I already know I'm going to get a lot of use the search replies for this, but I already have used the search and can't get a direct answer to my question. So here's the background and question.

I have an ls6 shortblock gapped for N2O but with stock pistons, crank and rods. I plan on going turbo when I eventually drop the motor in. I currently have a set of 243s that I planned on using but I am secondguessing my decision to use due to the 10.5:1 compression they produce. What I want to know is basically how much boost can I reliably put on a near stock ls6? This is so I can decide whether to stick with the 243s or get some 317s.
My second question is how much more boost can I run on the same block with 317s?
Also, would meth injection be a viable option to keep my 243s? Maybe run 6-7psi most of the time but turn the boost up and the meth on when I need it?
My power goals are 550 to 600ish rwhp. I want to daily drive it as well.
Thanks for all the help.
-Ryan

 

you could throw 6psi on it, just keep the timing down. it wont be ideal, but it will let you try out the setup and work out the bugs before the new motor.

 

Anybody else got any advice? Would really like to run 7-8lbs on 93 octane. If I can't with the 243s I'm gonna buy some 317s.

 

I am in the same boat as you I started a thread title procharger newb u might find some info there especially bobs last post stating ls2 run 8 psi all day and they r at 10.9:1 so I would run them Im currently at 10.75:1 and plan on running 8 psi hope this helps

 

I would get some 317 then you have more of a safety margin, you can get a nice set off ebay or craigslist for around $200 a pair, they flow just as good as the 243. 243 would probably be ok too but its nice to be as safe as possible on pump gas and the 243 will not get you anything over the 317 other than worry.

 

I have a set of 317s... pm me if interested.

 

I have found for longevity, 500ish RWHP is a safe number (IF tuned correctly). I am not saying you cannot make more, but the ones Ive seen above that in the range you want to be don't last long..

 

My setup has a 125,000 mile stock bottom end ls1 that made 444 rwhp before I did the turbo. I'm at 11:1 compression and 8.7:1 dcr which is really high. I'm running pump gas / alky control setup on 8lbs of boost with a tc76 turbo. I did just get the setup running but I've hit 12lbs in 4th gear (not on purpose wastegate too small) and have no issues yet. It's all in the tune. Keep the timing low, afr in line and it will live... for a while

I tuned my friends cam only ls1 (stock 241s) Trex GTO with a D1SC procharger around 9-12 lbs of using pump / meth. This car ran good all summer, good enough to put a 4000lb raceweight at a 10.79 @ 128mph in a 6 speed gto @ 2500' elevation. You will rely heavily on the meth at these levels.

 

keep the 243s and just get a good meth kit. itll be fine under at about 10psi and under if you have a good tune, over 10psi will really start to depend on how good your tune is. make sure you have a good enough fuel system too.

if your sticking to around 500whp youll be fine a with a walbro255 or the new aeromotive stealth pump, hotwire kit, 60lb injectors, and boost referenced fuel pressure regulator but closer to 600whp youll want to add another pump and bigger injectors down the line.

if you have all this then you could realistically skip the meth too, but there is no downside to meth imo so i dont see why not

 

Thanks for all the advice guys. I am leaning towards a meth kit. If I feel like I need more than 8psi, I'll swap on some 317 heads. Highly doubt it though. This setup is going in a 240sx that should be under 3k pounds when complete.
Quick question for you guys with meth kits. How much meth do you use between fill ups? I mean, does the resevoir hold enough to where I only have to refill it when I refill the gas tank?