Plans for LS3 rebuild

[Ravener]

Hi Guys, so I'm still sitting on my hands waiting for the verdict from the machine shop regarding forensics on my poor LS3 . Paying for a rental for weeks on end...hurts like hell.

Whatever the outcome, I need to think about next steps. I've been mulling over a 418 stroker build given that the whole damn thing is apart anyways...seems like a good excuse to do some heavy modification. Another thought is that I should just get it back together with a blower cam and think about going the whipple route. The thought of continuously sinking money into this thing irks the hell out of me. For pure cost effectiveness it's hard to gauge as a well built 418 can tangle with 600ish hp...and a SC can achieve the same.

Thoughts?

[thahemp]

I think you're going to need a high CR 418 to get anywhere close to 600 RWHP N/A. I'd be curious to know what combinations of pistons and milling people have done to get there.

[litle88]

NA will require those TFs heads, a well built 416, fast 102/102, -xx valve relieved pistons for a nice big cam.

On a mustang dyno I'm 545 on a dyno jet about ~595 with my set up. I'd have more if I could afford those tfs's lol.

[litle88]

What happened to your engine?

[thahemp]

Originally Posted by litle88

NA will require those TFs heads, a well built 416, fast 102/102, -xx valve relieved pistons for a nice big cam.

On a mustang dyno I'm 545 on a dyno jet about ~595 with my set up. I'd have more if I could afford those tfs's lol.

Did you put in -xx dished pistons or did you flycut the pistons? Let's say someone wanted to get around 12.5:1 CR. The 4" stroke gets you quite a ways. Where do you get the extra compression if you mill 0.0xx from the heads, then turn around and take 10cc out of the piston for PTV clearance? We need more details Mr. high CR! I have been pondering this lately too OP.

[litle88]

Lol well there's 2 compressions dynamic and static.

To achieve your desired compression you have to pick a piston and cam together as a whole.

With my 4.0 stroke and 65cc chambers and GM Mls gaskets and -2 cc valve reliefs and 4.0705 bore I have a 12 to one.
You can't go as far as -10 that's more of a dished piston for FI.

[KCS]

Originally Posted by thahemp

Did you put in -xx dished pistons or did you flycut the pistons? Let's say someone wanted to get around 12.5:1 CR. The 4" stroke gets you quite a ways. Where do you get the extra compression if you mill 0.0xx from the heads, then turn around and take 10cc out of the piston for PTV clearance? We need more details Mr. high CR! I have been pondering this lately too OP.

For 12.5:1, you would could run something like Wiseco's K448X7
5cc domed piston and just cut a little off the deck of the heads.

[Ravener]

My engine is apart after the "lifter fiasco" referenced in my other threads. Still an ongoing headache. Car has been apart for 3 weeks...I'm still waiting to get word on condition of block and an idea as to why things failed. I've seen some of the more robust 416/418 builds noted for having 620/585...though spending the coin for the uber heads and intakes may be a bit down the line in the future. Maybe it's better to go the FI route and be content for now.

[thahemp]

Originally Posted by KCS

For 12.5:1, you would could run something like Wiseco's K448X7
5cc domed piston and just cut a little off the deck of the heads.

I guess I had never looked at pics of the domed pistons. They're valve-relieved too. Cool. That clears some stuff up in my head. Thanks.

[thahemp]

Originally Posted by Ravener

My engine is apart after the "lifter fiasco" referenced in my other threads. Still an ongoing headache. Car has been apart for 3 weeks...I'm still waiting to get word on condition of block and an idea as to why things failed. I've seen some of the more robust 416/418 builds noted for having 620/585...though spending the coin for the uber heads and intakes may be a bit down the line in the future. Maybe it's better to go the FI route and be content for now.

Nah don't give up! That's why I was asking those questions. A little head milling and domed pistons is no big deal. Pretty sure litle is right around 12.5:1... that's why I chose that example .

[litle88]

I said -xx because there are lots of possibilities you can go with. But not that drastic. With my -2cc I still had lots of Ptv clearance and I knew I should if gone bigger.
Here's a pic for reference

[thahemp]

Yup. There's 2 more quarters worth! You must have gone home instead of big that day.

[litle88]

Lol
Here's a good place to get info.
http://www.wallaceracing.com/cr_test2.php

[litle88]

Originally Posted by Ravener

My engine is apart after the "lifter fiasco" referenced in my other threads. Still an ongoing headache. Car has been apart for 3 weeks...I'm still waiting to get word on condition of block and an idea as to why things failed. I've seen some of the more robust 416/418 builds noted for having 620/585...though spending the coin for the uber heads and intakes may be a bit down the line in the future. Maybe it's better to go the FI route and be content for now.

Yea I remember now!

Next time use morel/lunati lifters bud along with more phosphate/zinc in your oil. Good set of BTR springs set up correctly and correctly measures pushrods. Not that you didn't do it the first time. But I hope it turns out better bud.