In 1997, General Motors/Chevrolet debuted the 5.7L LS1 V8 engine inside the brand new C5 Corvette. The next year, they also put it inside the F-body Pontiac Firebird and Formula, as well as in the Chevy Camaro and briefly in the ‘04 Pontiac GTO. Depending on the model, it made between 305-350 horsepower and 335-365 lb-ft of torque. While the LS1 is already pretty powerful from the factory, it is also one of the most popular motors for modding. While it isn’t one of the Top 7 LS1 mods, an LS1 throttle body upgrade is still very popular.
In this article, we’ll cover everything you need to know about upgrading your LS1 throttle body. We’ll discuss what throttle bodies do and the different kinds of throttle setups the LS1 has. Finally, we’ll get into proper sizing and our recommendations for the top upgrades.
Stock LS1 Throttle Body Basics
Before we get into anything, it’s probably best we talk about what a throttle body is and its relationship to the engine and performance. The throttle body is part of the intake system for the engine. It sits between the air intake and the intake manifold and regulates the amount of air passing through. To do this, throttle bodies have what is called a throttle blade, which opens and closes to allow air through. The more air that gets through the more power the engine can produce.
The stock LS1 throttle body is 75 mm in diameter. Nearly all LS1 engines use a drive-by-cable throttle system, except the Corvette which uses a drive-by-wire system (we’ll cover both below. The LS1 also uses a 3-bolt design to connect to the intake manifold, instead of the 4-bolt design used by later LS series engines.
Why Upgrade your GM/Chevy 5.7 Throttle Body?
The idea behind getting a larger diameter throttle body is to increase the amount of air going into an engine. Larger throttle bodies mean more air can make it into the intake manifold and eventually into the engine. If you want to make more power you need to increase airflow and fueling, and a bigger throttle body allows for more air.
For most builds, the stock throttle body is honestly more than adequate. It really only becomes necessary to upgrade to a larger one if you are making a lot of horsepower and the stocker is becoming a restriction. Typically, this happens when you are upgrading the intake manifold to something larger, or adding forced induction, like a supercharger. Most larger intake manifolds require a larger throttle body, usually in the 92 mm+ range.
Putting a larger throttle body on a build making less than 600 horsepower won’t add very much in gains. Still, it will prevent a bottleneck from occurring if you push it harder in the future. You might see only 5-8 horsepower, and it probably won’t be a huge difference. In addition, putting too big of a throttle body for your power level can cause your engine to lose low-end torque and struggle at low loads. You want to make sure your throttle body size is optimized for your build, not too big or too small.
What are ported LS1 throttle bodies?
One option many people take is porting their stock throttle body instead of getting a bigger diameter one. Porting involves smoothing and honing the inside of the unit to promote air flow and velocity. While it does not make the diameter bigger, it allows air to travel through quicker with less resistance and turbulence. In many cases, a ported throttle body will do the equivalent of jumping up 1-3mm in size.
LS1 throttle body spacers
Another popular option for LS1 builds is to add an LS1 throttle body spacer. This is a small piece that goes between the intake manifold and throttle body. It is designed to increase airflow into the engine. The benefits of these are very hotly debated, with some people claiming they are amazing and others saying the opposite. For most builds, it’s probably not worth it, but it also likely won’t hurt anything, either.
GM/Chevy 5.7 Drive-by-Wire Throttle Body Setup
Earlier, we used the terms “drive-by-wire” and “drive-by-cable,” but what do those terms mean? Why is drive-by-cable considered to be superior by many people? The difference is in how the throttle blade is actuated during use. If you don’t remember from earlier, the throttle blade sits inside the throttle body and regulates the amount of air passing through. The C5 Corvette with the LS1 uses a drive-by-wire setup, whereas all other LS1 cars use a drive-by-cable setup.
On a drive-by-wire setup, the throttle blade is controlled by a series of sensors that relay the accelerator pedal position to the throttle body, telling it how much to open. It’s called drive-by-wire because the signal is sent electronically, through a series of wires. On a drive-by-cable setup, the throttle blade is controlled by a direct cable that links the throttle body to the accelerator pedal. The throttle blade opens or closes depending on its control from the cable, hence the term drive-by-cable.
Many people consider the drive-by-cable configuration to be superior on older cars because there is a faster response from the accelerator pedal to the throttle body. This means the car will be slightly more responsive at first touch, though it doesn’t have an effect on horsepower/torque. At this time, drive-by-wire was still new for production vehicles, and there were some kinks to work out.
While the drive-by-wire is adequate in the Corvette, the drive-by-cable system in the Pontiacs and Camaros is considered to be better. Nowadays, drive-by-wire setups are the norm, but in the late-’90s and early-’00s LS engines they still left a lot to be desired.
GM/Chevy 5.7 Throttle Body Sizing
As we mentioned earlier, the stock throttle body measures out to 75mm. For most applications, this is plenty, however there are times when a new throttle body is needed. Most often, a new throttle body is needed when putting a new intake manifold on the LS1. In addition, you can fit a larger throttle body to the stock intake manifold and pick up a few horsepower, too.
Most aftermarket intake manifolds use a larger than stock 92 mm or 102/3 mm throttle body. If you are using an LS1 for an engine swap, you might want to start with a larger throttle body if you are planning on getting a larger than stock intake manifold or want to make more horsepower. That way you have some headroom without having to worry about a restriction.
LS1 Throttle Body Upgrade Benefits
The top benefits of a larger or ported LS1 throttle body are:
- +5-15 horsepower
- +5-10 lb-ft of torque
- Improved air flow and velocity
- Smoother power band
- Improved throttle response
There are several benefits to upgrading from the stock LS1 throttle body. Most significantly, you will see a bump of 5-15 horsepower, depending on the build. If the stock throttle body is a restriction, you will see larger gains. Builds under 600 horsepower will probably see ~5 horsepower in gains, while bigger builds can see as much as 15 horsepower if the stock LS1 throttle body is a big bottleneck.
On applications where the throttle body is a restriction, you will see improved air flow and air velocity into the engine. This will allow your engine to breathe easier and work more efficiently, which leads to a smoother overall power band. You won’t see as many dips in power because any restrictions will be lifted. You’ll also see improved throttle response because of the increased flow.
Top LS1 Throttle Body Upgrades
Here are the top 3 LS1 Throttle Body upgrade options:
- 75 mm ported stock LS1 throttle body
- 92 mm upgraded LS1 throttle body
- 102/103 mm upgraded LS1 throttle body
We have three recommendations for upgrading your stock LS1 throttle body. First, we’ll look at the advantages of porting your stock throttle body, which is a very popular option. Next, we’ll discuss the two most popular sizes for throttle body upgrades, 92 mm and 102/103 mm. For naturally aspirated applications with the stock intake manifold we recommend porting the stock throttle body. For boosted applications with an aftermarket manifold we recommend a larger throttle body.
1) Ported stock LS1 throttle body
Purchase Link: Hawks Motorsports ported LS1 drive-by-cable throttle body
Our first suggestion is to go with a ported version of the stock 75 mm throttle body. For the majority of builds, especially those that are still naturally aspirated, the stock throttle body sizing is more than enough to make the horsepower you need. By porting the stock throttle body, you will increase air flow and air velocity while still retaining the stock fitment.
Porting is an especially popular option because it is much cheaper than a new throttle body. Many local machining shops will offer porting of throttle bodies for less than $100. You can also buy an already ported throttle body, such as the one linked above. With a ported throttle body, you probably will see about ~5 horsepower on most builds.
For basically any build that is making less than 600 horsepower, a ported unit will be the best option. It will fit the stock intake manifold the best and will more than likely not be a bottleneck. Many boosted applications utilize ported throttle bodies without any restriction. It’s really only necessary to go bigger if you’re running a lot of boost and have a larger intake manifold.
2) 92 mm LS1 throttle body
Price: $349.00 – $409.95
If your LS1 build is boosted and you have a new intake manifold, the 92 mm throttle body is a solid choice. It is a 17 mm increase over stock, allowing for much better air flow and air velocity. If you are moving up to a larger intake manifold, it makes no sense to stick with the stock throttle body sizing. You will definitely want something bigger, and the 92 mm is the smaller of your choices.
We have two options for 92 mm LS1 throttle bodies, one from Nick Williams and one from LS Racing. Nick Williams is the premiere LS series throttle body manufacturer, and they are by far the best reviewed and most respected in the industry. They have a drive-by-cable throttle body for the LS1 that is excellent.
LS Racing is not as well known as Nick Williams, but still provides solid units. If you have a C5 Corvette with the LS1 and need a larger drive-by-wire throttle body, LS Racing is your best option. It is originally intended for the LS2, so it uses a 4-bolt housing pattern. It will still fit the LS1, but you will also need an adapter harness for it to work.
3) 102/103 mm Nick Williams LS1 throttle body
Price: $424.95 – $694.99
Nick Williams 102 mm drive-by-cable throttle body
For boosted LS1 builds looking for the most horsepower and least restriction, the Nick Williams 102 and 103 mm throttle bodies are your best option. These are an increase of 27-28 mm over stock, and 10-11 mm over the smaller 92 mm versions. As we mentioned before, Nick Williams is considered the industry standard for LS series throttle bodies, and their pieces are immaculate.
Nick Williams manufactures both a 102 and 103 mm throttle body for the LS1, but with a caveat. The 102 mm version is for drive-by-cable setups, meaning Pontiacs and Camaros. The 103 mm version is only for the drive-by-wire setup found in the C5 Corvette. Yet, even though the drive-by-wire version is a bit bigger, they both will perform pretty much identically. Unless you are seriously pushing big horsepower, well over 1,000+ horsepower, you likely won’t notice any difference in restriction.
The Nick Williams throttle bodies are meant to fit the Fast LSX intake manifold series, which are among the best offered for the LS1. They can still fit other manifolds, but they were specifically designed for the Fast LSX series, and will fit those the best. This includes both the 92 mm and 102/103 mm options from Nick Williams above.
LS1 Throttle Body Upgrade Summary
While upgrading the LS1 throttle body might not be the most common mod, it can definitely be beneficial when used on the right builds. The stock unit is 75 mm, which is fine for naturally aspirated and moderate builds. However, if you really start cranking up the boost you’ll want something bigger. Alternatively, a ported stock unit can provide solid gains, too.
Our recommendations run porting the stock unit all the way up to the largest 103 mm option. As we’ve said, if you’re naturally aspirated or below 600 horsepower, stick with porting the stock throttle body. If you’re running boost and a new intake manifold, it becomes another story. The 92 mm options will be good for low boost, while the 102 mm and 103 mm recommendations are for 20+ PSI builds.
What experience do you have with upgraded LS1 throttle bodies?
Let us know in the comments below!