How much is good air worth?

[Rat Raceway]

Look into getting a speed density tune like Ed said. Hands down the best setup for racing applications. No reason to even have the O2's on board IMO.

I would kill to run in air like that.

Good run!

[art leong]

Originally Posted by Rat Raceway

Look into getting a speed density tune like Ed said. Hands down the best setup for racing applications. No reason to even have the O2's on board IMO.

I would kill to run in air like that.

Good run!

Doesn't speed density mean closed loop? Then it would need the sensors.
Alfa N is open loop ( I think ) Sensors are just for data logging.

[Ed Wright]

MAF sensor mode, Speed Density, and AlphaN can all be open or closed loop. With a Pure Stocker, I would certainly leave the MAF on it. I don't think it would be legal to remove it, would it. At least the original Pure Stock rules would not allow it. This new "pure stock " ain't really purely stock. May be legal now? I don't know.
Anyway, if you know how, you can stop long term fuel trims from effecting WOT fueling.

Do you guys run open headers? You most certainly don't want closed loop, with a factory computer, with open headers.

Thanks guys for your comments.

No Ed ... open headers are illegal. We can run the OEM exhaust manifolds open with no mufflers but if you run headers you must run mufflers. We run 1 & 7/8" American Racing Headers, an off-road X-pipe with no cats, and GM C5 Z06 titanium cat-back mufflers.

As far as the MAF I believe that has to be present as well. When you guys talk about open and closed loop, etc. I'm not sure what you're talking about. We get our tunes from Stephen Covington in Longview, Texas at East Texas Muscle Cars. He seems very knowledgable and takes him time tuning the car on the dyno and on the street when we go. The times and consistency that the car runs have been pleasing to us.

So just buy two new ones and replace them?

Scott

[Ed Wright]

Leaded fuel is hard on them. If you run race gas just have him put in in open loop, and shut off the codes. If you use unleaded fuel, I would wonder why they failed. They typically last over 100,000 miles.

[RacingRicki]

Originally Posted by Tar Heel

When you guys talk about open and closed loop, etc. I'm not sure what you're talking about. We get our tunes from Stephen Covington in Longview, Texas at East Texas Muscle Cars. He seems very knowledgable and takes him time tuning the car on the dyno and on the street when we go. The times and consistency that the car runs have been pleasing to us.

Open/closed loop is referring to whether or not corrections are being made in real time. If you run in closed loop, corrections based on O2 sensors, air temp, water temp, MAP sensor, etc. will be applied. These corrections are normally programmed in the ECU.

If you run open loop, you will just get the same amount of fuel no matter what the conditions are (except for maybe some factory programmed corrections).

[Ed Wright]

He runs a factory computer which does not make WOT air/fuel corrections unless something makes it "think" it is lean at idle & part throttle. If it sees (or "thinks" it sees lean conditions causing positive fuel trims it will, after a short time, add the same percentage of fuel at WOT it was adding at part throttle. That will, of course , cause over rich conditions racing. If he can run quicker after resetting the computer he has that problem. If so, he can pm me and I will tell him a simple way to cure it with a small jumper. :-)
A quick way to reset it's memory also.

We don't run leaded racing gas; only unleaded fuel. I've always used 93 octane from the gas station but the last time we were at the track (before this race) we put 5 gallons of a higher octane unleaded gas that the track was selling. I'm wondering if they gave me leaded fuel accidently.

[Ed Wright]

It would take longer than a day for lead to hurt the O2s.

[Todd Geisler]

Originally Posted by Ed Wright

It would take longer than a day for lead to hurt the O2s.

I used a wide band o2 system with my data logger for 3 or 4 seasons. Removed it and sold it to a friend, still being used today with the same sensor and lead racing fuel the entire time.