EGTS

[Ptothej]

Hey guys, I just pulled a 3000lb car on a tandem axel flatdeck trailer up a mountainess highway. Only one hill forced me to down shift, at the bottom I was already at 30lbs of boost and was afraid of it raising the bar on what I thought my max boost was! That was the intial reason for shifting down to 4th, so I held it in 4th at 90k/hr, 25lbs/boost and like 975f egt's. Truck is fine, didnt miss a beat, did start to smell a hot metal smell although, now alot of you guys say put the pyro in the manifold, mine is in the down pipe, I call on some truck shops as part of my job, and I notice they are all in the pipe, and talking to a few of them they all agree no more then 1200f, which is was Ive read on here, but Im sure you guys say 1200 in the manifold, and these guys say 1200 in the pipe. Ideas/comments/suggestions?

P.S The hill I was pulling was long, Im not sure of the exact kilometers/miles, Im sure it was at least 2-3kms.

[Richie O]

I am going to say 975 in the pipe you were most likley near 1300 in the manifold. Thats to high for pulling hills. Its a hard thing for me to grasp as timing will also effect heat on the pistons. So, whats safe at what timing? I know I won't hold over 1200 in my trucks for very long. I do 1500 plus lots of times, but thats empty, and I am at top speed before it has a chance to eat itself up.

[ciamcoop]

"They" say as a rule of thumb the temperature difference between the manifold and pipe is about 10 degrees per psi of boost. So at 1000* in the pipe at 30 psi boost is about 1300* in the manifold. That's a bit on the warm side, but you'd probably be fine running it there, but why risk it? Unless you're trying to show what you've got!!! The heat not only affects the pistons as Richie said but the fins on the turbine wheel also. The pistons have jets under them that constantly spray oil to keep the pistons cool. The turbo has 1500* exhaust going through the entire time so it tends to get the worst of it. Now if you're wanting a new turbo and the wife keeps saying no, well now you know how to get your way....

[ahale2772]

may be just a good idea to relocate your pyro? I know i couldnt sleep at night if my egts were maybe 300 degrees warmer than what the guage reads.

we tow at 1200degrees in the 24v very often, it seems to take the abuse fine but anything over that is ovekill, of course at 1200degrees that truck is pulling like a monstor and usually we are racing some FURD up a hill

[oldestof11]

Got blow-by?

[The_Head]

Why do some people still manage to place the probe post turbo?

[Richie O]

Why do some people still manage to place the probe post turbo?

Its a very common place in heavy trucks. I also know of marine engines set up that way.

[The_Head]

Ah, ok. I did not know that.

[Ptothej]

Thanks for all of your input! I did back off and drop to 4th, so I was only running 25lbs of boost up that hill so what 1250 at the manifold? No one touched on the big rigs running their pyros in the pipe and hitting 1200f, are our trucks not as beefy to handle the heat like they do? How can they get away with 1200 and having factory pyros in the pipe? Im having a hard time going along with this pyro probe in the manifold thing, another thought I came up with is maybe big rigs are more tolerant to heat and 1200 at the pipe is their max, but our trucks not being so strong against heat you need to put it in the manifold and and not let them get past 1200 in the manifold? I dont want to be unreliable or a hero by any means, and I was being very super sensitive to wierd noises or funny readings on gauges etc. When you get the egts up high doesnt the engine temp gauge start rising as well? Thankyou for reading and please bear with my ignorance.

[Richie O]

I went on a boat with a 1200 hp V12 and the captain said 900 degrees max in the pipe. The company that made the motor said never over 900.

[ciamcoop]

I've owned trucks and they were all not stock. The probes were all in the pipes and my rule was never over 1000*. One truck was a big cam 3 400 cummins, which was probably close to 600 HP, would hardly ever reach 1000 unless I was being mean to it. The larger engines are built the same, they just move a lot more air through them so they're more manageable. The newer electronic engines run much cooler because of fuel and air delivery improvements so it's almost unheard of for them to see 1200* egts in the manifold. I'm talking pre-egr engines. You'll be fine with yours the way it is, I just would never exceed 1000* when you're towing. As far as the water temp goes, it and egts are. 2 separate issues. The egt can skyrocket before the water temp rises, and the coolant can get too hot even with egt in check. You sound like you know what you're doing so you'll be fine. Keep on truckin'

[1990]

I've always been told 900 max in big trucks. These all had post turbo pyros.

[Ptothej]

Ciamcoop, thanks! Im no proffesional at anything but I like to think I have a pretty good idea of what Im doing! I cant say its ever gotten over 1000f, it always seems to max out at that, and Im talkin like 2 times since Ive owned it, normally the hottest it gets is 900f, and even at that thats the biggest load on the biggest hill for the longest amount of time Ive ever put it under, Ive pondered about even taking some fuel out just cause of the damn fuel prices and for what I haul with it I never floor it unless Im jack assin around, so the power is plentyand as you can tell it wouldnt hurt cooling it down a bit. Thanks for all the input guys!

[dunes450r]

the cat's in the big trucks i'm around hit 1200* post turbo.......................they have steel topped pistons

[Ptothej]

I would like to create a second part to my egt thread. I dont know if anyone else has tested this before, but I raised my intercooler about 2inchs after finding out some of it is hidden, and took out the factory grill inserts. Im looking for opinions on what you think is the best effective way to kill egts without turning fuel down (Im talking stock fuel delivery, injectors pump etc. I figure that shouldnt be too hard to accomplish), would you suggest meth, bigger turbo, bigger intercooler, I wanna hear your ideas, thanks guys!