I am building a 5.3 to put in a 1966 Nova and want to increase the horsepower as much as possible without changing the bore size. I want to stay around the 327CI (I know it is really 325). This is an attempt to duplicate or better the legendary L79 327/365 engine of that time period with a state of the art fuel injected engine.
I want to replce the dish pistons with Flat top to increase the compression. I also want to replace the cam,valves and springs with LS6 or comparable size.
I will need larger injectors also. I have already purchased a LS1 intake but do not know the best place to get these other parts. Any advise would be appreciated.

Thanks!

 

Hmmm, I have not heard of many or any sites making aftermarket engine components for the truck engines yet. You MIGHT check on a longer rod ( stock 6.098" on all the engines except 4.8L ) to 6.125" or so. This should let you keep the stock bore, not change the CID too much, and increase compression.
Or you could do like me and bore it out. I know you want to keep it close to the magic 327 displacement but for power and engine parts you open up a whole new world with the 5.7L bore size ( 3.78" to 3.898" ).
Last, be careful with the LS1 heads. The larger intake valves don't pose clearance issues but due to the low head angle ( 15 degrees ) you can get some valve "shielding" if you stay with the stock 5.3L bore.
Lots of good LSx engine folks on this site, hope we can help you out!

 

We had a discussion on the forums a while back... the 4.8L (LR4) motors have flat top pistons. Maybe someone can chime in about swapping the pistons and if it will work.

Welcome to the boards.

 

Thanks for replying.

How much did you have to bore your block in thousandths to get to the 5.7 size? What is the maximum bore on this block?

Did you have to modify your computer program?

 

Went from 3.78" to 3.905" for the JE pistons I used. The 0.125" is about the limit of the 4.8/5.3 block ( they are identical BTW ). I had a sonic check done afterward and the thinnest area was 0.153" ( recommend no less that 0.150" ). Others have had similar results. You can go thinner down to 0.100" on the iron blocks but it can cause hot spots and tuning issues.
The stock computer program is OK for any engine combo initially. It may not be optimal but you can play with it later thru LS1Edit or others if the urge strikes.
These LSx motors are the definition of ubiquitous or generic to each other. So many parts interchange, more so than the older small blocks ever did. Keep us up on your choices and ask away if you have more!

 

"The stock computer program is OK for any engine combo initially. It may not be optimal but you can play with it later thru LS1Edit or others if the urge strikes."

What is this LS1EDIT? IS it a box or a program that I can run on my laptop? Can I use it to turn off the VATS instead of sending my ECM out to Speed and Performance?

 

It's a program that you run on a laptop. Check out www.carputing.com.

 

Whoa! $7000.00!!!

I don't think I can justify that?????

 

Wow, not many can! FYI, you looked up the "Unlimited" business usage price. The listing for single users for LS1Edit is much, much more realistic at $550 minus $100 if you fill out a survey. You can add more computer programs later for a smaller fee. It's a one computer/one car ID device unlike the full open Unlimited version.
I'm not sure about the VAT killer but I believe the truck computers do not use that key off feature anymore like the LT1 computers did.

 

You can take a 6L block and add a 4.8 crank to it. Thats a 4" bore with a 3.267" stroke (101.6mm x 83mm). That would give you 328 cubic inches. You'd benefit from the higher revving short stroke and power from the larger bore. Add a set of diamond pistons and LS6 heads.