Bolt On Modifications for the GM Throttle Body Injection System

Okay, let's start dealing with what it takes to make more horsepower with the GM Tbi Systems. Like any engine we must first deal with the biggest restrictions to airflow to these engines - the throttle body and air induction components.

1) The Biggest Airflow Restriction to Airflow in the GM Tbi Engine

The stock throttle body only flows 480 or so cfm. Yuk! To address this biggest problem we offer two components - our CFM-Tech Tbi Power Plates and our High Flow Ported Throttle Bodies.

Our CFM Tech Tbi Power Plates

The cheapest of the two, of course, are our CFM-Tech Tbi Power Plates. These Power Plates are machined with our patented #D416618 airflow design for 2 throttle bore t-bodies (injection and carburetors) installed on a divided plenum intake manifold.  With this t-body and intake manifold configuration half of the engine's cylinders draw air from only one throttle body. This means that a cylinder can draw air and fuel from only one throttle bore.

You might think that the only way to get more air through the throttle body is to make the throttle bore physically larger. It's a good thought because this is true but it is not the only way. Our airflow breakthrough was made when we sat down and really thought about the basic and general characteristics  of 4 cycle automobile engines. A  cylinder only 'inhales' every other rotation of the crankshaft/rod/piston assembly. Furthermore, a cylinder only 'inhales'  during one of the 4 cycles - ie: just a portion of one engine revolution. What does this mean? It means that if one throttle bore feeds half the cylinders (3 on a V6 - 4 on a V8) during their short intake cycle that the throttle bore is not constantly  in the same demand for air. Okay, I'll say it another way. Given the same throttle angle and engine rpm, a throttle bore will have many high demand-low demand peaks and valleys for the amount of air   that each intake cycle is pulling through it.

If a cylinder cannot draw more air out of a throttle bore that is already at it' maximum 'breathing' capacity it cannot draw any more air in to make any more power. Simple. However, what if the other throttle bore that is 'feeding' air/fuel to the other half of the same engine's cylinders is at a time where it is not in much demand? BAM! You use it! That's what we've done with our Power Plate Spacers - let each cylinder be able to draw air/fuel from both throttle bores. Simple yet Ingenious.

What about fuel distribution? This is actually the second benefit to using our Tbi Power Plates.  Chances are that your fuel injectors to do not physically flow the same amount of fuel as each other - GM did not match them in identical pairs and then add the fact of your injectors being older and used for many. many miles with each wearing at different rates from each other.

Why does this 'mismatch' in flow rates need to be addressed? One injector feeds half your engine's cylinders and the the other injector feeds the other half of cylinders. Therefore, one bank of cylinders will be running richer or leaner than the other half. This not an ideal situation for max efficiency, mileage, nor power. Our CFM-Tech Power Plates let each cylinder draw from a common source of air/fuel.

Ported GM Throttle Body

Obviously, since the factory throttle body is a major restriction a bigger throttle bore size will let more air through. We all understand this, however, we don't stop here. We also address the large restriction caused by the relationship of the injectors with the top of the throttle bore. GM cast a ridge in the top of the bore that is in very close proximity of the injectors. We machine these ridges flat while precisely enlarging the throttle bore.

The bonus for you that have worn and binding throttle shafts is that since we have to remove the shafts to perform the machine work we install new shaft bushings and seals. Therefore, not only do we provide you with a rebuilt throttle body we provide you with much more performance!

CFM-Tech Ported GM Throttle Body

Benefits:

1. Cheap cost - Our regular price is $229 with core return.

2. Dependable and proven parts - keep your Tbi all GM.

3. Replacement parts (if ever needed) can be purchased at any local parts store

4. Bolt in - we send you a throttle body for your vehicle. A big  reason we need the core back.

Myths

The intake manifold bores need to be enlarged to add a larger throttle body.  In the case of a 2" 7.4L T-body placed on a 4.3/5.0/5.7 1 11/16" bore intake this is true. A ported 4.3/5.0/5.7 t-body on top of the OE intake does not have a major mismatch and not much (if any) power is to be gained by machining the intake to the same size. We have nothing against doing this mod to the intake for it will not hurt anything. Remember, the bores in the intake are straight and without any restrictions - they flow more air than comes thru the t-body's bore with it's "imposing" injector placement.