GT TDI data thread

[Greg Roles]

Ok, as my tinker thread is getting big, I'd like to compile raw data into a more easily searchable thread. Someone please let me know how to either convert an excel graph into a image, or how to host a webpage or excel graph directly to this forum please!

I'll have lots of graphs to post in coming weeks!

[mikinoz]

Maybe best to use screen capture and then convert/compress in photobucket.

Look forward to seeing the 'readers digest' version of your 'war and peace' thread!

[Greg Roles]

Degrees C

[gldgti]

thats a great graph mate....

i've never seen 800 degrees in my 1.9.... highest i've got to has been just on 650.

surely you were smoking up to that peak?

[Greg Roles]

Flat out mate, and I can't see it ever getting much hotter. It's a nice twisty steep pull, and it's double lanes, so I just pulled over and let all the traffic pass, waited and well, went for it.

All the same it's a worry it CAN spike that high, for my flash new diesel tuning book has Gale Banks recommending a 1250F ceiling, and Bullydog recommending a similar 1300F top. That's 675-700 celcius!

That IS for big pickup truck diesels towing for extended time in this range, whereas the VW is only spiking there. Still makes you think about chip tunes, or even propane which is only going to add to that.

I'll do some more out in the country, where it's a bit safer, and log some more parameters.

[benno]

That IS for big pickup truck diesels towing for extended time in this range, whereas the VW is only spiking there. Still makes you think about chip tunes, or even propane which is only going to add to that.

I thought propane actually had a cooling effect?

[gregozedobe]

Good to see some "empirical evidence", thank you.

I was interested to see how much higher (relatively, compared with revs) the EGT was when flooring it in 4th than in 1st to 3rd gears - shows you how much harder our turbos work in the higher gears. I'd expect it to be like that in 5th and 6th gears too (but don't go losing your licence just to collect data for us lot).

[Greg Roles]

I thought propane actually had a cooling effect?

Nope, it's a secondary fuel, and actually "pinches" the oxygen from the diesel on combustion, so in effect diesel is actually wasted, but more heat, energy and power is produced.

Why a lot of people SAY it's cooler is with the power gain of about 30%, you don't have to work the turbo as hard to get the necessary power. On a flat out effort though, I'd expect hotter EGT's unless it's tuned down at WOT.

Gale Banks isn't a fan, and his theory of pockets of detonation is rather interesting, and seems valid to me.

[Greg Roles]

Yeah, from my early attempts, EGT is all about load, not speed or revs. In fact I could get it to 500 degrees quite easily in traffic by lugging 4th at the 50-60kph mark, whereas a change to 3rd at 50kph dropped them back to the 300's. Load, load and load.

What I found amazing was at the top of the hill, where I took my foot off the pedal ( thanks to both gravity and inertia at that point!! ) the EGT's dropped back to below 150 degrees, and I saw 113 backed off "engine braking" down the other side.

I only stumbled onto a channel ( 69 from memory ) with what seemed to be EGT's and revs, so today I'll go hunting for a boost, revs and EGT channel, which I can log, and then export and graph in excel. I'm sure there's all manner of combinations from the sensors, my understanding of this program is only beginning.

[Greg Roles]

Good to see some "empirical evidence", thank you.

I was interested to see how much higher (relatively, compared with revs) the EGT was when flooring it in 4th than in 1st to 3rd gears - shows you how much harder our turbos work in the higher gears. I'd expect it to be like that in 5th and 6th gears too (but don't go losing your licence just to collect data for us lot).

1-3rd, the first 3/5th of the graph is normal driving mate, look at the revs. Only the spike at the end is "floored". Then again it would be hard to see 800 degrees in first unless you were attempting Ayres rock me thinks! You need to load the turbo, and the gearing is obviously a big part of that.

You can see when I changed into 4th, flat, that revs couldn't really rise ( twisty road and I was travelling by now! ) but the EGT's went crazy.

I must point out that I waited for empty roads, and picked the incline, speed limits and gears so as not to be too naughty!

[Mischa]

greg you're a champ keep it up

[Greg Roles]

I did another log on a normal law abiding drive to work today, on another channel, and got some odd results once plotted. I'd suggest not taking my EGT plot as the absolute, until I can work out what sensors there are, and what I could possibly be measuring. For instance you can get one "channel" that shows four temperatue boxes, and they are all just labelled "temp". I have to watch them, and use my aftermarket guages to correlate what is what, and well this morning's log confuses me. It's not like they say "per DPF temp" "post DPF temp" "MAF" etc. Some are labelled, such as the duty cycle of injectors, but a lot aren't.

The logging / learning shall continue!

[Greg Roles]

Same hill, take 2. Waited and took off in a more "spirited manner", and again got similar max egts. I ran a heap of temp readings on this run, and the "oher" sensor reading I have found follows the EGT's but at a few hundred less, so there must be a sensor in the DPF or just after it. I'm rather convinced this channel I'm using ( 74 ) is the EGT probe on top of the DPF.

This time I ran into traffic towards the top, ( do they not know this is a science experiment - geez! ) but at the end, following the car, I flattened it in 4th for a few seconds, made it try and accelerate, which is couldn't at that speed and gearing, but look what the egt's did.

If you drive in normal traffic in a higher gear, and make it pull, well you're running huge EGT numbers.



Yesterdays again...