The question on the table is just how much is an intake upgrade worth?
In reality, that is just one of the questions, as the power gains (if any) naturally come at some cost, so the real (two-fold) question is actually how much for how much?
Given an unlimited budget, we would all have twin-turbo, nitrous assisted, full forged stroker motors with the latest in cylinder head technology and valve train, but the reality is that most of us must be very picky when it comes to choosing performance parts. For the ultimate in low buck, it is hard to beat a cheap turbo, cam, and springs on your typical LS application, but what about those of you that don’t have or want boost, or might possibly add it at a later date?
After all, every junkyard LS is just a Turbo LS waiting to happen.
For the gearheads looking for ways to make power from their 4.8L, 5.3L, or even 6.0L (or you lucky 6.2L folks), the most common upgrade is the camshaft. Add a cam to just about any LS then sit back and marvel at the power gains. The question now is, what do you do after adding a cam? Where is there more power to be had just waiting to be unleashed in your LS? Well folks, one area you can find extra power is in the induction system, most notably the intake manifold.
Comparing LS Intake Manifolds
Are you crazy Richard?
With the possible exception of the original, factory LS1 intake, the remainder of the stock LS intakes are very good. Why should I replace something that already works?
To see how 20 or so of the available intakes fared on a hopped up cathedral port (6.0L) application, check out my channel for a video detailing all the results.
During your visit, make note of how well the FAST LSXR (and FAST LSXRT) did in the comparison. While the factory early truck (most common intake available in the junkyards), LS2, LS6, and (especially) the TBSS intakes all work well, that doesn’t mean there isn’t more power to be had with the proper intake upgrade. In the case of most aftermarket intakes (again, see the intake video), it is not terribly difficult to offer up an intake design that makes a higher peak power number.
The short-runner intakes (Holley Sniper, Hi Ram, Pro Flo etc…) all easily make more peak power or at least more top-end power near the maximum rpm of the engine, but so do these same short-runner intakes sacrifice torque production through much of the curve for the extra peak power. If your plan is to build a high-rpm combo, then these might be something to look at, but what about those hotrodders who want more power without all the losses, or, without resorting to the higher engine speeds?
What about folks who just want to go FAST?
The Intake Comparison 5.3L L33 LS Test Engine
Before getting to the results of our comparison between the FAST LSXR and a run-of-the-mill truck intake, we need to take a look at the test motor. You see, the test motor is every bit as important as the intake when it comes to upgrades. What do we mean by that statement? Well, what this means is that if you were to run a comparison between the factory truck intake and a FAST LSXR (or any other intake) on an otherwise stock 4.8L, the gains offered on would be much less than if you ran the same test on a highly modified stroker 408 (or bigger). The reason is that the stock intake represents much less of a power restriction to the smaller 4.8L than it does on the much more powerful 408.
Basically speaking, give the motor what it needs and you will be rewarded with extra power.
It is also important to point out that this is much more than just simple flow, as many of the short-runner intakes mentioned flow a lot more than the stock intake, but still lose power through much of the curve. Intake design (especially runner length) plays a major part in where the intake adds power. In the case of the FAST intake on our cammed 5.3L, it optimized power in roughly the same rpm range as the stock manifold, it just made a lot more.
Now that we understand this, we can get to the test motor and results. The test motor was an aluminum L33 sourced from a local junkyard.
Though they are rare, the aluminum 5.3L L33 motors offered a lightweight block, more compression than the more-common, iron LM7, and the desirable (to many), big-valve, 243/799 heads. For our test, the high-mileage L33 was equipped with a cam upgrade in the form of a Red Hot cam from Brian Tooley Racing.
The Red Hot cam offered a 617/619 lift split, a 221/24X degree duration split, and 113 degree LSA (see the full cam card here). The test mule was also equipped with a valve spring upgrade, 1-7/8 inch, long-tube headers and collector extensions and a Holley HP management system to control the 80 pound injectors.
LS Intake Comparison Dyno Test Results
After dialing in the 5.3L combo with the stock truck intake and throttle body, the cammed 5.3L produced peaks of 456.5 hp at 6,300 rpm and 411.7 lb.-ft. of torque at both 5,100 & 5,200 rpm.
After installation of the FAST LSXR intake and matching 102mm throttle body, the peak numbers jumped to 480.7 hp at 6,400 rpm and 416.7 lb.-ft. at 5,600 rpm.
Measured peak to peak, the FAST LSXR intake increased the power output of the cammed 5.3L by 24 hp, but it is important to note that the most of the gains came past 5,000 rpm. Below that rpm, the two intakes traded one or two lb.-ft. of torque back and forth, likely something you would not feel from behind the wheel, but your time slips will definitely reflect the extra power offered by the intake upgrade.