Trying to understand egt's

[93 W350 LE]

I get they are from the combustion of fuel, but how do we try to minimize them while still creating power. Without complicated coolant injection systems.
Is it adding more fuel or getting more air that causes a rise in temps? I am used to gas where when you lean it out, or add more air, things tend to get hotter.
Thanks for any insight or suggestions.

Eric

[oldestof11]

Yes, adding more air can add more heat to the exhaust if you are heavily over fueled. Sled pullers are known to dump way more fuel than needed to help cool the combustion temp.

Diesel runs real lean to begin with. A clean burning truck ruins around 17.1 afr. I seem to remember a paper saying diesels make the most power around 15:1 AFR.

Now i am done with the useless info...

A diesel engine is ran by limiting the fuel quantity, unlike a gas engine which is limited by air. You add more fuel to the air quantity in a gas. A diesel takes in all the air it is given and we try to match the fuel for it. It will, to a point, burn all the fuel it is given. Diesel is a fuel. More fuel the hotter it gets. Now some heat is needed to keep the turbo going. Some of the best power, in theory, is made when you run the hottest the weakest point can handle. In our case, AL pistons.

Things to help minimize heat but add more power is: more air, more timing, nitrous, bigger exhaust housing to spool turbo sooner, big housing to allow more air to get past the turbo, Wastegate settings, adding an external waste gate to relieve exhaust pressure and get some heat around the turbo

[Tacoclaw]

Timing won't lessen the heat, it'll just change what part sees it. The earlier you're spraying fuel the more heat the piston is exposed to, and also the more likely you're spraying outside the bowl and getting that sharp edge of the bowl mighty hot. Still, these engines are rated for 1200* EGT (pre turbo) continuous (as in all day) at stock timing.

I'd say just focus on a decent intercooler and inlet piping, throw a 4" exhaust on it, and drill/port out the wastegate and divider on the 12cm housing you're planning on using. I don't foresee too many EGT problems with your truck if you stick to stock injectors, just make sure the air has an easy time getting in and out.

[93 W350 LE]

So is the stocl H1C's 18cm exhaust housing ok for keeping egt's down? Because its so big? Or does it hurt because of the slower spool time? A bigger better flowing air filter, as well as a better intake manifold, to improve air flow?
It has a 93-94 vintage Banks exhaust, but the tailpipe is only 3". Should I go bigger?

Thanks.

Eric

[Tacoclaw]

You can go bigger on your exhaust if you want, the HX/H1's only have a 3" outlet so you're still squeezing through a 3" hole at one point.

In terms of the housing, the 18cm will help up top and hurt down low, so if you get a tighter converter it may not be the best option. If you get a looser one, it'll spoil easier but get worse mileage and get the fluid hotter quicker. It's kind of a dance that I can explain but unfortunately have no real experience on the results of.

Hopefully some people that toe with autos show up and can give you their EGTs, stalls, turbos, and other such info at various weights.

[BILTIT]

Most auto guys like a 14 or 16 ex. housing depending if they tow or not. Us std's need a 12-14 to keep the turbo spooled between shifts.

[1992gen1_fan]

The stock turbo on my truck had the 21cm3 housing, I really did'nt like it. lagy lagy lagy. The bigger housings flow better so less restrictive and maybe cooler during cruising rpm's. But for low end spool up, the smaller housings are better. The 18.5 is kind of in the middle/larger side. I've heared alot of good about the 16cm housings, I would'nt go any smaller if you'll be towing much.

Not sure on the auto's, but from what I've read people like the 16 over all fairly well.

For cooler towing egt's, an intercooler upgrade might be a good option.

[93 W350 LE]

So the more air in,boost,with the same fuel charge should help kwep egt's lower? Adding fuel to the same boost level increases egt?

Eric

[cmann250]

Compressing air makes it hot, hence the intercooler. To a point more air equals lower EGTs, but it's not that simple.

[welderboy250]

Typically no one ever measures charge air temperature but if Ur putting 300 degree air into the intake u cannot hope to make any power and still hope to keep egt in check.

[93 W350 LE]

So its not so critical going into the turbo, as it gets compressed and heated. Focus on bleeding off as much heat as I can before the air horn. But generating more boost for a set amount of fuel can help keep them lower also?


Eric

[Sutter1stgen]

One thing a wise old man once told me, I mean literally beat it into my brain, was more volume, not pressure.

People try to cram way too much air in there engines by overspeeding there stock chargers. This will be okay with a slight hp increase, but after a certain point they make way more heat than any intercooler/injectable can overcome. A friend of mine went from a gated WH1C to a superB turbo and dropped his temps quite a bit. He was flowing more air on both sides of the turbo.
He was getting more volume.

Another thing that helped lower my boost and egts all in itself was going to 3" intercooler piping. I even had a slight hp gain.

[93 W350 LE]

The volume instead of pressure makes alot of sense. I was looking at changing my IC piping from the 2.5 to 3", but didn't know how much it would help with the inlet size staying the same.
Thanks.

Eric