One bank hotter

[quattrorunner]

Any ideas why my egt is hotter on one side of the engine than another? It's always the same three cylinders. Example 600* or so on one side and 400* on the other at idle. What might cause this? Plugs, tune, cam timing difference?

[Tom_in_NH]

Are you using a point-and-shoot infrared temp meter or in-primary EGT probes? If using the infrared meter, disregard the rest of this post.

If you are using individual probes, full scale signal voltage of a K-type thermocouple is only in the sub 100 mV range. They are notoriously sensitive to connection issues. Exposed element types, although faster responding, are subject to much shorter life than the closed tip type.

Are you using extension cables on the sensors? If so, those present a cold-junction, and can throw off calibration.

Are you using one sensor per bank, or one on each exhaust port?

[stownsen914]

What Tom said. Connectors, even extending your leads with regular wire, can throw off readings significantly.

Also, where are your thermocouples tapped into the exhaust? I believe optimal is something like 1-2" from the head.

Do you happen to have wideband O2 data to compare to?

[quattrorunner]

Thanks for the responses.
My thermocouple is in the merge up to the turbo.
And it’s an open tip style. Its fast response is different than closed tip.
However the reading I’m referring too are hand held IR readings.
My afr gauge works and matches my other sensor. Theyre within 3” of each other. One for efi reference and one just for the gauge.

[stownsen914]

Once you get downstream a bit, there could be lots of reasons for differences in temp, including airflow and ambient temp of surroundings, that possibly affect cooling of exhaust. If your AFRs are as expected, I’d be less inclined to worry about it.

[Spetrow]

The lens on most hand held non color units is very wide. The laser is not what the sensor sees. You would need to be at the same very close distance, angle and surface conditions. Understanding emissivity is the key. With a high end Flir, you can move the curser to read a spot but still can get odd readings due to surface conditions. You need the thermal image superimposed on the visual image that a high end cameras do.

[RobFrost]

Variations in heat exchanger air flow? You could also test dynamic compression from one side to another, e.g. cam timing off. Check fuel air mix. Less oil cooling one side e.g. no piston oil squirters. Compromised oil flow.

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[quattrorunner]

It's something else. Could it be bad plugs?
Could it be a bank is slightly off on cam timing?
I just had the car on a dyno yesterday and am disappointed in my numbers. 320hp to the wheels at 1 bar.
It runs well but that's not much hp for efi on carrera heads and intake w 82lb injectors and a gt3582r turbo. I have a big intercooler. My headers are BB with heat in great shape.
I want to figure it out and make more safely.

[gsxrken]

I don’t think a slight cam timing difference would explain the missing 80hp I would have expected with your Garret and bigger ports. What boost level is that at?

Like RobFrost said, as much of a pain it might be, a compression test would be interesting.

[flightlead404]

absolute EGT isn't really much use anyway, unless it wildly different indicating a potential fueling or ignition problem, or even a stuck valve that sort of thing

what's much more important is where it peaks and getting them all to peak more or less at the same time.

[stownsen914]

I recall years ago when I first put an EGT on an air cooled motor, I was told idle and part throttle numbers weren’t that meaningful. Are you seeing similar temp differences under load?

[quattrorunner]

Firstly we're getting things like EGT confused with my temp difference.
I do have an EGT but lets put that aside for now, my problem of difference in temp is with an IR temperature tool and I'm taking samples with that at idle doing all 6 header pipes.
I get at least 100f difference side to side.
My Dyno tests and tuning was at 14.5psi or 1 bar. I really should be getting more than that on a dynojet no?
I will for sure check my compression again it's been a few months.
Does anyone have a baseline foe me? I have JE 8.1/1 pistons in 3.3 turbo cylinders.
My leakdown was less than 3% at 100psi across all cylinders. Pretty good no? It's very fresh engine with about 2000 miles or less on it.
I'm going to do what it takes to get my engine as much power safely at 1 bar as I can. I have all the ingredients to get at least 400hp.
After that I will go after bigger cams and turbo but for now Io want/need to get what I can get with this.

[47silver]

I would check air flow first:
is the alternator deflector installed correctly with the vanes intact?
is there a shop towel, paper towel, leaves or a rag on the higher temperature side?

[quattrorunner]

It doesn't have hot cht but I can scope that.

[stownsen914]

Yeah I was mixing IR temp and EGT again.
I didn’t notice in your post the actual hp you got, but saw another poster mention something about 320 ho? That does seem a little low given the specs you mention.
I’d want to verify some basic things like compression / leakdown, fuel, and spark.
I wouldn’t personally worry much about 100 deg difference in header pipe temp at idle. Too many variables to trust it as meaningful imo.

[quattrorunner]

Ya I'm gonna start simple with new plugs and compression test. Tune guy taught me about reading plugs with timing adjustments. I'm also going to add knock sensor.

[quattrorunner]

I suspect I have a fuel pressure variation from bank to bank. I have a Carrera intake and fuel system. My injectors are large but fresh 82lb size.
Question is whether it's possible the stock pressure regulator might be my issue?

[Alan L]

You have only 5 plugs in the pic. Assuming they are in order - you have the last 3 running cooler than the other 2 - but you knew that :-)
You are running EFI I think?
In which case I am lost. But I have seen an FD run different from one bank to the other (mine).
What you could do...................is run flow tests on the injectors - all 6.
That may give you the answer.
Alan

[quattrorunner]

Ya that last one was a bugger and I had to get to work. Ya my fuel system is a Carrera rail and regulator. I do have efi and theoretically adjust fuel trims in that but that pretty complicated (scary) and I don't want to mess with that till I can sort out other more traditional things. I just don't know much about that system and how different parts might affect the system.

[Alan L]

I would take all 6 injectors out and do the usual fuel numbers on them.
Alan