DBW throttle body size recommendations

[20B]

I'm looking for a 50mm size butterfly DBW throttle body to use in a custom application, any recommendations ?

[JamieA]

how much power are you trying to achieve?

[20B]

Jamie,
Power irrelevant, i am looking at re-doing my cable driven triple 50mm throttle body setup with a DBW4 driven setup so just need 3 x 50mm sized units.
Honda 2008- 2012 Jazz is all I have found so far but they look good for the money and should have a calibration already from Motec ?

[20B]

Another question to add, the OEM RX7 used a nice multistage opening throttle body to assist with low speed drive-ability which opens the primary throttle plate first then opens the secondary ( larger ports ) butterflies at around 8% TPS to aid in air velocity and scavenging. This was done with a nifty OEM throttle linkage system.
Is there any way to replicate this with a DBW4 ?
One smaller DBW throttle body opens first then the remaining three start opening at a set TPS from the first unit ?

[Blu302]

Maybe look at the E46 M3 DBW(S54 engine). They run an ITB setup with the cable pull replaced with a DBW motor and linkage. the motor is seperate to the ITB's and the ITB's are 6x single units linked together.

[20B]

Blu302,
Been there done that with the BMW system, I built a test rig and everything but just couldn't get it to work with my system. Once you change the throttle bodies to something custom it throws out the PID control on te motor as its been calibrated for that OEM setup. Just felt too dodgy changing stuff to try and make it work.
The DBW4 will solve my problems as its effectively a 'sealed' unit with everything integrated so I can concentrate on tuning it rather than messing with custom PID settings.
I have found the late model Honda Fit (Jazz) has the size (50mm) I'm after and the throttle bodies can be purchased on eBay for less than building a system with conventional mechanical multi throttle anyways !

[Scott@FP]

20B check your PM's.

[Blu302]

Thanks for that bit of info. I was looking at adapting it to drive a different ITB setup. If it doesn't work, I won't put in the effort just to fail. Maybe Motec could do a custom PID if the whole setup was sent to them?

[MattW]

Check out mark's webinar video On PID tuning. Tuning PID
If you have access to an oscilloscope you could do it all yourself.

Being able to PID tune is a good skill to have, so it's worth learning.
You will then be able to do your idle and boost control.