Virtual Dyno Day!

[stripSHO]

On my 391/470 dyno run, I pulled up my data log.

Ambient Air Temp: 78 degrees
Fuel: 91 octane mixed with Torco T85 for E30

Load x RPM x .00471

1.62 x 6293 x .00471 = 48.01

What's your STFT+LTFT at that point?

 

[SM105K]

What's your STFT+LTFT at that point?

.92 + 1.05 = 1.97

 

[FiveLeeter918]

.92 + 1.05 = 1.97

Average them dont just add together

 

[SM105K]

Average them dont just add together

Just following directions. STFT peaked at 1.01 but stayed in the .94 range most of the pull. LTFT held at 1.05 for the pull.

.94 + 1.05 = 1.99

FTIW, this was tune was a revision, loaded while on the dyno, and full pulled.

 

[stripSHO]

Just following directions. STFT peaked at 1.01 but stayed in the .94 range most of the pull. LTFT held at 1.05 for the pull.

.94 + 1.05 = 1.99

FTIW, this was tune was a revision, loaded while on the dyno, and full pulled.

Yeah sorry wasn't very specific was I? Yes add them, then subtract 2, multiply by 100 and that's your % error. So your airflow figure should be pretty accurate. Multiply by .97 and that should be REALLY CLOSE to reality. ~46.5 lb/min actual flow.

 

[stripSHO]

Finally decided to give this a try with a couple logs from my tunes. I also managed to scrounge up a partial stock pull so I added that in for a reference baseline.

Mods: none that matter (MSD coils, K&N Drop-in)

 

[stripSHO]

Just realized I'm probably the only one that turned off the app's default +9% dynojet correction factor. Here's the same graph with the default settings for apples to apples comparison

 

[stripSHO]

Spent some time tonight finally working on my tune for C10, cut with 40% ethanol. Or, C40, as I've been calling it. This virtual dyno thing has actually turned out to be fun to use, and helpful too. With this blend my engine seems essentially knock-proof in the lower boost regions (10 psi) so I couldn't just keep adding timing until I found the knock limit, and needed some way of gauging whether I was still going in the right direction. I didn't include it on the graph but I hit 377 whp at only 10 psi with this fuel!

I was anticipating being able to squeeze another 15-20 peak hp using the race gas, and it appears I was able to meet that goal. But I also gained a healthy +40 lbft of torque across most of the RPM range. There may be more left in the midrange yet- my driver demand torque tables where only set at 575 lbft, and the ecu was seeing that at about 3500 RPM so I've raised the limit to 650 lbft and we'll see where she goes next time.

All these trends match pretty closely to what the ECU's torque calculations are doing, and the uncalibrated butt dyno agrees with the results as well


p.s. @High on Ethanol all three of these tunes have identical 46 lb/min airflows in case you're wondering

 

[Ecoboost_xsport]

OK, tried to revisit this and got rid of the junk before 2k rpm and all runs where in 3rd gear.

All else is identical but I just can't put much faith in how accurate these are. All my charts always have a dip in the mid-range and wondering if that's a result of the tuning or I'm data logging incorrectly.

First run/tune on e85. Was the first tune and intended to be somewhat "light/easy":


Next revision. As I wasn't getting pure e85 from the pump, Brad decided to do an "e75" tune to allow for some crap at various pumps. This is the tune where it was discovered the low pressure fuel couldn't keep up:


After the BAP installation and no tune revision:


Run 01 after a tune revision (and this is where it starts going off the rails):


Run 02...jeeez..no WAY this is even close to accurate...


It's so wild, I don't even feel like I can use it as a tool to identify improvements...

That dip I get in all my tunes around the 3500 to 4000 rpm range...is that normal? Most dyno charts I'm used to seeing have a general consistant climb and drop off...

Wondering if I should smooth all the way to 6.

IDK what to make of all this...LOL...but 902ft-lbs sounds pretty bad ass in my book, haha

 

[High on Ethanol]

I just log #/min airflow and chart it out then x10 for power, and use the 5252 x Hp ÷ rpm=torque equation for torque.

 

[stripSHO]

OK, tried to revisit this and got rid of the junk before 2k rpm and all runs where in 3rd gear.

All else is identical but I just can't put much faith in how accurate these are. All my charts always have a dip in the mid-range and wondering if that's a result of the tuning or I'm data logging incorrectly.

First run/tune on e85. Was the first tune and intended to be somewhat "light/easy":


Next revision. As I wasn't getting pure e85 from the pump, Brad decided to do an "e75" tune to allow for some crap at various pumps. This is the tune where it was discovered the low pressure fuel couldn't keep up:


After the BAP installation and no tune revision:


Run 01 after a tune revision (and this is where it starts going off the rails):


Run 02...jeeez..no WAY this is even close to accurate...


It's so wild, I don't even feel like I can use it as a tool to identify improvements...

That dip I get in all my tunes around the 3500 to 4000 rpm range...is that normal? Most dyno charts I'm used to seeing have a general consistant climb and drop off...

Wondering if I should smooth all the way to 6.

IDK what to make of all this...LOL...but 902ft-lbs sounds pretty bad ass in my book, haha

The thing to understand is that ultimately all it is doing is looking at rpm over time and applying some calculus. With automatic transmissions the huge torque spikes at the beginning are normal due to RPM climbing rapidly until the torque converter reaches stall speed. Not accurate, but normal.
The 4k rpm dip is not normal though IMO. I'd be looking at the logs to see what might be occurring at that point and go from there. Maybe you're hitting the same hill in the road at that point. Maybe your torque converter is locking up at that point. Maybe it's VCT related. Maybe it's fuel related. Seems to be a boost spike right before that point...

 

[skyshadow07]

Did you do all this on the same road? The roughness of the road translates into the graph.

 

[Ecoboost_xsport]

Did you do all this on the same road? The roughness of the road translates into the graph.

Yes, I have a street in Mexico that I do all my data logging....hmmmm.

 

[skyshadow07]

I was having a dip in my logs and I discovered from forums that dips or bumps in the road will show up on the graph.

 

[Ecoboost_xsport]

Interesting...it's a pretty flat road but I think has a very gradual down then up...how significant does that dip have to be for it to effect the data?

 

[stripSHO]

Interesting...it's a pretty flat road but I think has a very gradual down then up...how significant does that dip have to be for it to effect the data?

Load some pulls prior to e85 and see if you still have that giant dip. That will at least give an idea if it's tune related or some external influence.

 

[FiveLeeter918]

Interesting...it's a pretty flat road but I think has a very gradual down then up...how significant does that dip have to be for it to effect the data?

Virtual Dyno only looks at input from a few sensors to calculate output, I'd recommending dumping those values into Excel and plotting them to see if one of them dumps. Are you getting throttle closure mid pull?

 

[Ta2dResqr]

I questioned it as well but this is what my buddy who is a Ford engineer gave me. Confirmed by a few other places online.

I found a couple places with other numbers. Would be interesting to see if it makes your numbers closer to accurate or farther off.

This has a weight for the 2015 model as 4343lbs (Ford Media site)
https://www.google.com/url?sa=t&rct...HO_Specs.pdf&usg=AOvVaw0Sv1gwhmmgR1IcsSpYYaAR

This has a drag coefficient of 0.3 and a frontal area of 2.48m^2 or 26.6945sqft. (Both are estimated)
https://www.automobile-catalog.com/auta_details1.php

 

[Ecoboost_xsport]

On my 391/470 dyno run, I pulled up my data log.

Ambient Air Temp: 78 degrees
Fuel: 91 octane mixed with Torco T85 for E30

Load x RPM x .00471

1.62 x 6293 x .00471 = 48.01

Old post from this thread, but was curious...where does the "0.oo471" come from or what does it represent? Some sort of constant?

 

[Ecoboost_xsport]

Yeah sorry wasn't very specific was I? Yes add them, then subtract 2, multiply by 100 and that's your % error. So your airflow figure should be pretty accurate. Multiply by .97 and that should be REALLY CLOSE to reality. ~46.5 lb/min actual flow.

This interests me but wanted to get some clarification on this error factor. The way you describe it sounds like it would be written out like this:

((STFT+LTFT)-2)100

Using @SM105K 1st set of results, that would be ((0.92+1.05)-2)100 = -3% error
Using his 2nd set of results, that would be ((0.94+1.05)-2)100 = -1% error

Trying to understand where you got the 0.97 from. I'm guessing you meant that is the correction factor gained from the error and written more like this (2-(STFT+LTFT))100?

That would get you that 3% error (or a 0.03 error factor) from his 1st set of results from (2-(0.92+1.05))100 and this would ultimately give you the 0.97 correction factor (1.00-error factor) you'd use to multiply the raw airflow data by?

Just wanted to be sure. @FiveLeeter918 mentioned averaging STFT and LTFT, using the same values from @SM105K

(0.92+1.05)/2

which would give you a correction factor of 0.985 instead of 0.97. I'm sure I'm splitting hairs here, but just curious. Is this just two ways to skin the same cat with each method having negligible differences? Thanks