Choosing the correct throttle body in today's market for your LS engine can be particularly confusing. There are presently so many options on the market, and it is often times hard to distinguish differences from the outside of the throttle body as they all are within reason holding similar shapes sizes and characteristics due to the size and compatibility constraints.
Using a large variety of LS throttle bodies we have uncovered and found some unique differences and sometimes short comings in designs and styles. We want to point out WHAT TO LOOK FOR here and ways you can avoid wasting money or buying things several times.
*I will note, Motion Raceworks designed a throttle body to solve every single short coming or concern mentioned below, we will link you to it after we discuss*
Bolt Patterns: There are 3 and 4 bolt pattern LS style intakes. Three bolt intakes were in the early versions of the LS engine family and ended completely when the LS2 (gen 4) engine took over in the 2004/5ish time frame. All LS (and LT for that matter) 4 bolt throttle bodies share the same size bolt pattern stock and aftermarket. However, bore restrictions, and oversizing will require you to have a matching throttle body. For instance some 102mm intakes will not seal a 92mm throttle body. Conversely, a 102mm throttle body will not fit on a 92mm opening without some massaging and porting if possible with intkae design.
Blade Sizing: This is not a shortcoming, but rather a topic to cover. Most aftermarket manufacturers produce throttle bodies in the 90-105mm range (some slightly larger) for use with stock and aftermarket LS intakes. Most factory intakes will not accept a throttle blade larger than a 90-92mm due to design with impregnated gasket and bore relation. Of course, if your intake does not have a gasket groove cut into it, you can "port" the throttle body opening to whatever desired size within reason.
But does size matter? The answer is generally no. For Naturally Aspirated, Turbocharged, and Centrifugal Superchargers (before the intake such as Procharger, Paxton,Vortech, etc.) most people have a false sense of importance of size. We have seen cars go deep into the bottom 4 second range with 92mm throttle bodies, these cars are making 2000+ hp and the size of the throttle body is not typically the restriction. For a 102mm throttle body the horsepower potential is even greater. On the LS platform I truly do not believe you can exceed the potential of a 102mm throttle body (right at 4") with what they're capable of making. Afterall 102mm is 4", and you rarely see a charge pipe larger than 4", meaning the throttle body is not a restriction. For reference a 92mm throttle body is a 3.62" opening, so larger than 3.5". Also remember tube sizing (3, 3.5, 4, etc.) is measured on the OD, not the inner diameter.
The one instance size does matter is in a roots or screw style supercharged application. That means a supercharger that is drawing in air from the throttle body before the supercharger. In this case, the throttle body can be or is the limiting factor. But that simply depends on needs of each individual supercharger. For some units the 92 or 102mm variations of a throttle body may still be adequate.
IAC/Idle Air Control: IAC function and design is often overlooked. Improperly designed and machined IAC can cause SO many headaches. They're often times difficult to tune with an improper designed IAC port, and that is something you do not find out until the end. On the ICON series we spent time testing on a variety of platforms both factory and aftermarket ECU types to ensure that it was optimized. Additionally, a poorly designed/machined IAC port can actually create a whistle at idle, super annoying. Finally many of the very inexpensive imported (Chinese) throttle bodies found on ebay or amazon actually are not machined correctly to fit the IAC electrical unit.
Attachments/Sizing: At Motion we make it a point to create modular and adaptable product that can evolve with your build. This was the sole purpose of the ICON series throttle body. While most aftermarket throttle bodies simply have the silicone coupler style standard attachment, some also have Vband and Wiggins style connections available. However, the ones that do have these other style attachments are not interchangeable. This means you will need to cut, weld, fabricate, and most importantly add in addition to whenever adding a different attachment. This makes the throttle body longer, ruins the aesthetics, ruins the finish, and creates spacial limitations (runs into fans/radiator). The ICON is simply a 4 bolt attachment that can be easily changed or swapped at anytime.
Clearance:. Most people do not take into account outside dimensions of a throttle body. You created a larger throttle body which pushes most manufacturers to create outer dimensions that grow also. The underneath side can cause clearance issues with waterpumps. The top side can cause hood clearance issues. We took both areas into account with the ICON and minimized clearance issues by removing material.
Learn more about the ICON throttle body here!
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