filmjay

Hi all. I'm at a bit of a wall with the math, so I gotta ask for some more educated opinions on the next mod.

What I have so far...

-Stock LS3 shortblock & heads.
-Paxton SL1500 SC @ 8psi (ECS SC600 kit)
-228/232 cam, .625, 113*

...and a few other CR irrelevant things. Which brings me to my questions...

A meth kit is definitely next on the "to do" list, but I'm thinking about what's next after that.

I'm considering either decking the heads .020 to not have to flycut the pistons and bump CR. OR swapping out to 1.8 quicklift or YT 1.85 rockers for more valve lift.

I have .675 lift dual springs, but the cam is already lifting to .625 so I'm concerned with overdoing it with the rockers and slapping the pistons with the valves.
And since I'm already boosted, I don't really want to stray into a higher CR since I'd like to keep it on pump 93. (iirc it's pushing 11.5 already)

Any advice either way?

Thanks.

camarols1

iTrader: (17)

The 1.85 rockers will put you at .680 lift, so that is out.
FYI - Valve events like tight LSA cams with large durations are what cause PTV issues. Valve lift has practically nothing to do with it.
I would bet your cam is nowhere near hitting the pistons.
Taking the engine apart to mill the already thin deck heads is not a good bang for the buck. You want the deck as thick as possible for a FI build.

I would advise just getting a smaller blower pulley to turn up up the boost for a good bump in power, and get a meth kit for insurance on pump 93.

Good luck!

filmjay

Thanks for the reply.

The 1.85's are out...what about 1.8's? And I notice there's some new 1.72's available....

What's the formula for figuring the ratio vs. added lift?..I can just figure it all myself instead of bothering anyone.
Plus, I figured just a .010 or .020 deck would still leave enough material in the heads since I'm not running insane boost. But after reading up on the topic a little closer, I'd tend to agree and will probably leave the decks alone for the stock heads under FI.

Though I am still wanting to port the runners, polish the chambers, back cut valves, etc... just assemble a stock head with better components. I've got everything in but valves/seats, and am still using the stock rockers. I wanted to upgrade the rockers as well, but just couldn't stand to simply replace the stock ratios.

someday

1st, figuring the lift is easy, divide ur lift by the stock ratio, then multiply by the new ratio... 2nd, with a SC, u want less compression, not more, so u can run more boost, and u want less overlap so ur not blowing the boost out the exhaust, i'd change the cam to something like a 218/232 on a 115LSA, and pulley for 8lbs, and check for knock retard... last, u should have the heads ported and lower the compression closer to 10:1, then u could run maybe 10lbs of boost for even more power...

Randy@RaginRacin

iTrader: (4)

Jay the lobes of the cam are fairly aggressive and I would not use a 1.8 rocker ratio with them, nor would I mill the heads. I would definately add the meth kit and then add a real fuel system to the car vs the KB BAP we are running. Then lets forge the motor and add a 8-rib system and pump up the boost. This would get to 700+ rwhp easily.

filmjay

Thanks guys.
Shawn, I thought I'd heard you mention it once, but got no sort of cam card so I wasn't sure about the lobes.
I was just asking about head work/component changes as I plan on taking the advice of head gaskets/studs shortly and figured "hmmm, the heads will already be off..."

Meth is definitely the next item on the list as soon as I can get rid of these other 63# injectors and Callaway CAI.
I ordered a set of boost/fuel pressure gauges, and I've most certainly got an eye on a nice Aeromotive fuel system. A forged shortblock/8-rib will be a while though...not sure I want to go for those levels just yet on the stock rear and A6.

Thanks again for the info.