EGTs and your AEB engine

[rockersteady]

I thought Id start this thread to try and compile and garner a little Exhaust Gas temp (EGT) info specific for those running an AEB engine (or any Turbo without EGT feedback to ECU.)

one example to start, When I was trialling out my new TIP setup (switchable between Stock maf and V8 maf) the Tip collapsed at one stage and it caused EGT to very easily rise to dangerous levels. Ie over 900degrees C (1650F)
My point being that without my monitoring, I could easily have cooked everything, For example if somebody was running a stock or un-reiforced TIP with higher boost ability.

my EGT setup, drilled and tapped 1/8" NPT into exhaust manifold collector

[rockersteady]

I know with large turbocharged Diesels that EGTs will climb, if there is a restriction on the exhaust post turbo, But I suspect it is also the case with those running small turbines/ turbine intakes and trying to push lots of gas through them. (Like my turbo)
With the large turbos I guess EGTs are/ can be lower as there is less backpressure (larger turbines/ turbine inlet)?

I am in the process of getting my stock AEB car fitted out with EGT and Wideband too, to do some other (related) testing,

Anybody want to add something about tuning an AEB and keeping EGT in mind?

[loopy]

mine is post turbo highest temps i see are 850 Fahrenheit .

[M-Hood]

My EGT's tend to run in the mid 1500.

[rockersteady]

mine is post turbo highest temps i see are 850 Fahrenheit .

What setup are you running loopy? (for comparison on any areas of possible restriction) turbo, Exhaust size, cat or cat-less, TIP, and how far is your EGT probe from the turbo?

Some causes for Turbo charged engine higher EGTS
are/ could be:
1. restricted intake pre turbo- case proved on my earlier TIP collapse
2. restriction post turbo Ie CAT, cloged Cat, stock exhaust on a higher flowing turbo? this could affect anyone giving more than a quick throttle squeeze.
3. running lean- Higher cylinder temps
4. running (too) rich, burn continues post cylinder head- (is there an accompanying increase in turbine speed due to the higher/temp pressure?)

My EGT's tend to run in the mid 1500.

Mike, where are you measuring the temp?

[loopy]

honestly my egt probe is in the wrong area im in the process of moving it to the same general area as yours pictured . i have read that i can kind of guess or add 300 degrees to my shown temp being post turbo . my egt is right after the flange mating turbo to the exhaust pipe so i know its probably way off . i will be moving it tomorrow and i will post temps
seen . do a little searching for mounting positions but from what i have read and seen the closer to the exhaust port the better . what i can say is pay attention to what the car is
doing .....is it pulling timing is it falling on its face when it gets high in the temps ?? if so its good sign its a tune issue . i.e lean ect. but there again a wide band would tell you if
your running lean . this is just my 2 cents from my limited experiences . im sure others on here have better info then me !!

[ZimbutheMonkey]

For the short time my pre-turbine probe was running om my GTRS elim I was seeing about 1300-1400 at full throttle with W/M.

[M-Hood]

What setup are you running loopy? (for comparison on any areas of possible restriction) turbo, Exhaust size, cat or cat-less, TIP, and how far is your EGT probe from the turbo?

Some causes for Turbo charged engine higher EGTS
are/ could be:
1. restricted intake pre turbo- case proved on my earlier TIP collapse
2. restriction post turbo Ie CAT, cloged Cat, stock exhaust on a higher flowing turbo? this could affect anyone giving more than a quick throttle squeeze.
3. running lean- Higher cylinder temps
4. running (too) rich, burn continues post cylinder head- (is there an accompanying increase in turbine speed due to the higher/temp pressure?)



Mike, where are you measuring the temp?

My EGT probe is in the 3rd runner of my Full-Race tube manifold.

[rockersteady]

For the short time my pre-turbine probe was running om my GTRS elim I was seeing about 1300-1400 at full throttle with W/M.

and you were running 22psi right, any idea what those temps were without WM?

If those temps were comparable without meth then the smaller exhaust port thing might not be a EGT issue if all else is good.
even at 15psi my temps are too high, if I try to run near redline.
Im trying to elliminate one potential source at a time.

my timing doesnt appear to be falling on its face loopy, it still pulls strong- I havent noticed any timing pull. although I should check my logs more carefully, I believe its running about 23 dbtdc at WOT and revs around 5000. Ill also log IATs to check to see if thats a contributor, but my intercooler has always done a great job in the past.

[ricekikr]

When I was trialling out my new TIP setup (switchable between Stock maf and V8 maf) the Tip collapsed at one stage and it caused EGT to very easily rise to dangerous levels. Ie over 900degrees C (1650F)

OT:

What's the reason for the collapsed TIP causing high EGTs?

Is it because the restriction is causing the turbo to work harder thus super heating the air?

My thinking is a collapsed TIP would simply restrict the amount of air going in (albeit hotter than normal), and MAF should still be measuring the correct amount of air going in the engine (proper AFR)

[rockersteady]

Not certain,
Just a noted cause and effect.
I was driving and I noticed that quite suddenly my EGTs went dangerous, with faster rise than I normally experience, under boost and even with medium load (going steady state up a hill.)
Later I found my 2 piece Tip had Partially collapsed at the joiner/ union. I fixed it and my EGTs went back to my normal state.

another theory to compliment yours of super heated air. (Wish I had a log of it but I dont)
In the open loop state perhaps the resultant AFR was too rich (although I cant recall observing that at the time), Fuel is injected according to the requested load (Ie throttle body angle) regardless of MAF output at that stage from all my logged observations, in that case the fuel could still be burning post combustion chamber raising temp and pressure pre turbine and compounded lack of turbine speed (exhaust gas escape route) due to the compressor being starved?

What needs to borne in mind that my car is not a poster child for well behaved EGTs to begin with. So my example of collapsed TIP leading to dangerous EGTs needs to be taken with a grain of salt.

[ZimbutheMonkey]

Nothing on the EGT's sans W/M. Honestly, if you're having EGT issues I would recommend looking into a W/M kit. Even a stage 1 without the adjustable set start point/max wouldn't set you back more than a few hundred and I can promise would do wonders for your EGT's.

However I do agree with your rationale of trying to find the root cause before applying what would be a band-aid solution in your case. But, at least it would give you a safety margin.

Also, the cat (even though it's a high flow variety) could be a factor as well.

Since you also have a bung setup in your manifold, I'd suggest checking your backpressure. I'm probably going to do mine on the weekend. I have an old fuel pressure gauge that's been gathering dust. So I'm going to get some copper tubing and the requisite fittings and actually get some use from those EGT bungs I put in.

Finally, regarding the collapsed TIP, what likely happened was that, yes, the turbine was working way, way harder than it should have to try and flow the gases out of the chamber. You would have been having some wicked reversion issues as a result, so in effect, you would have been re-burning what was already extremely hot gas.

[malanca]

mine is post turbo highest temps i see are 850 Fahrenheit .

I really think you mean 850 Celsius?


I see 870 Celsius max on my K03-0073 Turbo (that's about 1600 F).

I use a custom made high temperature thermocouple sensor, do my readings with a digital reader from an electronics store. Sensor is mounted in the manifold with a stainless 1/8" BSPT clamp.

[rockersteady]

Ill be in Saigon next week, They have a small covered "engineers " market in District 1,
You can buy everything for monitoring there you can think of. Ill be picking up an other iconel k type thermocouple and a driver display like that for my test B5 stock car. and some glycerine filled pressure gauges for my Back pressure test port (when I ran a standard 0-100 psi gauge the needle fluttered like a butterfly on crack.)

I had some luck with my EGTs today,
After ruling out running slightly rich (currently as rich as 10:1 when hard acceleration) as a cause (by temporarily dropping fuel pressure) and leaning to 12.5 made no difference to temp.
Then to check IAT and timing I very carefully logged 003, 101 and 114 (TB angle, In duty, Mass air, IAT, Timing, load and n75 duty) I found timing running to 12 dBTD from 23 dBTDC with IATS rising only 10c from 25c (70f rising to 98f). so those temps are really low, -Not bad at all from my Apikol SMI, I love it. ) (I think the timing drop are knock correction but thats for another log)


So next up I recall my wastegate preload was quite high last time I checked by running with the N75 unplugged (maybe 12psi? ) and after Zimbu mentioned wastegate porting on his exhaust manifold back-pressure thread I thought it might have something to do with it, it so I managed to slacken it down to 7psi- So far so good, my Wideband didnt drop out from overheat and nothing over 900c (1650f) so far on a short run to work. Ill run it again in the morning on my usual test road and see if its really still down at a more acceptable level.

[loopy]

I really think you mean 850 Celsius?


I see 870 Celsius max on my K03-0073 Turbo (that's about 1600 F).

I use a custom made high temperature thermocouple sensor, do my readings with a digital reader from an electronics store. Sensor is mounted in the manifold with a stainless 1/8" BSPT clamp.

you are exactly right right i didnt realize i had changed my temp reading !!! so ya its a bit high and im looking into why now !!