My Tuner at Xtreme Motorsports thinks I should go no higher than 9psi on Methanol. I'd really like to crank it up to 12psi. He wasn't getting any issue with it running around that psi but he said since I have the high compression LQ4 that I should stick with 9psi.

On the other hand, I've heard many of you out here say "go as high as you can go without knockin/pinging/etc".

It seems there isn't a perfect equation or answer to "how much boost can I really run without smoking the motor?"...

 

Ive been running 12 psi on my LQ9 which has higher compression than your motor and its been running like a champ for 20k miles now. But your turbo will stress things out a little more than the blower i have, just because you are gonna see 12lbs a lot longer than I see it. But Try it out and make sure you dont ping and that your IATs and EGTs arent too high and you should be ok. Id get a wideband too if you really want to push it if you dont already have one.

 

Well, my opinion is that if you aren't with concerned with reliability then go for it. If you are thinking about 12 psi then I'd say you fit into that category. Go as high as you can just don't be surprised/pissed if something can't take it. I think at 12 you might want to think about ARP head bolts/studs.

Personally, I'm pretty happy at 8.5 psi because I feel the truck is still driveable cross country if I so desired. Sure, I'd like more but I just like that I don't have to sweat it so much. I drive the H2 daily and don't want the inconvenience of down time.

 

I've got 11psi, but, it's a whipple not an sts

 

Weedo,

You've got the two step boost controller, right? So most of the time your driving around in the low boost setting, 5-6 pounds. I think you would be find to have your high boost set at 12 for the occasional romp around town or trip to the strip. Just make sure you spraying enough meth to handle it. That's about what I'm shooting for on my 4.8, but I have an intercooler and no meth, yet.

 

I ran 12psi on the LQ9 -- not religously and not very long (temps canceled out the benefits).

Try it and see if you can pull it off.

 

Hmmm, didn't think about that. So the temps got to high which made 12psi not worth it? Was that running Meth which should cool it?

kbracing96 - Yep, I have the 5psi/9psi settings. I've never run the 5psi setting (well, ok, once on the dyno and once on the street). I don't see any reason for it. The Meth lasts so long as it is I really don't need the 5psi setting. Most of my driving doesn't see above 4psi unless I'm getting on it which keeps me out of the Meth.

Right now I'm "tuned" for both settings. In other words, at 5psi I'm running a hair lean; at 9psi, I'm running too rich (10.9). I'm thinking about forgetting about the 5psi setting all together and tuning it better at the 9psi setting.

470awhp and 525awtq just isn't enough!

 

Yes, I was running meth and no FMIC at the time. Once you hit those boosts, you'll be seeing close to 190-200* IATs which pulls a bunch of timing, etc.

I ended up at 10psi, which produced more managable IATs.

The only way you'll know is to try, though. My compression was higher than yours (a little anyway )

 

I would invest in a FMIC before trying that amount of boost. You will put quite a bit more stress on the motor and may not see much more power due to the higher IAT's as TurboBerserker mentioned. Do you have logging software? I would do some logs of your IAT's before running that kind of boost on a day to day basis.
I got my OBX FMIC for $250 and $35 shipping. Stainless pipe was a little over $200 I think, but I should have quite a bit left over. I think I spent a little under $100 for high temp silicone couplers and T bar clamps.
Now if I could only put it together

 

I agree with Greentahoe and woudl get a FMIC before you even think about turning up that boost. You should be able to run 12psi with that LQ4 in there. I ran 11psi in my 4.8 eveyday it had the radix on it. But it was intercooled. You would be all set with a FMIC and your Meth injection.