Mongothemango

So I am fort3enough to have some choices on my build.. I have a 2000 ls1 and a 2000 lq4 to throw in the truck. Either way it's going to be backed up by a freshened up mostly stock t56 out of an fbody with a McLeod twin disk clutch. Already have an On3 76mm turbo, most of the turbo kit, stage 3 TSP truck cam, eagle forged I beam rods and exhaust from the down pipe back. It's already a 5 speed truck so that part is taken care of and either engine will mostly drop right in.. My goal is to be around 750 wheel horsepower at 10 psi. Back to the real question though, ls1 or lq4? Truck is a 99 rcsb 2wd.

wannafbody

iTrader: (2)

6.0 for turbo and slightly less compression

G Atsma

LQ4. Already has low compression (9.4:1) in light of it getting turbo boost, plus the extra displacement will help move the heavy truck. Besides, if you blow it, they're far easier to find than LS1's

Mongothemango

i already have both engines. Will be throwing in a forged rotating assembly either way so compression is going to be around 9:1 with around 30 ring gap. Going to be a weekend warrior.

Mongothemango

Will be putting in forged pistons in so I can drop the compression if I go ls1.

G Atsma

What do you see as any advantage the LS1 has? The cylinder walls are much thinner on the LS1 block.

Mongothemango

I have no idea when it comes to the thickness difference with these two, no doubt the ls1 will be fine with ten to fifteen pounds with forged rods and pistons though. Advantages of ls1 is wieght, more room for the turbo stuffs since the accessories are slightly shorter than truck accessories and having round port heads for an aftermarket intake to feed that healthy cam. I will surely need bigger injectors and another fuel pump either way I go. Lq4 advantages are that I can probably go a lot more boost and the displacement difference. That turbo is going to have trouble keeping up with the 6.0 over 5k rpms though right?

G Atsma

Any front end accessory setup fits any LS block.
Both the LS6 and LQ4 have cathedral port heads, port sizes being nearly identical.
I don't know where you are getting your info.

rogergm92

iTrader: (2)

I would go with the LS1 (assuming you already have both)

the higher the compression, the higher the HP. You are not going 11:1 so dont bother to think that the lower compression will make the LQ4 better for boost.

Also you will be lighter.

The LS1 is solid, first you will break a rod or a cylinder before a cylinder wall. BTW stock internals with gap will get you over 750whp easily

rogergm92

iTrader: (2)

Just drop in a LS6 intake from the Bahrain user that sells them in here (or a TBSS if you have space). BTW the stock truck intake from the LQ4 is better than the LS1 intake (LS1 intake < truck intake = LS6 intake < TBSS intake < fast 102 or msd)
fuel pump with regulator (450lph or twin 255 with hobbs switch)
SEP injectors or flow matched siemens deka 80lb or the 120lb
TUNE FOR GOD SAKE with
SS2 cam or Summit stage 2 turbo cam WITH SPRINGS
Billet china turbo with all the goodies (74mm to 80mm anything in there is good for a 5.7 6.0)

Mongothemango

yes, I am aware that both sets of accessories will fit either block. I did not know that the ls1 has cathedral heads as well that was simply me being wrong. Thank you for the input.

Mongothemango

yes, I have both engines and everything that i mentioned in the post minus the t56 a buddy is hanging on to it for me. Ls1 has 174k on it so I figure if I bulletproof it, should run forever on low boost. The lq4 has 140k so same with it.. i was thinking dished summit forged pistons with the rods that I already have.

Mongothemango

i will probably go with the truck intake, Ihave a few laying around. HP tuners. Already have the turbo and cam kit with push rods and springs.

G Atsma

Every Gen III LS engine has cathedral heads.

Mongothemango

that is great information to know, for some reason I thought that the aluminum blocks that came in the cars had squared intake ports. I guess that leaves the advantage of wieght then. My big problem is that I can't sell the ls1, if I could get some decent money for it then I would just go with the lq4.

wannafbody

iTrader: (2)

6.0 in HD trucks got squart ports in 08

Redbull87

iTrader: (3)

Id go with the lq4 for your goals.Mill the stock heads for a lil compression bump.It wont need large amount of boost and use a small meth kit if you run pump gas.Easy 750whp and broader powerband/torque curve fun for the street/strip.

Mongothemango

i was considering e85 since I won't be after crazy power. That doable?

omc8

iTrader: (7)

Yes the LQ4 has advantages of bigger selection of heads to choose from allows for bigger valves and more room to grow later down the the road..But t LS1 biggest advantage is weight so if this was for n/a race purpose especially autocross , trackX or road racing it might get the nod .

G Atsma

ANY aluminum LS block has that advantage. But since it's going in a truck, the weight difference will not be nearly as apparent as in a lighter car. IMHO the LQ4 would still be a better choice due to the additional low end torque.