LSU motor build

[Jim11h]

Been kicking idea around of building a 2 barrel alky motor. Currently running standard sbc 408 but everything 23 degree. My understanding is ls is 15 degree, more durable, better flowing head ports. What's the opinionstatus? There an advantage to be had? Gotta be cast head and block basically only rules

[Jking24]

Cast steel or aluminum head ? Their really isn't any practical steel ls head.i think their were only a very small amount ever made.

[JustAddDirt]

RHS used to have a 14º cast iron cylinder head. not sure if they still do. But worth looking into.

[Jim11h]

Iron head iron block. Yea know of rhs but have heard they Crack easily and they're definitely not cheap. Just looking and kicking around options. Think 99-2000 truck ls motors were the steel heads

[JustAddDirt]

If you run an LS motor, make sure to use thin synthetic oil.
They will not live very long if thicker oil is used.
10-40 is about as thick as I would go.

or you can go the direction of the World Products MoTown II that uses conventional SBC rotating assembly
and an LS top end.
link below:

https://www.onallcylinders.com/2017/08/23/best-worlds-building-gen-1ls-hybrid-world-products-motown-ii-ls-block-part-1/

[Jim11h]

Thanks for link. I'll read further when get chance.
gressman is just around corner from shop and hell of good guy and builds nice pieces

[LRtireCHANGER]

justad-dirt, are the bearing clearances on a ls motor tighter than a sbc, or is the oil pump in an ls type engine not capable of the same flow of a sbc??? I am confused as to why a ls would require a much dif oil than a sbc. I have zero experience with ls motors, and I am just nosy.

[Jking24]

Clearance are all roughly the same they actually use the same rod and crank bearings. Also lifters are near identical. Ls lifters can be used as a upgrade in a gen 2 sbc with factory roller. Besides the better rockers and crank mounted oil pump their very similar component and clearance wise so i don't know why this would be true

[JustAddDirt]

The oil pump is crank driven on LS, which is 1:1, where a standard SBC is cam driven at 2:1
oil pump spinning too quick at high RPM's and pumping oil to the top end, and lifter valley.

Which brings us to the next issue... oil will not return to pan efficiently, because of the deep skirt blocks, starving oil pump, which is already spinning too fast.
then...
BOOM

Thin oil helps this, but just a crutch.

[fastford]

with todays technology , as long as its a roller cam , synthetic is the norm in any engine...imo....

[JustAddDirt]

lubrication fluid

with todays technology , as long as its a roller cam , synthetic is the norm in any engine...imo....

completely agree.