This one is for all high altitude guys

[bot0611]

Last week i went to the local mountains (around 10,000 ft) i live near sea level so getting there my truck felt heavy and off, i stepped on the gas and not much of a performance so my question is would i need to tune the carb at high altitudes??

 

[Chaddy]

Yes.

 

[Big Ray]

pretty much.

less air = rich condition...

that's where fuel injection really shines

 

[bot0611]

How so??


Forgot to say its carbed

more air in the carb??

 

[Big Ray]

links

basically, you're mixing the same amount of gas with less air = rich.

same as having too large of jets at lower altitudes.

 

[K5dreamer]

Turbocharge that bizznatch, works for us diesel guys

or swap to TBI. Carbs are never self adjusting, so you set it for one set of conditions, and if they change, so does your performance. because of electronics and sensors, fuel injection setups detect those changing parameters, and alter fuel delivery on the fly.

option 3.... hire a midget to sit under the hood in a flame retardent suit with a screwdriver constantly adjusting your mixture screws.

 

[Hogback Fabrication]

As others mentioned, changing altitudes will change you air/fuel mixture.

Don't forget, however, that even if you get that dialed in right that at 10,000 ft you will make WAY less power (say, 35%) than you would at sea lever based on air pressure.

 

[miniwally]

I am not sure how this relates to trucks but in the snowmobile world we have to re jet every 2,000 feet in altitude.

Now thats not saying that we stop and re jet on the trail. We see 3,000 to 4,000 feet in elevation change from the parking lot to the highest riding areas we go to so we jet lean in the parking lot and rich at the highest altitude so we hit the middle area right on.

383 has it about right. 3% per thousand feet of elevation is a general number to use.

You were dumping about 30% more fuel than you needed in at 10,000 feet.

 

[bot0611]

You were dumping about 30% more fuel than you needed in at 10,000 feet.

Now i get it.

Thanks.

 

[mnstrburbon]

Where did you go big bear.. the power loss will be very noticable. if you have a holley they are easier to jet and you can find what jets work at both sea level and 10,000. Only takes 5 or 10 minutes to change the jets in a holley when you get up to elevation switch them out, and then back for the drive home.

 

[bot0611]

Are you guys familar with Baja and its numerous places well i went to the woods, Hanson Lake its called its 3,000 m above sea level (around 10,000 ft) the road has great straigt lanes were you can floor it cool turns and stuff and the eventuall rocky hills si getting up there i inmediatly felt it had no power like before

 

[80' 427]

don't have to rejet with propane, just sayin.