Dtownbrown

Im currently Running 13psi in my twin turbo 99 c5, its currently making 722whp and Im wanting to go ahead and get closer to 900hp, My engine is a ls2 bored to a 408 stroker with the Lq9 heads, it is studded and torqued to around 90ft lbs, So my queston is how much boost could I safely run before I have to worry about lifting the heads, Im hoping to be able to atleast get 18psi safely. Im also spraying meth. And my CR should be around 9:1.

Mods-
408ci stroker / 4340 eagle crank, Eagle H beam rods, JE custom turbo pistons, Reverse split turbo cam,
RSI twin walbro 255 fuel system
82# injectors
HPP twin turbo kit w/ prescision billet wheel 62's
Twin nozzle methanol Injection
Ls6 intake w/ stock throttle body

Y2KRoadster

What gaskets are you using? Heck, even with the stock GM, with those head studs, you should have no problems with 18 psi.

If you are running the LS9 gasket...you will be able to handle more than that!

Dtownbrown

I honestly cannot remember what brand gaskets im using, All i know is that they are steal gaskets. Maybe cometic?

user_name

You are probably not going to have issues with 18psi. Detonation is what usually lifts the heads under 1000rwhp imo unless the heads have some thin spots.

Y2KRoadster

Thin spots? As in, if they have been milled down and they were milled too much?

user_name

That will do it, but also just the way they are cast. Some heads, such as ls3's, have some thinner spots on the deck and don't clamp as well.

Turbo-Geist

Boost is not what lifts heads. On a leakdown test, I put 100 psi into each cylinder. The heads haven't lifted yet.

Y2KRoadster

Ahh ok...your LS3 comment jogged my memory...I remember hearing about the deck on them being kinda thin.

Chris Stewart

I've run 26psi on 4 bolt heads with 5/8 deck, and 9.25 compression. ARP studs at about 80 ft-lb. Stock GM MLS LS1 gaskets. No water pushed.

Dtownbrown

How much power did you make with 26psi?

Chris Stewart

1K at the wheels