Engine/Transmission (1998.5 - 2002) EGT and Boost - now how do I read them

[VicR]

About 5k ago - when I got the smarty - I installed an EGT and Boost guage. Did a couple of trips this fall and past summer with a small slide-in. I seem to hang around 800' on the EGT when cruising at the speed limit on flat roads, smarty on fuel saver SW1.



Is there an optimum EGT for these engines for efficiency? Years ago when I flew small airplanes the EGT was a useful gauge for determining the best settings for flight. Now that I have some control over engine settings with the smarty I am wondering if I can use these to optimize my fuel burn, but I don't know what the targets should be.



Thanks - Vic

 

[Joe Mc]

I'm not aware if there is an optimum egt for efficiency and think it would be hard to maintain a specific egt unless someone created an egt control that adjusted throttle to maintain.



However, I've heard and experienced first hand these engines have a "sweet spot" that is 2000 - 2100 rpms. In my truck when I'm running down the road at 2100 rpms you can hear the difference - the engine sounds like it's just "hummin" along and happy about this speed.



Sorry the sweet spot is 1900 rpm, not as previously mentioned.

 

[jcwehking]

There was a write up in TDR back a while ago. Optimum was around 700 degrees pre-turbo.

 

[jeepit]

I read somewhere SW 1, fuel saver should not be used for towing..... I always shoot for the lowest boost and lowest egt for the load. That does mean you may be running a higher rpm. The other night on a run home from Madison I could cruise at 63 or all the way up to 70 with pretty much the same boost and egt. So, I ran 70.

 

[georgej]

I like to keep the egt around 600 for mileage, up to 1250 when mountain towing and let it drop to 300 betfore shutting her down... pre turbo

 

[PC12Driver]

The egt in the plane was for a different purpose than the one in your truck. Since a gas engine developes max power at 14. 7:1 air/fuel ratio, the egt guage in the plane would let you know when you were at that mixture (peak egt), and then you'd adjust from there to the mfg's settings (50* rich-of-peak or whatever). With a diesel engine there is no set mixture. It can vary from 80:1 at idle to 18:1 or less at full load. Basically more fuel = more heat = more power. So the egt on a diesel is more of a power output indicator. Lower egts = better mpgs. I'd say the guage's primary function on our trucks would be keeping us away from melting down (1250* pre-turbo max continuous) followed by it's secondary function of wating for 300* for cool-down. And of course it's handy for diagnostics if things aren't running right. But there really isn't anything to adjust (aside from the throttle) and there isn't a target egt to shoot for.