Was wondering if anyone here is running one of these gauges, or an EGT gauge and if so what kind of temps are you trying to tune with. I have already heard various debates on where to mount it but still wondering on where the temps should be at WOT blasts. It seem to be that anything above 1200F could melt a piston. Thanks in advance as I have yet to see this topic mentioned on here yet.

 

The manufacturer of your EGT gauge should have included directions on where to mount the probe. Most that I have seen are mounted in the headers about 2 inches downstream of the exhaust port.

In F500 with the AMG and similar 440/500 engines, they run under 1200 degrees EGT. The closer to 1200, the more power they have but risk meltdown. Anything below 1100 tends to foul a cylinder.

In A friend's ITC Fiat, he was running about 1430 EGT for the low and about 1450 for the high, if I remember correctly.

I believe that 1475 EGT was a number for optimum on a small block or big block, but I can't find where I got that number from. Unfortunately, I ran across that a long time ago and have not found where I found it.

It stands that it is probably reasonable as using 1200 deg paint on the headers burned off about 6 to 8 inches downstream.

 

EGT measurements are practically mandatory on modified diesel engines. With no detonation to worry about, you can just keep adding air and fuel until the cylinder heads come off.

Since the pistons are cooled by engine oil from underneath, you can run EGT's well above the melting point of aluminum. I have personally seen 1350F on my Chevy diesel pickup truck, and hardcore guys (I have personnally seen a Duramax turn 725 RWHP) run up to 1500F EGT for short periods of time. These are 7,000+ pound trucks running the 1/4 mile in 11.9 secs, at 115 mph.

On a spark ignition engine, EGT would be more for curiosity, since the combustion is always pretty close to stoichiometric.

 

Actually, I believe that in aircraft engines it is used to fine tune the engine to best power.

In race cars, it is used to determine where best power is without sitting on a dyno.

 

Thanks for the feedback guys.

 

correct. we look for around 1175 on our 360 c.i. 4 cyls


and best power is found at 50 rich of peak EGT on FI engiens, and 125 rich of peak on carbs

 

Well I have a 383 with alum heads and run 1400-1500 .. so I certainly hope 1200 is not the melting point.

 

Yea this is an old topic/post but a good one as i read a lot of knowelegable posts here.

I think today most EGT's used in race cars is to save the cyl/piston/engine from meltdown more so than tuning.
Well most tuning for best power is done with A/F using an O2 sensor. Best power A/F is between 13 to 12 air to fuel mix which could be at different EGT's for different cyl's, air density/altitudes, engine loads.
Problem is EGT temps won't match/parrallel O2 sensor output - to many other variables affecting cyl temp reading.

Aircraft still use EGT since it ain't affected by the leaded fuel - an O2 sensor is ruined by leaded fuel, provides some limited mixure tuning (enough to compensate for density altitude changes) and saves the cyl from meltdown (as long as the pilot is paying attention). General Aviation aircraft today are caught in beauracratic limbo and force to use obsolete cylinders, ignition, induction, leaded fuel and highly reliable instruments (TC's require no pwr but provide no control function).

Before O2 sensors became availible a spark plug with transparent/clear glass insulator was used while eng on the dyno to tune A/F mix for correct color of burn inside cyl - probly very accurate but most labor/effort involved.

I need to install an EGT myself but on my Cummings powered PU to protect the tubocharger. And i need to install this before i make performance mods so i can read base line temperatures to avoid future piston/turbo meltdowns with higher turbo press.

cardo0