GTR Forum banner

1 - 7 of 7 Posts

·
Registered
Joined
·
34 Posts
Discussion Starter #1
I live at 5400 ft(1.6 kilometers or 1 mile) altitude(less barometric pressure/low O2 by 25% compared to Sea level) and need someone that IS a current tuner with ALOT of experience with the PowerFC. My build is as follows: PowerFC w/ hand controller, VG30 air meters, HKS 2530's, HKS hard pipe kit, Pace products intercooler, Power Enterprise 720 cc injectors, HKS fuel pressure regulator, HKS 256/264 cams, HPI exhaust manifolds, Blitz 90 mm full exhaust, Aeromotive A1000 fuel pump. I am the mgr at a shop that installs performance products on cars. Problem is some of the listings inside the Powerfc are in Japanese, and car is having major Turbo shuffling issues, and loading up issues when boost comes on. It will, on occasion, stick the injector duty at 3.2 or there abouts, when completely off the throttle, on decel.. and driver has to get on and off the throttle a few times quickly while at cruise to get rid of misses and fouling. I'm looking for someone that I will call from inside car with a cell phone and will talk me thru a drivability map or set up with PowerFC. We can get car set up with a wide band O2 and dyno for all High horsepower tuning of car, but the driveability and highway cruise and stop and go stuff is a MUST DO for this car for it is street drivin. If it is necc for a wide band for the uk tech to do what is needed for the tuning of this car for slow driving/cruise/idle etc.. it is avail also. I will pay 50 dollars(US) an hour to person who seems most qualified. And international call will be on my wallet. They have to understand the basics of how high altitude makes cars run too rich for a sea level maps, and with boost the turbos tend to make up for some of the lost barametric pressure, but air is still low on Oxygen. Please PM me here with ur overall experience, and we will discuss payment options. Paypal is easiest, but whatever works.
Hans
www.joulespeed.com
 

·
Registered
Joined
·
2,518 Posts
Hans,

AFAIK oxygen concentration is fairly static at around 20.9% at any altitude, so 1 bar of boost will require the same fuel at any altitude.

Clearly the lack of barometric pressure will cause the density of air to change at altitude.

The air flow meters should compensate for the lack of air density as the AFM voltage is a measure of the amount of energy that is required to maintain the AFM element at a given temperature while energy is transferred from the heated element to the passing particles of nitrogen and oxygen. They should, I think, more correctly be referred to as air mass meters.

I think that the humidity % will have an affect as the dry air at altitude will show up as a lower volume of air entering the engine and cause the engine to run weak.

My above comments are not meant to be hard statements of fact, more something to generate a discussion.

You should check your AFM voltages are the same, using your Power FC when the injector duty sticks, there is a possibility you have a wiring problem on your AFM's.

You can also check your AFM voltages with a vacuum cleaner using a plastic bottle to link to the vacuum cleaner.

The standard lambda voltages will also give you good information about how well set up you are around idle and light load.

Cheers

Hugh
 

·
Registered
Joined
·
53 Posts
A guy named Paul on SAU (Skylines Australia) maintains a great Power FC FAQ. He's got a DIY drivability tuning guide.

I'm running a Datalogit with mine and find the information very powerful. Kinda like turning on the lights in a dark room. :D

Good luck,
Dan
 

·
Registered
Joined
·
34 Posts
Discussion Starter #4
Sweet thanks guys... I did find one of my air meters was bad, and that took care of a little of it, still need to get the driveability of it in line.. Now gotta get this HICAS issue fixed.. ugh..always something..lol:flame:
Hans
 

·
Registered
Joined
·
1,761 Posts
Running at higher altitude DOES bring in some different dynamics.

I have run my stage 1 GTR in Johannesburg, South Africa which is 1,7km above sea level. The cars are very dead at this altitude.

You can tend to run lower octane fuels safer, as the cars will not detonate as easily. I can run at 0.7bar on 95RON without any hassles at all. I ran the car on 93RON before also but that did seem to be a little bit on the limit. However, the car was FAR from destroying itself. I am sure if you try 93RON at sea-level you are guaranteed some melted pistons.

Indeed the air is less dense and much more dry. Normally aspirated cars lose 18% (!!) power at this altitude. Turbo cars lose around 6%. (compared to sea-level).
 

·
Registered
Joined
·
1,166 Posts
Running at altitude increases the pressure ratio at compressor for the same manifold `boost` pressure. As the same manifold boost is maintained the charge density is also maintained. This is why turbo`s massively outperform NA at high altitude.

This is all well and good until either you overspeed the compressor due to the higher pressure ratio or you start to choke the turbine side due to the higher flow through the turbine to get the higher tip speed. Don`t forget that higher pressure ratio also means more air heating at compressor and possibly increasing manifold charge temps.

The lower air density at altitdue also effects cooling performance of both rad and intercooler.

You are more likely to det at altitude due to the above. Most OEM calibrations will hold manifold boost and then start to drop it to protect the system. PFC etc does not have this functionality.
 
1 - 7 of 7 Posts
Top