the tune or with a throttle manipulating device like pedal commander. i have testing this first hand with a larger TB, pedal commander and changing mapping in the tune all individually and every combination thereof.

All that is happening is the larger TB at say 10% throttle is now open flowing more air as if stock TB was really open 15% so it "feels" like it has higher response / torque delivery when driving around but that's also why peak numbers at WOT do not change unless you have FI and have a greater demand for air than the stock TB can fulfill.

This is also why people have no throttle "coasting" high rpm/higher speed issues because it is flowing more air at zero throttle input than it was before.

Right, I fully understand how and why the throttle response is different. Point being, I was just trying to let OP know that there is in fact a difference in how the car will feel with the throttle body and no additional changes. People were saying larger throttle bodies don't do anything, which is wrong. Throttle response and initial torque delivery will be different.

Quote:

Originally Posted by 86TOYO2k17 (Post 3359830)

The issue is that most tuners are changing the throttle mapping in the tune too aggressively. Same holds for the throttle manipulating devices and I prefer to have an OEM+ look and feel without extract devices. If you can change the ECU tune yourself and you know what you are doing, then yes it is the most cost effective and best option. Personally, I have an Ecutek locked tune and I couldn't play with the tune. A bigger OEM throttle body (65mm -> 67mm) gave the best result for my tastes. Just a bit better comparing to stock, but not going too far from the factory specs.

Quote:

Originally Posted by 86TOYO2k17 (Post 3359987)

I have re-scaled the MAF at some point but I did not do it prior or during the swap between TBs. When I did it was from switching intakes from MY17 airbox to TRD. The MAF was waaay off during closed loop. Other than that I did zero tuning for the TB in say the torque demand table or pedal angle table.

The IM was ported ran with with an OEM TB, then 72mm TB $300 and finally 68mm bored out OEM TB $160. Similar conditions for data logs as temps and barometric pressure make a big enough difference in MAF reads. Also extrude honed MY17 IM ~$550+ I know how people hate the butt dyno reference but literally vtec at 6.5k rpm..But this feeling goes away once the TB is enlarged. More area under the curve it seems.

I have played around with intake pipping diameter. The resonator on the OEM or Mishimoto intake keeps the MAF very happy in logs. Its so much smoother but larger tubes seem to have a positive effect for my setup. So currently its 75mm ID tube to the flange of the bored OEM TB 72mm-68mm iirc. Similar ID to all the tube available for this chassis.