EGT (exhaust gas temperature) tune and 33's

Titan Joe · **Joined:** Sat Aug 20, 2022 2:08 pm **Posts:** 16

I've done a bit of work to my KJ and it's turned out pretty good I think except my EGT's are insane. so it had me concerned. I've dont a bunch of reading on Lost jeeps and no one else seems to have seen this, but most people are not running a pyrometer and those that are running one only a few have it in the manifold. Some of the threads I've found are quite old. Here is one: viewtopic.php?f=5&t=62109 and another about what to expect for pre and post: https://www.lostjeeps.com/forum/phpBB3/ ... 495853ad60.

Good info but I'm sure my EGT's are too high, but why?

On country roads I'll see 800 at about 50- 55 mph.

On the interstate that goes up to 1000 - 1100 just to cruise at speed. To get to that speed I'll get to 1250 and that's taking it pretty easy. Up hills at speed are about that if I'm loosing speed and passing someone going quite slow just to merge into the next lane is the same thing. If I was pulling a trailer I could expect this, but I'm empty.

From what I've read I should maybe see 900 going up hill on the interstate.

My pyrometer is an Autometer kit with the probe installed right in the collector of the manifold.

The altitude here is about 4500 feet.

So now for my jeep configuration. I am running 33" tall tires. That's the number one issue that I could see. However I am geared a little slower than stock, so my RPMs are about 100RPMs higher than factory in top gear. So I have effectively re-geared for the wheel size change. There will be some extra weight from the rubber, but I though people were running 31" and 32" tall wheels here without re-gearing. The wheels I selected are pizza cutters so they are not fatty wheels. The whole reason for running this size is because I just manual swapped the Jeep and the overdrive is not as tall (.79 vs .67). Normally when people get higher EGTs from a wheel size change it is because they failed to re-gear, so that's why I'm hoping it is not an issue.

My jeep also has a 3" turbo-back exhaust without out a cat to restrict the airflow. That should help keep EGT's down.

I'm not rolling coal down the road and I'm getting 1000 at 10 pounds of boost. I am running a Yeti tune for full torque, but I doubt that it's the tune since everyone has had good experiences with him and ultimately I'm the one controlling the pedal. It might be able to be solved with a much more conservative tune, but I want to make sure I'm not missing something.

I' think I'm going to pickup a new air filter today, but I doubt that it will drop the EGT by 300 degrees if any at all. I'm going to also try to scrounge up another meter to verify the accuracy of my pyrometer.

I just rebuilt the engine so the intake has been cleaned, FCV is eliminated, EGR blocked, inconel exhaust valves installed and the pistons are ceramic coated on the crown. I have a 203 degree thermostat and I have never seen it creep up past normal running temp.

What your thoughts on EGTs, big wheels regeared and a tune?

WWDiesel · **Posted:** Tue Jun 11, 2024 5:07 pm

I don't have a EGT gauge in my Jeep, but I do have one in my Dodge Cummins and I will back out of the throttle if I see the EGT's exceed 1300 degrees.
I only ever see higher temps when towing a 10k loaded camper behind truck pulling long uphill steep grades. It has no CAT and 5 inch exhaust, turbo back, with a straight through muffler. I run 40 lbs boost at full throttle under load.

Keep in mind, exhaust restriction can have one of the biggest impacts on EGTs. No CAT and free flowing muffler can help lower EGTs.
Also not having ANY restriction on air flow coming in like the FCV causing a restriction and having the EGR exhaust blanked off or totally removed can also have an affect on holding EGTs down. I am running 245/75/16 AT tires. Stock gearing.

On my Jeep, I have no CAT, and all the EGR crap was removed years ago, 3 in turbo back exhaust with a Flowmaster muffler. It also has a Yeti Stage IV HOT Tune. I really don't worry about high EGTs on the Jeep, maybe one day I will install an EGT gauge. Just not a lot of room in the cab for more gauges since I already have transmission temperature and turbo boost gauges.

And, increasing boost pressure will also help lower EGTs, as the more air you can get into the engine it helps hold down combustion temperatures as long as the fuel/air ratio remains within limits. :wink:

Titan Joe · **Joined:** Sat Aug 20, 2022 2:08 pm **Posts:** 16

I think my EGTs sound pretty high. Do they sound that way to you?

My '97 Dodge rarely gets to 1100, but I'm pretty sure that is is underfueling.

03black · **Posted:** Tue Jun 11, 2024 8:44 pm

I'm running a very simular setup as you except I'm running 32" tires, 4:10 gears

My probe is in the exhaust manifold collector right before the turbo and I see EGT's around 1100° at 60mph with about 2200rpm's.

Like you I've asked if these are to high but i haven't found an answer to that. I did ask the facebook CRD group and got no real answers. Its been this way ever since I rebuilt the top end with new head and stock valves and I've put on about 20k miles and so far no problems (knock on wood). Was thinking of doing the 3" turbo back exhaust but if your seeing the same temps, it may not be worth it to me (I put on a 2.5" flowmaster flow through muffler & no cat).

Titan Joe · **Joined:** Sat Aug 20, 2022 2:08 pm **Posts:** 16

03black wrote:

I'm running a very simular setup as you except I'm running 32" tires, 4:10 gears

My probe is in the exhaust manifold collector right before the turbo and I see EGT's around 1100° at 60mph with about 2200rpm's.

Like you I've asked if these are to high but i haven't found an answer to that. I did ask the facebook CRD group and got no real answers. Its been this way ever since I rebuilt the top end with new head and stock valves and I've put on about 20k miles and so far no problems (knock on wood). Was thinking of doing the 3" turbo back exhaust but if your seeing the same temps, it may not be worth it to me (I put on a 2.5" flowmaster flow through muffler & no cat).

That's good to get another reference point. When going up hill I assume that the temps rise even higher too. I wish I had gotten my EGT installed before I modded the Jeep.

CATCRD · **Posted:** Mon Jun 24, 2024 11:42 am

I have 32" tires, stock gears and GDE Hot tune. Live at 5000ft elevation. My pyro is in the manifold before the turbo, and I see 550-650 cruising down the interstate at 70-75 on level ground. Boost hovers around 15psi. I don't have anything big to tow so I've never seen 1000+. It's hard to hit 900 unloaded.

Maybe something is off with your valve timing? Like one cam off by a tooth?

DieselJeepLuvr · **Posted:** Thu Jun 27, 2024 7:22 pm

Pretty sure I've answered this before. 1,400 F and you will be melting pistons. 1,200 F can be maintained for the couple few minutes on hard pulls uphill in high temperature s but anything below that is fine. An individual injector over fueling can cause a cylinder to get too hot which is why it's important to keep fresh injectors. You can also install methanol injection to help cool the intake charge which will reduce EGT's and increase HP/TQ.

Titan Joe · **Joined:** Sat Aug 20, 2022 2:08 pm **Posts:** 16

That's exactly how I understand it. I'm thinking that something in the original settings is trying to keep the injection timing longer to reduce NOx emissions. I think Green Diesel really had this figured out but I unfortunately cannot get one of their tunes now. I actually got a seconds CRD that's all factory. I need to install my spare turbo into it and do some testing. I think I can read rail pressure and get an idea of what is going on with the tune. I think that numbers like CATCRD is seeing are a lot more practical. I can put the timing pins in it to check valve timing I suppose.

Still, great data to hear.

WWDiesel · **Posted:** Thu Aug 01, 2024 3:14 am

You can PM or email Marco aka "Yeti" on this forum and he can supply you with a custom tune to fit your needs.
email link:> memberlist.php?mode=email&u=42474
PM link:> ucp.php?i=pm&mode=compose&u=42474

or you can contact him on facebook at:> Yeti ChipTuning di Giacomelli Marco

contact:

Titan Joe · **Joined:** Sat Aug 20, 2022 2:08 pm **Posts:** 16

This is a Yeti tune I'm running. I've hit him up with some questions about it and what he can do for me, but most of my technical questions go unanswered and he has told me that I can buy another tune. But without knowing if it's going to even target the changes I want I've been hesitant. I always hope that our email exchanges will end up getting into a technical discussion on what will help change things, like - the rail pressure can be boosted from this to this, shorten injection times or start of injection and we should see approximately these results, but it hasn't. So for the time being I've been trying to learn as much as I can about the current state of things. I've just got my DRB3 emulator working and I need to collect more running data, like what is the rail pressure at while I'm cruising. There are a large amount of parameters I can watch, so I need to get setup so I can log some data. If he can whip up the tune of all my dreams and I'd be spending my money already, but I just want to make sure that can happen. So, time to collect more data.

EGT (exhaust gas temperature) tune and 33's

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