Forcefed86

iTrader: (4)

I’ve run the 3 common LS platforms in the same chassis. IMO find the best deal on the most complete and newest gen4 engine. 4.8/5.3 doesn’t really matter if you have the correct supporting part combo. Either should easily meet your goals. You are talking about a 10-20hp and 20-30ft lb between the typical gen4 5.3/4.8’s. Main difference in my experience is where the torque peaks. 5.3 peak torque comes in about 500 rpm earlier than a 4.8. 6.0 500 earlier than the 5.3.

G-bodies are generally pretty heavy. So if you go with a smaller engine you generally need a looser converter and more stout top end/intake to take advantage of higher RPM power.

If you plan on a machine shop visit anyway, you can pick up the 4.8/5.3 and usually bore it out to 3.9”. Speedpro hyper piston sets are pretty darn cheap. Around $200 last I looked. So that’s another option.

Lastly The S364 turbo mentioned is a poor choice for an 800hp goal. It isn’t going to make 800+hp on an LS with any kind of efficiency. Plot the numbers and pressure ratios you see on a 5.3 liter and it will be WAY off the map at 800hp boost levels.

IMO for your power levels the “go to” turbo is the $640 shipped cast S475 1.32 T6 Borg. I’ve run a ton of turbos on LS platforms and I wouldn’t bother with T4 single setups for an 800hp goal. Not that some can’t do it, but you’ll make more power per pound with the T6 and it’s cheaper! Can also run a more aggressive camshaft with less back pressure. I have ZERO issues spooling a S480 1.32 T6 with a very mild 4.8 on what is considered a “tight converter” spec’d for my 370” engine.

Good luck!

JoshL83

First off thank you for all the replies and all the information ,second I decided on a 4.8 because of the ability to spin it a little higher and the better rod ratio.I picked up a gen 3 4.8/4l60e and computer for 375$ at the local u pull it lot.i know the little 4l60e won't last very long but for 125$ I couldn't resist it.It is a jasper replacement. I'm going to pull the motor down gap the rings for Matt's specs " sloppy mechanics " just checking make sure nothing is falling apart and shove it in and see what happens LOL Now my next question though which I'll probably have to start a new thread but there's been so many responses to this one that I'm just going to ask it What tuning software does everybody like to use for stock GM computers . I was going to run A microsquirt set up but seeing as how I'm using the 4L 60 E transmission and I have a computer I might as well try to use it to save me a transmission controller also. I've been looking in the HP tuners and it seems pretty straightforward but there's a lot of people tied in between EFI live also. I'm now going to have 2 LS based vehicle and I need to learn to do the tuning myself. I'm just wondering what people have experienced in the do it yourself category/learning curve. I downloaded the free sample version of HP tuners and it seems pretty straightforward with a decent platform just was looking for peoples ideas either way. Thanks!

BudRacing

iTrader: (3)

Matt's got Vimeo videos available for purchase that review tuning--training videos essentially.

mightyquickz28

iTrader: (8)

Yes. HPTuners, just be sure to get the Pro, though there's guys that have adapted other sensor connectors (ex: A/C pressure) to pull the Wide Band into the log.
Get a base line tune setup and then start logging, changing.
You'll need to figure out/determine:

• MAP sensor - 1, 2, 2.5 or 3 bar. Get the offset and linear. Use a known good brand, not whatever is for sale in the classifieds.
• Fuel injectors and the data sheet for them. Keep in mind your HP goals and the 85% duty cycle needed when spec'ing them.
• Speed Density or MAF tune?

truckdoug

iTrader: (25)

my 2 cents. skip the 4l60e. go directly to an engine management system that can control boost. MS3 or holley HP.