Bink, NoGo, anyone air/fuel change???
08-04-2004, 07:47 PM
#1
12 Second Truck Club
Thread Starter
Join Date: Oct 2002
Location: Salt Lake City, Utah
Posts: 1,678
Likes: 0
Received 0 Likes
on
0 Posts
Bink, NoGo, anyone air/fuel change??? OK,I have an ATI supercharger and recently, I upgraded my intercooler from a very restrictive one that didn't cool well at all to a BIG free flowing unit.
With no other changes I gained 5lb/min at 4000rpm steadily increasing to 11+ lb/min at redline. IAT's also were drastically reduced.
My air/fuel ratio went from 11.7-1 across the rpm range to 10.5-1 across the rpm range with just the intercooler change.
What would cause this? Does it have to do with increased VE from the better intercooler. I plan on adjusting pe/rpm to bring it back in line so it's no big deal. I'd just like to better understand the reason behind this.
With no other changes I gained 5lb/min at 4000rpm steadily increasing to 11+ lb/min at redline. IAT's also were drastically reduced.
My air/fuel ratio went from 11.7-1 across the rpm range to 10.5-1 across the rpm range with just the intercooler change.
What would cause this? Does it have to do with increased VE from the better intercooler. I plan on adjusting pe/rpm to bring it back in line so it's no big deal. I'd just like to better understand the reason behind this.
08-04-2004, 09:10 PM
#3
12 Second Truck Club
Thread Starter
Join Date: Oct 2002
Location: Salt Lake City, Utah
Posts: 1,678
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by Slowhawk
The best way to explain it is that with more boost pressure from the free flowing intercooler,the Mass air is reading more air which then adds more fuel.With that much boost I would only bring it up to 11-1 on the dyno and maybe add some timing.
I've changed pulleys before and airflow changes, and AFR stays the same. Same deal with weather and DA changes, airflow goes up and down, but AFR stays the same.
I have an onboard wideband.
08-04-2004, 10:44 PM
#4
Originally Posted by Black Blown 02
OK,I have an ATI supercharger and recently, I upgraded my intercooler from a very restrictive one that didn't cool well at all to a BIG free flowing unit.
With no other changes I gained 5lb/min at 4000rpm steadily increasing to 11+ lb/min at redline. IAT's also were drastically reduced.
My air/fuel ratio went from 11.7-1 across the rpm range to 10.5-1 across the rpm range with just the intercooler change.
What would cause this? Does it have to do with increased VE from the better intercooler. I plan on adjusting pe/rpm to bring it back in line so it's no big deal. I'd just like to better understand the reason behind this.
With no other changes I gained 5lb/min at 4000rpm steadily increasing to 11+ lb/min at redline. IAT's also were drastically reduced.
My air/fuel ratio went from 11.7-1 across the rpm range to 10.5-1 across the rpm range with just the intercooler change.
What would cause this? Does it have to do with increased VE from the better intercooler. I plan on adjusting pe/rpm to bring it back in line so it's no big deal. I'd just like to better understand the reason behind this.
By changing your intercooler to a better, free-flowing piece, you have made your system more efficient. Basically you have lowered what is called the Brake Specific Fuel Consumption of your setup.
Brake specific fuel consumption is the amount of fuel it takes for you to make 1 HP.
A BSFC of .6 means that it takes .6 lbs of fuel to make 1 HP. A typical forced induction setup will net you around .6 to .65 BSFC. A forced induction system of .6 BSFC is more efficient than a system with a BSFC of .65. Your motor now has to work less for it's horsepower.
Our PCM attempts to reach a target a/f at WOT (14.7 / PE). With the change in BSFC it now takes less fuel, as a function of air flow, to reach the same a/f ratio. By not reprogramming after the intercooler change you are still adding the same amount of fuel, per air flow, as you were adding earlier. Being it takes slightly less fuel to make the same HP you are now running slightly richer.
I hope that made sense.