EB338

For those who are building modified engines with Individual Throttle Body setups and aftermarket computers (Motec, etc) what is done to allow for the use of MAP and MAF sensors?

Also, where is everyone getting their vacuum sources now with the manifold gone?

atb

Here's Louie's set up.

atb

Note throttle position sensor on the rear left. The spigot on the blue box (front-center) is for the idle stabilizer.

EB338

In the center am I seeing 8 individual vacuum lines coming together to....what exactly? Have any more pics of his setup? Guess I should also ask how everyone is addressing the throttle linkage issue.......

Jim bailey - 928 International

Erich I believe you can probably count the number of Individual Throttle Body 928 engines on one hand...Kelly Moss,Ott, Hanson,Devek car (Ott) , ? So there is not a lot of experience on which to draw. Very few 928 engines are running aftermarket injection either.

EB338

Well my question could apply to any ITB setup engine, how are these issues addressed? Then you can add me to that list.....

Jim bailey - 928 International

For vacuum you run eight lines from below each individual throttle body below the butterfly to a small box(manifold) there you can also use a MAP sensor if you wish. To run a mass air flow sensor you need to fabricate a sealed box around all the intake stacks very difficult to make it sealed yet easy to remove and install. The linkage is something you simply fabricate most vendors of throttle bodies have various bits and pieces to bridge the gap from shaft to shaft jumping from one bank to the other gets more difficult due to thermal expansion on the engine to keep the idle throttle positions the same /syncronized but often involves using a bell crank etc... My 911 mechanical injection engine has 6 individual butterflys and threaded adjuster rods on each as well as adjusters from bank to bank plus and adjustable link to the injection pump!

atb

Jim's got it right Erich.

I was planning on using the stock LH/EZK with my MAF in a snorkel in front on an enclosed plenum on top of the throttle bodies, but it looks more and more like I'll be moving to a stand alone system using a MAP and TPS.

EB338

Jim, Adam thank you!

Still would be interested in more pictures if you have any. I suppose the size of the "box" would have some impact on vacuum at lower engine speeds? Adapting whoever throttle bodies to the 928 is going to require some form of adapter plates and I assume this is where the vacuum will have to be ported, or do some throttle bodies already have such provisions for vacuum, etc? Needless to say my whole mission is to keep my power brakes and HVAC system functional.

How does the linkage on Louie's setup compensate for thermal expansion-contraction? For that matter what does the Devek setup use, or does their "kit" leave you on your own for linkage? I am comfortable to fabricate functional linkage but I was not sure how big an issue the thermal expansion on the aluminum block would be. I wasn't sure if it was serious enough to mandate the use of some sort of "fly by wire" throttle system and if so how to synchronize such a setup. Not that synchronization of a mechanical setup is a trivial task.

Does a system like Motec or anyone else's allow for the use of more than one MAF sensor? If the inlet air was divided into the two separate banks can two such sensors be used together?

Also what more is there to the idle stabilization setup Louie is using?

Jim bailey - 928 International

For an idle stabilizer to work you need a port above the throttle body and one below so the idle valve can regulate how much air the engine is seeing If going by throttle postion or MAP or both then there is no need to pull air from above the throttle body any air will do..