Idle AFR what do you want?

[Skydog]

I thought 12.0 but looks like lots of guys running like 14-15??

Thank you Skydog

 

[TWIN TURBO]

Idle : 13.5:1
Cruise: 13:1 No Boost
WOT: 11.7:1

 

[tko47]

don't know why but when I start the sled cold 13.5-14 , cruising 11-12.5 wot 13.5 but when warm the afr at idle 16+ so I guess I just shut it off after a short cooldown??... Apex w/MPI stage II 15psi with that GEMS controller

 

[gsxr]

bov or not ?

 

[rxrider]

I though so as well - was at 12.3-12.7 idle on a warm motor, way too fat down low. If I my brain works, I remember Ted Jannetty said to have idle AFRs at 14.5 with a transition to 13.5 at slow cruising tapering down to 11.8-12.0 at 10 lbs or higher.

 

[lakercr]

I though so as well - was at 12.3-12.7 idle on a warm motor, way too fat down low. If I my brain works, I remember Ted Jannetty said to have idle AFRs at 14.5 with a transition to 13.5 at slow cruising tapering down to 11.8-12.0 at 10 lbs or higher.

I would agree with this.

 

[tko47]

no BOV , I don't know what to do half say put one on the half say no, apparently what MPI says that boost spikes will not hurt their blowers only the turbos, I'm not blowing the throttle bodies or cooler off any more since I glued and anchored, but when you release it spikes to almost 25 psi my stage 1 only spiked to 17

 

[Colorado Yamaha]

03 RX-1 Mtn with S/C Stage 1 at 10 lbs. - 14.5 at idle (cold) runs 13.5 to 14 crusing the packed trail and WOT runs I'll get 12.5 to 13 (mostly 13.0). The above ~~ I just replaced my sensor and ran it this weekend but it was pretty warm at about 30+ degrees at 11.6k feet.

My sensor was down for about 5 rides, but last season I got pretty much the exact same. I did see some lower WOT's in the 12's.

Do the Apex's run in the 12's all through the throttle range? (stock) or if the you Stage 1 do you use the controller to lean it out? Derek

 

[woodsrider]

At zero boost your sled, in essence, is naturally aspirated. Therefore 14.5.

 

[HAMMER]

Short version:

"In most cases the target wide open throttle A/F ratio for naturally aspirated engines will be between 12.8:1 and 13.2:1 whereas supercharged, turbocharged, and nitrous-injected engines will like a richer mixture between 11.5:1 and 12.5:1"

"Due to the low port velocity and frictional losses Idle mixtures are typically set at a fuel ratio of 12.25:1. Your motor will idle at stoichiometry (14.7:1) or less than stoichiometry but this is very near misfiring and if operating temperatures are not stabilized at a high level the motor will die. For example, operational fluid temperatures can vary from 150 degrees Fahrenheit to 250 degrees Fahrenheit and inlet air temperatures can easily vary 100 degrees Fahrenheit. These variations in temperature all necessitate different mixture requirements in an Open-Loop system so it is far better to keep the fuel ratio in the 12.25:1 region to preserve idle quality and off-idle response"

"There is no magical, absolute, digitized answer to developing your applications fuel requirements. You must drive your machine and a considerable amount of judgment must be placed in such areas as cold start, warm-up, acceleration fueling, idle quality, and drivability. Each motor is different and the calibration will be only as good as the effort you put into it. Much subjective decision making will take place and the A/F ratio meter will not provide you all the answers. Stop watches, elapsed times, lap times and your own opinions as a tester are equally valid"

 

[gsxr]

As usual Hammer has the answer ! Thanks.