Altitudes affect on diff. engines

[vmax2fast]

Being in Colorado, and driving over mounting passes to go snowboarding often, I know the effects on n/a engines. But I was discussing w/ my uncle what effects if any it had on a turbocharged engine. I beleive it would still have an effect but not as much. I hear of people blowing away turbo diesels at lower elevations, and have done my share too here, but definitely not blowin the doors off. especially in the mountains around 10k feet. They kinda walk away then. ofcourse some programmers add like 150 hp which is totally unfair I know there are a lot of knowledgable folk on here so i wanted to throw it up.

 

Brian

[Vortec MAX]

It should effect turbocharged and supercharged engines as well, but not as badly as an NA engine. There is less oxygen in the same volume of atmosphere (gas) at higher elevations. It makes sense that NA engines would see more of an effect since they have to use vacuum to "suck" the air in VS having it forced in. At that altitude, a truck would run the quarter mile 2 to 2.5 seconds slower than at sea level. It may not effect the forced induction engines that much, however.

 

Where I live, my truck runs probably a second slower than at sea level (4,400 ft).

 

Mike

[wody]

i went to a detroit diesel class and the insructor said that one year at the olympics they had generators on the slopes for the lights, but they weren't working to peak power so they had to run ducting down the slope.

[vmax2fast]

i went to a detroit diesel class and the insructor said that one year at the olympics they had generators on the slopes for the lights,  but they weren't working to peak power so they had to run ducting down the slope.

<{POST_SNAPBACK}>

i suppose those were not turbo diesel generators

Edited January 4, 2007 by vmax2fast (see edit history)

[misterp]

It should effect turbocharged and supercharged engines as well, but not as badly as an NA engine.  There is less oxygen in the same volume of atmosphere (gas) at higher elevations.  It makes sense that NA engines would see more of an effect since they have to use vacuum to "suck" the air in VS having it forced in.  At that altitude, a truck would run the quarter mile 2 to 2.5 seconds slower than at sea level.  It may not effect the forced induction engines that much, however.

 

Where I live, my truck runs probably a second slower than at sea level (4,400 ft).

 

Mike

The air is thinner, period; FI engines are affected just the same as N/A. That is why superchargers were invented, to assist piston-powered aircraft at higher altitudes.

 

Mr. P.

[vmax2fast]

but what i'm saying is it's affects on an n/a engine is by some percentage not as much. Therefore some turbo vehicles at a mile high would have a little more advantage than at sea level. It still has the same thinner air, but is helped by the fact that the air is being slammed in there.

[misterp]

Well the generally accepted rule is a 3% drop in power per 1000/ft increase in altitude for gas/diesel/propane, and 5% for natural gas. I think that ethanol-blend fuels are worse with altitude, like around 3.5-4% drop in power per 1000/ft but again not sure on the exact number.

 

So your question is, if a N/A gasoline engine looses 3% power per 1000/ft climb in altitude, will a FI gasoline engine also loose power at the same 3% rate? IMO the answer is yes, again that's just my guess.

 

FYI octane requirements run inverse to altitude, you don't need as much octane at higher elevations.

 

Mr. P.

[misterp]

A quote from Bombardier (the snowmobile manufacturer):

 

The atmosphere surrounding our planet is most dense at sea level and

as you move up from sea level, the air becomes “thinner”. Air is composed

of 78 percent nitrogen, 21 percent oxygen and 1 percent total of

carbon dioxide, argon, neon and water. The percentage of these gases is

essentially the same at all altitudes but at higher altitudes where the

barometric pressure is lower, there are fewer atoms or molecules of

each of these gases per cubic foot of air. The ‘’thinner’’ air at 10,000 feet

is still 78 percent nitrogen and 21 percent oxygen but there are fewer

molecules of each in a cubic foot of air. At standard temperatures, atmospheric

pressure at sea level is 14.7 Ib per square inch while at 10,000 ft,

atmospheric pressure is only 10 Ib per square inch.

 

So at 10,000 feet you would have to run 4.7-lbs boost just to see the same engine operation (and power/torque curve) normally achieved at sea level.

 

Mr. P.

[vmax2fast]

Mr. P..... You da man That was exactly what I was looking for.

Thus I believe at sea level some of these cummins (w/ 150 hp chip )that can walk away from me at 10k feet would be in for a good race!

[misterp]

Well I know that altitude is DEATH on a diesel; that's why they put turbos on them, to swallow enough air to be able to pull a trailer over the passes. I got an extreme example of this first-hand, my dad bought a brand new Ford Powerstroke years ago (we were both still living in northern CA) and rode with him in his new truck to Reno NV, and that truck (empty, not towing a trailer) was only going 23-mph on I-80 over Donner Pass, no exaggeration. But back in the low altitude central CA valley floor it ran like a bat outta hell. The other vehicles on the freeway were also greatly affected by the altitude, but they were at least going 55; that was a hell of a long drive to Reno let me tell you... with my father no less.

 

Mr. P.

Edited January 5, 2007 by misterp (see edit history)

[vmax2fast]

I've been there too w/ my dad none the less. I was just a kid though, all i remember is looking in his pass. side mirror at the cars getting lost in the black fog of smoke behind us.