how many degrees to add on egt reading?

[rockmike]

Ive got some differant info from differant peeps.My hx35 has the egt probe in the cast exhaust elbow(this is where the PO put it) How many degrees should I be adding to what my gauge is reading for tru piston air temps?

Thanks.

[skilletky]

i think its 250 to 300*f

[RCCUMMINS89]

Depends on some things.....

It'll be slower to heat up when it's in the downpipe. So by the time your engine reaches 1300 your probe may only be reading 800.... but if you keep in it long enough it'll show closer to the real reading.

But the "rule of thumb" is 300. So when you are towing down the road and it reads 700 you are around a grand.

[rockmike]

Excellant.Ya I was having guys tell me 200* Ithought that was kinda low...then others are telling me 350* 150* range of info? wasnt sure what to trust.Im talkin my readings while pullin a looong grade,thats really the only time im runnin hot.I hate doing math in my head when im pullin a hill,cause im busy watchin my boost trying to keep it under 35 psi,watching my EGT's then adding numbers to it,meanwhile watching my mirrors planning my time to pull out and make the pass on the slow movin big rigs as to not lose rpms...ALOT! going on driving these hoped up tow rigs lol

[dunes450r]

I read someone's info somewhere about having both pre and post turbo probes, and there wasn't a set difference between the two. depending on how high the temp was determined if the spread was greater or less. can't seem to find it now though

[rockmike]

Interesting,I dont like the probe there.Like I said earlier, somtimes you got alot going on in the cab when pullin long hills in traffic,I would prefer to just look at my gauge and know what temps are hitting my pistons and of coarse the actual temp thats hitting my pistons with out doing math.I got a rebuild kit for hx35 when I pull it to rebuild im going to plug that hole in the elbow and drill my exhaust manifold.

Appreciate the great info.

[rockmike]

Off topic now: you guys mind givin a stab at what HP range y'all think im at with my truck?Hoping to get it on a dyno this spring so I know.

Fuel screw is a ways from run away,quite a ways away from that I believe,I run about 35psi WFO Full synthetic throughout the drivetrain.

Thanks!

[RCCUMMINS89]

275 range to the ground.

[Tacoclaw]

I'd bet around 200-230, do you have an upgraded lift pump?

[rockmike]

Yes I do,it runs at about 13-14 psi at cruise.I think im close to 275 teasing 300hp the truck runs hard!I was goin around a gradual corner the other day at about 40 mph in 4th gear and stomped on it a bit and it broke the duals loose and went slide ways but whatever its at im pretty damn happy with my truck now,shes got strong fuel press with awsome volume and runs strong!

[RCCUMMINS89]

Ya... the more I think about it you might be around that 300+ mark. Even though you don't have a maxed pump and have small injectors, it is moving quite a bit of fuel. I can tell from your egts, boost, and what you pull the pump down to.

[Diesel Dawg]

On post turbo egt keep it below 975-1,000 and youll be ok. You can pull sustained mountains at that temp.

[bmoeller]

Some say, kind of figure the spread on the EGTs as 10* per 1# of boost. Still think that may be a bit on the low side.

[RCCUMMINS89]

Um..... I could almost buy that.

at 30# the spread would be 300, at 40 400.... I would say it is a little low though.

[cougar]

I read someone's info somewhere about having both pre and post turbo probes, and there wasn't a set difference between the two. depending on how high the temp was determined if the spread was greater or less. can't seem to find it now though

That might have been me. I have never seen more the a 200° split in all conditions. It all depends on were your probes are relative to each other.