AMS and C02 setup

[sackracing]

Going to do some testing tonite, and I was trying to figure out what to set the C02 pressure at for a baseline. I have a 9 pound spring in the gate, and it actually makes about 6 or 7 pounds on spring alone. I was hoping to get it set up for around 20 pounds. The AMS stage 2 is set at 18.

 

[pacecarta]

if you are running wastegate mode the psi needs to be set at the desired boost less the springpressure
i would set controller at 9 and go from there

i run at 30psi on my Co2 ,
the higher the head pressure the more it will have to bleed away under boost controlling

 

[sackracing]

I was wondering if I need to deduct the spring pressure. You can't really get a straight answer out of NLR on it, they make it sound like it's trial and error, which it probably is.

I did find where they recommend 10-15 psi above target on the c02 regulator pressure, and I assume the spring pressure should be deducted from that as well.

 

[Blazer406]

I think it is trial and error. On the car I have played with, it wasn't 1:1. He has an 8 lb spring.... and if we set the AMS to 12 lb...... we didn't get 20 psi..... more like 16-17 in our case.....

I'm sure it varies by the size of the wastegate and the actual back pressure it sees in the exhaust......

 

[sackracing]

Thanks for the help

 

[kidglok]

i have an 8psi spring in mine right now, running manifold pressure with the controller on 1 stage set to 8psi, i get 20psi

 

[bison]

You need to baseline it to see where you are. If the engine has a lot of mass flow you will see that as you go up in boost it will take more and more pressure to overcome the ex pressure. An example is with a 70 gtq and the car is making 800hp@25psi using 10psi of CO2 depending on the spring. If you go up to 15psi you might get 28-29psi. It might take 35-40psi to get 32-33psi. Once you get to the end of the line on the wheels the pressure needed to make boost goes up drastically. Its because the ex pressure is climbing much faster than the intake pressure. Even though the ex pressure is climbing it may not be an ex side restriction. If the compressor and compressor housing arent working well together or there is some other inlet restriction the air will stack in the diffuser and create a huge amount of energy needed to drive the compressor and actually increase backpressure itself. Even if you dropped backpressure at that point by going to a larger housing you wont see power. What you will probably see is a boost drop off since you lost ex energy that was driving the turbine. If your not looking at running it for all its worth once you get your baseline you will be able to get the pressure you need fairly easily. If you go from a bad air day to a good air day you will need to adjust the CO2 pressure also.

 

[sackracing]

That makes sense. I'm just trying to get a baseline and I'm not going to throw the wood to it until the Nationals. I should have some data to work off of by then.