High EGT's

The car: 14b @ 19lbs on 450cc injectors. Tuning with MAFT and AFC.

According to my egt monitor that's located 4 inches from cylinder #1 exhaust valve, under full boost the egt's reach 1350+ degrees after a moment. Now my wideband says, at that point, that my a/f ratio is 11.4:1 - 10.7:1.
I guess my question is, am I running a little lean or am I over-working the injectors? Or is it too rich and I'm just burning excess fuel on the exhaust stroke?
My rear bumper has alot of black around the exhaust which leads me to believe that I'm rich, tho I don't see black smoke. I checked the timing to make sure it wasn't retarded aswell.

Anything else I should take into consideration or check?
Please help. Thanks in advance.

 

[GVR4_1057]

That is a bit rich. Is that EGT reading Fahrenheit (I assume) or Celsius. 1350F at WOT is not dangerously hot. 1600F is hot.

 

Yeah that's fahrenheit. So you think I'm burning excess fuel on the exhaust stroke? The other thing we have to keep in mind is that regular gas stoichiometric ratio is 14.7:1 and the fuel we typically use days has about 10% or less ethanol in it. The fuel ratio for 10% ethanol (or E10) is 14.0:1~ meaning you need more fuel.

 

[GVR4_1057]

These are 2 articles on EGT temps. And I do agree that it seems logical that E-10 should be a bit richer to reach stoichometric.

click

click

 

Thanks the first link was really helpful and cleared up alot of questions. I suppose the only question I have left is how hot is too hot for a 4g63 block and head?

 

[boostedinaz]

On my old Talon I would try to get around 1500 max. with an A/F ration of about 11:1.

 

[Brianawd]

Why are you using a egt gauge when you have a wideband.

 

I originally got it out of curiosity. I don't use it to tune anything, that's not what it's there for. I more or less use it for engine saftey, so I know I'm not too hot via timing issues or fuel delivery problems. If I had it my way I'd install one on the remaining three runners for logging variations between cylinders. That's why I mounted the egt probe as close to the head as possible. An egt prob near or on the exhaust collector only tells me what the temp is in my exhaust manifold, Not the actual combustion temp. Monitoring the combustion temp for saftey practices is important, IMO. I shoulda titled this thread with how hot is too hot for our engines.

 

[biglady112]

I can tell you that EGT's are way more accurate than a wideband. We just use the widebands as a reference. We use them very heavily in Land Speed Racing.

With that said, we tune for 1500*. 1550 and we have the warning lights start flashing on the Racepak. 1600 and we have the Racepak set to go nuts. So 1500-1550 is what we generally shoot for. Regardless of the fuel. And we monitor all four cylinders just after the manifold flange coming out of the head.

 

[toybreaker]

Different horses for different courses...

Steve, you need to quantify your responses on this board.

Please note this is not a land speed forum, or a tOOner board, this is Galant vr4.org /ubbthreads/images/graemlins/smile.gif

Egt is an indicator of many different factors, and while your tune works for you and what you do, it leaves very little room for error on the street.

Running around with a tune set on kill works for some people, but the vast majority of the folks here want to be able to roll down the road without having to worry about a meltdown, and running that close to the edge is not condusive to a long and reliable service life.

It has been my experience that (measured where most people will have their egt probes) continued operation above 15-- will shorten the life of many of the components.



That's not heresay, that's not guesses, that's cold hard experience gained over many years of running expensive equipment under real world conditions with an expectation that I can drive the car to work tommorow. /ubbthreads/images/graemlins/smile.gif