86 GXL 388sbc to 5.3 turbo

[spacevomit]

No there's no difference in terms of power holding ability per se. One block could be better than the other due to manufacturing variances in the casting, but there's no way to just look at them and know which without something like sonic testing or an xray (non-destructively, ie short of cutting it up).

[rex388]

I thought the Gen IV blocks where able to handle more do to the siamese factor of the cylinders.

I think it was ERL would only really like to work with them when they were around

[spacevomit]

I'm not sure about that, but I do tend to go for newer stuff just because manufacturing processes tend to improve over time generally. Fwiw, I am doing an LH6 build and the rods im using (Manley forged) are rated to 775 bhp for a set of eight, so that's the number I'm using as hard limit.

Eta: I have just found that LS7 and certain non production racing blocks have siamesed cylinders due to the huge bores, could that be it?

[rex388]

Yeah I have read on a few places that the LH6 are siamese bore to add strength to them. And my plan is to use Callies and shoot for the moon haha

[rex388]

Also summit makes a nice little kit with LS2 lifter trays, LS7 lifters, and new bolts for getting rid of the dod.

[spacevomit]

Ok, just went and took this pic of my gen iv LH6 to clear this up. The bores are not siamesed.

[rex388]

They are referring to it not having coolant running between them. Non Siamese the coolant can flow in-between the bores. Siamese they are just solid inbetween them.

[spacevomit]

Oh that makes sense. If more of the deck is closed then that is better. (Or otherwise increases the rigidity of the block)

[rex388]

Exactly my friend. So in theory more abuse haha

[spacevomit]

Since you are wanting to push the envelope, on 4 bolt heads and aluminum block no less, are you doing anything special for head sealing? Some solutions use a sort of thermal/pressure fuse feature so instead of a catastrophic failure it just blows out the seal. Ie fire rings /rupture panels.

[rex388]

I have seen a lot of people going into the 8's and a handful of 7's with L33 and lh6 engines. So Iam not that worried.

I am going to keep my lm7 also add a back up just incase.