5.3 L33 Autocross Build
Thread Starter
Registered User
Joined: Nov 2024
Posts: 1
Likes: 0
5.3 L33 Autocross Build Hello, I am in the process of building an L33 5.3 to swap into one of my cars. I'm planning on doing autocross as well as street use. My main goal is 400+ horsepower, and high RPM limits (somewhere in the 6500-7000 range). This is my first time ever working on an engine and it may be a little over-ambitious, but I want to learn and that's part of why I am doing it. I'm gonna lay out the parts I plan on buying below, I'm hoping for feedback on other people's experiences with the parts, as well as any better recommendations. My engine already has a Melling's high-pressure oil pump and the internals are gen 4 (Also has some cam unsure of what it is yet. Can the stock bottom end hold up to the higher RPM range?
LS6 intake with stock LS6 injectors
LS1/LS6 BTR stage 3 NA Cam kit (Includes their platinum .660 Duel spring kit)
BTR Delphi lifters
Upgraded one-piece pushrods (Unsure of what to get yet until I check with the other new components)
Comp Cams Pro Magnum LS1/LS6 Roller Rocker Arms (The ratio increases from the stock 1:7:1 to 1:8:1 I'm unsure of how much this affects and would like to know if I will need specific pushrods because of it. I plan on using a pushrod checker before buying my pushrods)
LS6 intake with stock LS6 injectors
LS1/LS6 BTR stage 3 NA Cam kit (Includes their platinum .660 Duel spring kit)
BTR Delphi lifters
Upgraded one-piece pushrods (Unsure of what to get yet until I check with the other new components)
Comp Cams Pro Magnum LS1/LS6 Roller Rocker Arms (The ratio increases from the stock 1:7:1 to 1:8:1 I'm unsure of how much this affects and would like to know if I will need specific pushrods because of it. I plan on using a pushrod checker before buying my pushrods)
Joined: Apr 2006
Posts: 3,909
Likes: 1,158
From: Grand Rapids, Michigan
Stock bottom end will basically take any RPM you throw at it. I shift my SBE LS3 in my Camaro at 7100RPM. Are you looking for 400 RWHP, or crank HP? That changes cam choice significantly. I run BTR pushrods in both of my cars, so all you need to do is assemble and then measure for length. Spend the extra money for the titanium retainer option with the springs. Don't get the Comp Cams rockers. Waste of money. Stock rockers with the BTR V2 trunnion kit is all you need. You will not need the extra lift provided by the 1.8 ratio rockers. If you have 243 or 799 heads ( common on the L33 ), they're going to be tapped out at around .600" lift anyway. If you want 400 at the wheels, you may want to look into a FAST LSX intake instead of an LS6 intake. Also may want to look into porting your heads.
TECH Fanatic
Joined: Dec 2019
Posts: 1,129
Likes: 478
If your L33 already has a cam, there's a chance you're at 400 horsepower at the crank right now.
A stock L33 with a gen 4 truck intake and a 222/225 cam made 426 horsepower at the crank on the engine dyno.
-Stock rockers are more than enough for 98% of all setups.
-The L33 comes stock with the same lifters you're looking to buy.
-Pushrods aren't always necessary, they're somewhat setup dependent. I've been 7600 RPM on stock pushrods.
A stock L33 with a gen 4 truck intake and a 222/225 cam made 426 horsepower at the crank on the engine dyno.
-Stock rockers are more than enough for 98% of all setups.
-The L33 comes stock with the same lifters you're looking to buy.
-Pushrods aren't always necessary, they're somewhat setup dependent. I've been 7600 RPM on stock pushrods.
