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Title: 1.8T high EGT big turbo Post by: IAmAnEngineer on March 16, 2021, 03:32:47 AM Hi,
I have a car here which drives me crazy. Engine is 1.8T AUQ Setup: Forged pistons H beam rods 2mm head gasket for 8.5:1 252/272 cams Rebuild head Cams were adjusted using a adjustable cam wheel, crankshaft and cam TDC is the same. I did tune the injectors and the maf, the stft's are always under 10%, car already drives very good (needs a bit of fine tuning ofcourse). Lambda at partial load stays steady at lambda 1, like stock. But now the problem: EGTs are way too high at partial load. 6th gear 140 km/h (around 2600 rpm), the egts rise above 820°C, they should be at 650° in my opinion. At full boost (2 bar) everything is fine, egt stays at max 930°C (5120 hack applied). Just at partial load egts are too high. - Ignition angle perfectly follows KFZW (added 6 degrees in whole partial load area as a beginning, could be more) - Absolutely no knocking - Lambda stays at lambda 1 Anybody has an idea? Else I have to lower lambda at partial load... Log attached, shortened it a little bit to the exact area, where the egt problem occurs (gangi = 6 / nmot > 2500). I have more logs if wanted, but often contains just "driving around". Title: Re: 1.8T high EGT big turbo Post by: prj on March 16, 2021, 03:45:36 AM You need to dyno tune the ignition map to MBT, especially with changed compression ratio.
And after that start enriching. Title: Re: 1.8T high EGT big turbo Post by: IAmAnEngineer on March 16, 2021, 03:49:30 AM Thanks prj, I'm gonna give some love to kfzw, will try and report.
Title: Re: 1.8T high EGT big turbo Post by: prj on March 16, 2021, 03:51:18 AM Also make sure you are not switching NWS on at cruising part load by accident.
That'll do it too. You should only switch NWS from the point the throttle is completely floored. Title: Re: 1.8T high EGT big turbo Post by: IAmAnEngineer on May 17, 2021, 06:30:08 AM Late reply I know
After giving love to kfzw egts were a lot lower, ofcourse part load throttle response was much better, too. But EGTs still a bit too high, now I run Lambda 0,95 on part load, and everything is fine. Thanks for your help guys. ;) Title: Re: 1.8T high EGT big turbo Post by: prj on May 17, 2021, 10:19:47 AM I don't think you need to run 0.95 lambda.
820C is totally OK. The components are usually specified to 950C continuous. This means that 950C is a temperature where it can operate constantly without significant degradation in service life. I would just run the best timing possible and then if you are really worried, set ATR at 900C and call it a day, but there is no need really. Title: Re: 1.8T high EGT big turbo Post by: IAmAnEngineer on May 17, 2021, 10:30:36 AM Hmmm... 820° for partial load (like cruise control enabled at 130 kmh) make me worried, mainly because the head was completely rebuild, I don't think the outlet valve guides like that for a long time. :P
Now, with max timing and lambda 0,95 egts are at 680° Title: Re: 1.8T high EGT big turbo Post by: prj on May 18, 2021, 12:50:44 AM As I said, components are rated for that.
Just because you are worried by an arbitrary temperature number, does not make it a problem in reality. I am guessing timing you added randomly, and not on a dyno? That's probably your issue in the first place. But nothing wrong whatsoever with running 820C. They do that stock too at higher speed. |