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View Full Version : sct , how much boost?



BryanRT360
01-23-2013, 06:54 PM
Now that my fuel system is up for it. I'm thinking about pulley ing down again. On the dyno with a 3.12" pulley it made 12#s. For the last year i have been running a 3.0 pulley. According to my gauge i see a good 14#s max.

So what will happen if I drop down a pulley size again? It will probably make 16#s ??

Fuel cut?

huskerrt79
01-23-2013, 07:07 PM
Are you going to retune it?

BryanRT360
01-23-2013, 07:12 PM
Are you going to retune it?

Pretty sure I'm running off the map, so no. Next upgrade is an air/water intercooler. I will get a retune at that point. But for now I can makes small adjustments by adjusting my fuel pressure.

huskerrt79
01-23-2013, 07:13 PM
Pretty sure I'm running off the map, so no. Next upgrade is an air/water intercooler. I will get a retune at that point. But for now I can makes small adjustments by adjusting my fuel pressure.

I made 17#s on the dyno last time and it was fine but It was retuned. Sorry cant help:idunno:

BluRT00
01-23-2013, 09:04 PM
I believe 2 bar resolution goes out the window around 16 psi. You will love a A/W setup trust me. Best money I spent and even with water running on the street seeing 8 psi on a 90 degree day have seen 94 IAT's. Throw in some ice and you can imagine the perks.

BryanRT360
01-23-2013, 09:12 PM
I believe 2 bar resolution goes out the window around 16 psi. You will love a A/W setup trust me. Best money I spent and even with water running on the street seeing 8 psi on a 90 degree day have seen 94 IAT's. Throw in some ice and you can imagine the perks.

Nice. :rockwoot: 90* ain't bad at all. I will be spraying meth along with the intercooler.

Crappy resolution is ok. Fuel cut is not. I probably won't see 16#s but if I have to spin the motor a few hundred more rpm to clear the traps it might..

BluRT00
01-23-2013, 09:16 PM
Nice. :rockwoot: 90* ain't bad at all. I will be spraying meth along with the intercooler.

Crappy resolution is ok. Fuel cut is not. I probably won't see 16#s but if I have to spin the motor a few hundred more rpm to clear the traps it might..

Sounds like a frosty combo! This gonna be on the truck when you come to the nats?

BryanRT360
01-23-2013, 09:17 PM
Sounds like a frosty combo! This gonna be on the truck when you come to the nats?

:-(

FlyinRyan
01-23-2013, 10:10 PM
I'd swap to a 2.25 bar map sensor if you're not running one already. 2 bar should max out at ~15 psi.

BryanRT360
01-23-2013, 10:13 PM
I'd swap to a 2.25 bar map sensor if you're not running one already. 2 bar should max out at ~15 psi.

What happens when my 2bar sees 15 psi?

Got a part #?

wyotech_cuda440
01-23-2013, 11:11 PM
What happens when my 2bar sees 15 psi?

Got a part #?

2 bar is good for 2 "atmosphere's" of pressure, the first being the regular atmospheric pressure of 14.7 PSI (theoretical perfect atmosphere at sea level) and 14.7 psi of boost added in.

"IF" the map is perfectly made and calibrated, being a basic 1-5v sensor, it "SHOULD" be at 5v exactly at 14.7 psi. If you go over 14.7 psi, it will stay at that same 5v, and your pcm will not have any signal to add more fuel. Obviously, there's a lot of variables and tolerances here, so I wouldn't try it without watching the A/F like a hawk.

You could bump up the fuel pressure a bit to keep it safe at the slightly higher boost if needed, but that would cause it to run richer at lower boost.

By tweaking tune, you should be able to bump up the fuel pressure, then lean out the lower RPM ranges to bring it back to happy, before richening it back up right at the MAPs 5v mark. This will give you a slight rich bump at 14.7 psi that will level back out by the max boost you tune for, and the rest of the rpm range will be tuned correctly.