Why does my LC loose so much power at altitude?

[flagstaff]

I live in Flagstaff, AZ with an elevation of 7000 feet and my LC drives with acceptable power. It feels sluggish but does OK.
When I drive it down to Phoenix (1000 feet) the power is noticeably higher.
I understand that the higher elevation means that the air is less dense and that's why there is less power but I didn't expect such a difference. Do I have any options other than bolting on a super charger? Also, are diesel engines just a susseptable to altitude differences?
Eventually I want to put on 35s or 37s but I don't think I can stomach the power loss.

 

[lt1fire]

I live in Flagstaff, AZ with an elevation of 7000 feet and my LC drives with acceptable power. It feels sluggish but does OK.
When I drive it down to Phoenix (1000 feet) the power is noticeably higher.
I understand that the higher elevation means that the air is less dense and that's why there is less power but I didn't expect such a difference. Do I have any options other than bolting on a super charger? Also, are diesel engines just a susseptable to altitude differences?
Eventually I want to put on 35s or 37s but I don't think I can stomach the power loss.

That is why, SC is a good idea but you can also do a regear

 

[edog's 80]

I live at 5600, and tow my popup trailer over I70 5-10 times per year. I am also on 33's, you can't imagine the power loss up at 10,000-11,000 ft trying to keep up with modern power. SC is the quickest way to get extra power, swaps or turbo are more involved, but I think the latter is the route I will go someday.

 

[huntir]

I live at about 7200 feet and drive up to 1200 and you definitely need a S/C or something make it bearable.
I read in a auto mag that every 1000 feet you lose a percentage of HP. At 7500 you have lost about 25% of your HP

 

[SoCal_80]

Clogged charcoal canister ?

 

[86tuning]

https://forum.ih8mud.com/80-series-tech/449343-towing-dilemma-need-good-advice.html

I posted some numbers. The gist of it is that the higher the altitude, the less dense the air, and the more hp is affected.

sea level = 14psi
3000' = 10% loss
6000' = 20% loss
8800' = 28% loss
12000' = 36% loss

A turbocharger is boost regulated and would be the best altitude compensating device. However, there is no kit available from Toyota. The supercharger would give you a boost in output, but still suffers from altitude related loss.

 

[80t0ylc]

............Why does my LC loose so much power at altitude?............

Most folks that ask this question have not experienced altitude change in their own body. I don't know how long you've lived at 7K, but those that visit that altitude or higher from, say, sea level know what I'm talking about. It's still not completely understood. Of course, engines handle it differently than humans, but it gives you an idea. Humans adapt, given time. Engines need help, whether it be gearing or SCs.

 

[greentruck]

I'll echo 86tuning's recommendation that it's a turbo you need, not the SC, if you want to compensate for altitude power loss. The SC will help, but the turbo is able to keep pumping in boost.

If you look at the history of internal combustion engines in aircraft -- which obviously have a great need to work at differing altitudes -- you'll see that supercharging was set aside in favor of the more effective turbo-charging. Then came jets...

 

[StopGap]

https://forum.ih8mud.com/80-series-tech/449343-towing-dilemma-need-good-advice.html
sea level = 14psi
3000' = 10% loss -- 140hp
6000' = 20% loss -- 124hp
8800' = 28% loss -- 112hp
12000' = 36% loss -- 99hp

A turbocharger is boost ... The supercharger would give you a boost in output, but still suffers from altitude related loss.

86Tuning has it about right. If you have the 10% corn gas formulation you can reduce these number another 3%. You can increase your timing, with a higher octane gasoline. Its helps a little depending on type and hours on your engine. New O2 sensors help a little, again.......your engine.

A SC can give you a big jump in HP... its bigger bucks than adjusting your timing. SCs suffer from altitude sickness at low rpms. Increasing the pulleys ratio helps with the low end boost. If your LC is before '93, you may not be able to add a SC not easily or at low cost, there is no SC kit or ecu for it. A universal ecu costs between $500 and $1500 depending on vendor.

I have a '92 @ 5500 ft. Getting on US 25 where the speed limit is 75mph is always interesting. Trips though the eisenhower tunnel it just doesn't want to go. I'm trying to put a kit together for an ecu conversion to a OEM OBDII ecu. Then I can look at boost options.

 

[maybe_a_80...]

...I live in Frisco, Colorado, about 9,300 feet. I drive through Eisenhower-Johnson tunnels frequently. What's the elevation at the tunnels? 11,000 feet?

The truck is slow on the climb to the tunnels. But so is everyone else. Remember we're talking about a relatively underpowered 6,000 lb truck with full time 4wd. I used to get all worked up about how slow the truck is sometimes. But no one else is having an easier time managing their engine on those annoying grades, unless they are driving an overpowered vehicle, like Audi S or 10 (or12!) cylinder turbo diesel. I'm not afraid to let the truck shift back to 2nd gear for a bit at higher RPMs as I figure if the truck wants to make that shift, the factory-tuned ECU has decided the truck will be more efficient etc with the gear change.

Because of the elevation at which I live, I go out of my way to make sure that basics like plugs, wires, rotor, cap, engine and gear oil, exhaust components and air intake are updated and working properly. It makes a huge difference on such an old vehicle for high-country operation, especially at highway speeds.

Without a doubt the 2 upgrades that would make the most difference are a re-gear and turbo for driving at elevation. The re-gear would do a great job, if done correctly, of putting the power band of the truck at a (possibly) more appropriate point relative to the grades and tire size selection. The turbo would help to ram air into the engine to make it hold HP and speed on the long uphill grades, where the truck bogs down power- and speed-wise. I have not dived into either so I don't know which would be more effective or the first thing to do if I were to consider making the truck faster.

Ironically, if I want to make time on the drive to Denver, I can still get around people and drive fast enough to not get caught in traffic snarls...if I really want to. But that behavior just raises the blood pressure and increases the likelihood of gaining the attention of State Patrol, which are not by and large enjoyable activities.

 

[Sno bored]

I work up at the eisenhower tunnel and drive my 80 up every once in awhile. I installed the Landtank MAF sensor a couple of years ago and I think it makes a big difference. It doesn't feel like it makes more power, but it changes the shift points of the transmission. Even with the OD button turned off my truck would want to downshift all of the time coming up the hill, after the MAF no more downshifting.

I love driving at sea level because it feels like my truck has a turbo.

 

[Nay]

37's work nicely with 2nd gear at high altitude

Just chant "I think I can, I think I can" up the steep grades and you'll probably make it.

 

[pmccumber]

Actually, I think the number is approximately 3% power loss per 1,000 feet. Air temperature plays a pretty major role too. The colder the better.

 

[Nay]

Actually, I think the number is approximately 3% power loss per 1,000 feet. Air temperature plays a pretty major role too. The colder the better.

I think the number is "my max speed is now 35 mph"

 

[kbahus]

I took the 80 up the tunnel and then up through Kremmling to Steamboat last weekend full of ski gear and kids. With the stock gears I expected to be going 20 but was able to hold 50 almost the whole way up the tunnel without really hammering on it. Rabbit Ears was down into the 45mph range but that climb out of Steamboat is wicked. I was pretty happy about the performance but am now wondering what will happen when I go to 35's this summer without a re-gear. If I loose 5mph I will still be satisfied with the performance.

 

[Nay]

I took the 80 up the tunnel and then up through Kremmling to Steamboat last weekend full of ski gear and kids. With the stock gears I expected to be going 20 but was able to hold 50 almost the whole way up the tunnel without really hammering on it. Rabbit Ears was down into the 45mph range but that climb out of Steamboat is wicked. I was pretty happy about the performance but am now wondering what will happen when I go to 35's this summer without a re-gear. If I loose 5mph I will still be satisfied with the performance.

It won't be materially different than 33's. And when you regear, it won't be materially different than stock gears. I can hold 50 up I-70 at the worst spots, and like you passes like Berthoud are 45, but with 5.29's that is revving high in 2nd gear.

It's not the worst thing in the world, you just have to really manage your kick down points, etc. to keep speed. After five years of that, I mind it more than I did when I bought the rig...

 

[kbahus]

That is good to hear. I need to find someone to buy my Duratracs before summer hits so I can go up in size. I figure by the time a full front end service is due I will just add in a gear install at the same time. Hopefully it is not for another year or so.

 

[Atoyot1031]

I don't know what you guys are talking about. I live at 8,000' and can maintain at least 65MPH up any of the passes on I-70.



























Of course a motor that's bored out .040 over, SC'd, vented hood, auxilary fan, and every other cooling gizmo with 4.88s doesn't hurt...

 

[maybe_a_80...]

I don't know what you guys are talking about. I live at 8,000' and can maintain at least 65MPH up any of the passes on I-70.

...

Of course a motor that's bored out .040 over, SC'd, vented hood, auxilary fan, and every other cooling gizmo with 4.88s doesn't hurt...

Well now that would pretty much take care of the issue we're discussing...in a very nice way. Note none of us Colorado folk are complaining, just stating our stock engine capabilities.

Did you entertain a turbo or did you go straight to the SC?

 

[mhanssens]

just think of it this way. at pikes peak every year they race rally cars, they loose 30% of there power by the time they hit the top of the mountain. even the turbos that push these 4cyl. to 800hp loose power. i live here in flagstaff as well btw haha. i got the 3fe and i feel the pain too dude