Octane vs Air/Fuel Readings

[BigDog05]

Since stock RX1's run fine on 87 octane, does running high octane gas show a lean reading on the a/f guage.

I ended up running 20 pilots at 2 turns last year to keep my a/f readings in the 14.3 to 15.3 range depending on weather conditions and elevation.
At home I'm just under 1000ft and where I ride in Pa is between 2200-3000ft elevation.

Last year I ran 93 pump with 103 VP oxygenated unleaded. I'd fill it with 103 at home and add 93 if we got fuel on the trail and cut the boost back a little.

But this sled sounds better, revs better and just plain feels better with
17.5 at 2 turns. Plugs look better, sounds crisper.

I'm running an innovative a/f and have changed sensors, did open air calibrations etc. And the readings are always consistant, no matter which sensor etc. 17.5's always go to 16.5-17+

 

[gsxr]

TOOOO lean , you should see 12.5's at wot.

 

[BigDog05]

This is at idle, I'm fine at full throttle.

 

[HAMMER]

Probe location in exhaust stream ???

 

[BigDog05]

My probe is right past the turbo, and I have the Bender dual exhaust so there is at least 14-16 inches of pipe to the exhaust tip.

As a point of info, Justin at Full Power Performance suggested a 15 pilot at 2-2.5 turns. I never made it out of the driveway. Idle readings were in the 18'+.

 

[BlgsRX-1mtn]

I agree with Hammer and think your idle is a false lean reading due to the O2 sensor location. I run mine in the baffle chamber of my Whiteknuckle Exhaust (just above where the pipes go in) and had similar readings. Even going all the way to 22.5 pilots @ 2 turns out on the screws it would still read 14s at idle and ran like crap.

After calling MPI and talking to Mac; he told me the readings at idle were due to negative exhaust pulses puling air back throught the exhaust pipes and baffle chamber. I have the 17.5s in it again and just live with the high 16+ idle readings with screws at 2 1/4 turns out. I have 1300 miles like this now with no issues.

Jim

 

[BigDog05]

That sounds very possible. I guess a better way to explain this is, the first year I had the sled, I was running a dual boost/egt guage.

My set up was: pilots 17.5 @ 2 turns, needles 1 notch rich, stock jets and adjust pitot jet as needed.

The second year I had the sled, the A/F guage became the hot item. I think I found myself sitting and looking at the A/F guage everytime I was stopped or going very slow.

Where I ride in Pa there are times when you may have to go for a mile or so thru the woods to get to another trail. With the 20's in, the sled just sounds and feels bad. I'm talking 5-10 MPH.

Also I'm running billet caps and T's and 2 lines from the intercooler to the carbs.

Thanks for the replies guys.

 

[TWIN TURBO]

Something doesn't sound right. My engine won't run at 16:1. I'm at 750 ft and ride at 1600 in northern Wisconsin.
There must be exhaust leaks drawning in fresh air or maybe you have enough misfires to make you think your 16:1. Misfires make the engine look lean as you have fuel and unburned air in the exhaust.
Stock Yamaha Apex's will idle at about 13.2 :1 maybe 13.5:1 over 14:1 is too lean.