Tuning for Elevation

[Track Junky]

Last year I did the 341Challenge and although I didn't do too bad after multiple runs my car ran terrible due to the 5000-6000' elevations. Anybody know of a shop that can help me tune for these elevations?

[Vegas69]

There are some simple jet calculations you can do. I used to do it for my 450 Honda when I went to different elevations and it always ran great. My guess is you take your current jet and multiple by .96.(Do your own due diligence) You may also need to step down your accel cam and/or squirter size. Depending on what your problem was?

[Track Junky]

Thanks Todd, is there a book or a website that can give me some detailed info? I really dont want to screw this up, I'd hate to create a lean condition. Dyno tuning would be the prefered route.

[Track Junky]

Thanks Guy, I'll do a search and see what I can come up with.

[Sieg]

Holley's jetting instructions for a 4150 Ultra HP Series:
Carburetors are calibrated at 70° at sea level. Decrease the jet size one number (approx. .002) for approximately every
2000 ft. increase in altitude. Increase jet size one number for every 35° drop in temperature.

Here's a converter:
http://bgsoflex.com/auto.html
They also have numerous other calculators

[Track Junky]

Originally Posted by Sieg

Holley's jetting instructions for a 4150 Ultra HP Series:
Carburetors are calibrated at 70° at sea level. Decrease the jet size one number (approx. .002) for approximately every
2000 ft. increase in altitude. Increase jet size one number for every 35° drop in temperature.

Here's a converter:
http://bgsoflex.com/auto.html
They also have numerous other calculators

That is awesome, thanks. At least it should get me in the ball park. In addition, if I record temp reading at header primaries with current set up hopefully I could avoid a lean condition. Better yet, maybe its time to get an AFR gauge.

[Vegas69]

I should ask more questions. What is the difference in elevation from where you live to the top of 314? I agree a dyno tune would be ideal but it would need to be done at similar elevation. Have you ever dialed in your engine at current elevation? I can't find the info....

[Track Junky]

Huge difference. Im at about 900' and the 341 starts from 5200 and finishes at 6000.

[DEIGuy38]

search for a program that you can enter your know parameters that works for your car now. Maybe you can change the elevation and it will recommend a jet to run. That is what the motor leasing company would do on the stock cars I worked on. They had the conditions of the dyno room tune and would set up and get elevations, etc and rejet the motor for the race track conditions. (I don't know the program, it was back in 96) This might help
http://www.bgsoflex.com/holley.html

Guy