I was wondering how much the altitiude affects et's? I live in El Paso TX and I know the altitude is pretty high, but I'm not sure how high. I was asking because I've read that stock TPI cars can run in the low 15's and high 14's. Also that TBI's run 16's. Last year at the track I saw a 305 TPI/auto IROC run high 17's!
My friend has an 89 Camaro with a 350 w/a stock roller cam out of a truck, Vortec heads, stock TBI, headers, exhaust, and some other small stuff. His best time with the tranny shifting automatically was a 16.3. Does this seem right? I've also seen mustangs 5.0's running low 17's or high 16's mostly stock. New Z28's are running 14's or high 13's.
Does anyone have the correction table for the different altitudes, and what time do you guys say you run. The actual or corrected?
16.3 sounds pretty bad if you're telling someone what you run!!

 

I meant that my friends 350 came out of a truck, not the cam.

 

Track Elevation (in ft) ET Factor MPH Factor

1200 .9874 1.0129
1300 .9861 1.0143
1400 .9848 1.0157
1500 .9835 1.0171
1600 .9822 1.0185
1700 .9809 1.0199
1800 .9796 1.0213
1900 .9783 1.0227
2000 .9770 1.0241
2100 .9757 1.0255
2200 .9744 1.0269
2300 .9731 1.0283
2400 .9718 1.0297
2500 .9705 1.0311
2600 .9692 1.0325
2700 .9679 1.0339
2800 .9666 1.0353
2900 .9653 1.0367
3000 .9640 1.0381
3100 .9627 1.0395
3200 .9614 1.0409
3300 .9601 1.0423
3400 .9588 1.0437
3500 .9575 1.0451
3600 .9562 1.0465
3700 .9549 1.0479
3800 .9536 1.0493
3900 .9523 1.0507
4000 .9510 1.0521
4100 .9497 1.0535
4200 .9484 1.0549
4300 .9471 1.0563
4400 .9458 1.0577
4500 .9445 1.0591
4600 .9432 1.0605
4700 .9419 1.0619
4800 .9406 1.0633
4900 .9393 1.0647
5000 .9380 1.0661
5100 .9367 1.0675
5200 .9354 1.0689
5300 .9341 1.0703
5400 .9328 1.0717
5500 .9315 1.0731
5600 .9302 1.0745
5700 .9289 1.0759
5800 .9276 1.0773
5900 .9263 1.0787
6000 .9250 1.0801

Here in Tucson we are at 3100 ft and I think El Paso is alittle higher.
If you ran 16.3 X .9614 = 15.6. Find out for sure what Altitude you are at.

 

thanks!!

 

Those tables are reasonably good for conversion but don't forget that the weather conditions affect altitude also. Here in Calgary the track's official altitude is 3500 feet. When you factor in the weather conditions, we usually have a Density Altitude of around 5000 feet on race days (See below results).

When you're at the track, find a racer with a weather station and ask him what the density altitude is. You might be suprised at how high you really are. Since each day can be different, your results can be different also. One day you run 15.8's the next week it's only 16.1's and you never did anything to the car.

 

Thats a very good idea!! I wonder why I've never sought somone out. Just a few more months until the track opens again.
SSC