Pelican Parts Forums - Tuning, AFR, Altitude and More Questions

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Quote:

Originally Posted by gumba (Post 8094617)

What fuel head/wur adjustments would you make to compensate for the elevation change? My motor was built and tuned at sea level (Bay Area). At 7,000 ft my a/f's at wot seem to be the same as sea level, 11.5 wot. I recently had a full rebuild on the K27 and was checking the a/f's. I did crank up the boost knob slightly to get up to 1.1.

Here's what I've seen traveling between altitudes. Idle AFR varied quite bit, but once you cracked the throttle and got some airflow throw the metering plate the AFR's were close to the same, just the curve was offset a little.

This makes sense when you think CIS is just measuring air density by the amount of flow past the metering plate. At idle, it's just a stop screw without much measurable air flow, but once the air flow increases to move the plate it's measuring density. Less dense air, less fuel flow.

I was getting the same WOT AFR's at various altitudes when I adjusted the boost pressure up to compensate for the higher altitudes.

Your 11.5 AFR was at 1.1 bar at 7000 ft? 11.5 AFR at 1 bar sea level? Sounds about the same as my results.

.9 bar 11.5 a/f at sea level on engine dyno. 1.1 bar 11.5 a/f at 7,000. Next time I'm out I can check it at .9 bar. Just trying to figure out if I need to do something.

Quote:

Originally Posted by T77911S (Post 8090823)

here is something that is REALLY far fetched.

if you were to run a tube from earth to outer space, would it suck all the oxygen out?

LOL.
A. NO.
You already have the same pressure gradient between outer space and atmospheric pressure - without your straw. A bit OT, but the explanation is................................................ .................................................. ..............
Gravity. Thank heaven for gravity - so we still have the O2 to breathe, and the other gasses - nitrogen CO2, Argon etc. The lighter Big Bang gasses - helium/Hydrogen escaped the gravitational field before you and I wore diapers.
Alan

good to hear from you alan. i think the last time i really talked to you you had done some bodywork on your 930, non-intensional. i picked up an 86 930 since then.

Ha, yes. Car all re arranged back to normal. Painful process. Off to track this w/end.
My greatest fear is always about damaging the car. Just waiting for Chris @ Turbokraft to assemble some more go-fast bits.
Regards
Alan