Twin Turbo 5.3L

[SS Killer]

There's no info on a TT 5.3L on the site as far as I can tell so I just wanted to start some discussion and see if we can't work through this set-up.

As far as engine size, I know "there's no replacement for displacement", but, I'm thinkin a 5.3 under gobs of boost would be a blast. You'd just have to build this thing right.

Take the bore to 3.790" for a good fresh cylinder wall but leave the stroke alone. That's 326.9ci. I wouldn't touch the crank for now, just use a nice bearing.

I'd need to get some different rods for sure.

I'm assuming 9.5:1 compression is a little high for a turbo application. I could probably make it work as long as I ran an intercooler. How could I lower compression though? I could use a different head if I had to but if you're gonna push the air in anyway, new heads aren't really necessary I wouldn't think. Is there any room on the piston to move the wrist pin toward the top little bit?

As far as location of the turbos themselves, I was toying with the idea of a pseudo-remote mount set-up with the turbos mounted just off the LT's.

Let's hear what you guys have to say.

[txarkitekt]

Ok, well you could throw on a set of 243 heads. They have a 65cc size compared to the 862 61cc size. That would lower the CR to a little over 9.1:1. The 243 heads would allow you a better flowing lower CR and they have bigger valve dia. than the 862. The LS motors can handle a decent amount of boost. Get you a 58mm turbo for the small one, then a 76mm for the big one. Throw max boost between 10-12 psi. That would freakin scream like no other.

[SS Killer]

Get you a 58mm turbo for the small one, then a 76mm for the big one.

You can run two un-equal size turbos?

[txarkitekt]

Yes, but it would be a PITA to tune...

[txarkitekt]

Why not run sequential unequal size turbos? It would allow you to build boost fast with the smaller ones spool time, then once you are peaking with the small one, the larger one comes in...

[SS Killer]

Yes, but it would be a PITA to tune...

I'd probably just run a couple 76mm

Now how bout a cam. I'm running a 212/218 with a 112LSA and just under .600" lift, how about a 224/224 with 115LSA with the same lift?

[txarkitekt]

Eh, you can. I would try and cut back on the exhaust lift to get you some decent backpressure to help build boost on the turbo--make the engine work to get the exhaust out. Not only does it help build boost better, but it gives more low end torque. But I would even go up to like a 117.5 or 118 LSA for FI applications.

I would try something like a 224/224 .588/.563 117.5 LSA.

[SS Killer]

so isn't a single 76mm capable of supporting somewhere around 1,000hp by itself?

Should I go with a couple 60's or something?

[ducky]

so isn't a single 76mm capable of supporting somewhere around 1,000hp by itself?

Should I go with a couple 60's or something?

I think the biggest you would wanna go is 60 anyway. The stock sts kit comes with a 60 and just right for the 5.3 with not too many supporting mods internally

[COWL327]

here ya go!
http://www.ls1truck.com/forums/sale-...le-4000-a.html