Altitude effect?

[Browzer52]

Am midway through a driving vacation,left Campbell River BC and followed Hwy 1 along the US west coast as far as Oceanside, California.Looking at returning home taking a detour through Reno/Tahoe.Concerned about engine performance at elevations as the car has always been at or very close to sea level.Any thoughs?

[tevake]

I can't comment on altitude tuning.
But do look at going east thru Yosemite and past mono lake then north to reno. Nice drive

[Flat Six]

Altitude shouldn't be an issue, really -- about 4-5,000 ft. along Hwy 395 on eastern side of Sierras. I've driven CIS (though not turbo) cars up to ~7,000 feet with only minor loss of power. Beautiful drive; high desert in fall. Watch out for speed traps in/near Bishop and Lone Pine. ;-)

If you have the time, when leaving Reno/Tahoe I'd suggest Hwy 44/89 -- takes you NW through Lassen National Forest and Shasta National Forest; then I-5 up through OR and WA.

Even better, though, is Hwy 139/97 north from Reno; takes you through Klamath Lake and Crater Lake area then north through eastern OR and Deschutes National Forest. Stop in Bend for some great microbrew at the Deschutes Brewery. From there Hwy 26 NW to Portland past Mt. Hood and through Santiam National Forest. Both great drives. Finish up in the next 2-3 weeks, though, as pass conditions either way can change quickly.

For Oregon road/traffic/weather conditions go to: TripCheck - Road Cams, Road & Weather Conditions in Oregon - ODOT
For Washington: WSDOT - Statewide Mountain Pass Map

Hope this helps; have fun.

D

[Flat Six]

Originally Posted by tevake

I can't comment on altitude tuning.
But do look at going east thru Yosemite and past mono lake then north to reno. Nice drive

Tevake's right, this is a great drive. Beware, though, this route east through Yosemite is closed during the winter. Don't know if it's closed yet, but Mammoth Mountain got snow last weekend; if you choose this route make triple sure the road's not closed for the winter.

Safer bet this time of year is to pick up 395 either at Victorville/Hesperia (if you take I-15 from Oceanside) or at Inyokern (if you take I-5/SR-14).

D

[longhornchris04]

A turbo should have no trouble... they inherently correct for altitude because the thinner air is easier to compress, and thus the turbo will spool up slightly more.

That said, it wouldn't hurt to have the 3mm key handy (I keep mine in my glovebox, but I'm an NA car). If your car is already set rich, altitude may push it to be very rich. I had that problem going from Manhattan Beach up to Big Bear Lake. Driving performance was fine, but idle was terrible. 1/4 turn toward lean (maybe less) and it worked perfectly. If you do that, make sure you undo it when you get back to sea level.

EDIT: I had my engine running somewhat rich to begin with... at the time I was having some issues with startup so I had to adjust w/o access to a exhaust sensor and I'd rather err on the side of rich then go lean and risk pinging.

[carreraken]

I recommend the Tahoe route - it's beautiful there. They even had some snow at the higher peaks earlier this week (not at lake level).

I notice a slight power loss at the lake with my na, but didn't have any idling issues.

[Drisump]

Being from your part of the world and having just did the trip you're talking about doing (in a N/A 3.2), I think you should have no issues at all. The altitude should affect your 930 far less than my 3.2 and I have to say the trip was great. Performance decline is noticed at altitude but not much of the route is at what I consider that high. Try some those +10,000 foot passes you get in a few places. Once again, great trip!

[gduke2010]

I'm in the higher altitudes every week end. So, I really only notice a loss of power in the higher elevations while ocasionally, driving in the lower elevations of the California foothills. Then, the car has noticably more power.

Only cars w/ carbs have problems with the carb loading up at higher elevations, like 9000'. You won't have any problems. But, the less dense air in the higher elevations do rob power.

BTW, 395 is heavily policed. Watch out for cops.

Gary

[5String43]

+1 on taking California 395, it really is a wonderful drive.

+1 also on being wary of traffic police. A radar detector is a good thing.

And here's a tip, if you do take 395. Once past Mammoth, keep an eye peeled for June Lake. Take that turnoff. It's maybe 20 miles north of Mammoth. It'll take you around what's called the June Lake Loop and deposit you back on 395 just south of a little town called Lee Vining. It's an incredibly pretty drive past some wonderful trout-fishing lakes, and past Carson Peak, named for old Kit himself.

And south of there, in Bishop, be sure to stop at Schatt's Bakery. Jalapeno bread, and cheese bread! Yum!

[GrantG]

Originally Posted by Flat Six

I've driven CIS (though not turbo) cars up to ~7,000 feet with only minor loss of power.
D

It may have felt minor, but the power loss was around 25% or more compared to sea level.

[Browzer52]

Good morning all,I thank you for all your input and advice.Will be leaving Monday or Tuesdy morning and will consider all routes suggested making a decision on the road.Car is equipped with a Laser Blinder as well as a V1 radar detector,both of which have paid for themselves several times over on this trip alone.
Regards!

[Jim Garfield]

The Motronic cars have an altitude sensor and correct for it as the pressure changes.

[86 911 Targa]

Originally Posted by Jim Garfield

The Motronic cars have an altitude sensor and correct for it as the pressure changes.

I thought it did, but was not certain about the 930.

[big911fan]

I live in the area you're planning on driving through. I'm on the west side of the Sierra's along Hyw 108 (Sonora Pass). Both Tioga Pass (Hwy 120) and Sonora Pass (Hwy 108) were closed for a few days last weekend due to rain and snow in the high country. They are both open now but ALWAYS check the highway reports this time of year before you take either route. They close both roads for the season every year starting anytime now, depending on weather which can change quickly.

The two passes that are open year around will be Hwy 88 (through Jackson, CA)and Hwy 50 through Lake Tahoe. They might close during an active storm for a day or so but CalTrans will open them quickly.

If you need assistance in this area, drop me a PM and I'll give you my phone number. Have a great trip. If you get a chance, stop at the old ghost town of Bodie along Hwy 395 just north of Mono Lake as you approach Bridgeport.

[Flat Six]

Originally Posted by 5String43

And here's a tip, if you do take 395. Once past Mammoth, keep an eye peeled for June Lake. Take that turnoff. It's maybe 20 miles north of Mammoth. It'll take you around what's called the June Lake Loop and deposit you back on 395 just south of a little town called Lee Vining. It's an incredibly pretty drive past some wonderful trout-fishing lakes, and past Carson Peak, named for old Kit himself.

+1 on June Lake Loop
+1 on Schatt's Bakery

FWIW, I'm pretty sure 930 are CIS not Motronic. Don't know if your particular flavor of CIS has altitude compensator, though.

What a great forum! Where else can someone ask a technical question and get not only technical answers, but route suggestions and offers for en route help?

Pelicans are the best community on the 'net.

D

[kidrock]

Originally Posted by 86 911 Targa

I thought it did, but was not certain about the 930.

I've often wondered if mine still works after 20-something years...

[Quicksilver]

For long road trips I recommend regularly checking http://www.roadsideamerica.com to see what oddball sights are nearby.
It will find you the wacky things like the worlds largest ball of twine, string or yarn (there is a difference!). It has lead me to fossilized dinosaur tracks and underground gardens.

A great way to make a road trip into a road trip.

[big911fan]

You can check the resistance of the altitude sensor if you're inclined to do so. If you have a Bentley manual they have the resistance specs. From what I remember it's just a binary switch. Either on or off. Below 3000' it's off, above 3000' it's on. I think it enriches the fuel mixture by about 1% when on.

The problem you'll have in TX is testing it above 3000' unless you're close to the mountains to take it above 3000' and test it.

I'm not sure if anyone has a way of simulating altitude to test it some other way.

[Zeke]

Originally Posted by big911fan

You can check the resistance of the altitude sensor if you're inclined to do so. If you have a Bentley manual they have the resistance specs. From what I remember it's just a binary switch. Either on or off. Below 3000' it's off, above 3000' it's on. I think it enriches the fuel mixture by about 1% when on.

I would question that. Last CIS car I owned ran OK at 5000' but would not idle. I attributed that to being too rich. Don't know about turbos.

[gduke2010]

I'm about 100 miles north of Tioga Pass in Minden, NV. It'll be a beautiful drive. There will be some nice color on the June Lakes Loop.

Hope you have a nice drive.

Also, Lake Tahoe is awesome to drive around, too. There's a lot less traffic after Labor Day.

Gary