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So, I’m building a turbo VW R32 engine. I’m just finishing the turbo manifold at the moment. I am looking to add EGT sensors to each runner to help monitor variations per cylinder but I’m wondering if anyone has experience with this on these engines. Being a single head on a narrow angle V motor you effectively end up with 3 long and 3 short runs from exhaust valve to header. Clearly this will make a big difference to the EGT seen at the sensor but what I don’t know is how much. This same effect exists on the inlet side so you have the same 3 short and 3 long runs on the inlet. I have previously heard that this can make a 2% difference in furling between front and rear cylinders which would may show as a difference in EGT.
Am I wasting my time with the individual EGT and should I perhaps just use a lambda sensor in 1 short and 1 long runner to see the difference?
Im kind of have the opinion that I can never have too much information and given that I’m aiming for 1000+hp anything I have that can help with the tune would be an advantage.
Anyone have any thought or experience with this?
That is a tough one since you're correct - The distance from the exhaust valve will affect the measured EGT and usually you want to equalise that distance. If you had the option I'd tend to run individual EGTs fitted to each runner and then an O2 sensor in a short and long runner as you suggested to get a feel for how the EGT difference translates into lambda. You can then apply what you fine to the remaining cylinders. Of course if budget allows then 6 individual O2 sensors would be ideal.
I used a little trick on my engine. Of course it is not that precise comparing to electronics but still good enough to avoid huge difference. After a quick WOT pull I would stop the car, shut down the engine and remove spark plugs to check if they are all the same color on the tip side. In case the spark plug color was too clean and sort of white comparing to other ones( which is a sign of a leaner mixture) I would add more fuel in corresponding cylinder. Then i would do the same thing to all of them until they all are the same color. I ended up adding 10% more fuel to cylinder 4 and 5% to cylinder 3. Not perfect but something is better than nothing...
The other benefit of this technic is that you can observe the spark plug for any signs of knock which would be little metal particles heat welded to the spark plug surface.
Thanks for the reply’s guys. I think your advice Andre is probably the direction I was heading in. I will use a pair of lambda sensors to get an idea of how the EGT’s are comparing. May even do a bit of old school spark plug reading just to see if it looks like everything is on track.