Build Thread Enola- Finishing touches

With the alignment set to the MM specs the car drives much better, it feels like the time and money i invested on the suspension setup was worth it. The car gives a feel of confidence when driving spiritedly and no longer wonders the road.

I posted an idea in mikes thread about redoing my throttle body linkage so that the secondary throttle body is progressive instead of directly tied to the primary. Basically i want to design it so that the second throttle body acts like a mechanical carb secondary.

Here is why... under low speed low throttle conditions the supercharger bypass valve is held open so the system does not put undo strain on the blower, this makes the entire system more efficient. In my system the bypass valve is vacuum actuated and pulls this vacuum source from the plenum behind the throttle bodies, this works well most of the time. However under low speed low load conditions (like leaving a stop light or casual driving in town) having both TB open at the same rate (both of them 65mm explorer making an effective 130mm opening) causes the vacuum in the plenum to go below 6" closing the bypass. This creates a spot in the throttle movement from 1%to 15% where the blower always creates boost spikes when the pedal is touched. On top of that the pumpshot enrichment must be set so high even at such low throttle conditions that sometimes the engine will cough causing the car to buck this in turn makes you stab the throttle and the bucking continues until the clutch is depressed. This to me is not safe, i must try something to rid myself of this issue.. The engine constantly going into boost and the high pumpshot enrichment are costing me precious MPG... right now the car gets around 11MPG.... i know i have a heavy foot sometimes (on ramps or any backroad really) but i think i can get it to 15 MPG or so if i can keep it out of boost.

The basic idea is to make the secondary TB linkage arm shorter (as simple as drilling a new hole to put the bolt in for the linkage) then i will take a fresh piece of aluminum flat bar and make a linkage bar that is slightly longer and cut a slot in it for the secondary. As the primary opens the slot in the linkage bar will slide on the secondary until the primary reaches about 50% open then the secondary TB will open at a rate of 2:1 until WOT....


Am i crazy or does this idea have any merit??

Noobz347 said:

I still don't honestly see a benefit to having multiple throttle bodies. It's the likely source of low speed drivability weirdness.

Click to expand...

yes it is, that is the purpose of doing the mod described so that only one TB functions under normal driving conditions. both are needed at WOT to reduce the restriction to the blower..... also it looks cool duh

I currently have this. if I'm not mistaken shortening the linkage arm on the second TB will reduce the necessary throw to open it correct?