I have a question....

If A/F ratio is measured on a dyno and tuned for a specific value (12/1 or 14/1 or whatever) then when cruising on the freeway at a high rate of speed, can the engine get more air than is expected and therefor have a different (possibly lean) condition that couldn't be simulated on the dyno? I don't think there are a lot of fans you could set in front of a dyno that can blow at 140mph.

Sorry if this is an ignorant question. It is just that most people seem to tout "more air more fuel=more power"....and that is their reason for CAI etc, so if CAI really delivers more air, how can the engine make use of it without running lean? Okay, I've asked more than enough questions.

Damn, tuning my 1971 Chevy Camaro was easy, this fuel injection/ECU crap is tricky. Wish I could just put a big holly carb on top of the intake..tose are so easy to tune j/k

Gonna post this on another board as well, the more responses the better...

 

carbs ahhhhh!!! i hate jets.....tuning my motorcycle was a PITA.

I would imagine that the A/F won't change too drastically while driving to warrant any concern. If you are concerned get a A/F ratio gauge. I'm going to eventually get it even though I'm N/A.

 

Mikestro,

On several cars now I have always had some dyno tuning done and then finished the car on the track. We have found better results both in terms of power and driveability when we have refined on the street.

Just my 2 cents....

Mike

 

just noticed, mike, mike (my alias), and mike. hah

 

Tuning on a dyno vs WOT on the street you have to worry about the weight of the drums vs weight of the car. If the dyno you are tuning on has drums weighing less than your car then you will tune with engine seeing less load than on the street. If the dyno has more weight then you should be tuned for worst case on the street.

Cruising on the highway you are not at WOT and the engine well under max load. And most places don't tune partial throttle when they tune on the dyno.

Also at WOT the computer is in Open Loop operations, not reading the O2's it's using Lookup Tables to figure out the AF ratio(stock Narrowband O2's are terrible reading anything but 14.7 AF the error is huge at 13:1 and only gets worst further away you go from 14.7 ), cruising it's in Closed Loop and the feed back from the O2's will keep the AF set at the desired level.