AlkyControl and High Altitude

[Mountain GN]

First off, Julio is THE MAN!

I've had my AlkyControl kit on for about a month now, and my knock-retard problem is history.

Another issue has now surfaced. I live at an altitude of about 5600 feet, but I commute down to sea level. I'm running about 20 lbs of boost, and when I jump on it while at high altitude, it really sputters when the alky hits. I've turned the gain knob down, slightly, but the problem still exists. I know I probably need less Alky at altitude because the octane requirements are lower the higher up you go.

Question is, what's the best way to tune this problem out? Also, are there some good compromise settings that will work both at sea level and 5600 feet?

Mods are in sig!

 

[Razor]

Well if the alcohol is spraying into your motor.. thats one part. the next part is to get it dialed in.

If you turn the alky off.. does it get better? What are the O2's when you get into the issues? It could very well be your running the engine rich at WOT.. and when you go into elevation.. it makes it worse.

I dont have any experience tuning in higher elevations.. but the basics will apply..

hth

 

[BDC]

This is an interesting one. Part of my business involves travelling around the country doing tuning. Sometimes I wind up out in Denver and Colorado Springs, CO doing some cars there. The air is very thin there and it seems to throw everything off. The barometric pressure in CoSprings is around 790mb and in Denver about 830mb or so from what I recall. Basically, what it amounts to is that at 0" of vacuum (engine off), a MAP sensor up there will read 5 to 6" of vacuum. I remember calling Razor about this to see if he'd ever heard of it and it turns out that the MAP sensor reading is indeed valid. The sensors are calibrated for sea-level altitude where most everyone is so they'll read right at or right around 1.66VDC at 0", I believe. It's done a number on how I'm able to tune stuff so I'm a bit at a loss also as to how you'd solve this. The dramatic difference from high altitude back down to low will most definitely throw the fuelling requirements off to sustain proper air/fuel ratios for loads in boost since the density of air that's being pressurized by the turbo is different. I think this will therefore louse up the requirements for alcohol injection as well. I wish I could think of a better answer to this but I'm not sure how you'd go abbout getting around it.

B

 

[howracer]

FWIW,

as the altitude rises from sea level the amount of oxygen molecules per volume decreases on a non-linear progressive basis.

oxygen per volume determines everything in that if we have less oxygen we have less power etc.

tuning regiman should not be effected.

you tune for knock and egt and let the boost, timing and fuel fall where they need to be to get good numbers. if you are above sea level you will be using less pump and meth, and of course make less power. you will still be tuning for the same egt and knock threshold.

howard coleman

 

[Razor]

I was last night at the track and was talking with Matt Scraton about the tuneup on their car.. its a 6.50/217mph.. they tuned their car at Denver,, ran the numbers.. back here the program they used in Denver doesnt work. Nor does the English Town one either.. they start from scratch figuring out the car.

I guess tune the car at 3200 elevation.. it will be off at 5200 and at sea level.. but tuning at 5200.. it will be way off at sea level.

I dont blame the methanol on the issues, since its only a very small portion of your fuel tables.. I would look at fueling issues with the chip.. and concentrate on getting a tuneup at mid elevation.. bet the upper and lower elevation will be close enough to not cuase concern.

So.. the Scraton answer.. "Dont know.. we're trying to figure it out."