Let me hear your thoughts on how you would engineer twin 90mm throttle bodies on an LS3 drive-by-wire engine. There are two options:
1. Mechanical - extract (with great difficulty) the shaft from a LS3 throttle body and replace with a longer shaft that protrudes from the opposite side. This can be ganged up with standard linkages to drive a "slave" throttle. BTW, has anyone pulled a shaft out of an LS3 TB? - it appears to be welded in place...
2. Electronically - more involved to design & build a voltage following electronic module with error checking between the throttle position sensors. This would be an easy installation though for multiple applications. Not impossible, but difficult and there could be legal issues if it failed.
I believe he is trying to build a manifold with 2 TB's similar to the Viper's . I've always thought this would be a great idea . Are you fabbing the intake ? I want to fab an ITB but I can't get the info I need and I don't have an engine to build it from .
there was a guy in town with a 426hemi in his magnum and it had twin tb's but it was one in the front and one in the rear, and only opened up in high rpm's it would be interesting to see some research done on this,
possibly ducting run through the firewall to a "cold air" location, i think if the research, and fab work were done well it could turn out some good power increases.
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TSP 402, ETP 245cc, cammotion cam, Ported FAST 90, FRE 91mm tb, Fast toys 104mm lid,
full sphon suspension, umi k-member, ground control coil-overs, bilstein shocks.
To come: TH400 with Neil Chance 4000, 9", and a diet.
It would be similar to a Viper manifold with two throttles at the front opening in parallel. I will either remake a longer LS3 shaft or make a fixture that bolts onto the throttle body and holds a shaft that slots into a groove in the stubby end of the existing shaft. An electronic module will possibly be in the future.
Below is where the problem lies. It looks like it is laser welded in place (typical OEM non-servicable part).
Why not just set up mechanical linkage to run both off the electronic signal of one? It might present some tuning issues but I would think that would be easier to overcome than setting up two electronic signals. It wouldn't be very pretty though. Mechanical would be simpler but it would still present tuning issues.
Dont plan on running all motor at the LSX shootout with that. You can only run a single throttle body? The SAM car would have run faster with there dual T/B setup.
Back to advanced engineering (not the LSX shootout, Harrop intake or running mechanical throttle activation)
The LS3 drive-by-wire is what I need to run a second throttle off. Has anyone ever driven more than 1 throttle off the late model (non LS1/LS2) drive-by-wire motors? Or has anyone ever pulled a shaft out of a later than mid-2009 LS3 throttle body?
The LS3 error checking of the TB is very sensitive and throws codes easily (e.g. if you flip the TB upside down, or higher torque on the shaft). Also the current draw by linking 2 TBs directly to the computer will throw codes.
Unfortunately it wont work. The electronic signal uses feedback from the throttle position sensors to determine where the butterfly is. e.g. a 4V input to one drive-by-wire (DBW) motor may yield 80% open, and on another DBW motor it could be 75%. This is due to manufacturing tolerances.
Also, splitting the signal will result in twice the current draw through the computer and it doesnt like this...
The only way I see that it can be done (electronically) is to make an integrated circuit with programming to develop a signal to a second DBW motor based on inputs from the 1st DBW throttle position sensors. Then have error checking between the two throttle position sensors and set a max deviation (e.g. 5%).
Dual throttle bodies 
