Hey so I need some help. I have a 2004 Tahoe z71. I'm building a new 5.3 motor for it. It only has 62k miles, I'm going to take it to the machine shop and have it torn down and rebuilt with some new parts I have already purchased. Parts are
Trick Flow cam 216/220 114 Lsa .560 lift
Pac Racing 1218 springs .600 lift
BTR trunion kit
ARP headbolt kit
Summit Racing LS lifter & guide kit
Sealed Power timing chain
Vette Servo
And I plan on getting some Bosch 80# injectors, new water pump, and oil pump. I have also recently decided that I am going to turbo it once it's swapped in since I've already gone this far. With this being my first turbo I have a few questions. I've decided to do the On3 kit now to save some money, because I'll still need to buy a 4l80e to swap in, and then later on I'll swap turbos out for a much better turbo. But my question is, which turbo will fit me best with these current mods I have for the engine. The standard 70mm turbo that comes with the kit, the 76mm for $99 more, or the 78mm for $199 more? Also the Tahoe is on 26 inch wheels 305/30/26 and will be getting a 2/4 drop done. I'd like the turbo to spool at lower rpms since this is a daily driver but also be able to hold boost for higher rpms for when I get the 80e swapped in. Hopping to push 8-12psi or so. I've been leaning toward the 76mm turbo, but again this is my first turbo so any input is greatly appreciated. Thanks!

 

70mm turbo will do just fine. I'd go with a ISKY triple 12 cam if you are going straight to a turbo. Still a pretty mild cam for a smaller turbo setup.

Also in my eyes you are wasting money doing a complete tear down and rebuild on a such a low mileage engine. I doubt the bearings are worn or in need of any service to the bottom end. Slap the cam, oil pump and chain in then go on your way. Some people end up worse off after spending all the money.

If you've been around these LS motors for a while you'd know the bottom end is soild and many many people take junkyard blocks well north of 500-600hp without even touching the rods/pistons/bearings.

 

I just bought this cam so I'm gonna stick with this one. Why do you suggest the 70mm or 76mm? I know it spoils a bit faster, will it hold it as long too? And yea I hear u. Once I get it to the shop he was gonna tell me if it needs to be torn down or not. It's been sitting tho and got dust in it and the blocks pretty dirty so I kinda wanted it torn down and cleaned up before I do all this to it, but shoot if it ends up not needing all that that will definitely be a plus! How long do u think this trans will last if I'm not driving it hard?

 

Return your current cam.
Buy thos guys trip12, https://www.performancetrucks.net/fo...m-sale-544918/

Everything you need for a turbo kt os avalible in the clasified right now minus a turbo.
There are injectors, cold aide kit, hot side kit. Etc.. Only thing i have not seen in a few weeks is a down pipe. But im sure if you ask, someone has one laying in their garage forsale, thats ready to bolt to oem catback.
Save money.

On3 while cheap, is know for fitment issues. Why not buy peoples take pffs, that you know fit and assemble a kit.

 

Isn't that cam a little smaller than the one I have tho? Plus it's cost more.. I'd kind of rather put that money towards the turbo kit itself...

 

And I hear u on buying other ppls take offs. Honestly with this being my first time doing this I just figured it would be easier for me to just buy a kit. And from what I've seen/heard the on3 kits did have figment issues before but seem to have worked those kinks out. But I def will do some research and take a look at those classifieds, may be easier than I think. Thanks!

 

Also so which turbo would people recommend out of the 3? Thats my main concern

 

Figure out a HP goal and pick your turbo size around that.

70mm will make 500hp and even at that you will have trouble with street tires on the road.

 

I'd like 600-700 or 750ish but for now I'll have to down tune it until I get a 80e swapped in. Ideally 600ish would be great since it's a daily driver and is on 26" wheels, but I'd like to have the potential to make more power of later on I desired that ya know? I'd also like it to spool fairly quick or at least in lower rpms so I don't have to get on the gas all the time, again with it being my daily driver I need the longevity out of it as well. If I'm asking for too much let me know lol I know some things u can either get one or the other so iono if this is that kind of thing

 

You might want to think about re-gearing/re-thinking your wheels if you really want to run such large rims, you'll never get the power down with rubber band tires.

The stock G80 year will be dead quick even at 500hp and same with the 4L60e.

I think you are better off starting lower on the HP scale then seeing what the limits are with your tires/suspension. It really makes no difference if you have 600, 700 or even 750+ if that power cannot meet the road.