High Altitude PTF Custom Tune

The_Dude · 06-10-2014, 11:19 PM

Almost 6000ft ASL, 77F, 91 Octane fuel. Stage 2+ FMIC, PTF e-tune.

340/380.

Anyone else at high altitude have a comparable dyno for me to perform a comparison with?

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foghat · 06-11-2014, 07:44 AM

Is Virtual Dyno Accurate? See my sig for Dynojet numbers and mods. About 3500ft - my numbers are corrected.

The_Dude · 06-11-2014, 09:53 AM

Virtual Dyno is like any other tool and depends greatly on accuracy of the input numbers, especially weight. It also requires a flat stretch of road with no bumps. As you can see two separate pulls are almost identical. I used it on my Evo VIII and when I dyno'd it the numbers were withing 5hp/5tq which is about the margin of error from one pull to the next.

I don't believe in corrected numbers as the SAE correction factor doesn't take into account forced induction engines. I agree altitude will make the turbos work harder (more heat) for a given boost pressure, but nowhere near what the correction formula implies.

foghat · 06-11-2014, 06:16 PM

Quote:

Originally Posted by The_Dude

Virtual Dyno is like any other tool and depends greatly on accuracy of the input numbers, especially weight. It also requires a flat stretch of road with no bumps. As you can see two separate pulls are almost identical. I used it on my Evo VIII and when I dyno'd it the numbers were withing 5hp/5tq which is about the margin of error from one pull to the next.

I don't believe in corrected numbers as the SAE correction factor doesn't take into account forced induction engines. I agree altitude will make the turbos work harder (more heat) for a given boost pressure, but nowhere near what the correction formula implies.

My correction factor on the dynojet was about 14%, which would put me at about 350/395 uncorrected.

If those are uncorrected numbers, that is very good at your altitude - though it is tough comparing dyno numbers at the best of times. I'd be curious to see what you put down on a dyno compared to the virtual dyno.

The_Dude · 06-11-2014, 08:37 PM

Those are uncorrected numbers. The corrected numbers were 420/470 using 24.51 inHg and 77F. I don't believe my numbers are that high.

foghat · 06-11-2014, 09:21 PM

Seems a little high to me. 420/470 would definitely be at the upper end of FBO. Probably even a bit beyond, especially with 91 octane.

But whatever, car is running well and dynos are meant as tuning tools, even though they are often used for bragging rights.

Did you get any baseline numbers? The delta tells the story.

foghat · 06-11-2014, 09:57 PM

It looks like the dynojet profile on virtual dyno auto applies a 9% correction factor? Not sure what that 9% is vs. checking off the SAE checkbox.

At any rate, I plugged in my numbers. I don't know what the total weight would be so I used the same 3618 as you. As per my dynojet file, the in/Hg was 26.6 and air temp 89F

With these parameters I put down dynojet uncorrected numbers of 357/411 and corrected of 404/465.

So indeed, very close to what the actual dynojet said.

The_Dude · 06-12-2014, 12:00 AM

The multiplier is to bring the calculated numbers inline with a dynojet, as is the multiplier for lower reading mustang dynos. This was based on a lot of empirical virtual dyno vs actual dyno comparisons.

Going by your higher octane and slightly lower elevation it seems that my lower hp/tq numbers are about in line with expectations.

06-10-2014, 11:19 PM	#1
The_Dude Enlisted Member 0 Rep 41 Posts Drives: Evo VIII, n54 135i 6mt Join Date: Sep 2007 Location: Four Corners, NM iTrader: (1)	High Altitude PTF Custom Tune Almost 6000ft ASL, 77F, 91 Octane fuel. Stage 2+ FMIC, PTF e-tune. 340/380. Anyone else at high altitude have a comparable dyno for me to perform a comparison with? [IMG][/IMG]
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06-11-2014, 07:44 AM	#2
foghat Captain 59 Rep 913 Posts Drives: 2008 135i Join Date: Jun 2009 Location: Great White North iTrader: (1)	Is Virtual Dyno Accurate? See my sig for Dynojet numbers and mods. About 3500ft - my numbers are corrected.
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06-11-2014, 09:53 AM	#3
The_Dude Enlisted Member 0 Rep 41 Posts Drives: Evo VIII, n54 135i 6mt Join Date: Sep 2007 Location: Four Corners, NM iTrader: (1)	Virtual Dyno is like any other tool and depends greatly on accuracy of the input numbers, especially weight. It also requires a flat stretch of road with no bumps. As you can see two separate pulls are almost identical. I used it on my Evo VIII and when I dyno'd it the numbers were withing 5hp/5tq which is about the margin of error from one pull to the next. I don't believe in corrected numbers as the SAE correction factor doesn't take into account forced induction engines. I agree altitude will make the turbos work harder (more heat) for a given boost pressure, but nowhere near what the correction formula implies.
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06-11-2014, 08:37 PM	#5
The_Dude Enlisted Member 0 Rep 41 Posts Drives: Evo VIII, n54 135i 6mt Join Date: Sep 2007 Location: Four Corners, NM iTrader: (1)	Those are uncorrected numbers. The corrected numbers were 420/470 using 24.51 inHg and 77F. I don't believe my numbers are that high.
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06-11-2014, 09:21 PM	#6
foghat Captain 59 Rep 913 Posts Drives: 2008 135i Join Date: Jun 2009 Location: Great White North iTrader: (1)	Seems a little high to me. 420/470 would definitely be at the upper end of FBO. Probably even a bit beyond, especially with 91 octane. But whatever, car is running well and dynos are meant as tuning tools, even though they are often used for bragging rights. Did you get any baseline numbers? The delta tells the story.
	Appreciate 0 Quote

06-11-2014, 09:57 PM	#7
foghat Captain 59 Rep 913 Posts Drives: 2008 135i Join Date: Jun 2009 Location: Great White North iTrader: (1)	It looks like the dynojet profile on virtual dyno auto applies a 9% correction factor? Not sure what that 9% is vs. checking off the SAE checkbox. At any rate, I plugged in my numbers. I don't know what the total weight would be so I used the same 3618 as you. As per my dynojet file, the in/Hg was 26.6 and air temp 89F With these parameters I put down dynojet uncorrected numbers of 357/411 and corrected of 404/465. So indeed, very close to what the actual dynojet said.
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06-12-2014, 12:00 AM	#8
The_Dude Enlisted Member 0 Rep 41 Posts Drives: Evo VIII, n54 135i 6mt Join Date: Sep 2007 Location: Four Corners, NM iTrader: (1)	The multiplier is to bring the calculated numbers inline with a dynojet, as is the multiplier for lower reading mustang dynos. This was based on a lot of empirical virtual dyno vs actual dyno comparisons. Going by your higher octane and slightly lower elevation it seems that my lower hp/tq numbers are about in line with expectations.
	Appreciate 0 Quote