boost vs pyro temps

[maverick_935]

Just put in new gauges and am learning what the engine is doing. Is the pyro reading climbing as fast as the boost normal. The pyro settles right down as soon as you let off again. The pyro is pre-turbo.

Just cruising around town(no load) I have no boost showing and the pyro temp around 350-400.

Does this sound normal.
Anyone who does not have a pyro should invest in one to see what they could be doing to their motors if they don't let off. I was amazed at what I saw.

[DaveNY]

My post turbo temps are around 300' light throttle around town. If I lay on it I can easily see 700 or better. That is with the Cat removed.
Dave

[DennisG01]

Your numbers are good. Yes, the pyro does move rather quickly. It's not quite as fast of a swing as the boost gauge, but it does react MUCH quicker than post-turbo (I originally had my probe installed Post - I was amazed at how much faster it reacted Pre).

[Robyn]

Pre turbo (at the outlet of the LH manifold or similar) is a very real test of what the valves are seeing as well as the tops of the pistons.

Post turbo is still a good thing but the "crispy Zone" is much lower, say 900 F tops for any duration of time.

Now there is also a situation that can exist where the turbo is putting out loads of boost but the temps are fairly low.

I have helped a fellow member here with his 94 6.5 which has seen a rebuild and conversion from a DS4 to a DB2. The DB2 pump that was delivered from the pump shop was one that was designed originally for a "J" 6.2 and even turned all the way up does not provide the fuel that a 6.5 can use.

With the Turbo Master set fairly tight the boost is there under heavy throttle but the temp never exceeds 700 F Pre turbo.

This is a very lopsided condition. It will not hurt the engine at all but there is not the abundance of power that was the goal.

My 95 Dually 6.5 with a power chip from one of our fine contributing dealers will shove the Pyro to around 900 F and 12 PSI (Turbo master controled) under a hard pull with 7-8 K worth of load behind the rig.

The boost snaps right over to 12 PSI almost imediately after planting the throttle and the pyro will rise much more slowly.

As the engine RPM's rise out of the peak power band (close to shift points) the boost will fall off to about 7PSI and then as the next shift puts the engine back into the sweet spot the boost will climb right back to the set limits.

Cruising at highway speeds see about 300-400 F

What you are seeing is very normal.

Remember, "Never get caught driving in the Crispy Zone" :eek:

It takes very little time when the temps get up to the limits for things to start going south.

The engineers went to great lengths on the 6.5 to keep owners from being able to get into trouble.
The fuel settings were and are very conservative and the turbo limiting systems (Both the mechanical ones 92-93 and the vacuum and electronic on later units) all play a very important part in keeping the average driver from MELTING the little creature under the hood.

The 6.5 can and will give a very respectable amount of power output, but, the driver has to run the thing with a very careful eye on the gauges and when things get near the Crispy Zone, get the boot off the skinny pedal.

Had GM built these things with far more evailable power at the command of the driver, there would have been huge numbers of failures.

When we decide to take the 6.5 into the land of big power we are its only protection from certain destruction.

Have fun and enjoy

Robyn

[maverick_935]

How much difference will an intercooler make on egt's?

I thought I read somewhere that increasing boost wil help cool egt's by forcing more air in to mix with the fuel. My fuel system is stock at this point and the egt's seem to climb very fast, I would be worried about adding more fuel at this point. Would a boost fooler setup help or hurt at this point.

I am going to find out this weekend pulling one of my trailers just how hard I was pushing it before gauges.

[Robyn]

An aftercooler will help lower the EGT if you are running boost pressures above 12-15 pounds.

The more boost you run the higher the intake air temps will be and resulting EGT.

The 6.5 really does not need an aftercooler unless you are looking to really power the little creature up.

Hope this helps

Robyn

[maverick_935]

In order to have power to pull up hill loaded and not bury the egt needle you need to back off big time. Even backing off the fuel and trying to pull up a grade at 6-7 psi the egt reached around 1000. Was pulling about 5000lbs. Quickly cooled down after going over the top; but I know what it was doing before I was driving on the gauges.

The Diy charge air cooler on the forum looks to be a lot bigger than what is advertised anywhere for this truck.

By the looks of the pictures this install will interfere with the minute mount plow that I have.

Has anyone installed the cooler somewhere else and is there a pictures to show how to do this?

[DennisG01]

In order to have power to pull up hill loaded and not bury the egt needle you need to back off big time. Even backing off the fuel and trying to pull up a grade at 6-7 psi the egt reached around 1000. Was pulling about 5000lbs.

Hmmm... Maybe you have something else going on? When I was pulling with my stock engine (with a Kennedy re-flash which ran about 12 - 14 psi) I did hill runs with my foot planted and would only get to about 950* and then it didn't go any higher (post turbo, at the time). I was pulling a 6,000lb boat (lot's of wind resistance!!!) and my Suburban, I think, weighs in a little more than your truck.

Maybe just a re-flash will take care of your issue?

[6.5 Detroit Diesel]

Hmm, two questions before I install my pyro. What is the point that things start melting and where is the best spot to put in the probe?

[DaveBr]

The best place to put your pyro is 2" below the manifold in the x-over pipe. As Robin said it is a true picture of egt coming from the manifold. 1250*F is the max you can go before entering the danger zone. Today I went fishing and pulled my boat up a 7% grade hill for about 1.5 miles with 11 lbs of boost and 1000*F on the pyro. I did not back off the throttle at all as I was well under the max.

[maverick_935]

my pyro is installed just below the exhaust manifold on the driver's side crossover.

What other causes would there be for the exhaust temp to climb like that?

I've been driving the truck for over a year and did not know this was happening.

[Robyn]

Maverick
Do you have an aftermarket program in the ECM or are you running a boost fooler????

The aftermarket programs have modified timing and fueling parameters and should cool the little beast off a lot.

With a 4 inch exhaust your engine should be free to flow as good as it gets.

If you stay on the power, how high will the EGT go before it levels off ??

Let us know

Robyn

[maverick_935]

I have no ecm program or boost fooler. Truck is stock other than what is in my signature. Everything that I have done to this truck was meant to help it not hurt it.

The EGT's showed no signs of stopping yesterday with 5-6000lbs on. I let off the fuel at 1000 degrees. It held there until I crawled over the top of the little hill then quickly cooled down.

Accelerating with no load (boost at 12lbs then drops to 9 and keeps dropping until it shifts again) will put the egt's at 1000 and again will have to let of.

If I drive it like a little old lady with only trailer on at about 3000lbs the boost runs at about 6-7lbs and the egt's are at 850-900degrees.

110 kms/h-trans 160/ pyro at 550/ boost about 2-3lbs(with no load)

Is it the way I am driving it or am I too heavy.

[rhsub]

Maverick
I am also getting similiar readings on the pyro as you are and I am wondering if the guage is accurate
I installed guages in spring of 08 and when towing TT (18' Terry approx 4000 lbs) by the time it downshifted once (on cruise control)the pyro was going past 1200'F (probe is in right manifold before turbo). Last year (07) we went to P.E.I. and I ran it a lot harder than I did this year and had no problems so that makes me question the accuracy of the guage
If anybody knows how I can check guage let me know:confused::confused:
Truck is stock
Thanks in advance
Ron

[DennisG01]

Maverick
I am also getting similiar readings on the pyro as you are and I am wondering if the guage is accurate
I installed guages in spring of 08 and when towing TT (18' Terry approx 4000 lbs) by the time it downshifted once (on cruise control)the pyro was going past 1200'F (probe is in right manifold before turbo). Last year (07) we went to P.E.I. and I ran it a lot harder than I did this year and had no problems so that makes me question the accuracy of the guage
If anybody knows how I can check guage let me know:confused::confused:
Truck is stock
Thanks in advance
Ron

Just a shot here, but I would guess that you could take the probe out (does it ground through the mount?) and blow a heat gun on it - at varying settings. You would need a known measuring device to compare your gauges reading to. Maybe a DVM that has a temp probe?

[DaveBr]

Hey maverick

I re-read the entire thread to make sure I didn't misunderstand. So you have a pre-turbo pyro and the max you've allowed it to go is 1000*F according to what I read. Have you tried going to 1200*F before backing off the throttle? It just may settle out at 1100 - 1150*F which is acceptable. There is a thread I posted a couple of months ago called turning up the IP. In that thread is a really good explanation of egt maxes. Check it out.

[maverick_935]

No load, just the truck, full throttle acceleration at 9 psi boost up to 80 mph it seemed to settle at 1150 degrees.

Cools down to 900 just as quick as it climbed up when I ease off the throttle.
I will have to try the truck with the trailer on.

Do these numbers sound correct or is it the gauge.

[DaveBr]

I read your post and went out to take the truck for a comparison run. I hit 1100*F and that is as High as it went. It doesn't sound like your gauge is too far out. I run a mechanical IP as my truck is a 93 2500 so there are some fundamental differences between the two. When I pull my 5th wheel I can easily hit 1250*F on steeper hills so I back off the throttle and let her roll at 1200*F. On flat ground pulling the trailer at 70 mph pyro readings are between 750 & 800*F. Maybe some other readers could do a 0 - 80 run and post their numbers to see if we can come up with an average.

[6.5 Detroit Diesel]

Sorry, just want to make sure I put this in the best spot. Put the probe into the crossover pipe right below the LH side manifold? Wouldn't it be better to place it directly beneath the turbo?

[DaveBr]

The closer to the left side exhaust manifold you are with your pyro, the more accurate your reading will be. I want to know as best I can what the egt is at it's hottest point in the engine. The closer to the manifold the better. If your pyro is in the x-over pipe directly below the turbo(still pre-turbo) you may lose temp as exhaust gas has to travel distance in a far cooler enviroment to get to the pyro causing a lower than actual reading. How much, I don't know but again... accuracy is the goal.

If your pyro is in the turbo down pipe(post turbo) do not let your engine hit the temps we are talking about in this thread or you will fry your engine. From what I understand 1000*F is max EGT for post turbo application.

[cranky old fart]

I did all the up grades to my truck 4 months ago so I could pull my 8000lb.+ fifth wheel from Or. to Yellow Stone.boost is set at 14lb. max. When I started out it was pretty easy to run the EGT up to 1200 and I was wondering if the truck was going to be able to do it. I babied it to Idaho where the pyro started to malfunction.It would read 400 stone cold in the morning.I was pissed at Heath for a bad gauge and now I was driving blind.As time went on I quit babying the truck and just pulled with it. Long story short,Ipulled that 8000lb.trailer 2800 miles with no problem ,burned 1/2 qt. of oil. I've put 4000 miles more on and it runs as good as ever. The gauge started working as soon as I got home . Was it the altitude that screwed it up?

[chambie]

I pull this trailer with 2 horses and full water tanks, plus all our other stuff. We're close to 10k .... Living in Pa every direction we go is up over mountains. Pulling hard at 14 in boost ... my pyro ranges from 900 to 1150 depending on the hill. Just cruising around town with no load. 4 to 6 in boost and 350 -450 on the pyro. My truck is stock except for the mods in my sig. This truck is really working well right now !
Hope this helps.

[maverick_935]

just cruising in town I have little or no boost and 400 degrees. What has the boost controler done for you. You seem to be showing a lot higher boost numbers than me.

What is rear gear ratio for pulling that weight?

[JetBoater]

Question... with everyone maxing out their pyro's between 1000 degrees (post turbo) and 1200 degree (pre-turbo)... what engine temps are being developed?

[maverick_935]

with no trailer on my engine gauge sits at normal operating temp and never seems to climb. With my trailer on it moves some and sometimes gets warm enough to engage the fan.

[DaveBr]

Pulling up-hill with 5th wheel & boat in tandem at 1200 * EGT, temp gauge will go as high as 100*C(212*F) before the clutch fan pulls it back down. Before cooling system mods it was right to the red. Still haven't got the dual thermostats or High flow water pump but will be done before next towing season starts.

[rustyk]

My setup is quite different, and I have a factory-fresh AMG 18:1 mill, and a non-wastegated TC. But I shove around a 16K lb. motorhome, so I'm in the top band of GVW for the 6.5. On an 8% grade, I get 1150°F (pre-turbo) at 15" boost at 85°F ambient. In my diesel pusher, the engine temp rarely hits 200°F, but OTOH, the radiator is about 3X the size in pickemups.

[chambie]

My truck has 4:10 gears. Motor temps generally stay around 210 when i'm pulling. Peaks at 220 +/- on a big grade. No trailer motor temps are 160- 180

[JeepSJ]

I can peg my EGT at 1200+ pushing 11lbs of boost if I really push it hard - and that is unloaded with a vehicle that only weighs 4500lbs. But, I think I'm way retarded on the timing. I was retarding the timing to try to get my boost more responsive with that big TE06H turbo. I get no visible smoke and opacity at my last emissions test was only 3%. I've since come to the conclusion that my turbo was lazy because I was not pushing enough fuel, so I'm going to back down the timing and put more fuel into it and see what happens.

Now when I say pushing it hard...anyone familiar with Hwy 62 from Palm Springs up into the high desert? I'm talking 90mph+ up that grade! If I keep it at the speed limit then boost is 6-7lbs and EGTs are 700-800. But, I can also get 1100+ on a freeway onramp if I mash the stupid pedal.

[cranky old fart]

With my Max e tork chip and the pedal mashed my truck doesn't want to shift until 4000rpm but red line on the tac starts at 3500. Is this a problem ? Right now I let off the gas a little so it will shift.

[motown]

there is about 300 degrees diffrence in pre turbo and post turbo i always put probes post turbo so they last longer i dont run mine over 1000 and dont like holding it there long

[rustyk]

I should have included this in my prior post, but cruising with the M/H at around 15K lbs. at 65 mph, EGT runs around 575°F, boost around 5 psi. Frontal area on this is basically an 85 sq. ft. slab.