Vettedriver986

So Ive got a new forged 347 in my car... I have put only 541 miles on the new build. Now I realize before I throw big boost at it, I want to install LS9 gaskets and make sure the arp head studs are torqued as best as possible.

I dont have any issues right now, just want to have the best.

So my question is, after 541 miles will I need to resurface the heads or deck?

manley845

Well, after you take the engine apart and measure clearances of the surfaces, you can post them and we can offer answers.

vettenuts

Why do you feel the need to change gaskets? Did you do a re-torque on the current build?

Vettedriver986

I torqued them once... I just feel better with the ls9 gasket option. I dont want problems with this area because Ill be running 19 or 20 psi max on this turbo. Taking it all off to re torque is a Biotch, so I might as well change them. To re torque I need to remove fancy fuel system, and complete hot parts of turbo and the turbo it self. So might as well throw on ls9 gaskets.

I dont see why I would need to clean up the deck or mill the head, other than cleaning the two surfaces, but just wanted to see what you all thought.

Luv2Fly

You should be fine. Just measure them with a good machinists straight edge and feelers if you are picky.

AU N EGL

Leave it alone. Taking the heads off now could cause more trouble.

scott1974

I just had a set of heads surfaced. They were on the previous motor for about 2k mikes. It took removing .003 to get them flat.

Vettedriver986

should I just go another pass on the setup the way it is to make sure theyre torqued where I wanted them?

vettenuts

There is a method to re-tighten (re-torque) and it is not just making a pass at the final value.

quadman

Which heads are you using that will hold 19-20 psi without pushing water? Not a criticism, just a question.

Vettedriver986

317 heads, with ls2 GM MLS gaskets. ARP studs.

quadman

Wow, that's a lot of boost for those factory heads. I am not well-versed in FI applications, but from what I have heard, it may be a bit overly-optimistic to expect them to hold 19-20 psi.

Vettedriver986

well, enlighten me as to what in your opinion would be a high yet safe boost level with freshly milled heads and decked block with ls2 gaskets and arp studs torqued to 90 lbs?

I want to make above 700 wheel, so I feel that Ill need to run a decent amount of boost to do so.

Luv2Fly

You can make over 700 without 20 psi. Check the big dawg thread for some ideas on who uses what system and how much they put down. Great thread for what makes what.

Vettedriver986

how must boost would I need you think to run 800 rwhp? Also keep in mind I am using LS6 camshaft

Luv2Fly

Do you have the fuel system/flow for that much power?

quadman

700ish definitely do-able. 800 possible, but MUCH more $$$$, I think.
In either case, Luv2Fly raises a very valid point. You're going to need an upgraded fuel system for that much power.
These projects can go from $ to $$$$$ in a hurry. Just my opinion, I think 700 rwhp is more realistic without breaking the bank.

Vettedriver986

Ive already broken the bank... 34k when I bought the car, and about 57k in work to the car. Im past that point.

I actually have a pretty good fuel system setup. Not sure If I said that earlier.

Right now I have the stock pump in tanks, however I have A & A corvettes fuel system running secondary to the stock setup. I have the huge bosch pump which kicks on at 4psi, and a paxton boost referenced FPR which ups the pressure with every lb of boost.
In doing so I have also turned my returnless style fuel system into a return style. All new (larger) feed and return lines run. Lastly I installed a racetronix wiring harness to ensure that the pump in the tank always has ample voltage.

My limiting factor in fuel may very well be my 60 ln injectors, but I dont see why a 83 lb injector couldnt get me to 800 wheel. The question is what boost level will it take to do so, and is it true I can keep my cylinder pressure down by toying with the timing? In turn controlling whether or not I lift heads?

Also will be running dual nozzle meth setup.

Luv2Fly

Without knowing all the fine details 11-15 psi should get you 800. This depends on turbo size and trim, backpressure, compression ratio etc. I would get some upgraded heads if you are already into this build for so much. Some AFR or TFS or whatever you prefer. Also the 60lb injectors will not cut it.

quadman

Some good info there. I like the aftermarket heads. They have a thicker deck=less likely to push water.
We had a 370 single turbo on the dyno here. If I recall correctly, 12 psi, 317s, 697 rwhp. The tuner (edcmat-l1) was trying to get 700 out of it. It maxed at 697. Was mean, though..........lol.
Presently I am building a forged 402 for one of the local GTOs. 317s and SCR @ 9.4:1. It's gonna be a single turbo. The owner wants to run 15 psi eventually. Should be interesting to see how much we get out of it.