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Discussion Starter #1 (Edited)
Tuning The VVT Using The Datalogit

There has been discussions around tuning the VVT and lift transition, so I thought I would post some information for the tuners out there who want to tune their VVT using the PFC and Datalogit. This tuning method is what I use and what you do and how you do it is up to you.

Background:
The method I used to tune my VVT is based on the simple fact that better breathing means more air in the engine. More air in the engine means you can add more fuel at the right mixture and produce more power. Basically, the amount of airflow through the engine is related to the amount of horsepower produced at the wheels, therefore by tuning for best airflow you theoretically should be able to come very close to the optimum VVT power tune. I
 

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Can this method be adapted to using a scan tool that measures g/sec of air from the MAFS and a camcon for adjusting VVT? If so, any recomendations?
 

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Very nice writeup Torqued. I'll be playing around with this on the weekend, this should help out. This should be a sticky.
 

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Excellent work. I'll put together a spreadsheet that people can download to do this type of tuning.

The one question I have relates to:
Torqued said:
I found it best to add a moving average of 3 data points to remove noise and smooth the graph.
I see what you've done, but I just want to make sure that what you're graphing is Diff + Rolling Diff
 

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Well I set up a spreadsheet, which I named VVT Tune and you can download it here to use for this:

http://users.ameritech.net/jesse11/VVT_Tune.xls

I have to say that the second order term in the polynomial can't be ignored. In fact, I had to make the trendline equation display a large number of decimal places in order to get anything useful out of it.

You're going to have to play around with scales and other things, but that's a working sheet anyways. You can see a log from a 4th gear pull from around 2500 rpm to redline. Take a look at my normalized AFL V plot and you can see the massive torque dip from about 5500-6500 rpm :thumbdown

Some interesting telemetry I pulled off of my log...

In the span of 14.671 seconds, I went from:

3117-8571 rpm
38-110 mph

To give you a better idea of how hard a turbo GT-S pulls in lift in 4th gear, the car accelerated from 6448-8571 rpm, which is 81-110 mph in 6.8 seconds.
 

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Jesse IL said:
Well I set up a spreadsheet, which I named VVT Tune and you can download it here to use for this:

http://users.ameritech.net/jesse11/VVT_Tune.xls

I have to say that the second order term in the polynomial can't be ignored. In fact, I had to make the trendline equation display a large number of decimal places in order to get anything useful out of it.

You're going to have to play around with scales and other things, but that's a working sheet anyways. You can see a log from a 4th gear pull from around 2500 rpm to redline. Take a look at my normalized AFL V plot and you can see the massive torque dip from about 5500-6500 rpm :thumbdown

Some interesting telemetry I pulled off of my log...

In the span of 14.671 seconds, I went from:

3117-8571 rpm
38-110 mph

To give you a better idea of how hard a turbo GT-S pulls in lift in 4th gear, the car accelerated from 6448-8571 rpm, which is 81-110 mph in 6.8 seconds.
Hey Jesse can I change all the numbers in my commander from the LOG 20060823 0705 because I don't have datalogic?
 

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:confused:

This whole method doesn't work if you don't have a Datalogit. The whole point is that you need to log the data, then crunch the numbers in Excel. I have been using this method successfully for some time. What I have in the spreadsheet above is just an example.
 

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I have a question...I hope I can get an answer to it.

Can one assume that (for the purpose of street tuning), the highest AFV in any range of cells that the car uses in either full throttle or part throttle, is the best VVT setting to have, not taking into consideration lift engagement?

Refer to the pictures below and only pay attention to 2000rpm to 5450rpm. I was playing with my map the other night and after different VVT settings, I found these to be the strongest for AFV.

Log:


VVT used:


Now when I floor it, there's no knock...no sign of it at all, but the car feels a lot flatter than it used to and then at 5000rpm it gets a sudden surge in power towards lift and beyond.

Timing from 4000rpm to 5450rpm is 28-29, so it's not too shabby. I wont add anymore timing for now until I'm on a dyno though. I can't attempt to remove fuel without a working wideband for now, so I'll have to wait till I go back to the dyno again to sort my midrange out. But to save time on the dyno, I want to know if having the strongest AFV at least puts me very close to where I need to optimise on the dyno for best power?

Also, is it correct to assume that for the best fuel economy, full retard is the way to go under those light throttle positions?

(and yeah if anyone is wondering, I'm only really fully tuned on the high cam...everything else is still a mess)
 

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^^For a start,read thoroughly this and the other thread about VVT tuning(dyno method).You will learn many things on that and you will start changing your settings very close to what you would need at full tune!And you won't make any progress if you won't use a spreadsheet for VVT tuning...

Yes,50 is where you get full economy at light throttle.
 

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It seems a lot of the initial write-up here has disappeared... ?
 

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yea it will be great if some one uploaded the photos again

Please


regards
 
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