TorqueHD

I have another thread going (moving very slowly as I'm playing the long-game waiting on money for parts) on my LQ4 build. But this topic is more specific to the LSA blower that I'm planning to drop on top of it.
L8T crank- 3.86" bore, 4.020 stroke so that's like 6.4 liters. Ported 823 heads, 73cc chambers.
This is going to be a daily driver and a tow rig. Most people running blowers want max HP, or a mild street-friendly build. I am just wondering what a max mid-range-torque build would look like. At this point probably the only real variable I have left is the cam, as I already have the heads. I imagine the regular truck heads, like 706's would still net the most bottom-end torque even with the LSA.
Most of the max-effort builds seem to indicate that ~700hp is the most you can squeeze out of the LSA, but that's normally just screaming top-end. TQ is normally a much lower number. I just wonder how much you could squeeze out of the bottom end.

FFDP

iTrader: (2)

I guess it's hard to say because there can be so many variables. Like how much boost you are running, the intake temps, the fuel you are going to run. On an engine like that I don't see why it wouldn't make 400-500 ft lbs pretty easy.

But with that many cubes, the LSA blower does become something on a smaller size for blowers. Like a TVS2300 would be better you'd think. But I know you can port the LSA and all that to make it make more horsepower. Also what sucks in those adapter plates if you have to run them, square port heads would be a way better option.

TorqueHD

Yeah if money were no object of course a bigger blower would be the way. But I'm lucky to have what I have. It came with the adapter plates (from boost district) but the 823 heads I have are rec port and do not need them. I have read that porting the LSA only adds ~40hp. (i say "only"- that would be a big gain on my stock motor but not as much on a 600horse motor, and porting a blower is expensive from what I've read).
I know the LS3 heads make more power up top but in NA config, the 706 heads were better for down low, hence their use on truck motors.

My goal with this motor originally was to make an LS platform perform like a duramax. I hate duramaxes, they are wonderful for power but they suck to work on. Wrenching on them takes 3x longer and costs 3x as much as a gas motor.
When it comes time to pick a cam I'm planning to have BTR custom-grind me a cam so I'm sure they can maximize whatever parameters I ask for. I just wonder how much bottom/mid-range TQ you can get, and if the smaller heads actually work better like in NA config.
I do plan on getting an E-85 setup but I think i'll need to find a flex-fuel ECM as my 02 silverado is not flex-compatible. E85 should be a lot better since I'm tentatively looking at ~10.7:1 static CR.

terravast4

iTrader: (25)

A LSA or 2300, for that matter will have to be spun out of its efficiency range to see good boost numbers. On my 6.3 I ran a 2300 with a 2.7 pulley, 10% overdrive and only managed 14 psi. You need to move a lot of air. I think a 2650 is what you need to breath right and keep the blower in a happy place.

smokinlmm

I’m going 2650 next. I’m spinning my 1900 way to hard.

_zebra

iTrader: (5)

instead of quoting boost, you should talk CFM.
my car dynoed 525hp at 11psi on configuration #2. configuration #3 only made 10psi but resulted in 650hp.
config #2 used a stock long block LS1, while config #3 increased blower speed but added better heads & a huge cam. it moved more air into higher RPMs... and didn't have to work as hard to do it, neither.

point being, it depends on how & where he wants to make the power. i've seen a guy make 700hp with a MP112 on a 402, and a couple others making high 600s with 2300s on 427s and a 454. this 1900 blower would be perfectly fine on a little 376 stroker - especially since he wants it to be mid-range grunt. Plenty of folks have made more power using LSAs on bigger engines because LSA blowers are actually a pretty efficient design (especially when using the improved intercoolers & lids).

i wouldn't worry about your SCR yet because the bump stick will determine your actual compression ratio (dynamic compression). because of my donkey dick cam, my cylinder pressure at 13psi with 10.6:1 heads is actually lower than when i pushed 11psi through 10:1 heads... and i'm still good on 91 octane (at 4000ft elevation... was tuned on 93 at 1000ft).

and am i crazy, or don't 823 heads need a 4" bore? pretty sure i've read some trial & error about that a while back... otherwise, people would run them on LS1s and 5.3s left and right.

smokinlmm

My 408 and 1900 combo lay down over 700 wheel torque and I was told an LSA with all the mods can do over 1000.

ALL ULL C

iTrader: (18)

He has the bore/stroke swapped, L8T 3.858 stroke and 4.020 bore (391.74ci) so heads will be good.

I'd believe with the correct camshaft spec'd that 6-700whtq should be attainable on a non-ported especially with raising the CR over what a typical LSA is based off of (9:1). Just need to spend the money on your heat exchanger system to ensure keeping IAT temps in check (largest exchanger that can fit, big expansion tank, good flowing pump). Porting would be a waste of money for your objective as then you start barreling down the path of max effort that is of no benefit in towing unless you are drag racing with your trailer.