jpierson77

iTrader: (3)

Need a little help, Im trying to get to a max boost of 24-25 psi holding at 18. I just cant seem to get there with what I am trying in ecufash. I tried upping the passive solenoid to 100%, increasing the BTEL, and all i can get out of evoscan is 18 psi, my boost guage gets closer to 20 psi but not over. What have you guys tried that worked. I do have a stock boost pill is this my major problem. I would really like to firgure this out as it is nice not having part throttle oveboost problems like when I had my MBC. Tried searching the forum but all I come up with is info on previous years.

BigT

iTrader: (8)

Download Gunzo's 93OctIntExh map and use his boost tables. They netted me a peak of 25psi and it dropped to 18 by 7k.

jpierson77

iTrader: (3)

Tried this holds boost to 15-16 but still only 18psi peak on evoscan 20ish on my boost guage. Ill look to make sure I copied all of the boost tables.

gunzo

iTrader: (2)

you're in colorado.. you're at 6000+' elevation ?? .. thats the max boost your turbo can give you at that altitude

you do NOT want to go 25 psi at 6000+' ...

And don't thank me .. thank LAXGSR for his maths

BigT

iTrader: (8)

Even with a boost pill or 3 port?

LaXGSR

Ya if you are at high elevation, you definitely don't want to go to 25 psi. Here's the math that I sent to gunzo

To your turbo, pressure ratio is what matters. Pressure Ratio = (Relative boost + atmospheric pressure) / atmosphere pressure.

At sea level (atmospheric pressure of 14.7 psi), if you run 25 psi, you get:
Pressure Ratio = (25 + 14.7) / 14. 7 = 39.7 / 14.7 = 2.7 pressure ratio

At 5000-6000 feet elevation, atmostpheric pressure is roughly 12 psi, so for pressure ratio, we get:
Pressure Ratio = (X + 12) / 12.

So at high elevation, if we also want to run the same pressure ratio, let's see what PSI we can run:
2.7 = (X+12) / 12
2.7*12 = X+12
X = 2.7*12 - 12
X = 20.4 psi

So...your turbo is working just as hard running 20.4 psi at 5000 feet elevation as someone else's turbo running 25 psi at sea level. With that said, you still should be able to run a bit over 20 psi without exceeding the turbo' efficiency too much. I would not try to run more than 23-24 psi peak, with boost quickly dropping once you hit peak. If someone has a compressor map for the stock turbo, please share!

BTW, in case you're wondering, the reason you don't want to run too high of a pressure ratio is that as you exceed the turbo's most efficient range, the turbo will just blow hot air and you may actually lose power. Your turbo also won't be happy if it's constantly being overworked.

gunzo

iTrader: (2)

You can increase the boost using these things ..

But 6000' with stock solenoids and pills .. you will probably get around 22-23 psi max ..

There might be other reasons he's not getting the boost he wants too .. so it really depends on the setup

jpierson77

iTrader: (3)

Makes perfect sense never thought of it in that way. I have always tried to just get back the 2.7 psi my elevation takes from me. I am actually at 4900 ft I did have the car running 25 psi dropping quickly to 20 or so the butt dyno said the car ran well. But the 93 oct map pulls very well as well. Why though if that map is setup to run 24-25 is my car not getting there? I suppose because of altitude I'm never getting to the load cells that would drive it to the 24-25 mark?

jpierson77

iTrader: (3)

Am I wrong in my thinking tthat to raise boost passive duty cycle and Btel need to be raised or is there some other caveat I'm missing?

jpierson77

iTrader: (3)

When I did try the 93 oct map I did keepthe stock fuel and timing maps to be safe as I have been getting 1-2 counts of knock from time to time. Thinking this is possibly due to my external dump hitting a heatshield. Once I fix this I'll try the 93 map fuel and timing to see what I get. I wouldn't think this would hold the boost back 5-7 psi though right?

LaXGSR

The BTEL and reactive/passive WGDC tables are what drives how much boost your car will run. That in turn, dictates what load cells it will hit. If you have everything maxed out, that is the most your car will run. I would not recommend maxing it out for the long term though. At 5000 feet, your car should be able to hit at least 22-23 psi. You will have a hard time imo hitting 25 psi efficiently at that altitude. Not sure why you can only hit 20 psi though.

jpierson77

iTrader: (3)

Well seems im on the right track as far trying to get the boos to come up. I would think that with a full tbe (no cat) 4" fmic, intake and cooler piping the thing would flow better, the last thing I expected was to have a problem getting the boost to come up.

LaXGSR

If boost won't come up, I would highly suspect a boost leak. Check the intercooler pipe connections especially - too loose or too tight can cause leaks.

jpierson77

iTrader: (3)

I'll check the piping. Got to thinking late last night I had the NBC on when I put a forge actuator in, thinking maybe I just have that set too soft. Thanks for the help everyone.