cousblake11

I have a 01 LM7 5.3l with 150k and im wanting hp, reliability, and decent mileage. We tore the motor down and it barely has any wear at all! its actually still in the factory specs. I know I could just throw the motor back together but I don't want just a regular 5.3, ive been doing research on boring and ive seen guys boring the block to a LS1 bore of 3.905 to make it a 5.7l but I was thinking about it and that is a huge difference from 3.78.... wouldn't the cylinder walls be thin?or would it be perfectly fine? I know everybody says buy 6.0l, but I want to be different and have my own unique motor. if boring the 5.3l to a 5.7l would be fine and I shouldn't have issues with it then ill do it. I just need to see what other people think or have done. Whats the biggest and safest bore for 5.3 without being to thin or have overheating probs?

MechE

iTrader: (3)

what's your budget? you could do a forced induction build instead

gamble686

iTrader: (3)

You would have basically an iron LS1 motor and they seem to just fine with aluminum so I think the iron block will be plenty strong. My main issue is that you will spend almost as much building a good iron 5.7 as swapping to a 6.0 different is all good in my book, but is it worth it.... I would say probably not.

Suburbazine

A .120 over bore is plenty strong. I did it and I beat on it every day. Flat top forged pistons and milled 862's, CR somewhere close to 11:1.

Mine actually takes longer to build heat after the bore job.

Everyone likes to call it an "Iron LS1", but a milled 5.3 is superior. Better heads, exhaust, crank, computer controls, etc.

iamkeniff

iTrader: (16)

What
A 4.8 5.3 5.7 6.0 gen 3 have all the same options as that "superior 5.3"
Same thing with a 6.2 using a 243 style head instead of an L92 based head.

Suburbazine

Oh. For some reason I went "350 = LS1 = Rectangle ports"

Duh. Wrong information LOL.

cousblake11

If I bought a 6.0 itd prob have some mileage.... so either I buy a 6.0 with so many miles versus building a brand new iron block 5.7l that not a lot of people have and probably with my combo im thinkin ill have a hell of a motor. idk I could build the iron 5.7l for prob under $1000 then with the rest of the stuff itd prob be round 4g's. what would the cheapest way to go on the heads be? I want to put a 212/218 cam in, so I think im gonna get some LS6 springs for it and 7.4" pushrods and I should be good on that. but I know the 706 heads are 61cc's should I port them or just buy some new heads? I still want to be able to run pump gas by the way. so prob wont go over 10:1 CR

Suburbazine

You can run 11:1 on 93 (or 91 octane if you're careful).

Since you're running a cam and tuning I would run 93 anyways so you have room for error.

cousblake11

What would my CR bump up to? with ported 706 heads

cousblake11

Alright so if I use the stock 706 heads and port n polish them to 64cc the compression would be around 10.6:1, could I run 83 octane with that?
Also I put a list together for a altogether price of what I want in it, so here it is.
LS1 JE Piston and Rings - $700
XR265HR - $400
LS6 Springs - $60
Comp Hardened 7.4" pushrods - $100
706 heads Port/Polish - $1000? idk
Gaskets - $250
Bearings - $200
----------------------------
Motor alone around $3300

later performance mods...
F.A.S.T. 102mm intake - $900
102mm TB - $400
Fuel rail assembly - $200
Flex-a-lite electric fan kit - $620
Pace Setter 1 3/4 Long tube Headers - $300
-----------------------------
Total of all around $5800
and on a B&M 4l60 Transmission - $1200
The whole build would be probably around $7000....

That would be the full build of everything I think I want to do with my motor.
Tell me what ya'll think of my list, or anything I could get cheaper and it work just the same. Thank you!