NefMoto

Hey Peeps

Looking for some input on something we might have missed, We are setting LDRXN for WOT and this is the result of our 3rd gear boost log. Im running external 38mm Tial wastegate with the N75 connected to bottom port. The only changes to the map are KFLDHBN, KFMLDMX, LDRXN, LDRXNZK currently.

Other Specs
1.8T AMK
GT2871R
630cc Deka's
OEM N75

(http://i435.photobucket.com/albums/qq71/tpietersen123/boost_actvsspec.png)

You missed the entire LDRPID module.

Also the boost rises too slow for 2871.

as prj mentioned above, have a look at KFLDRL and the whole PID and tune it to match the wastegates "cracking pressure" and characteristics.

whats up with the slow spool? building 1.0 bar boost should not take untill 4900rpm with this turbo unless using 1.06 turbine and camshafts with race/high rpm profiles.. (normally you would se 1.0bar at ~3600rpm.)

this is still the very first step of the map basically, also its fitted with a .84 housing and in Johannesburg we are around 5500ft above sea level. We still have a long way to go I beleive!

Probably you mean .82...

And .82 is too big for the 1.8T engine.
Your spool characteristics are like a GT30R car I mapped a while ago with a 0.63 hotside.

It had 2.3 bar at 5000 rpm.

my apology, yes .82, think .84 is t3 housing? I do plan on upgrading valve train at a later stage to accomodate shifting at 8000rpm and the .82 housing should keep power up to 8k rpm. I didnt expect the lag to be this bad as I was hoping to have my full boost 20 psi at around 4500  :-\, not looking at changing the turbine AR thou.

That looks slow even for a .82, looks like you have a 30r housing on a 28 :D

I have a brand new Garrett t25 .64 housing laying in my garage after I built my HTA2868r to an eliminator. Let me know if you are interested.

on a 2871R 0.8x isn't too big if it's a T2 housing.

Rick

What am I doing wrong then that its spooling so slow? I have no leaks, and also a 3" downpipe, custom manifold with a peak in the merge collector.  :'(

More logs needed.  First you need to work out if it's software or hardware.  N75 duty will go a long way to telling you that. 

Rick

This is one of my logs

i see what you mean.
this on stock capacity on this 0.8x hotside?

not much timing in there on spool

n75 duty is at 100% until actual meets spec

I have Airtite assisting me with my car mapping so we will still get to timing and so on, this is a base file just so I can drive the car, going to try swap out N75 tonight to see if the unit might be failing mechanically.

Just not the spool I expected from the current setup as this is my first BB turbo, and it spools like my journal spec t3.
I know with some more time spent on the map that it could increase but I doubt we could get it to spool 500 RPM quicker without running really high EGT.

This turbo flows nowhere enough to go all the way to 8000 rpm.
The GT2871R will make about 400hp, if that on pump. You can be easily within the stock rev limit/7200 and have a usable power band.
8000 is GT30R territory on this motor.

Please explain what you mean by this sentence.

BB turbos do not produce boost any earlier in the RPM range than journal.  What they do do is spool up quicker once the exhaust gas energy is available - e.g. after a gear change.

If the N75 is flat out then there is little extra to come from tuning the software response wise.  You need to pressure test your intake and check you have enough preload on the wastegate.

Also, what gear was that log taken in?

Rick

I think he mean retarding ignition to aid spool.  It may aid spool but it doesn't make the car accelerate quicker!

I don't think he meant this.
And retarding timing at low load is irrelevant in context of EGT's.

I am more thinking of runner diameter on the EM, but let's see what the OP has to say.

What I mean with that sentence PJR is to pull fuel in the spool range by running leaner, this would then increase EGT which will aid with spool?

My wastegate's cracking pressue is 0.6 bar (9 psi)

@ rick - this log was taken in 3rd gear. Application used ME 7 Logger.

You need to make sure you have enough preload on the wastegate, regardless of spring pressure.

EGT is not even a problem until high in the rev range on full boost.
In the spoolup area you must tune for best torque. And regardless your spoolup will not be 500 rpm earlier if you lean out the mixture.
You need to learn/understand some tuning fundamentals and fix the hardware issues that plague your car.

Agreed and noted, I am here to learn and expand my motor knowledge as well as meet new people along my build . I did a fresh log now, Also got a 16514/P0130/000304 - Oxygen (Lambda) Sensor B1 S1: Malfunction in Circuit after this log.

I suspect a boot leak perhaps, or the actual lambda probe might have failed.

as said make sure you have some decent preload on the actuator so it stays shut during spool... and small amount of opening will delay spool.  until its spooling you dont need to be fueling it rich... too much fueling slows spooling. once its got going, then fuel is required.  I would add timing personally before its spooled to get the motor to want to "perk up" and and get some gas flow happening sooner so the turbo will wake up.  Any pre-turbine leaks will cock up spool also... in case there's and blows going on.
0.8x on std cc motor is'nt going to help spool in my experience.  I used 0.6x hotside on stock cc motor... 0.8x on stroker to try and preserve spool.. 

good luck

Alright, I have been reading about the Boost PID, Im still running stock k04-02x PID maps as Im trying to map from my base file, Cant find a reference file for a BT 630cc tune. From my understanding LDRXN would have capped the boost because from S4 wiki it states

"Specifically, on a full throttle pull, your boost profile will follow LDRXN." however Im still overshooting targer, so from further reading on this thread

http://nefariousmotorsports.com/forum/index.php?topic=315.15 adjusting KFLDIMX might resolve my problem.

So brings me to the question would lowering KFLDIMX from 5k-7k perhaps keep my boost more inline, if this would help does that mean that I could increase KFLDIMX in lower RPM to try aid spool?

I've attached a screen shot of my PID, something I did spot is LDIATA value (69.72) doesnt look correct according to the rest?

Your N75 duty cycle is maxed, your problem is hardware, not software.

Stop screwing around with the maps and pressure test your intake, check your dump valve and blank off the check valve at the back of the manifold.

Did a boost leak test last week already, no leaks found!

Dump Valve is a OEM TT 710N diaphram keeps suction as it should when sucking the top nipple of the valve.

The check valve on the brake servo line? I have redone the servo line some time back with a New one way valve after deleting the EVAP system.

There is nothing else hardware wise that I can look at. check every single bolt on the manifold and turbo, they are tight and gaskets are still in perfect condition...

Edit: In both logs there are different actual boost vs requested, with the exact same configuration. I have removed the wastegate and it moves as it should with load applied... I have different WG duty cycle's on both logs... Could wiring to the N75 cause a problem, would it not throw a code as if it was unplugged then? If unplugged its happy to run wastegate pressure as well.

When do you see full boost when only running WG pressure?

You are missing out ALOT if it is in fact the .82 housing causing the GT35r spool.. My HTA does 22psi at 3700rpm flat, tuned not to spike. Thats over 1500rpm sooner, given the 2871r is not as responsive as my HTA, you should see 20psi at 4000rpm at least(with a .64 housing).

I replied to your email, didnt you get it?

On wastegate pressure I see .5 bar (8 psi) at 4000 rpm

The check valve is inside a round rubber hose that goes to the breather. Remove it and blank off both ends.
In the log you posted N75 is at 100% duty cycle all the time. This means that nothing you will do with your software is going to increase the spoolup.
So it is a hardware issue.

Wrong size housing, huge backpressure, leaks between the suction side and pressure side and so on can all cause this.

Thank you for additional input PRJ

If im understanding you correclty your talking about the check valve that is in the PCV system?

I deleted this as I did a catch can install, so valve cover and Block T into one line into catch can, then back into TIP. The nipple at the bottom of the intake is also blocked off.

All vacuum lines have been replaced with silicone lines.

Ok, then you most likely removed that valve.
I guess it's time for you to start looking at hardware...

What kind of exhaust manifold do you have? What cams do you have? How is the cam timing setup?
If your cams are timed incorrectly, it can easily cause this.

My Motor is stock bottom end and top end. Nothing has been touched motor wise, removed the k04 and bolted the GT2871R on, The manifold custom steam pipe made from one of our local guys.

(http://i435.photobucket.com/albums/qq71/tpietersen123/IMG_2075.jpg)

Well, if there's nothing else, then it's probably the exhaust housing being too big.
That looks like a T3 flange to me, and you should be running a 0.63 A/R housing.

stock displacement 1.8t and 0.8x hotside is going to be laggy... 0.6x hotside T25 flanged internal gated version I did a few years ago on an A3TQ spooled mid 3krpm and full on 4krpm, 1781cc also

Is this turbo used? (damaged cartridge perhaps?  Is it noisy when spooling down?)  I've heard noisy bearings on these and they've been slow to spool also.. (my own damaged gt35 hybrid is slower to get going with its damaged chra bearings)

Oh, my housing is an internal gated T25 .64, its not going to fit with that manifold/DP..

0.82 T3 is huge for a 1800cc motor.
I think that's the main problem, and it should 500 rpm earlier with the 0.63.

Get that changed and then start working on the tune.
Right now the turbo is mismatched. By the time it comes on boost, the compressor is already working hard, and you can't rev higher because the compressor is going to max out.

So your power band will basically just not exist. A GTX3071R / 0.63 would give you about this spool and more top end. or a GT3076R/0.63.

For the 0.82 housing to make any sense you would need about 2.1-2.2 liters of displacement.

I have a 0.86 as its a T2 housing not a T3 housing, Yes the turbo was purchased in a used condition with with barely 500kilos to it and really no strange noises either    :-\


Did another run tonight after removing the Wastegate and removing the gasket, doing a straight bolt onto manifold, there was a small black marking on the edge of the gasket which might have been a slight leak. Perhaps not but here is another log from tonight

The LDRXN has been shifted more inline with boost delivery, and the WGDC seems to respond better?

(http://i435.photobucket.com/albums/qq71/tpietersen123/8N0906018AG_tiaan_20121126_210636.png)

(http://i435.photobucket.com/albums/qq71/tpietersen123/ActualvsDesiredWGDC.png)

First run AFR was running pretty well, second log the probe threw code again  :(

This is not even nearly right.

Your spool is 1000 rpm late.

so concise.

N75 duty should be 100% until pid-d kicks in. You're leaving a ton of spool on the table with that log.

Thanks elRey but this is still a very basic map, Was just trying to get WGDC back as this was the previous log

This was before LDRXN was set to match the boost curve.

(http://i435.photobucket.com/albums/qq71/tpietersen123/noWGDC.png)

I'm not sure this will help at all, but I had a similar challange and I placed
a plate (removed the wastegate) to force all exhaust gas into the turbine at all
times and then shut the boost deviation function off completely to see when my
boost started rising at WOT (just keep an eye on a separate boost gauge to avoid a
blown angine) and despite these actions my boost didn't show up as early as I
expected. Checked for leaks but no problems, changed the turbo charger to another
one with smaller turbine housing and then did the test again and it all workd fine.
At the end of the day, I had a too large turbine housing.

I will be changing to a .64 in the new year, when I do rods. Will see the result from once thats done, still havent replaced my wideband probe, Will continue with the project in the new year  ;D

How did that go? with the .64 turbine? what is ur spool time now

BTW you should put boost on one axis, and DC on another, so it scales right.

Thanks Nyet, sold this setup... Starting from scratch with better planning for hardware and then back to remapping  :)

I had the same Problem 2 times this year.
My Problem was some cracks on the wastegate hole of turbocharger.
I changed exhaust housing of turbo and spoolup was much earlier.

I was running external Tial WG with this setup... However it was small port head with no porting, manifold was really terrible interms of Runners and ID for the manifold was more for a t3 hotside.

Starting from scratch with new chassis  :)