How much does altitude affecte an NA IDI

[FordGuy100]

Well I just got back from a camping trip in the High Sierras. I flew down there last thursday, and then flew back up here yesterday. The trip was really fun, and I'm going to be making it a yearly thing (about 10 of family and friends of the family go every summer). Since I will be turning 16 in march, I'm thinking instead of flying down there and then driving 6 hours either way, I should drive (that way I can also bring my rifles with me).

So now that you are all up to date I got some questions.

First off were we are going to be camped its going to be about 10,500' above sea level. I'm going to be driving my truck all the way up to were we are going to be camped. So how much power will I be down when I'm up there?

And my other question is can I when I'm up there turn the fuel down so I dont waste a bunch of fuel?

 

[Builder Bob]

With some degree of accuracy, I am going to guess that any engine will lose 3% for every 1000' of elevation.
10,000' = 30%
Only a reasonable guess
BB

 

[argve]

Bob you made it over Glad to see ya...

Now to the question in the first post...

Yep you'll be down on power but seriously it will still run and still motor down the road - just keep yer eye on the tailpipe and when you start blowing black smoke let off the go pedal some. Now some smoke with a NA IDI is normal but you don't want to be fogging for skeeters the entire way up because that means your heating up and....well just don't blow too much and you'll be fine...

 

[Huntersbo]

I do not mean to pirate this thread but would'nt running a turbo with too much boost at sea level run good and make up for power loss at higher altitude? Adjust the waste gate so more boost hits the cylinders when you go up and as you go down open up the waste gate to bleed off some boost.
???

 

[seanpistol]

i lived in mammoth lakes last ski season and had my 90 7.3L along with me. it's 8,000 feet above sea level and we had 637" of snow from october to may.

global warming...

anyways, on the drive up 395 my truck runs fine until i get to bishop where it's about 5,000 ft. then there is a long(i'm guessing 10 mile) 6% grade that starts at around 500 and ends at close to 7000. completely empty i blow black smoke and have to keep it at 3200 rpms to hold 60 mph. that's not the case back home where i'm a mere 800 ft. above sea level.

around town where it's 8,000 feet, there is a noticeable loss in power. slow acceleration, hard starts. black smoke when you're barely on it, and things like that. despite the power loss, i was one of the few vehicles that managed not to get stuck, and i pulled many a small car out of the snowbank.

at 10,500 you're going to see a lot of power loss. just curious, but where in the sierras are you going?

 

[seanpistol]

I do not mean to pirate this thread but would'nt running a turbo with too much boost at sea level run good and make up for power loss at higher altitude? Adjust the waste gate so more boost hits the cylinders when you go up and as you go down open up the waste gate to bleed off some boost.
???

to answer that question, my dads 96 powerstoke can easily do 80 up that 6% grade when i have a hard time doing 60.

 

[argve]

Hunter you misunderstand how a wastegate works... A wastegate is nothing more than a pressure relief valve of sorts - meaning that once a set psi is reached then it will start to open which starts to limit the boost. Now operation of the wastegate will be the same at sea level at is at 10,000 feet meaning if the system would produce 10psi of boost down low it will only produce 10psi at alt. Now the amount of air in 10 psi at SL is the same at 10k so adjusting the wastegate would buy you nothing other than you would then produce more boost at both alt's.

 

[FordGuy100]

at 10,500 you're going to see a lot of power loss. just curious, but where in the sierras are you going?

We started climbing out of bishop, and we camped at South Lake. South lake is only at 9800', and we only went there because one in our party is in poor health, and its easier to get there than were we are going to go next year (the normal camping spot). And by the way the only way to get to were we are going next year is to take a 20 mile or so 4x4 road (I've been told that a stock rig will go up it), and it will take about 2-2 1/2 hours to get up it.

Any thoughts on if you can turn down an IP?

 

[Huntersbo]

I was reading a turbo charger book and under the High altitude section; Read only if interested as I am very much a novice at the turbo and this is out of a published book; Turbo chargers by Hugh Machines.

High altitude turbo charging.

A naturally aspirated engine will produce power in direct proportion to the diesity of the intake air. At sea level air has a desity of .0765 lb per cubic foor. At 10,000 feet aitiltde the desity drops to .0565 lb per cunic foot. This means an engine that delivers 100 hp at sea level will deliver;
100x .0565 diveded into .0765 = 73.9 hp.

An airplane engine that uses a turbo charger to regain the power lost at high altitude is referrede to as a normalized engine. A normalized engine usually has a waste gate to pass all of the exasut gas at sea level, Consequently no turbo charging takes place at sea level. As the engine starts to lose power with increased altitude, the waste gate grasually closes, either manually or by an automatic control. The turbo charger then compresses the inlet air to sea level pressure. This allows the engine to deliver teh essentially sea level horsepower.

The engien continues to develop sea level horsepower up to an altitude where the waste gate is conpletely closed. At this point, called critical altitude, all the exaust gases pass thorugh the turbine. When the airplane climbs above critical altitude, the engine will start to lose power. The turbo charger can no longer deliver air at sea level pressure.

To simplify the next two pages worth you need to maintain the same manafold pressure to maintain power. If you have 15 psi at sea level then you need 15 psi at 5,7, and 10,000 feet. They use aneroid sensors to correct altitude to manafold pressure.

 

[Huntersbo]

Can you run more boost at higher altitudes?

 

[FordGuy100]

So after doing the math I will be making 129 horsepower at the crank @ 10,000'.

I'm still wondering that if you can turn up the IP, then you should also be able to turn it down.

 

[seanpistol]

We started climbing out of bishop

so then you know the exact grade i'm talking about.

 

[towcat]

So after doing the math I will be making 129 horsepower at the crank @ 10,000'.

I'm still wondering that if you can turn up the IP, then you should also be able to turn it down.

i'd leave the IP alone and use your intelligence by driving by pyro and eyeball on the rearview mirror. I have a mirror aimed at the lower part of the doghouse to monitor the smoke output.

 

[Huntersbo]

I mean't 15 psi of manafold pressure, the book siad that the less air density the lowere you manafold pressure is. Mabe it is valuble to get a manafold pressure gague and see how the pressure changes as I gain altitude.

 

[tractorman86]

So after doing the math I will be making 129 horsepower at the crank @ 10,000'.

I'm still wondering that if you can turn up the IP, then you should also be able to turn it down.

yes u can it is exactly the opposite opperation as turning it up. line up the skrew in the access hole on the left(passinger) side and turn counterclockwise to lower fuel output clockwise to raise fuel outupt how ever i dont think u will gain much from this as long as u use the mirror pyro (a lot of smoke= alot of fuel and high temps= not good) just be easy on the pedal and you'll be fine!