openecu.org

Here's a question that is killing me and I can't seem to find a good answer for. I have a Cobb SF Short Ram intake that I have been running until I started some logging. I noted that my intake temperatures were getting pretty high. I am in Tucson, AZ but these were high even for here. I saw 143 degrees in stop and go traffic. 118 during mid day pulls at 100 degree temperature. I decided that I was going to put my modified stock intake box (with the resonator cut off) back in the car with a K&N filter to see if I noticed any significant difference in temperatures and I did note 2 differences. First, I noted that the Intake Temperature was a little more stable and about 3-5 degrees lower, but the airflow was 20-30 g/s lower than the Cobb values at similar load, temp, and RPM. This brought me to my question. Which is more important;

A) More air that is slightly warmer, or

B) less air that is slightly colder

I am going on the dyno for my Super 16G and Ported Exhaust Manifolds this saturday and I want to have my car set up for what's best for me. My tuner said that he didn't really know if one would be better than the other, but if he were me, that he'd run the Cobb since I have it. I am sure that there is an answer out there. I have had suggestions to Tune with the Cobb and reinstall the stock box during the summer months. Any help would be appreciated

Thanks

Matt

Modlist
Deadbolt Super 16G
STI Pinks
Walbro FP
X02 Turbo Inlet
X02 TMIC
MrJosh Lightened Pulley
Helix UP/Catted DP
Greddy EVO II Catback Exhaust
GrimmSpeed Ported/Coated Exhaust Manifolds W/ High Flow Crossover
ProDrive 3-Port Boost Solenoid

20-30 g/s is HUGE! You can probably feel that on the butt dyno if it is indeed reading correctly. That should be close to 20-30whp, again, if that reading is correct. FWIW, a 16G should probably hit about 270-280g/s on an accurate intake. That's 35-38 lbs/min off the top of my head, but you can figure it out if you want.

What you describe doesn't make sense to me. With a 16G the stock airbox shouldn't kill airflow that much unless the filter is really dirty. Can you confirm with a wideband that your AFR isn't going way leaner with the lower airflow? I'd bet it is.

I'd take 20-30g/s over 3-5 degrees any day of the week. But I think the difference in intake is just throwing the numbers off rather than there being a true airflow difference.

trd6209 wrote:... but the airflow was 20-30 g/s lower than the Cobb values at similar load, temp, and RPM.

That's not possible. Airflow (g/s) is a linear function of load (g/rev) and RPM. If load and RPM are the same, then airflow must be the same, regardless of temperature.