Installation of a Mounting Surface for the BMW Intake Throttle Body

The throttle body in the ICE is attached to the gasoline engine's air intake and the mechanism is directly connected to the driver's accelerator pedal on the floor.  When the accelerator pedal is depressed, a cable linkage rotates open an internal vane within the throttle body to permit greater air passage for greater combustion.  As the vane rotates,  the shaft of a three wire potentiometer simultaneously rotates and a changing signal voltage is supplied to the engine computer.  Alternatively this same voltage signal could be supplied to the Soliton 1 and used as an electronic throttle.  The cruise control is also attached to the same throttle body vane, and if one can use the OEM device from the original donor car, then one may be able to both save the cost of a new throttle body and possibly incorporate the cruise control into the final EV build.

Using the BMW throttle potentiometer poses a problem in terms of how to mount the oddly shaped throttle body as well as where, since the cable within the motor compartment only extends about 16 inches from the firewall.  One possible solution that will be tested with this 325i build will be to utilize the driver side engine mounting bolts to create a mounting platform that is both elevated above the motor  mounts and sufficiently close to the firewall so that no cable modification is required.   

Installation started with a 12" long section of  6" x 6" x 0.25" x 6061 Aluminum 90 degree angle (McMaster 8982K46, $37.46).  The mounting bracket and lifting arm of the driver side motor mount was then removed from the car and matched to the 90 degree angle on the bench top.

Picture DSC04183 of the  6" x 6" x 0.25" x 6061 Aluminum 90 degree angle before machining.

Picture DSC04190 side view of the modified Aluminum angle shown in picture DSC04183 above.  Note that the notch was cut away  to allow the motor mount strut to pass through the plate.  The cuts were made initially with a 1.6 mm abrasive cutoff wheel in a Ryobi grinder to notch the Aluminum (this prevented the Sawzall blade from jumping off the cut line), followed by a rough cut with a metal cutting blade in a Sawzall, and finally the cut surfaces were smoothed with a metal file. 

Picture DSC04193 oblique view that shows the width of top surface was reduced from 6" to 4" to prevent the top surface from contacting the Warp 11 clam shell mounting hardware.

Picture DSC04194 showing the mounting bolts reversed and protruding in preparation for the addition of the mounting platform.

Picture DSC04196 top view of the mounting platform in place.  Note that there is a gap between the edge of the new mounting platform and the existing clam shell style Warp 11 motor mount.

Picture DSC04197 showing oblique side view of the mounting platform.  Note that the motor mount strut fits nicely through the notch that was cut from the side of Aluminum angle.  

Picture DSC04202 trial fitting of the  throttle body.  For ease of manipulation, in this picture the cruise control cable was temporarily disconnected from the throttle body vane mechanism.

Picture DSC04212 showing an alternate trial fitting in which an electric power steering pump is placed forward of the lighter weight throttle body.  Note that the length of cable within the motor compartment is long enough to permit the throttle body to be located anywhere on the platform.