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Hi All, i was wondering if anybody has Dyno knowledge/experience. the reason i ask is i ran on a dyno when i was at Sturgis. the elevation at Sturgis is 3650 ft. my question is this. on the bottom of the dyno sheet it shows the air fuel mixture. as you can see, the upper RPM range the bike starts to run very rich. this is the stock ecm. no changes. would the air fuel mixture be leaner at Minnesota elevation 935 ft? everybody says the stock settings are lean but i am showing rich at WOT which i believe is a fixed loop (or something like that). if you have any input please let me know what you think.
 

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My thought would be there is not that big a change in elevation that the computer couldn't make up for.In theory the lower elevation should run leaner and the high elevation run rich less air.Now the stock computer may be set up to run rich on wot so we won't burn a piston from running too lean.Just my thoughts of an old mc rider.
 

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In theory, Air/fuel mixture should be the same at any altitude.

My take on the air/fuel mixture, knowing we're ECU controlled, electronic fuel injection, and in a perfect world, changing from near sea level to less than 4000 above sea level should not be an issue with power on any modern engine. Pilot's use a mixture control for peak EGT on a gauge, for keeping the engine happy while flying at all altitudes.
So my idea would be the power output curve should stay close to the same on a properly setup engine. Also keeping things in order here, our light General avaition aircraft are using 30's technology with the engines, Magneto's, dual plugs per cylinder, manual throttle bodies (fuel injected) or carbs, manual mixture controls and commonly fly from sea level to 12k.
I hope this don't confuse the issue here.
EGT is Exhaust gas temp.

OH and the idea of making our monster engines go rich for cooling and protection at near the max designed output is a valid point. The engineers knowing how we tweak and modify our engines, I'm sure there are some limits in there somewhere.
I did find my RPM limit in 4th last week, didn't realize how different the bike sounds when I'm wearing my full face helmet and balaclava. OOPs. can't go there. I am planning on using my helmet cam to watch my GPS for real speed measures as I don't want to be looking down so far with a full face helmet blocking my view of the speed indicator. I'll post it oneday. I already know my speedo is off a few miles. Mine reads about 4MPH faster than the GPS so it's protecting me in the long run.

Just for info and fun, our aircraft engines are air cooled, most are 4/6/8 opposed cylinders, and designed for 1/2 HP per Cubic inch.
All typical Lycomings and Continental use two plugs per cylinder for redundant ignition, they all have dual magneto's. And can run on one as designed in the years 20-30's. No DC power required other than for the starter.

Enjoy.
 

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Discussion Starter #4
I wasn't sure.

My take on the air/fuel mixture, knowing we're ECU controlled, electronic fuel injection, and in a perfect world, changing from near sea level to less than 4000 above sea level should not be an issue with power on any modern engine. Pilot's use a mixture control for peak EGT on a gauge, for keeping the engine happy while flying at all altitudes.
So my idea would be the power output curve should stay close to the same on a properly setup engine. Also keeping things in order here, our light General avaition aircraft are using 30's technology with the engines, Magneto's, dual plugs per cylinder, manual throttle bodies (fuel injected) or carbs, manual mixture controls and commonly fly from sea level to 12k.
I hope this don't confuse the issue here.
EGT is Exhaust gas temp.

OH and the idea of making our monster engines go rich for cooling and protection at near the max designed output is a valid point. The engineers knowing how we tweak and modify our engines, I'm sure there are some limits in there somewhere.
I did find my RPM limit in 4th last week, didn't realize how different the bike sounds when I'm wearing my full face helmet and balaclava. OOPs. can't go there. I am planning on using my helmet cam to watch my GPS for real speed measures as I don't want to be looking down so far with a full face helmet blocking my view of the speed indicator. I'll post it oneday. I already know my speedo is off a few miles. Mine reads about 4MPH faster than the GPS so it's protecting me in the long run.

Just for info and fun, our aircraft engines are air cooled, most are 4/6/8 opposed cylinders, and designed for 1/2 HP per Cubic inch.
All typical Lycomings and Continental use two plugs per cylinder for redundant ignition, they all have dual magneto's. And can run on one as designed in the years 20-30's. No DC power required other than for the starter.

Enjoy.
I agree with you as far as running at less than WOT but i think i read somewhere that when at WOT the bike doesnt run off the O2 sensor but is in a closed loop ( i think this means hard programmed) fuel mixture. the reason i bring this up is because my bike is running way rich at 4500 rpm and higher. there would be more power made with the correct AF ratio. If i was at sea level i would get denser air and it might lean it out some which might make more power in the closed loop condition. also it could be a sign of inadequate inlet air. in essence i'm choking the bike. if it is a restriction i can raise the top cover and tank a bit more. if it is altitude them maybe i shouldn't mess with it. they make a real time O2 sniffer that you can install. read about it in my Car Craft magazine. with this unit a guy with a power commander could fine tune your own bike at any time as all you would have to do it look at the gauge and mentally log the RPM where it runs out of spec. i think the thing cost a 100 bucks. less than a dyno run and you have it all the time. getting off track a bit. mainly i'm trying to figure out if i need to raise the top cover of the airbox more due to restriction or not because of altitude.
 
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