james007moore

I am looking for opinions about using NOS (dry) to oxygenate the thin air here in Denver. My car was built, tuned and raced on the east coast near sea level, Now I am living in the mile high city.. I have NOT had my car at the track yet and I will certainly need to make some adjustments to the tune. But since my car is supercharged I was thinking of spraying a calculated amount of dry nitrous via a fogger nozzel plumbed into the intake tube after the super charger and before the intake air temp sensor. I am thinking that this will help by cooling the air from the charger AND also making the air more dense and more oxygen rich.

Injuneer

Would work, but why not just pulley up the S/C?

james007moore

Hey Injuneer how are you doing Sir? I was thinking that if i simply increase the boost that I would still be dealing with the same issue (higher intake air temps and less VE due to the thin air)

Injuneer

Maybe do both. You lost 20% of the HP due to the elevation. It would seem that spinning the blower faster (depending on the flow curves) would bring the air density back to where it was at sea level. Yes, the fact you are increasing the compression ratio across the S/C may increase the discharge temp. I think you would need to look at the curves, or ask ATI what they recommend. What kind of boost are you seeing in Denver?

james007moore

I havent run it yet here in Denver so I am not sure what the boost level is, I have a few other issues to work out before I can really lean on it and see. When you talk about "the curves" I am not sure what you mean, can you explain?

thanks

Injuneer

The compressor has a set of operating curves (or a "map"), showing flow vs pressure ratio, and the efficiency at each operating point. I believe a centrifugal S/C will flow the same CFM at a given RPM, but the compressed density is going to drop because the density is less at the inlet, due to altitude. So you increase the RPM too increase the flow and the pressure at the outlet to increase air density.

The big problem with compressing air (or any gas) is that there is a temperature increase as part of the process (you can't avoid it), and then an additional temperature increase due to compressor efficiency. You have to keep the compressor operating where it is most efficient, to minimize the air temperature gain.

It gets complex, so a call to ATI may be in order, or post the question on the Forced Induction forum. You are more likely to get someone who can answer your question, with regard to the relative benefit of increasing the blower RPM, vs. adding the N2O. The Forced Induction forum still seems to have a core of hard-core S/C users, willing to help.

This is a Vortech map, but you will find something similar for the procharger.

james007moore

Thanks very much for that..I never knew that and it is very GOOD info..

I will read up on that and see what I come up with..

Thanks again, You are always so helpful and knowledgeable (seriously).