DBW Throttlebodies

[bobqzzi]

I'm doing an engine for an A4 with DBW, adn we are going to keep the stock management.   I'll be using a Ross Machine Racing Manifold which I will have to modify for the A4 (no one makes anything as far as I know).  We are keeping the stock management, so I need a larger DBW throttlebody.

Stock 1.8T is 60mm
Toureg is 83mm- too big, I'd worry about driveabilty and the ecu freaking out
S4 is 70mm (078 133 062C)- just right, but a bit pricey
I can get part number 078 133 062B  which fits a N/A V6 Passat/Audi ATQ for a much better price, but I don't have one to measure.

So, anyone have one they can measure and advise, or perhaps a recommendation for another DBW TB of 70mm or so that is available inexpensively?

[O2VW18T]

how big is a R32 TB, i can get them for around 270 from the dealer with my discount. retial they are 350 bucks

[EVIL]

VR6 TB is 2.75" ID, which is roughly 70mm. I have one.

To clarify this is the 12v VR6, 1999-2001.

[badger5]

R32 t'body I have measures 75mm ID
dwg here of flange mounting.
http://badger-5.com/bin/new-ibiza-engine/r32-throttle-body%20Model%20(1).pdf

regards
bill

[O2VW18T]

you think drivabilty will be bad with the 75mm ID TB on a OEM ecu

[bobqzzi]

you think drivabilty will be bad with the 75mm ID TB on a OEM ecu

I don't know- new ground for me.  70mm is 27% bigger than stock, 75mm  36%   My project engine had a 65mm TB, so I'm thinking 70  would be good.

[Don®]

I suspect running with larger TB's TIP in response will be effected. For a standalone and DBC an increase in timing would help with that whereas on a stock ECU timing increase and e-gas ratio would have to be tweaked.

[fast_a2_20v]

With those really big throttle's, you run into an issue where ~20% or less throttle position causes a LARGE reaction from such a small displacement motor. Although it still takes till 100% to truely be "wide open" you'll get what feels like wide open way way before that. This kinda screws up the dynamics of the feel and pedal position in a dbc car and I would assume it would also cause some havoc in a dbw one. In the case of a dbc I would recommend machining an elliptical throttle wheel with a nonlinear throttle movement.

Honestly though, I really don't feel its worth the hassle. I'm not sure what your power goal is, but I've seen plenty of honda guys making a whole bunch ton of power try huge throttle bodies, make NO more power, and end up going back to a stock or slightly overbored ITR throttle (or similar).

my 2c

[Don®]

Very interesting to say the least & I like the eliptical throttle pulley idea... On a specific tuned closed loop setup where adaptation is involved I don't think it would be all that bad.

[20V18Tnut]

I somewhat agree with fasta2, if the TB wouldn't be overly larger than stock it could help for a faster response and top end power, may be even without any map recalibration. but beside the adaptation issues, that may not let the TB fully open there are some other things. if one would install considerably larger TB, there results will not be as expected. 1.8T has it's certain volumetric efficiency and a tuner can only use an oversized TB to a certain extent to make further improvements, even if supported by ported head and agressive cams. Also less air velocity with oversized TB will not help air to apropriately fill cylinders especially at high RPM.

[bobqzzi]

I somewhat agree with fasta2, if the TB wouldn't be overly larger than stock it could help for a faster response and top end power, may be even without any map recalibration. but beside the adaptation issues, that may not let the TB fully open there are some other things. if one would install considerably larger TB, there results will not be as expected. 1.8T has it's certain volumetric efficiency and a tuner can only use an oversized TB to a certain extent to make further improvements, even if supported by ported head and agressive cams. Also less air velocity with oversized TB will not help air to apropriately fill cylinders especially at high RPM.

Well, velocity through a  TB is not a particularly good thing, and can become a problem at higher airflows with small TBs. High velocity through a TB is not a good thing- it indicates a restriction.
 60mm is a bit on the small side for this particular project, with which I hope to make 500hp or so.

Point taken about about the tip in and possible non-linear response.  Apparently APR has worked around this, and I'm I'll be interested to see if it is a problem.

Funny story about the elliptical (progressive) throttle linkage: GM used to make their linakges so the 1st 10% of pedal movement was about 50% of the throttle plate movement. This was to improve "tip in" and make people think the engines had more power than they did.

[fast_a2_20v]

LOL @ GM... What we need is exactly the opposite. When I had a 75mm accufab on my car it felt like the first half inch of pedal movement was about 3/4 throttle.

I don't think a 65mm throttle is hurting anything. Like I said, I've seen the local honda guys go mid 9's / 940whp corrected (850ish? uncorrected) on stock ITR throttles. GT42r / 35psi / 100 shot.

I really *really* don't think we're getting anywhere near having a velocity issue with 2.5" charge piping and a 60-65mm throttle.

[badger5]

some of the bhp claims from the APR largeport intake manifold is from their RS4 throttle body..
Is this overstated do you think?  Wondering what is contributing to the power (claims), is it the manifold for 50% and throttle body for the other 50%?

just figures plucked out of the air of course..

I'm hoping my 007 mani with R32 t'body will be ok on mine.
will let you know when its up & running with dyno's etc.

[fast_a2_20v]

Honestly I suspect a good chunk of the gains from the APR setup is from hogging the head out from small port to big port. I haven't seen a big port --> big port dyno yet.

I'm just running a deramped OBDI VR throttle on mine, I couldn't deal with the 75mm throttle it drove me crazy, and at the time I didn't have a mill so couldn't really easily do anything about it.

[badger5]

Honestly I suspect a good chunk of the gains from the APR setup is from hogging the head out from small port to big port. I haven't seen a big port --> big port dyno yet.

I'm just running a deramped OBDI VR throttle on mine, I couldn't deal with the 75mm throttle it drove me crazy, and at the time I didn't have a mill so couldn't really easily do anything about it.

Is that the basis of their "gains"?
did'nt realise it was small port to big port change, and not just big port to big port with APR intake and RS4 t'body.

not actual gains from mani/t'body combo then.
questionable results then.

 

[Don®]

fast_a2_20v is correct. The results of APR's combo is a stock head port matched to the big port but I beleive the head also has some other head work done.

I'm expecting a 30-40hp gain with the 007 Intake in a big port version coupled with the larger TB.

[badger5]

fast_a2_20v is correct. The results of APR's combo is a stock head port matched to the big port but I beleive the head also has some other head work done.

I'm expecting a 30-40hp gain with the 007 Intake in a big port version coupled with the larger TB.

wondering what my turbo will get it to... on subaru's its 460bhp apparently.
then 007p mani with R32 t'body
then cat cams

wondering what it'll produce then.

wotcha think don?

[Don®]

Bill, I just got a set of 3651 CATCams from Bob and soon I'll do a before and after dyno with the stock intake then another another dyno with the intake to obtain Stock (Baseline)-->Cams-->Intake. We can get a better idea on what the cams will do on a stock small port head and on top of that what the intake will do with cams on a small port head.

...getting excited.

[Dizzy]

Great info.   

[badger5]

Bill, I just got a set of 3651 CATCams from Bob and soon I'll do a before and after dyno with the stock intake then another before and then another dyno with the intake Stock (Baseline)-->Cams-->Intake. We can get a better idea on what the cams will do on a stock small port head and on top of that what the intake will do with cams on a small port head.

...getting excited.

3651 catcams?
I gave them my motor spec and they ground me a pair. will look out spec when I can find which computer I saved the info on (DOH!)

[Don®]

3651 = 245°/262°

[Bastard]

mine are 248/258 and 8.9mm/10.9mm

intake/exhaust

fairly close, id say you are going to wake the top end right up.

[badger5]

3651 = 245°/262°

I'm with ya now... found their part numbers.
when I gave em my spec I was expecting them to send me some stock part number cams, but they ground me some specials instead. 

[Don®]

Bill you have an idea what the specs are?

[badger5]

Bill you have an idea what the specs are?

{edit}
found em.
ENGINE TYPE   :   AUDI 4cyl20v Turbo            
      INLET         EXHAUST   
Valve clearance (hot)   :   0.00   mm      0.00   mm
                        (cold)   :   0.00   mm (+0,00 / 0,05)      0.05   mm (+0,05 / 0,10)
CAM LIFT   :   9.25   mm      10.00   mm
ROCKER ARM RATIO   :   1.00         1.00   
VALVE LIFT   :   9.25   mm      10.00   mm
                  
DURATION @ 0.1mm Valve lift   :   268   °      246   °
DURATION @ 1.0mm Valve lift   :   226   °      210   °
PEAK DIFF.: maxlift @   :   108   ° ATDC      116   ° BTDC
Valve lift at TDC w/o clearance   :   1.51   mm      0.26   mm
                  
1. w/o clearance at   :   0.10   mm valve lift      0.10   mm valve lift
      Valve opens   :   21   ° BTDC      56   ° BBDC
      Valve closes   :   67   ° ABDC      10   ° ATDC
                  
2. w/o clearance at   :   1.00   mm valve lift      1.00   mm valve lift
      Valve opens   :   6   ° BTDC      41   ° BBDC
      Valve closes   :   41   ° ABDC      -11   ° ATDC
                  
VALVE SPRINGS                  
      partnr.   :   -         -   
      fitted length   :   -   mm      -   mm
RETAINERS partnr.   :   -         -   
CAM FOLLOWERS partnr.   :   -         -   
                  
REMARKS   :   B/A TDC= before/after top dead centre            
      B/A BDC= before/after bottom dead centre