Hi all! So I've got my trusty HZJ80, with the solid 1HZ engine about to tick over 500,000kms on the odometer. It's naturally aspirated, no turbo, which is how I like them. Fuel pump and injectors done a couple of years back. Running great, no issues. However, I've created one I'm currently split about how to solve.
I live in Australia, which is pretty notoriously flat. The highest point on the continent a road can reach is 1840m (6000ft) above sea level, and I've been there in my 80. Having done that drive, and while being a bit down on power still fully capable, I was satisfied my 80 didn't need to worry about altitude for anywhere I was going to take it. Five months ago however I moved house. My previous height above sea level was 32m (100ft), whereas I now live around 700m (2300ft) above sea level, and most days I'm driving further up the mountain to 1000m (3300ft), and every week or so back down to about 30m again. Things seemed ok, until summer hit. In the Australian summer, even at my altitude, the temps get to around 35c (95f).
So to cut to the chase, I'm getting quite noticeable black smoke now. I know this indicates I'm running a bit rich, too much fuel vs air. Smoke is black, not blue. Happens under high load when climbing steep sections of road, but with that 700m to 1000m climb I'm doing that's a pretty regular occurrence. I believe the hotter air in the summer is less dense than the cool air I was getting in the winter, which is magnifying the effect of altitude. Rough calculations tell me air density is around 20-25% lower than before I moved. When I drive down the mountain, black smoke is gone. As I climb back up I see it increase as I go higher.
So I'm pretty satisfied I know what's going on. I'm conflicted however on what to do about it. The smoke isn't really a "problem", but it's making me pretty self-conscious driving my rig, when I see a trail of black smoke behind it. I'd like to reduce or eliminate it. Here are the options I've thought about so far:
1. Back off the fuel screw. This would reduce my power across the board. Not thrilled on the idea, but it should eliminate my black smoke. I can currently just hold the speed limit of 80kph (50mph) up the steep sections when I hit them right and rev high in 3rd, but I expect that would stop if I back off the fuel, which would probably see me dropping down to 2nd and doing 50kph max, not to mention that loss in power even when I'm back in winter or down the mountain at 32m elevation again. Seems wasteful.
2. Fit a turbo. The forced induction will solve my problems instantly. I'll have better aspiration at higher altitudes, and depending on tuning, more power. I'm not keen on this idea. I may be one of the only people who definitely doesn't want a turbo, but what I like about my 1HZ is its simplicity and rock solid reliability. It feels to me like a turbo would kill that. I'll have to worry about EGTs, I'll have two external oil lines to worry about, and this is an engine with half a million kms, running 1HZ pistons and conrods. Seems like a quick way to kill a good engine. Maybe I can tune it to effectively not be doing anything at sea level, and have it ramp up as my altitude increases?
3. Experiment with the HAC (High Altitude Compensator) device for the 1HZ fuel pump. I've seen people talk about it here, but I have yet to see anyone who said "I fitted one and it made things better". I'm interested in any experience and/or thoughts about this, because it seems like a good option I'm seriously considering. One potential reason for hesitation is I do river crossings with reasonable frequency, sometimes up over the bonnet a bit, and I have a snorkel for this reason. My understanding is the HAC is open to atmosphere (so it can work) and I'm not sure at this point if that means it going under some water would potentially suck water into my pump. I'm guessing not otherwise it would suck in air into the fuel system, there are membranes which I assume fully separate things, but I'd be curious to know of the implications of giving the HAC system a good dunking. Same concerns about a turbo too.
4. Ignore it.
I'm interested in any and all thoughts here, and if there are any options I'm missing. If I had potential for higher altitudes still, a turbo would become a no-brainer, but since the absolute maximum height on this continent is only another 840m above what I go daily, it seems like using a cannon to kill a mosquito. Maybe if it's done not for power, just for altitude compensation, and tuned as such, a lot of my pre-existing concerns about turbos don't apply? As I said, interested in people's thoughts. I'm not after more power, but ideally I don't want to lose any more. I just want to keep what I have, and not worry about black smoke depending on the weather and the direction I'm driving that morning.
I live in Australia, which is pretty notoriously flat. The highest point on the continent a road can reach is 1840m (6000ft) above sea level, and I've been there in my 80. Having done that drive, and while being a bit down on power still fully capable, I was satisfied my 80 didn't need to worry about altitude for anywhere I was going to take it. Five months ago however I moved house. My previous height above sea level was 32m (100ft), whereas I now live around 700m (2300ft) above sea level, and most days I'm driving further up the mountain to 1000m (3300ft), and every week or so back down to about 30m again. Things seemed ok, until summer hit. In the Australian summer, even at my altitude, the temps get to around 35c (95f).
So to cut to the chase, I'm getting quite noticeable black smoke now. I know this indicates I'm running a bit rich, too much fuel vs air. Smoke is black, not blue. Happens under high load when climbing steep sections of road, but with that 700m to 1000m climb I'm doing that's a pretty regular occurrence. I believe the hotter air in the summer is less dense than the cool air I was getting in the winter, which is magnifying the effect of altitude. Rough calculations tell me air density is around 20-25% lower than before I moved. When I drive down the mountain, black smoke is gone. As I climb back up I see it increase as I go higher.
So I'm pretty satisfied I know what's going on. I'm conflicted however on what to do about it. The smoke isn't really a "problem", but it's making me pretty self-conscious driving my rig, when I see a trail of black smoke behind it. I'd like to reduce or eliminate it. Here are the options I've thought about so far:
1. Back off the fuel screw. This would reduce my power across the board. Not thrilled on the idea, but it should eliminate my black smoke. I can currently just hold the speed limit of 80kph (50mph) up the steep sections when I hit them right and rev high in 3rd, but I expect that would stop if I back off the fuel, which would probably see me dropping down to 2nd and doing 50kph max, not to mention that loss in power even when I'm back in winter or down the mountain at 32m elevation again. Seems wasteful.
2. Fit a turbo. The forced induction will solve my problems instantly. I'll have better aspiration at higher altitudes, and depending on tuning, more power. I'm not keen on this idea. I may be one of the only people who definitely doesn't want a turbo, but what I like about my 1HZ is its simplicity and rock solid reliability. It feels to me like a turbo would kill that. I'll have to worry about EGTs, I'll have two external oil lines to worry about, and this is an engine with half a million kms, running 1HZ pistons and conrods. Seems like a quick way to kill a good engine. Maybe I can tune it to effectively not be doing anything at sea level, and have it ramp up as my altitude increases?
3. Experiment with the HAC (High Altitude Compensator) device for the 1HZ fuel pump. I've seen people talk about it here, but I have yet to see anyone who said "I fitted one and it made things better". I'm interested in any experience and/or thoughts about this, because it seems like a good option I'm seriously considering. One potential reason for hesitation is I do river crossings with reasonable frequency, sometimes up over the bonnet a bit, and I have a snorkel for this reason. My understanding is the HAC is open to atmosphere (so it can work) and I'm not sure at this point if that means it going under some water would potentially suck water into my pump. I'm guessing not otherwise it would suck in air into the fuel system, there are membranes which I assume fully separate things, but I'd be curious to know of the implications of giving the HAC system a good dunking. Same concerns about a turbo too.
4. Ignore it.
I'm interested in any and all thoughts here, and if there are any options I'm missing. If I had potential for higher altitudes still, a turbo would become a no-brainer, but since the absolute maximum height on this continent is only another 840m above what I go daily, it seems like using a cannon to kill a mosquito. Maybe if it's done not for power, just for altitude compensation, and tuned as such, a lot of my pre-existing concerns about turbos don't apply? As I said, interested in people's thoughts. I'm not after more power, but ideally I don't want to lose any more. I just want to keep what I have, and not worry about black smoke depending on the weather and the direction I'm driving that morning.
