1fastirocz

iTrader: (4)

I have decided to do a 6.0 LSX swap to my 1988 IROC. What engine would be a better engine LQ4 or LQ9? What heads would be better the stock 317 heads or L92 heads? What cam would be the best I want a big street cam. I would like to get 500+ horsepower n/a if possible, stock bottom end with ARP bolts and studs, new rings and bearings, and ported & polished heads and a 150 shot of nitrous. It will not be my daily driver but I want to be able to drive in where ever I want with pump gas (93 octane) Any advice would be appreciated.

deadhorse66

iTrader: (2)

I don't know how much valve piston clearance you'll have, but the L92 is proven, and its what I chose for a full buildup. That's going to be the issue, but you'll have more problems with the LQ9s flat tops clearing that monster 2.16" intake valve with higher lift. 500 horsepower would be pretty easily done with some other mods though, either way you choose. You'll just need to talk to your cam man about whatever it is you end up with, and what cam you can get away with without fly cutting your pistons.

the_merv

iTrader: (88)

The LQ9 with the flat-tops would be more ideal, but you go to big of a lift you may run into PTV issues like mentioned.

1fastirocz

iTrader: (4)

So I can run a bigger cam with a LQ4 and the L92 heads than a LQ9? I don't know much about these LSX motors.

deadhorse66

iTrader: (2)

You probably will still run into vtp problems even with the LQ4. L92 heads have a giant (2.16") intake valve, and when you couple that with high valve lift, you get valve clearance problems. I have a friend with an LQ4 and some heads with much less radical valve sizes that ran into problems with his magic stick IV. If you want to avoid all this, but get your compression up, hunt up some 799 castings that will push you to about 11:1 with an LQ9. They use the same valve sizes as your 6.0 head and have a smaller chamber. Talk to some cam grinders and find one that will accommodate your needs. You should still be able to get a grin with that setup. You can go ahead with the L92s, but your cam will end up being a little bit smaller, and they really do their best work when coupled with a higher lift cam. If you aren't afraid of it, get the L92s, flycut until they fit, and run the best cam for the application. That probably would be your best power maker.

the_merv

iTrader: (88)

The L92's are picky, but with the right Cam they are making nice power. I have one of the early close-split Cams spec'd for the L92 Heads, and it runs mean.

WHITEBOY_ZACH

iTrader: (2)

i just bought a LQ4 so ive been learning all i can and i learned that you can get the L92 heads.assembled..from any chevy dealership in the nation for 800 bucks. and they flow over 300cfm out of the box...for 800...
i read that on a tri-five website but it was a tech article from some magizine.



im saving for a set now.

the_merv

iTrader: (88)

Yea, they flow over 300, it's true. It's nice to tell the BBC guys that a small-block Head has them beat..lol

1fastirocz

iTrader: (4)

What is a good street cam for the LQ4 and L92 heads?

ss.slp.ls1

iTrader: (36)

Custom spec'd cam is probably your best bet.

the_merv

iTrader: (88)

Definately get one spec'd, it might cost you $25 more, but worth it.

1fastirocz

iTrader: (4)

What will the compression ratio be with a LQ4 and L92 heads?

the_merv

iTrader: (88)

Depends on if you mill them or not, stock Chamber is ~71cc.

1fastirocz

iTrader: (4)

I was thinking about this set from TSP http://texas-speed.com/shop/item.asp...d=697&catid=40

bhop42

iTrader: (2)

Kill three birds with one stone by buying an LY6 6.0l engine from a 2007 and up NBS Silverado or Sierra. Its and iron block that comes with the L92 heads and the pistons already have valve reliefs. You could mill the heads and still run a beefy cam without worrying about PTV clearance like the LQ4,LQ9, or LS2 engines.

BES Stroked Nova

iTrader: (24)

Thats what I have ^^^ milled the hell out of the heads, down to 57cc chambers, NOT ported, cut the pistons for PTV clearance and I am running a MS4 set in a 108 lsa. peak power is right at 7100, and I have had it to 7600 on the dyno. stock bottom with rod bolts.

I also have the GMPP intake, not ported or matched and the short edelbrock elbow. Made 458 with a older style elbow, but I know it makes more now cause the car runs a few MPH better with the new elbow. I still need to get it matched to the intake for a few more horses.

and the LY6 pistons ONLY have exhaust valve reliefs..... so be careful.

I have several LY6 cranks, rods and pistons, if interested PM me. they have 2-5 miles, yes one 2 to 5 miles on these!

1fastirocz

iTrader: (4)

Can I use a LQ4 block and the LY6 crank, rods and pistons and L92 heads?

alocker

iTrader: (10)

I dont see why not, you need to swap to a 24 tooth reluctor though.

1fastirocz

iTrader: (4)

Are the crank and rods the same in the LY6 and the LQ4 or are they different? What would I need to convert a LQ4 to a LY6

BES Stroked Nova

iTrader: (24)

I was told by my engine builder that the LY6 cranks seem to be better machined, and have some differences in the oiling holes and what not. lol I am no expert but I take their word for it.

I have LY6 crank rods and pistons with L92's heads(LY6 comes with L92's) all on a 6.0L block. Yes I did switch it to a 24 tooth also.

agiain let me know.