Much more room to grow in the future with an ls3 and the stock ls3 heads likely outflow aftermarket cathedral port heads. I’d be interested to see what
@J Alper has to say though.
Depends what you want to do with it and long term,
We all get rapped around HP, but really it is the Torque that makes all these cars fast in the Dunes, HP will be fast on the flats but the torque will pull the car up the hill,
it is like towing with gas compared to Deisel, the gas is fast on the flats and down the hill because more HP the faster it will rap out under small loads, Torque will keep on pulling if the grade or the load increases,
The 383 will out perform the ls3 in the dunes, on the drags like Logan mentioned it might outperform the 383 due to the heads,
But they now make a LS7 Head That fits on a LS1 bore, It uses a LS3 intake but ls7 dimensions, if you had a ls3 that was the same specs as a ls7 the ls7 might flow the same on a bench but it will out perform due to Valve angle,
383 with rectangular port heads should be a great combo,
The one issue i see with purchasing a ls3 crate motor is that if you decide to stroke it, most of the parts might go away, you will only use the block rockers and the heads, the factory heads are OK nothing great compared to what is on the market for aftermarket heads, The factory heads will get gutted, new valves and springs, so really not much used from the crate motor,
The 416 would be a better choice if there was no budget, but building a 416, i think i would just purchase a block and start from the ground up, 383 are great motors.
Crate ls3 make around 1.3-1.4 per cubic inch of HP, and 1.2 per cube of torque.
383 Makes around 1.5-1.7 depending on stock heads or full aftermarket heads
416 will do the same 1.5-1.7
Hope this is enough data to help make your goals on HP vs TQ.
At the end of the day our most popular is the 440 because it uses a 5.3 block and then sent to Mast Motorsports to have the block sleeved to a LS-7 style block, doing this it will be almost the same price as a new LS3 block.
Remember it is just math, you will see talk of motor making crazy HP on loose dynos, you tell me what you want the dyno to read, and you can fudge the number by saying the drum weighs X, Not saying any names because both tuners are awesome tuners but same car same motor, One dyno made 620 at the wheels the other made 510 at the wheels, nothing changed.
the most you will get from a LS3 crate motor is 564 HP, change the motor was rated at 500hp then they upgrade the cam to get around 550-560, if you get more than that without changing the heads, then you can sell the motor to nascar or F1 for a couple hundred thousand dollars.
The proven number across the US for a Crate LS3 is 1.3-1.4 per cube.
