GM Tbi engines use a 2 throttle bore TBI unit and a divided plenum (dual plenum or dual plane) intake manifold. Each throttle bore resides over it's respective plenum. Therefore on a V6, each throttle bore feeds 3 cylinders. On a V8 each feeds 4 cylinders.
Automobile engines are 4 stroke, meaning each cylinder draws air only every 2nd rotation of it's piston/crankshaft assembly. Also, all 4 stroke engines are designed in such a way that each cylinder starts it's intake cycle at a different time than all the other cylinders in the engine.
All the above means this - at any given time one throttle bore is in much more airflow demand than the other. Add to this fact, each throttle bore in the GM tbi does not flow enough air to sustain the demand it is given.
The Horsepower Answer : use our Tbi Power Plate . They enable each cylinder to draw air from both throttle bores at the same time. Our open plenum design that incorporates a specially contoured divider which smoothly directs air/fuel into each manifold opening was given a patent #d416618.
Information on Our Competition:
1) You know who they are. They advertise that twisting air in the same form of a tornado will give you huge hp gains. They don't stand behind their product with a money back guarantee do they ? Will a "twisting" air charge stay in it's same form making a straight turn from the top of the intake into an intake runner which has a very tight turn in a GM tbi intake, through the cylinder head runner and it's sharp turn into the valve bowl area, and past the huge obstacle called the "intake valve." No!
Swirling air , however, is good for combustion. This is known fact. Where's the best place to create this swirl? Right where the auto manufacturers do it - in the combustion chamber. No obstructions!
2) You know these companies also. They design 2 hole spacers that lengthen the intake bores to try to create faster air velocity . Faster air = more air, right? Not necessarily. Their are two main airflow properties to make maximum horsepower in a certain rpm range for a certain engine size - air flow cfm (volume) and air velocity (speed).
GM designed all the tbi motors with high air flow velocities, not volume. They used small cfm tbi units, small diameter + long intake manifold runners, small cylinder head ports, small valves, and very small camshafts- all designed to give good low rpm torque. Well, they went overboard on this high air velocity passion (they did it with tpi's also) of theirs and missed the boat on better low speed torque and much better mid rpm horsepower. With velocity being overkill with these engines why would one decide to build a two hole spacer that's designed to try to increase air velocity. 1) It's much easier to design, test, and manufacturing. In fact, all you need to do is copy the gasket on a blank piece of material and drill 5 holes.
The GM tbi engines need more air volume!
10hp on stock 2.8
