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Discussion Starter #1
Hello All,

I am trying to figure out what it would take to make this tune safest and most effective for my car up at altitude (5500-14000ft). I spoke with the guys at BOE this afternoon and they said it would be best to get some data for them to correctly build the tune for me. I was hoping someone (Phil? :bow:) could shed some more light on exactly what this would entail so I can start working my way to the 270 magic.

Thanks,
Zack
 

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Absolute power does what?
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Zack,

You need to connect up with Frank Amoroso about this as he went through the same issue with a BOE tune. I'm not sure if he bought or borrowed the cables but he logged and flashed his I believe. PM or drop me an email and I'll connect you guys.

I'll forward this to him so he sees it and you guys can update the thread

-Ross
 

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Zack,

Get yourself a wide band o2 sensor, do a baseline dyno...get yourself the tune and then go back for a final dyno. You'll probably find that the tune is fine out of the box. I had a tune from BOE and it was almost spot on, but could have used some minor tweaks.

I ran the BOE tune around Denver all the way up to 13,000ft and it was great. I just found that it could have used some additional tuning mid-revs (4-6k). Phil and the gang will take care of you! :)
 

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Discussion Starter #4
Glad to know a few of the guys I know have had good luck with the tune! Its making me more interested in going through the pain of the dyno and testing. I guess I should probably get out on the track right Ross?
 

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Glad to know a few of the guys I know have had good luck with the tune! Its making me more interested in going through the pain of the dyno and testing. I guess I should probably get out on the track right Ross?
14,000 feet! Now that's hardcore! You planning on running Pike's Peak?

I think a dyno day is a good idea. I missed out on one in Boulder a few years ago...
http://www.lotustalk.com/forums/f108/denver-area-dyno-day-67949/

I think getting Phil out here to tune cars on the dyno though is a GREAT idea and one that I would be in for. I'll ping him to check feasibility. I would VERY MUCH like to have my car tuned in its playground / indigenous habitat. I would also like to get Phil out to HPR. Perhaps we can talk him into schlepping his car out for a NASA event and then have him stick around a few days for some dyno tuning, work, etc.

Thoughts?
 

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Discussion Starter #6
Getting Phil out would obviously be the ideal case. From what I can gather BOE has done a few cars but there are still many unknowns with the altitude. Maybe I will wait and see of anything develops from your end Frank. Please let me know.
 

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Plug Whisperer
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Hi Guys,

Frank turned me on to this thread...

So here's the deal. It's hard and almost impossibe for me to travel for this. There's just no way to justify the $$. Much easier and would be cheaper for people to just send the data logs and then we remote tune. We do this very frequently... I really don't need to be there. If someone wants to invest the dollars on a LM-2 ($350 or so) and some time on the dyno, we can do the custom tuning over a about a week of bouncing some emails around... We're not starting from scratch and the reality is that the tune may be just perfect right out of the box. If it needs some tweaking, the basic data logs are all we need. The dyno is practically an option, as we know what we're looking for in the data logs...

So if you need tune tweaking at altitude, you'll need a stretch of quiet road to run the car out in 4th or a dyno, a KF flash cable, a LM-2 data logger (comes with a wideband 02), a windoz OS on your laptop (or macbook), some patience, and a Lotus :D

Hope that helps,

Phil
 

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Discussion Starter #8
Thanks Phil for chiming in for me. I really appreciate it. I will start looking into the data logging and try and start getting this going
 

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I suspect the tune will require little adjustment. As you lift your foot off the gas pedal, you already create a partial vacuum between the throttle plate and the supercharger input. The tune already adjust the injectors for that reduction in supercharger inlet pressure when the throttle plate is partially or totally closed. At any rate, expect a marked reduction in power over 8k feet. With less air, the ECU must reduce fuel to maintain a correct fuel air ratio. With less fuel and air you will have less power regardless of tune. Turbophil is spot on, a datalogger will absolutely settle my armchair musings, and replace them with absolute fact.
 

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I suspect the tune will require little adjustment. As you lift your foot off the gas pedal, you already create a partial vacuum between the throttle plate and the supercharger input. The tune already adjust the injectors for that reduction in supercharger inlet pressure when the throttle plate is partially or totally closed. At any rate, expect a marked reduction in power over 8k feet. With less air, the ECU must reduce fuel to maintain a correct fuel air ratio. With less fuel and air you will have less power regardless of tune. Turbophil is spot on, a datalogger will absolutely settle my armchair musings, and replace them with absolute fact.
The joy of tuning with a stock ECU is that it does a pretty good job of adjusting for altitude. As for power and altitude you will experience a pretty good drop in power before you hit 8000ft.

For anyone who has ever flown a small piston aircraft you definitely notice a drop in available MP and power as you climb. Lucky for the Lotus owners - ECUs they have barometers built in and instead of grabbing that mixture knob to lean for max power the ECU does it for you automagically when you're on top of the mountain...

-Michael
 

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Cyclingdude723,
Naw, my car and my kids absorb all my "investment opportunities". However, I do live at about a mile of altitude and take jaunts to about 8500 feet periodically. For me, above 9000 feet is the great unknown. For the folks in Colorado, they might be able to give you a better idea of the characteristics at higher altitudes.
 

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Discussion Starter #13
I also live in Colorado. I have taken my exige to the top of pikes peaks (boy did I have about 15hp up there!) the characteristics are almost identical to those of the human body. I used to be a professional cyclist and when I did a few power studies my heartrate and power climbed and decreases respectively as a trudged up mt Evans. Now I guess it's just time to figure out what pulley would give me "stock" boost at 5000ft starting level
 

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You can achieve stock boost (sea level equivalent) at 5000 feet. What you will not achieve is stock boost *and* stock (sea level) intake air temperature IAT at 5000 feet. The additional "work" the supercharger is performing will equate to a higher IAT. But to be fair, I considered the same thing because I live at a mile of altitude. IAT difference is what kept me from following through with the smaller pulley plans. A smaller pulley can also overspin the supercharger, which will shorten it's useful life.
 

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Discussion Starter #15
I may be missing something here, but with the supercharger it spins at X rpms with a given pulley. So if there is less air to compress you get less boost. Thus with a smaller pulley you can get the supercharger to spin at Y which will help to compress more of the thinner air and thus give a more "stock" level of boost. Why would your IAT change if you increased the supercharger speed? Are you assuming that since the supercharger is spinning fast it will create more heat? Because I agree, but you could also supplement the airflow to the intercooler to help alleviate this issue. Maybe I'm missing something here, but these were my assumptions with the system.
 

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Ahhh, well, I am non-intercooled, so extra IAT is a deal killer for me. With thinner air, the cooling efficiency of the intercooler is reduced (fewer atoms carrying the heat away). You might be able to correct with greater flow over your intercooler (depending on your mechanism). Heat is also a factor of the ratio of supercharger inlet air pressure versus outlet pressure. All the heat energy in the air gets squeezed into a smaller space, raising the temp (charles gas law). There is also a mechanical aspect of the increased temp as well, it is related to rotational rate of the supercharger. Somewhere around 10 thousand feet, you lose about 4.6 pounds of inlet pressure, so the supercharger has to create a 10.6 pound differential to be equal to sea level 6 pounds of boost. Atmospheric pressure is around 8.5 pounds per square inch at 14k feet, requiring about 12.2 pounds of differential boost to be equal to 6 pounds of boost at sea level. Enough of the math, I think you get the picture. I didn't even touch on the factor that the ratio of oxygen to other gasses shifts as altitude goes up, so the same amount of air is not the same amount of oxygen.
 

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Discussion Starter #17
Alright so we were on the same page. The lack of intercooler is what hurts your IAT as the efficiency decreases and heat increases. I guess there isn't a great method I add cooking to yours is there?
 

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The point which I was trying to make is, even with an intercooler, you might not be able to get the same boost with a smaller pulley and the same IAT. Even if you get the same air pressure in your intake manifold, the percentage of oxygen drops as altitude goes up. The only boost method which does not care about altitude is nitrous. The shot gives the same hp added with no consideration of altitude. But, due to tuning challenges for nitrous, I respect it, and tend to not endorse it. Some people have had great luck with it, some have had amazingly bad results.
 
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