Since in OEM throttle body porting, the TB flab blade size won't change (hence what can be considered as a bottle neck for air flow), I tired to search where possible gain may come from. Following is what I could come out with.
This is an exagerated sketch of porting on OE throttle body, keeping OE flab plate.
From above: (A) Partial Throttle, porting OE TB relates as giving more gap space to air flow at a given partial throttle position %P. The increased air flow (due to increased gap) translates to increased power at that given partial throttle %P. If we draw power vs TBP grapgh, we would notice power band shift toward lower TBP values. In real life, reporting "better throttle response" IMO is just descriping this shift of power band curve (more power for less throttle).
(B) WOT, the bottle neck remains same (OE flab size not increased), hence wouldn't see direct increase in air flow that can actually add direct power gain. But due to shape of air flow passage, Ported TB shape might have "less friction" to air flow compared to original OE TB. This might yield few horses to power peak.
I guess "porting" should go little farther than "polishing" by removing littl material from TB inner wall surface. Although both work in same line, to reduce friction to intake air flow (by more area and/or less wall friction).
On a side note, got call from postoffice today, I've got package (from Vmax ). Shall collect package tomorrow, but would take few days for weather to clearup and put it on to see what/how it does.
At last weather cleared a bit and I got chance to put Vmax ported TB on car today.
Install was straight forward, but took me sometime cleaning trace of my old TB paper gasket .
While at it, I took chance to do little chamfer on intake manifold port entry edge . Also I smoothed/polished intake manifold neck (wherever I could reach inside with my fingers and sandpaper-400). Then cleaned every thing, put new oem metal gasket and new TB. Pluged, reconnected battery, and switched on and let it set idling for couple minutes.
I didnt drive it yet, but from today:
1- got no CEL (myself was worried, because oem TB part number given to Vmax to pick and process, I had %0.001 doubt about, because my car isn't actually 2008 G8 LY7, but the Aussi 2007 variant LE0 engine which is basicly same but not %100 identical).
2- while idling I pushed pedal few times, that intake whistle which I have due my CAI at certain gas pedal position, for sure today came at earlier pedal position.
Thats about it for now. Later will give driving feedback and/or any fuel consumption effect.
- Fuel: Reset dash trip meters. Then on approx 30miles combined city/highway road to work, trip computer showed 10.6Ltr/100km. Previous measure was 10.9Ltr/100km on same road, same traffic hour and conditions (winter and same avg climate). Shall see later if it continues like that on long term fuel consumption average.
Edit: Day3 after ECU reset, have driven around 150miles, did another reset to trip computer, displayed fuel consumption on same road/conditions 10.3Ltr/100km.
(average speed in all measures was 54-55km/hr)
- Throttle response on rolling: This is where I loved it and noticed improvement. Pushing pedal in gradually, response felt more steady and linearly linked to pedal as in "push-go". Previously there was a spot right before autoshift kicks in when car felt like "push-think-wait-go" !
- From a stop: tad little better throttle response. But I wouldn't place high bets on this!
- Power/Torque gains: sorry, no dyno to prove any. And my buttutronic dyno isn't quite accurate below 20hp
so just to sum everything up here, you sent in your OEM TB to vmax, and they ported it and sent it back to you correct? or did i miss something, and also how much in all did you spend on this mod? and also how long did it take to get your TB back to you after you sent it?
having international shipping involved, I didn't do it on exchange base. 2way international shipping wouldn't be feasible!. I paid for core new TB.
I gave Vmax oem TB part number, they bought brand new oem, processed, and shipped to me. It took them around 10days (to get oem piece, and do the porting job), add another 10days till I got it (international shipping).
Vmax charge on porting job -on exchange base: $150.
(and in my case another $210 for core unit and international postage.)
I took my time and M.P.H in the quater and used the Drag times app on my samsung sIII on the play store on Droid. And had the car dynoed ans was only off about 10%.
2009 GT White Hot, AKA CASPER, Superchips 93 octane tune, Volant C.A.I with HSRK,Slotted and cross drilled rotors with ceramic pads,GXP Diffuser,Debadged.Solo axle backs, Coronet 440 style tips
Dyno 4/26/15,343 MAX H.P.,338.6 MAX TORQ
5/13/15 email@example.com, 2.03- 60'."WE ARE THE LAST OF OUR KIND"
2009.1 V6 STRYKER BLUE, TRADED IN 1/10/13
everyone thinks about HP all the time but throttle response makes the difference between a smooth riding car and a rough one and the g8 could definitely use some better throttle response im a stickler for getting instant response when i hit the throttle, i hate noticeable delay in throttle response, my g6 when i had it was really bad until i hadded a CAI and it helped a lot