Here is my understanding of the issues surrounding Diesel engines when used at altitude.
A few years ago I took a trip in the mountains in Bolivia, which involved being driven through some very spectacular mountain scenary. At one point we were climbing up a hill and I was very aware that the vehicle seemed to have very little power - not like it had been the previous day. I hadn't realised until then that we were at approximately 5000m (yes, metres not feet!) of altitude, and so I now had reason to think about the whole issue of engines, turbochargers and altitude. At the end of the day it's all about how much oxygen you can get into the cylinder. If you turbocharge the engine, you get more, and if you're at altitude, you get less. If you use a turbocharger at altitude, the two effects partially cancel each other out. But basically, for a given engine and a given fuel, you will always get less power at higher altitude than at sea level, for this reason. Changing fuel will not be able to 'counteract' the altitude, nor will fitting a turbocharger - you will only get the same benefits you would get anyway at sea level. (These may of course prove to be useful benefits at high altitude if the engine would otherwise be underpowered, for example). Of course, a consequence of less oxygen in the cylinder is that the maximum amount of fuel you can burn will be less (this is why you get less power!). Depending on how sophisticated your injection system is, it may not be aware of the fact that there is less oxygen, and may pump too much fuel - with the result that you get lots of soot and incomplete combustion. If your injection system does not know about the altitude, you may be able to adjust it to reduce the maximum fuel charge it delivers. Alternatively, if you don't press the accelerator pedal so far you will reduce the fuel delivered, hence reducing the soot. The only way to get lots of power at high altitude is to fit a bigger engine to compensate. This will then be seriously overpowered when used at sea level. This is one of the drawbacks of internal combustion engines, and they generally need to be set up correctly for the altitude they will be driving at. I'm not an expert on fuel injection systems, but I wouldn't be surprised if modern systems sold in mountainous regions had a means of automatically reducing the maximum fuel delivery when at altitude. As an aside, can anyone tell me what the air pressure is at 5000m? There were some volcanic steam vents in this area and I was surprised that I could put my hand in the steam without it scalding - I guess this means that the water was boiling at around 50-60 degrees, rather than 100. Hope this helps, Donald --- Greg Harbican <[EMAIL PROTECTED]> wrote: > It is a HP issue as well. If I can increase the HP, I can lean it > out a > little, so that I don't get as much soot. > > The Diesel engine is naturally aspirated engine, it only has a > compression > near 14 ( normal for this engine type ), with the thin air (above > 5000 ft ), > and lower O2 of the altitude - so, the combination of natural > aspiration, > low compression, thin air, and lower O2 is a killer no matter what > fuel I > use. I actually was talking to a State Diesel Emissions Tech, and he > liked > BioDiesel, but, where it can be found in the state, it is only a BD20 > blend, > and he didn't think that BD100, would solve my issues even if I could > get > some ( or had the ability to make it - still looking for parts and a > good > source of oil ) > > I have already lost 15% to 25% of the rated HP ( 98 HP at sea level > ), even > with the injectors near full open ( or is it the metering pump that > measures > how much fuel is injected? ). > > So I'm trying to figure out low cost ways of raising the O2 levels to > kill > the soot, or raising the HP so I can cut lean out the fuel to kill > the soot > levels. > > I'm getting about 20 mpg, for my Land Cruiser as it is, which is not > bad at > all for it's age ( 1985 model ), it's the engine model that is > causing the > issues, because it just does not breath well over 3000 ft. > > Greg H. > > ----- Original Message ----- > From: "Christopher" <[EMAIL PROTECTED]> > To: <biofuel@yahoogroups.com> > Sent: Thursday, August 12, 2004 16:28 > Subject: RE: [biofuel] High altitude diesel issues emissions > > > > Hi Greg: > > > > If you try biodiesel you'll get far less soot. > > > > regards, > > Chris > > > > -----Original Message----- > > From: Greg Harbican [mailto:[EMAIL PROTECTED] > > Sent: Saturday, August 07, 2004 3:06 PM > > To: biofuel@yahoogroups.com > > Subject: Re: [biofuel] High altitude diesel issues emissions > > > > > > Turbocharging will cause steeper emissions requirements ( even less > soot > > allowable ). All I have is a naturally aspirated engine, putting > a turbo > > on it, will cost almost as much as the Land Cruiser itself, and I > don't > have > > any near that kind of money. The cost to gain ratio is too high, > the > > turbo's for the engine would not give all that big a difference, in > the > > horsepower, only an effective increase of 15-25 HP or so. > > > > > > Funny thing, last year, it didn't have a problem at all, passing > emissions. > > > > > > The diesel emissions around here are geared for the larger engines > or > newer > > engines with higher HP, that can handle the altitude. > > > > Greg H. > > > > ----- Original Message ----- > > From: Derek Sceats > > To: biofuel@yahoogroups.com > > Sent: Saturday, August 07, 2004 10:41 > > Subject: RE: [biofuel] High altitude diesel issues emissions > > > > > > Have you taken steps to improve the intake system? Is your > engine > > turbocharged (preferably with an intercooler)? This would help > get more > > air > > into the system. Just my 2 cents worth. > > Derek > > > > -----Original Message----- > > From: Greg Harbican [mailto:[EMAIL PROTECTED] > > Sent: Friday, August 06, 2004 9:20 PM > > To: biofuel@yahoogroups.com > > Subject: [biofuel] High altatude diesel issues emmisions > > > > > > > > One of the problems I have is I have too much soot in the > emissions and > > still retaining the horsepower of my Land Cruiser. The issue > seams to > be > > with the lack of O2 at the higher altitude, so increasing the > amount of > > fuel > > to the injectors would not solve the problems ( in fact it would > make my > > mileage worse ). > > > > Would leaving the some of methanol in or adding more help, since > it is > one > > of the additives that increase the O2 content of the fuel ( so I > have > > heard )? > > > > I was also wondering if it would help in the winter, reducing the > amount > > gelling or otherwise make the fuel easier to ignite in the cold? > > > > Greg H. > > > > [Non-text portions of this message have been removed] > > > > > > > > > > > > Biofuel at Journey to Forever: > > http://journeytoforever.org/biofuel.html > > > > Biofuels list archives: > > http://infoarchive.net/sgroup/biofuel/ > > > > Please do NOT send Unsubscribe messages to the list address. > > To unsubscribe, send an email to: > > [EMAIL PROTECTED] > > Yahoo! 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