how much boost on 91 octane

Ok my question is. I'm running 18psi right now. I have a 60 trim 2g ported manifold and o2 housing. hard piped ic piping an 18" spearco intercooler 255 pump and 550 rc injectors 2g mas safc. the block and head are stock and I was wonting to know if it would be safe to run more boost lets say 20-24psi? I know I can hold 18psi but I was told on stock internals that you dont want to run more then that.
thanks
409/2000
serving daily driver duties /ubbthreads/images/graemlins/cool.gif

 

[Brianawd]

When it starts Knocking more then 3counts on a pocket logger then its to much on pump.

 

[mooserage]

Yep, for your setup, just use knock as a reference and go up slowly, dont start at 30psi and work back down /ubbthreads/images/graemlins/cool.gif

 

On cali 91 I am running 25psi on a 37r.

 

cool thanks guys 25psi damn lol /ubbthreads/images/graemlins/shocked.gif

409/2000

 

You can run just about as much boost as you want. You will need to make timing and fuel changes. So you will get to a point of diminishing returns for boost.

Example.
I can run more timing at 20psi than I can at 25psi. If running more timing will net the same HP and TQ as 25psi then I should only run 20psi. There is no point in putting the extra stress on the parts if you are making the same power at a lower PSI.

Also for me for every 1psi, I pickup about 10hp and 10tq. Now you can normally get that from running 1 more degree of timing and leaner ARF's. So the moral of the story, is you are going to have to play with your tune and figure out what your car likes.

When I was tuning Q16 last weekend I did over 30 pulls at 30psi. So that I could get it super dialed in, and make as much power as possible and run as much timing as possible. I played with timing in the low, mid, and top end. Now that I am done with that, I can crank the boost up to 40psi and see what happens /ubbthreads/images/graemlins/smile.gif.

 

[Specter]

^^Could you post a video of your car (driver view) while doing some pulls? /ubbthreads/images/graemlins/grin.gif

 

Quoting 409GRV4:
I know I can hold 18psi but I was told on stock internals that you dont want to run more then that.



The stock internals aren't the problem. Its the poor knock resistance of 91 octane. What are you using for fuel management? You will need to pull a lot of timing and get bigger injectors to do much over 20psi.

 

Quoting Specter:
^^Could you post a video of your car (driver view) while doing some pulls? /ubbthreads/images/graemlins/grin.gif



Ya, I am going to post up some videos on how to street tune your car soon enough.

For anyone else that wants to look at a pump gas map for a 37r and a q16 map here is a link:
http://forum.aempower.com/forum/index.php/topic,26131.0.html

Pump gas car is 508hp/344tq, still needs a lot of timing but got excited and switched to Q16 for a while /ubbthreads/images/graemlins/smile.gif.

That link has Log files and my maps for 22psi, 25psi, on Cali 91 pump and 29-30psi Q16. On q16 the car is at about 600whp and 450tq. So I still need to do a little tweaking, however I have maxed out my Bosch 044.

 

I have a safc and 550cc injectors 2g mas kinda basic.

409/2000

 

[Dialcaliper]

Also keep in mind that you can get away with a surprising amount of boost on the stock pistons because of the lower CR (7.8:1) You should be fine in the low-mid 20's with a small turbo. Anything higher will probably require a very large intercooler to bring the heat down (or water injection). A larger turbo would help too.

The main problem is high intake temperatures, made worse by turbos run outside of their ideal efficiency range. Keep the temperatures down and you can make usable power well up into the high 20's, maybe even low 30's, even on 91 octane. Most often, people either use more intercooler than is required, or one that is too small. Balance is key.

With that turbo and intercooler setup, you'll probably run out of fuel and run lean on those 550's before you need to worry about boost vs timing.

After you get the kinks worked out of that setup, your next investments should be a chip to go with the AFC and larger injectors.

 

IT has a tecknomotive chip setup for 550cc 5k6k7k launch 8k rev limit no lift to shift 2g mas.