Opinions Of This GTB1756VK Log

I'm still doing some minor tweaking with the vacuum actuator, trying to get the most out of the turbo on my engine build. The tune with Malone is coming along well, but I was wondering about other people's opinion of this log of measuring block 011:

https://malonetuning.com/graph/view...VR1V+cHlzwphNUhzDmC7CrcK8w78DPFLDicOMwqIAAAA=

(local atmospheric pressure is around 960 mbar according to the ECU)

To be honest, I'm a little disappointed with how long it takes the turbo to get up to speed. I specifically chose a GTB1756VK for quicker spool than the larger variants. The boost spike doesn't bother me so much, and it'll probably be taken care of in a future revision of the tune, but I was really expecting to see the turbo get up to speed quicker. This is a 3rd gear pull, which gets me up to about 70 mph before I step off the go-pedal.

To be clear, once the turbo gets up to speed, the car flies like a bat out of hell all the way to 4500+ rpm. It's one heck of an adrenaline rush. But I was hoping to putter around at 1800-2200 rpm most of the time and still be able to wake up the turbo on a whim. Instead, I'm seeing more lag than I expected. Are my expectations set too high?

ack! Can't edit the subject of this thread! My phone mistyped the turbo name

That doesn't look to bad for a 56mm compressor. The only way to get quicker spool with be dangerous to the turbo. It's going to take a while going from 1200rpm full throttle - downshift. It's a little different than running a smaller turbo. It's a compromise, more power up top, you'll loose some response at low rpm.

JFettig said:

That doesn't look to bad for a 56mm compressor. The only way to get quicker spool with be dangerous to the turbo. It's going to take a while going from 1200rpm full throttle - downshift. It's a little different than running a smaller turbo. It's a compromise, more power up top, you'll loose some response at low rpm.

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Thanks for the input That's a little reassuring.

I realize I shouldn't be expecting miracles from 1200 rpm That's just a log for tuning purposes, I've purposely been trying to log long gear pulls from down low to make sure I get a clear picture of what the turbo is doing for the entire rpm range.

Guess it's a good thing I passed on the GTB2260VK I was originally planning on!

You should be doing multiple logs - one like this, one starting at 1800, one starting at 2000, 2200, 2400, etc. They'll all respond slightly different. You get lots of PID spool up doing long logs. I usually just do a full log, and another mashing it starting at various RPM, speed up, slow down, speed up, slow down. You're not looking for the overall high RPM log when checking the transient response at lower RPM, you can do it real quick.

This is interesting, I plan in a not so near future to upgrade my ALH and I was thinking about a 1756VK because people in the internetz say that they spool pretty fast, faster than the 1756vb's, but if power only comes at 2400 rpm(and you have a PD engine, mine is a VP..), now I'm thinking that the 1756vk might not be the best idea

JFettig said:

You should be doing multiple logs - one like this, one starting at 1800, one starting at 2000, 2200, 2400, etc. They'll all respond slightly different. You get lots of PID spool up doing long logs. I usually just do a full log, and another mashing it starting at various RPM, speed up, slow down, speed up, slow down. You're not looking for the overall high RPM log when checking the transient response at lower RPM, you can do it real quick.

Click to expand...

I guess I was going more for a "worse case scenario" kinda thing, but you're right, the turbo does behave differently under different scenarios. I've been trying lots of different situations, but I haven't been logging them. Just checking my EMP/boost gauge out of the corner of my eye. I'm getting so sick of logging...

senso said:

This is interesting, I plan in a not so near future to upgrade my ALH and I was thinking about a 1756VK because people in the internetz say that they spool pretty fast, faster than the 1756vb's, but if power only comes at 2400 rpm(and you have a PD engine, mine is a VP..), now I'm thinking that the 1756vk might not be the best idea

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I not only have a PD, I have a 2.0 PD that's been bored out beyond the original 2.0 and all kinds of enhancements to retain as much exhaust heat and velocity as possible, AND Bosio 783 Race nozzles. I can't think of anything else I could do to speed up the spool. There's a chance that my Stage 3 Colt Cam might be slowing things down a bit at the bottom end, though. I got that to open up the higher rpm range figuring a PD TDI doesn't really need much enhancing at the bottom end, but I didn't really consider the effect on spool-up time for a bigger turbo.

To be fair, I think power comes on long before 2400 rpm. I've got a full 1 bar by 2000 rpm, and that's when it really starts to get going. I can still putter around at 1800 rpm most of the time, it just takes a while for the turbo to get up to speed when the engine load climbs suddenly, like if I start climbing a hill and want to maintain my speed without necessarily accelerating.

I frequently find that worst case is actually stabbing he throttle over 3000rpm on some setups.


Even a 2260VK is ok around 2000rpm, but it's not super responsive.

JFettig said:

I frequently find that worst case is actually stabbing he throttle over 3000rpm on some setups.

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LOL! I'll have to try that, now.

I have a 1756vk and it's awesome. I tend to use my foot along with down-shifting to get it where I need to be when trying to pass someone if I'm tooling along at about 55mph. It spools just fine, in my book. Malone-5 custom, all set-up by Matt Whitbread about 2 years ago. I believe it works well because of the tune. Things start to get wakey-wakey around 1600... lots of pull all the way to 4500+. No downshifting needed from 6th when you're doing about 70mph. Just gradually push the pedal closer to the floor and hold-on. Very happy with it.

I think I just need to learn to drive it better to take advantage of the sweet spot. I've spent years short-shifting a 1.8T gasser to try and maximize fuel efficiency, same with my GM 6.5TD, and that's just not how a TDI wants to be driven. The more I drive it, the better it's getting

I drive mine with some vigor and it still returns about 47 - 49mpg. Surely, the 02M helps and my long distance driving on the weekends.

you could try to move the play around with vnt screw ,start by unscrewing till the vanes touches and take it from there till you find the sweet spot .Also make the log from 1500 rpm or so,wooting from 1000 rpm is not very good for the engine,also don't care much how the turbo behaves under 1500 rpm since should never drive under 1500 rpm.

Ciprian is back!

you got me

I would wonder if maybe your pushing too much throttle down low. You have to ease into a bigger turbo. Do you smoke alot doing those pulls? I find the 2260 a great daily driver, would imagine the 17 to be even easier.

Actually since I've taken that log, the engine has broken in a lot more and the turbo response has improved dramatically. It used to smoke a little bit at WOT, especially before the turbo spooled up. Now there's absolutely zero smoke, and turbo spool is much faster. I'm considering getting the fueling increased.

One of the drawbacks of tuning a brand new engine that has less than 1000 miles on it, I guess...

when you get a chance, show us a 011 log so we can see the actual requested and duty cycle now.

Would be interesting to see the difference

That's all incorporated into the log viewer, we've added tables below the graph

right, I was assuming he would do the viewer since he linked it earlier on =)