17 replies to this topic

[chris]

I am wondering what is the maximum acceptable (Turbo Inlet Temperature) EGT for a Z20LEH turbo ?

 

I have read somwhere the figurer of 1050 °C but this figure seems very high !

 

Edited by chris, 16 June 2014 - 03:49 AM.

[siztenboots]

the map setting in the motronic TABGBTS is set at 790°C , if the modelled EGT temp ( you can fit an EGT sensor as used in VAG setup ) exceeds this then a component protection map is used for lambda control.

 

its a common thing even for OEM to set to use this KFLBTS protection map for WOT high load use as its a 16x16 rpm vs load map which allows more fine control.

 

Original map protection , has a lot of safety

 

 

TVXR Stage 4 , 0.77 lambda

[chris]

OEM map seting has been established for Z20LET turbocharger (which has a bad reputation), the exhaust manifold was not the same for the Z20LEH (Z20LEH has a better quality exhaust manifold).

 

Morever in adavanced tuning stages based on Z20LEH turbocharger, MAP EGT threshold is setting at 839°C or 849 °C

 

In real the live, my ECU start to switch from LAMFA map to TABGBTS map at approx 880-890 °C of EGT (with a threshold of 849 °C in the ECU). The ECU calculation model is not in line with the real EGT taken on my turbocharger exhaust manifold at approx 2" of head cylinder exhaust outlet.

 

In hard engine operation  my AFR fall down at 10,5, and EGT are maintained at approx 922 °C

 

I am wondering if I could increase a little bit this limit up to 940 °C ...

 

 

 

[slindborg]

It was fun setting the EGT limits on a pikey chinky motorbike.

we ran a time delay along with the protection fuelling as the EGT's didnt go too high for the first few seconds of sustained load, the time delay was only reset if sustained load was reduced for long enough etc.

[siztenboots]

if you have a EGT installed, then you have a lot more info to work with

 

TABGBTS , Klasen uses a lower 750° and KFLBTS target lambda 0.77λ from 3600rpm , Regelin much higher 850°

 

the exhaust gaskets can be weak point , plus you put a lot of heat into the studs and nuts , holding back the gas pressure

 

10.5 , would be 0.71λ , presumably you have a wideband as the normal narrowband setup would be outside of its optimum measurement range.

[cnrandall]

On track mine peaks at about 950 with a VERY effective charge cooler setup (within 10 degrees ambient) and now the whole system is very stable with those temps.  Before the charge cooling was sorted I would see upwards of 1000 and that was much more stressful on all the exhaust and turbocharger components.

[chris]

I have a wide band installed, with a simulation of narrow band signal injected in the ECU.

(I do calibration twice a year)

 

My WOT AFR is about of 11,5 -11,6 (lambda 0,78)

 

I have a reinforced Head gasket (athena 1,3 mm) with Wiseco piston (86,18 mm bore)

 

My only concern is to optimize my EGT with turbocharger component lifes expectancy

 

 

 

[siztenboots]

do you both using a k-type thermocouple and something basic like a Fluke meter or can your datalog work with thermocouple or with an amplifier ?

[chris]

Yes I can datalog everything

 

The pink curve is the EGT

 

 

[siztenboots]

ignition timing? the yellow 4bar is fuel rail pressure? impressive figure for the airflow , 292 g/s

[chris]

Ignition timing is not recorded in this diagram, which is a mix of OBDII data with other external sensors data.

 

Z20 LET OBDII recording frequency is very low and depends of the nb of recorded parameters, so I have to choose carefully my OBDII data.

 

For the time beeing, I look only for fueling and EGT values.

 

The max aiflow value (MAF) for this run is only 286 g/s (you should read 282 g/s, not 292 g/s)

 

the "4 bar value" is the oil pressure value,

 

Otherwise, no idea regarding max EGT values ?

 

  

 

 

 

Edited by chris, 16 June 2014 - 11:42 AM.

[chris]

On track mine peaks at about 950 with a VERY effective charge cooler setup (within 10 degrees ambient) and now the whole system is very stable with those temps.  Before the charge cooling was sorted I would see upwards of 1000 and that was much more stressful on all the exhaust and turbocharger components.

 

Sorry Chris, I have just seen your reply.

 

So according to your opinion, you think 950 °C is the safe limit for K04 (or K04 hybrid turbo) ?

[cnrandall]

 

On track mine peaks at about 950 with a VERY effective charge cooler setup (within 10 degrees ambient) and now the whole system is very stable with those temps.  Before the charge cooling was sorted I would see upwards of 1000 and that was much more stressful on all the exhaust and turbocharger components.

 

Sorry Chris, I have just seen your reply.

 

So according to your opinion, you think 950 °C is the safe limit for K04 (or K04 hybrid turbo) ?

 

 

There are lots of ifs/buts.  We ran a stock turbo on a customers car for a couple of seasons including a 1000km race and that was probably doing nearly 1000 degrees and didn't miss a beat. 1000 degrees on the road I would be worried though as it sin't going to last 100000 miles!

[Nev]

Ive never heard of a K04 failing due to high EGT on a VX220 or an Astra. If they get good water and oil supply in/out I don't see why they would ever fail due to heat unless you switch off without a sensible cooldown period. I've inspected a couple of Astra VXR turbos on my old engine and they showed no signed of fin break up/erosion at all, even though I beasted the things. What fails with them is the thrust bearing (not heat related).

Edited by Nev, 16 June 2014 - 06:28 PM.

[techieboy]

Talking of EGT's, does anybody know what sort of temps we get on SC cars?

[slindborg]

Talking of EGT's, does anybody know what sort of temps we get on SC cars?

 

 

Higher than 100Deg C

[siztenboots]

Ive never heard of a K04 failing due to high EGT on a VX220 or an Astra. If they get good water and oil supply in/out I don't see why they would ever fail due to heat unless you switch off without a sensible cooldown period. I've inspected a couple of Astra VXR turbos on my old engine and they showed no signed of fin break up/erosion at all, even though I beasted the things. What fails with them is the thrust bearing (not heat related).

I have seen K04-0049 failing with the wastegate cracked having said that , on the VAG stock fuelling is lambda 0.953 on max load until it gets 920'c at which point fuel dump occurs for egt protection

[fezzasus]

Talking of EGT's, does anybody know what sort of temps we get on SC cars?

 

shouldn't be hard to instrument the EGR valve.