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Another glowing turbine housing post - are my high EGT concerns warranted?
Some background - FD, single BW SXE300 series turbo, Super Core part # 13009097008 (~87mm compressor & ~76mm turbine wheels), 1,0 A/R turbine housing, 3" DP with twin 40mm external WGs that recirculate back to the DP. Self-tuned on the road up to ~11psi boost, Link G4+ Fury ECU. Stock 13B-REW short block, 13B-RE Cosmo LIM & UIM, GM LS3 90mm DBW throttle. Car is running great all around - idles smooth & stable, pull like a beast from idle to redline, consistently hits my closed loop boost control targets; AFRs track well to their AFR targets and the knock sensors are not seeing any evidence of ping/pre-detonation.
Since I don't have any EGT sensors fitted, my concern is what you're all seeing in the photo below. That snapshot was taken in my garage at night, after a 20 minute drive where I wasn't particularly flogging the car - last few miles were residential streets, stop & go, 2nd/3rd gear mostly <35 MPH, and not much boost prior to that. Photo was taken about 30 seconds after I shut it down in my garage, and temperature of the glowing part of the housing you see at that time as measured by an electronic IR thermometer was between 725~790*F.
Question is should I be concerned about this as an indication of excessive EGTs, and if so, what might it indicate on my car's state of tune? i.e., running too lean/rich/timing too retarded, etc? I can post up my current tune later if it would help spur discussion.
Picture taken about 30 seconds after shutdown in my garage following a relatively easy 20 minute drive. Temp of glowing part was 725~790*F according to my IR thermometer
When my car was doing this it turned out to be a bad spark plug. I installed a brand new set and ruled it out as a possibility...... turns out that was my whole problem. Based on what you're describing, I would suggest troubleshooting an ignition related "issue"
When my car was doing this it turned out to be a bad spark plug. I installed a brand new set and ruled it out as a possibility...... turns out that was my whole problem. Based on what you're describing, I would suggest troubleshooting an ignition related "issue"
That's a good point, although I'm not seeing any of the usual symptoms of fouling plugs (i.e., crappy idle, harder starts, ignition misfires under load) I've got about 3000 miles on them since they went in a little over a year ago. Certainly wouldn't hurt to put in a fresh set now just to rule out the plugs, since a lot of those miles were piled up road tuning.
Last edited by Pete_89T2; Jun 2, 2024 at 03:50 PM.
Same... absolutely no symptoms whatsoever other than the glowing turbo. Idle, cruise, afr, pulls.... all of it perfect. This is why I dismissed it but I was wrong lol. Quite the humbling experience 😅
^That exhaust mani looks like it will be a liquid soon
Arghx once posted a training thing from the BMW turbo engine (around 2009?) and that thing runs temps that would just melt a rotary. the one i remember, EGT 2100f
although coolant and oil temps were high too
i could find the thread, but the link to the BMW stuff is broken.
What do your idle AFR look like at idle? Wondering if you need to add a little more fuel to cool it down at idle.
I currently have target Lambda of my idle cells at 0.960L, which results in an AFR of around 13.56 for the typical 93 octane pump gas I get that contains anywhere from 8~10% ethanol. I'm using my Link's modeled/multi-fuel equation mode with an ethanol sensor, so my stoich AFRs at Lambda = 1.00 are continually adjusted based on the ethanol content of my fuel - pure gas (E0) has a stoich AFR is 14.7; and E10 would be 14.13 AFR at stoich, which is where the 13.56 figure comes from @ Lambda = 0.960L
Anyway, the closed loop lambda control keeps it pretty tight around my 0.960L target, within +/- 0.005L usually. And in the past I've experimented with going leaner or richer than this at idle, and while the engine will idle fine as lean as 1.000L or as rich as 0.860L, the engine seems happiest around 0.960L from a drive-ability & throttle response perspective
Understood. Mine also idles better in the 13.5 AFR range. Just curious if you let the car idle if the exhaust will glow still. I am curious if adding a little gas(12.5-12.9AFR) would keep it a little cooler.
It's pretty normal for a turbine to glow if running normal cruise fuel mixtures (1.0 lambda or leaner)
I run 1.0 lambda at both idle and cruise
If you want to lower Idle and cruise EGT Use a lot more ignition timing on idle and cruise and youll see less turbine temperature.
I'm running 1.0 lambda in the vacuum cruise regions, and a little richer at idle, 0.960 lambda. Below is my current lambda target table, leading ignition timing and trailing split timing tables. FYI, for reference, the Link takes the data in the trailing table and adds/subtracts it to the corresponding cell in the leading timing table. So if leading is at 30* BTDC, and the corresponding trailing cell is at -10, the trailing plug will fire at 20* BTDC. What do you think of my timing tables? This is based on a slightly more conservative take on what a pro tuner did with my FC (S5 13BT, street ported with a BNR Stage 3 turbo) at equivalent MAP/RPM cells. No evidence of ping/knock with this setup yet, so perhaps I can advance the leading a bit in the low load/vacuum/cruise & idle cells?
Lambda Target table Leading Timing Table Trailing Split Table
Of course this is just my opinion but your timing table is very conservative. I like to run 0 split in the cruise areas
Even leading up to 1 bar absolute you could run significantly more timing
I'm a newbie at tuning, so the conservative timing table & trailing split tables are intentional - I'm very risk averse to knock/ping which can quickly kill a rotor motor. I based these tables on what a pro tuner did for my FC (13BT, aggressive street porting & BNR Stage 3 turbo) for similar MAP/RPM cells, and retarded all the cells above & near 1 bar MAP by a few degrees. Since my FC doesn't knock/ping, I figured this was a safe starting point for the FD - perhaps I can stand to advance the leading timing and reduce split a bit in the vacuum cruise & idle regions a bit to reduce EGTs? The question is by how much can I advance without risking knock?
Pete i think its time to invest in egt monitoring. I have been pretty happy with the sensor connection sensors . Not sure whats available for the link ecu for an egt CAN module but worst case you could use a 0-5v amplifier from the same vendor and hook up at least one sensor and use it as a regular 0-5v input sensor
I'm a newbie at tuning, so the conservative timing table & trailing split tables are intentional - I'm very risk averse to knock/ping which can quickly kill a rotor motor. I based these tables on what a pro tuner did for my FC (13BT, aggressive street porting & BNR Stage 3 turbo) for similar MAP/RPM cells, and retarded all the cells above & near 1 bar MAP by a few degrees. Since my FC doesn't knock/ping, I figured this was a safe starting point for the FD - perhaps I can stand to advance the leading timing and reduce split a bit in the vacuum cruise & idle regions a bit to reduce EGTs? The question is by how much can I advance without risking knock?
Your boost timing is probably ok. Won't have much effect on whether a turbo glows during cruise and idle conditions. You're not going to break an engine during cruise conditions so don't be afraid to wind some timing in those areas.
Pete i think its time to invest in egt monitoring. I have been pretty happy with the sensor connection sensors . Not sure whats available for the link ecu for an egt CAN module but worst case you could use a 0-5v amplifier from the same vendor and hook up at least one sensor and use it as a regular 0-5v input sensor
Thanks for the links for the EGT stuff. Unfortunately I'm out of analog inputs on my G4+ Fury, so any additional sensors I want to log from would have to be piped thru the CAN bus. Not impossible, but much more difficult on the older G4+ compared to the newer G4X/G5 series - G4+ isn't as flexible with regards to setting up custom CAN streams, but I'm pretty sure EGTs are supported. Adding the EGT bungs to my exhaust mani is the sticking point, as that would have wait for winter, so I could pull the manifold for a competent welder/fabricator to weld the bungs on for me.
Originally Posted by rx72c
Your boost timing is probably ok. Won't have much effect on whether a turbo glows during cruise and idle conditions. You're not going to break an engine during cruise conditions so don't be afraid to wind some timing in those areas.
I'll try that, figure I'll advance the vacuum cruise range in 1* increments, drive, log, and use the IR thermometer to get some idea if it's having any effect on EGTs. If I'm consistent with how I do that measurement, it should at least give me an indirect indication of which way the EGTs are trending, up or down.
I had glowing turbo issue before. Every time I'd cruise for about half an hour turbo would start glowing. It turned out one of the trailing spark-plug wires was disconnected from the coil (there was corrosion inside the wire and on the tip of the coil). Replacing that wire fixed the issue.
I had glowing turbo issue before. Every time I'd cruise for about half an hour turbo would start glowing. It turned out one of the trailing spark-plug wires was disconnected from the coil (there was corrosion inside the wire and on the tip of the coil). Replacing that wire fixed the issue.
I've had the exact same issue in the past. Bad trailing plug wire. EGT temp pointed out which rotor had the bad wire.
Haven't messed with the timing yet, but I did put in a fresh set of spark plugs today, NGK BUR9EQP's in all 4 holes. Here's a picture of the used old ones - after a little more than one year and roughly 3000 miles of use. Sorry for the bad lighting in the picture, but they had a bit of carbon buildup in case you can't tell. Looking forward to driving the car tomorrow when the crappy weather here clears up, and see if the new plugs change anything WRT the glowing turbo.
I'm running 1.0 lambda in the vacuum cruise regions, and a little richer at idle, 0.960 lambda. Below is my current lambda target table, leading ignition timing and trailing split timing tables. FYI, for reference, the Link takes the data in the trailing table and adds/subtracts it to the corresponding cell in the leading timing table. So if leading is at 30* BTDC, and the corresponding trailing cell is at -10, the trailing plug will fire at 20* BTDC. What do you think of my timing tables? This is based on a slightly more conservative take on what a pro tuner did with my FC (S5 13BT, street ported with a BNR Stage 3 turbo) at equivalent MAP/RPM cells. No evidence of ping/knock with this setup yet, so perhaps I can advance the leading a bit in the low load/vacuum/cruise & idle cells?
Lambda Target table
Leading Timing Table
Trailing Split Table
Change plugs, if that resolves your issues then ignore the below.
If it doesn't then try the below.
Where you are running lambda of 1 in cruise areas, try running 0.95 to 0.92 and see if it helps. Could be your setup doesnt like running 1 lambda.
Try the below Ign table. Could be where it was 5 deg off throttle in vacuum it wasn't liking it.
Trailing table - feel free to try the below in vacuum and see if it helps.
I had a situation also with ignition.
I didn't see glowing but boost was too fast, wanted to boost all the time but had no extra power, melted a metal core cat and it ended up being the HKS-Twinpower went bad and I was running trailing plugs only
Well it looks like changing to a set of fresh plugs alone is trending the EGTs downward a bit, based on my indirect IR thermometer measurements. Basically I drove my usual "light tuning loop" 3x so far over the last 2 days after the new plugs went in, and used the IR thermometer to measure the same exposed part of my turbine housing / DP V-band junction within 30 seconds of shutting down the engine in the garage, and the temps have definitely trended downwards. I'm seeing 600* - 680*F now, before it was running in the 725* - 790*F range. Also the turbine housing is visibly glowing less (darker/deeper red vs. bright red/orange).
I also experimented with some of the trailing split table data that @rx7srbad shared, for the idle & vacuum cruise regions. Basically I took a slightly more conservative take on his trailing split table, so where he had -2*, I entered a -5; -8 became a -10 and so on. This change resulted in better idle quality and a subjectively improved throttle tip-in on light acceleration. Noticed in my logs that since I made the split timing change, the closed loop lambda control at idle and steady-state cruise is apparently having an easier time following my target lambda - status reads "target reached" more often than it did before. Don't know why that is, but I suspect it has something to do with the trailing ignition tweaks improve the flame front propagation and result in a more complete burn.
This was happening to me and turned out to be a bad plug wire to a trailing plug. This caused it to put more unburnt fuel into the exhaust where it then ignited resulting in way to much heat. If the turbo stays red hot after a hard drive I would check your idle AFR. I keep mine around 12.6-13 and that does a decent job of cooling down the turbo after Im done beating on the car. Also another thing probably not the cause but check your oil cooler or both if you have an r1/r2 and make sure there working properly.
