BigBurdLs

Hey, guys so I’ve bought an ls engine pretty much all stock but it’s been rebuilt and I want to make about 400hp and my set up so far to get which tell me if it’s mix matched.
comp cams 54-416-11
beehive springs or ls6 springs
243 heads
new set of pushrods
hydraulic roller lifters
ls6 intake
I was looking into switching the rockers but i don’t even know if most of the stock things could be used but since I’m getting new heads I want what will work best

BigBurdLs

forgot to mention it’s a 5.3 with 862 heads right now

AwesomeAuto

Is this at the flywheel or at the wheels?
Are the parts listed what you currently have in it?

SLP IROC-Z

iTrader: (14)

Youre going to be better off with the 862 heads since its a 5.3.

BigBurdLs

not gonna lie I’ve never understood the difference
and nah I probably should’ve been more clear but those are what I want to put into the motor

and I chose 243 heads cause I planned on putting a supercharger on it later in the future, the Magnuson heartthrob I think what it’s called

cino

iTrader: (28)

862 have smaller valves and same ports like 853/241. They have smaller combustion chambers
243 have bigger ports and bigger valves, but your compression will be lower.
Is your goal 400 fhp or whp?

BigBurdLs

fhp but if that’ll only get me so far what else will I need to achieve my goal?
i was going to throw 3.73 posi into it and looking into putting 305/45/r17 in the rear but I’m sure that stuff only works for whp

Dragls

What chassis is this engine in?

dreadpirateroberts

iTrader: (1)

706/862's have shown to make a bit more power over the 243's, if not just for the compression difference.

advanced induction has a port program for those heads. give them a heads up, although they are probably hard to reach.

BigBurdLs

swapped it into a 1989 firebird so f body

BigBurdLs

so keep the heads is what I’m getting at?

Bspeck82

So the only goal is to make 400 fly? It almost makes that stock. Small cam headers and ls6 heads will get you there. Use stock rockers and aftermarket pushrods and springs with tool steel retainers. If possible get a valve job on heads or a cnc port if you can. If you add a blower that would change plans entirely for you wouldn't build a car to run hard NA and slap a blower on it and call it good. Many things need to be taken into consideration so you dont toast the motor.

LilJayV10

iTrader: (39)

If you are wanting to push 400hp, you need at least 425 to do it.

Tuskyz28

TLM7 5.3-Liter Block: StockCrank: StockRods: StockPistons: Stock Cam: Trick Flow Specialties .575 lift, 220/224 duration split, 112-degree LSA Heads: TEA Stage 1 CNC 5.3-literIntake: Stock TB: Accufab 78 mmHeaders: QTP 1¾-inch long-tube Peak Power: 436 hp at 6,200 rpmPeak Torque: 410 lb-ft at 5,100 rpmTorque Curve: Exceeded 375 lb-ft of torque from 3,800-6,100 rpm

Matt_ws6

If you're still confused about fhp vs whp. Flywheel horsepower is measuring the output at the flywheel. This is what the engine makes powerwise. Wheel horsepower is measuring the output at the rear wheels. Whp will read lower as there will be parasitic loss as the output travels through the drive-line. Manufacturers advertise fhp due to the fact that it's a "bigger" number, and due to the fact that it's easier to standardize fhp due to all the different variables that come into play when measuring wheel horsepower. Hope that helps

bigsapper

Flywheel HP also excludes the drag from the accessories added once the engine is in a car. Dyno rooms are also climate controlled, so optimal ambient conditions.