what has been your experience with TBI independant throttle bodies?

[sozaysven]

There are several strategies for independant throttle bodies on older 911 motors. There are cool creative frankensteins like using Triumph TBI and a custom manifold and full turn key systems. Many running on MegaSquirt or pro control systems.
I was thinking of doing this to a 3.0.
Here is my question. Are you always fiddling with it and have bad around town driveability? or can you get it to a point where it drives like a factory car?

Some of my questioning comes from my days with Weber systems and the finickyiness of them and the tunning, and the issues with balancing flow that don't exist with a complete single manifold?

[evan9eleven]

Without going into lots of detail here, I’ve got Triumph S3 ITBs and Megasquirt with EDIS ignition. I have a very good and driveable street tune, but it has taken a lot of tuning to get it like this. EFI takes work to get right. I have also invested huge amounts of time into the throttle linkage and general tweaking.

Next time I will go with top shelf everything— direct to head ITBs and a pro EFI.

I’ll follow this thread and contribute more when I have time.

[PhillIB]

I have found the opposite to Evan. I have the same set up and it didn't take much to get it running nicely. It drives better than factory, nicer to drive round town and is fabulous on the open road. I fitted all of it myself and had my tuner tune it. No rolling road necessary, just done on the fly. It helps if you have a competent and friendly tuner.
I designed my own linkage.
You will need some gauges to balance the throttles occasionally but this takes half an hour once you get used to doing it.

[jjeffries]

One of the best builders here on PP has told me finding a tuner to dial in a new system is now surprisingly difficult ... they just want to apply their craft to newer vehicles and are either intimidated by a (dead simple) old 911, or just don't want to be bothered to do something which will likely be a one-off. Is this the experience of others? John

[tirwin]

Speaking as someone who is about to make the ITB plunge, I’m curious to hear responses.

Given the improvements in tuning software and the ability to share maps, I can’t imagine that it’s a lack of access to knowledge problem.

There is probably a more well-worn path for the components. The more you vary from that, the more you’ll be on your own. My guess is it’s not too profitable to tune a completely unique system as it is to tune something where there are fewer variables to control for. Predictable = profitable.

[Bobboloo]

Turn-key solutions cost more upfront because the R&D has been done already but should be less expensive than paying a tuner to finish the job. Problem is people buy an open ended system thinking they can just pay a mechanic to just finish the job and save money. That will only work if the mechanic is willing to finish the R&D on his own nickle. How can a mechanic even quote such a job.

Open ended systems are great for people who have the desire to spend the hours necessary to go through the learning curve and finish the job. If that's not your thing then buy a turnkey system and save money.