Mild Fuel + Lots of Air = High EGT's??

[JRussell3176]

I can't figure this out. Here are some of the facts:



I'm at 5,000' of elevation.

Mods in signature below.

Outside temps around 80*.

Max boost is 34psi.

Max EGT's are 1250-1300.

Pyro is pre-turbo.



When testing my max EGT's I use the same highway grade each time. Not sure of the exact % and it isn't the steepest around, but it is a decent grade. I use OD and floor it at 70mph to get the "max" EGT's.



Does this sound right, or should I have some room to crank the fuel screw a little more since I still have stock injectors? The Stage III upgrade lowered my max EGT's by about 150-200 and increased max boost by 5-6psi. I then put on a turbo-back 4" exhaust and the max EGT's did not drop (had 3" w/high-flow muffler and turndown). Today I installed a 14cm non-wg housing and max EGT's seem to be about the same or maybe 50* higher. Max boost increased about 4psi with the new housing.



I'm a little disappointed that I can't turn the fuel scew in some more with the mods I have (it's actually just under 2 turns right now). I hear about everyone running POD's or 5 turns on their fuel screw with a stock turbo or hybrid similar to mine and it seems their EGT's are just slightly higher than mine. Does the 5k' of elevation really make that much of a difference when it comes to EGT's? I'm so desperate at this point, I'm trying to convince myself that maybe I really have more power than I think I do. :-laf

 

[cerberusiam]

It's a little tough to make power and keep things cool at that altitude.



What exactly is a HTT Stage III turbo and what are its specs? What speed are you getting when you back out of it? Is that the max EGT or are you backing off?

 

[backroad]

Your egts don't really seem to be bad considering your pyro is pre-turbo. I do like your boost numbers.

 

[JRussell3176]

The HTT Stage III is a 60mm compressor wheel and new compressor housing which upgrades the stock H1C.



You know what, I have no idea what speed I'm reaching when I back out of it. I've always just run it up the hill for 15-20 seconds with my foot to the floor and the pyro seems to stabilize. I usually just back out because it feels like I'm going fast and there are other cars around. I guess if I held it for minutes the temp would probaby creep up another 50* or so.



Also takes me forever to cool down after a few "hot runs". I live at the top of a short, but steep hill so that doesn't help. I rarely see it go all the way down to 300* though and usually have to shut it down around 312*. This is after a good 5-8 minutes of idling and 80* temps outside.

 

[cerberusiam]

The temps don't really sound that bad for what you have and where you are. Add some more fuel and lift as little earlier, thats what I do. The 1300 degrees is not bad considering in the same conditions mine will easily top 1500 degrees, and a lot faster than 15 seconds.



Unfortunately unless you add a turbo that is capable of making some better air EGT's are the limiting factor. A little water/meth or NOS is said to help.

 

[Flexiheep]

I can't give specifics, but when I lived on the california coast I could drive on the highway at 600 degree pre turbo, now that I live at 4K ft in Las Cruces NM I run at 900 most of the time! Scared me a little untill I decided that the altitude had to be what did it, and my max EGT doesn't seem to be any higher at about 1200. I think that is controled my the auto transmission (Dodges version of a CVT) more than atmospheric conditions. :-laf



I miss watching my pyro run nice and low, but I would rather live here than Cali so it is a good trade off

 

[dpuckett]

JRussel-

Your numbers sound right in line with what I observed at 6000ft when in ColoSpgs. Believe me, you are in no danger if 1300 is all you reach. I'd be more concerned about cruise temps than full throttle, as there are many factors that influence peak temp and boost. I run the same temps in my 92 that I did in my early 91, sometimes higher. Makes me think my pump isnt up to par. But who'dve thunk that after sitting for 8mo, and having 250K to boot... ...



Daniel

 

[JRussell3176]

Thanks for the reassurance guys.



I guess it is due to the altitude then. Maybe I need to take a trip somewhere closer to sea level and find out for sure. :-laf



dpuckett: Did you mean to type 6,000' of elevation when you were referring to CO? 600' doesn't seem like CO.



Flexiheep: Your cruising EGT's seem to correspond with mine. I'm at about 800-900* doing 70mph in OD on flat ground.



So my truck's inability to cool down to 300 or below is also pretty normal on a hot day (~80*)?

 

[HRDROKN]

On a hot day I can get down to 300, but not below. Now on a real hot day 95+ I won't even see 300..... this is at 90 to 300 feet elevation.

 

[dpuckett]

Yeah, I meant to type in 6000ft. 600 is higher than where I am now.



I can get below 300 EGT on most days, be it 75 or 100deg.



-DP

 

[cerberusiam]

Neither my 92 or 05 will get much under 350, more likely 400, unless its pretty chilly. Just the nature of the beast when yer makin' HP. :-laf

 

[JRussell3176]

It's a little tough to make power and keep things cool at that altitude.



What exactly is a HTT Stage III turbo and what are its specs? What speed are you getting when you back out of it? Is that the max EGT or are you backing off?

Ok, I bumped the timing a hair more to a full 1/8". When I originally went in to bump it I noticed the marks were already almost 1/8" apart so I left it alone. The truck was a one-owner and he was 83yo so everything else besides the starwheel was stock (all caps still in place). I seriously doubt he would of had the timing bumped for performance reasons. Maybe his timing was just off from the factory and the dealer bumped it to correct the issue? Has anyone else noticed their timing marks aren't lined up on a stock truck?



Also, when you first bump the stock timing to 1/16" or 1/8" do you normally notice a slight sound increase and a little more throatiness? It doesn't sound like a straight pipe or anything, but you can tell a little when you start driving. Is that normal or am I maybe too advanced?



I went and ran another max EGT and boost test today, only it's 95* here instead of 80* outside (80* when I ran the other tests). I stayed into it a little longer this time and the max EGT's were 1200-1250 at first, then creeped up to around 1300 and seemed to stabilize. I was doing about 78mph when I backed out and started at around 68-69mph. Using the 1* of air temp = 3* of EGT formula, that means my max EGT's dropped by about 50* with the very tiny timing bump. I also lost 1-2psi of max boost, but that is to be expected when you advance the timing (so I hear). Max boost could have also been affected by the 15* higher outside temps too.



What do you think guys?

 

[dpuckett]

If it sounded better, and EGTs were better, I'd say you went in the right direction. Try it for a while, and see what happens. You'll know you got too much advance when it starts to get tinny sounding, and you lose bottom end.



-DP

 

[JRussell3176]

"See what happens"... as in, if my head gasket holds it's OK to run like that? :-laf



So there is normally a slight sound increase when you make the initial bump from stock to 1/16" or 1/8"? When you mentioned "tinny" sounding it got me thinking that the "throatiness" I'm hearing may be the same sound. It was a very slight change, but I also have the huge muffler that comes with the Stan's kit so that might be taking some of the "tinny" sounds and toning them down.

 

[dpuckett]

No, "tinny" is leaning to a PSD or DMax rattle- really high pitched, almost sounds like it needs valve adjusting; not the throaty/growl you mentioned. I wouldnt be worried about your head gasket- the one on my 91 held 40+ psi daily for a LOOONG time, and no ill effects. Let me say no signs of failure. As for drive it and see, I meant drive it and see how you liked it overall- EGT, power, MPGs, etc. Great thing about mechanical controls- you can always go back.



-DP

 

[JRussell3176]

Thanks, DP. That helps a lot.



I was just kidding with ya about the head gasket. I've heard a blown HG can be a negative effect of far too advanced timing, but I don't think I'm there just yet.

 

[JRussell3176]

Bumped it a hair more and lost the bottom end and definitely makes the tinny sound now. Max EGT's were about the same, but definitely creeped from 1100-1250 much slower. Oh well, guess I'll go back it off a little and see how it does.



Thanks for the help!