$275.00
Rod Mod Only
During the “Rod-Mod” process, we take the LS3 intake manifold and install radius bars lengthwise in the plenum. Through research and development, we have learned that air does not like moving over sharp turns – it creates unwanted turbulence. The radius bars we install are carefully selected, measured, and cut to a specific length and assists in transitioning air from the main plenum into the runners. This helps to maintain proper airflow and velocity. In addition, we minimally grind and smooth the area inside the runners where the injector boss protrudes into the runner, ensuring minimal disturbance to airflow from the injector boss. The Rod-Mod is ideal for forced induction applications, as well as nitrous applications as it does not compromise the structural integrity of the manifold during high-pressure events.
Est Gains: 6 HP for bolt-ons & 12 HP for cammed setups.
Ported Rod Mod (Popular)
During the “Ported-Rod-Mod” process, we begin by removing the vertical stands that run inside the manifold plenum. These stands are large and very obstructive to flowing air. Once removed, we adequately seal the plenum floor back up, and slightly grind/smooth the floor of the plenum. Next, we port the air inlet section of the manifold along with grinding/smoothing the injector bosses protruding into the runners. Once all porting/grinding work is completed, we then install the same carefully selected radius bars that we use in the Rod-Mod. Again, these bars greatly assist with transitioning air from the plenum into the runners, maintaining maximum airflow and velocity. The Porting-Mod is ideal for naturally aspirated applications and performs at its best in a cammed setup. At no point do we recommend the Porting-Mod for forced induction or nitrous applications, as the stand removal does lessen the structural strength of the manifold.
Est Gain: We don’t see significantly more peak power over Rod Mod (+1 or 2 HP), but we see it across the entire powerband and the midrange torque increase is worth doing the Porting Mod if you can.
Induction
Induction
We have often wondered and been asked if porting in addition to the radius rod addition would improve the LS3 intake manifold. We figured it would be a great time to find out – so Mike and Ryan quickly built 2 manifolds, one with just rods and the other with the stands removed and ported. Both we and our customers have tested the radius rods on chassis dynos and at the track many times and usually see from 6 to as much as 12 RWHP. We saw 11HP at 6600.
Both we and our customers have tested the radius rods on chassis dynos and at the track, and usually see from 6 to as much as 12rwhp. We saw 11rwhp at 6600.
The ported version looked quite a bit better. We were disappointed with the positive result as the porting is very labor intensive and it’s probably going to be requested a lot going forward. Although we didn’t find significantly more peak power, but we got it everywhere and the midrange torque increase was worth the effort.
We didn’t find significantly more peak power, but we got it everywhere and the midrange torque increase was worth the effort.
The “Mod My Manifold” option allows you to send in your LS3 / L99 Intake Manifold in to us (shipping instructions below) to have the modifications completed. This option is best for the individual who doesn’t use their car as a daily driver, or can stand for the car to sit for a short period of time – while we are modifying your manifold. This is the least expensive option.
The “Buy Modded Manifold” option is our most popular option – because it doesn’t require any downtime at all. We send you one of our modified manifolds from inventory.
We will optionally buy your stock LS3 manifold back for $350. Just send yours back in the box you received yours in. It’s that easy! When we receive yours (and verify it is not damaged…) you receive your core refund back.
If you decide to ship us your stock manifold back for the $350 credit – pack up and ship your intake manifold to:
Gwatney Performance
200 Municipal Dr
Jacksonville, AR 72076
Please include a copy of your invoice in the box with your manifold.
Please remove all vacuum hoses and sensors from manifold before shipping.
We HIGHLY recommend using generous amounts of shipping peanuts / bubble wrap. We’ve had a few “less than cautious” packing jobs (thrown in a box and taped up) which led to manifolds getting damaged in shipping. Unfortunately we are unable to issue core refunds on broken / damaged manifolds.
Induction
Induction
Customer Images
LS3 Intake Manifold Mod (Ported Rod Mod or Rod Mod Only)
love it. Great bang for your buck especially if you got a cam installed
Absolute best bang for buck manifold for HCI!
Great porting work and tidy final product, nice addition to my GPI ported heads!
Have not installed yet using it to replace my ported rod mod cause I’m going boost
It looks great nice porting in and out is fantastic really clean work