Turbine Doc
Just Another Diesel Guy
Nice to be seen and recognized still 
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GMx turbo upgrades for towing heavy, worth it?
- Thread starter red
- Start date
Will L.
Well-Known Member
Hey, there’s a friendly name!
Good to heard from you.
Good to heard from you.
ak diesel driver
6.5 driver
Been awhile.
MrMarty51
Well-Known Member
I always love watching that video.
Turbine Doc
Just Another Diesel Guy
If you have been following my posting last couple of days, you might have picked up on that I have left the "flat-lands" and have ventured North via I-10 from MS to I-65 in Mobile AL, to I-85 Montgomery to Atlanta, then I-295, to US-23N into NC bound for Swannanoa NC where I am at present on a mission trip to help with some post flooding repairs Sept/Oct. 2024 ....grrrr. don't get me started on travesty still home without power & water here.
Anyway these mountains put a bit of a scare into me today, I was pulling hard making good time passing others struggling, 14 PSI then all of a sudden midway up mountain truck all but died on me, EGTs that had been at 900F-ish at 1200 in blink of eye and climbing fast, I pulled into slow lane to stabilize at 1100F EGT running at 45-50 where I was at 60-70 before, black smoke.... low boost....craaaap.
Did I blow a boost host or coupling clamp ??? I sort of limped to top of mountain EGT temps back down to normal, coolant never got over 195F, oill pressure good, and at bottom of hill I got boost & acceleration back......Heyyyy I've been here before but I didn't have my MT2500 scanner connected, but I remember this event before I experienced in my Burb. Tier 1 defense for 6.5 in high IAT situation is dump boost/open waste-gate....well no WG on mine both vehicles have ATT now, and turbo master when I still was running GM-8s.
Tier2 defense if tier1 did not work, limp fuel to 55mm max, you have to have scanner plugged in to see it, no codes reported during said "limpimg", and when you shut down and restart "limp" resets to normal max mm fuel setting in your program. So now inspite of the lag I felt in intercooler I'm thinking maybe I might want to put it back in, or install the water mist kit I bought but never installed.
A couple of questions for those of you running high boost sutained 12+psi, how are you getting around high IAT defue/ limpl, and does anyone here know what that limit max IAT actually is, I think I remember 285F/
How high of a IAT/Charge air temp can one run without doing harm to the engine? There must be a design threshold otherwise engines designed from factory to run high boost would not have an intercooler from factory?
With IDI how much boost really is hurtful to the engine, vs. DI ? I'm takling about long hauls, not brief excursions to high boost. When I was with the GM-8 because of high drive/backpressure I self limited to 12psi, even though with a TM it could bury my 0-15psi Banks gauge?
On lowlands high speed drives and heavy towing with ATT it has never been an issue, but a big load in mountains, or running hard to climb the hill, required a different mind set for me.
When I got to my destination nothing found that could point to engine issue, it never dawned on me having full time IAT monitoring might be worthwhile to keep her in the green, I will be adding that monitor in the future.
Anyway these mountains put a bit of a scare into me today, I was pulling hard making good time passing others struggling, 14 PSI then all of a sudden midway up mountain truck all but died on me, EGTs that had been at 900F-ish at 1200 in blink of eye and climbing fast, I pulled into slow lane to stabilize at 1100F EGT running at 45-50 where I was at 60-70 before, black smoke.... low boost....craaaap.
Did I blow a boost host or coupling clamp ??? I sort of limped to top of mountain EGT temps back down to normal, coolant never got over 195F, oill pressure good, and at bottom of hill I got boost & acceleration back......Heyyyy I've been here before but I didn't have my MT2500 scanner connected, but I remember this event before I experienced in my Burb. Tier 1 defense for 6.5 in high IAT situation is dump boost/open waste-gate....well no WG on mine both vehicles have ATT now, and turbo master when I still was running GM-8s.
Tier2 defense if tier1 did not work, limp fuel to 55mm max, you have to have scanner plugged in to see it, no codes reported during said "limpimg", and when you shut down and restart "limp" resets to normal max mm fuel setting in your program. So now inspite of the lag I felt in intercooler I'm thinking maybe I might want to put it back in, or install the water mist kit I bought but never installed.
A couple of questions for those of you running high boost sutained 12+psi, how are you getting around high IAT defue/ limpl, and does anyone here know what that limit max IAT actually is, I think I remember 285F/
How high of a IAT/Charge air temp can one run without doing harm to the engine? There must be a design threshold otherwise engines designed from factory to run high boost would not have an intercooler from factory?
With IDI how much boost really is hurtful to the engine, vs. DI ? I'm takling about long hauls, not brief excursions to high boost. When I was with the GM-8 because of high drive/backpressure I self limited to 12psi, even though with a TM it could bury my 0-15psi Banks gauge?
On lowlands high speed drives and heavy towing with ATT it has never been an issue, but a big load in mountains, or running hard to climb the hill, required a different mind set for me.
When I got to my destination nothing found that could point to engine issue, it never dawned on me having full time IAT monitoring might be worthwhile to keep her in the green, I will be adding that monitor in the future.
Big T
Well-Known Member
I have the ATT. Hauling on flat level ground I think I saw boost at 4 to 6 psi. Hauling up a grade I saw 12 to 14 psi and 1200 on the pyrometer. Only the first grade south of Vegas did I have to pull over because ECT hit 210.
ak diesel driver
6.5 driver
I've got a dual IAT gauge. Was going to have pre and post turbo. Never got around to the pre. I have an aftermarket tune and have never been limited by high IATs. Don't remember what my max IAT was but probably in the high 200s low 300s. Also probably helps not having hot weather too.
MrMarty51
Well-Known Member
I was running the GM8 turbo when I first got My truck.
I can remember reading something about not exceeding 1200 or 1250 degrees F.
I could not hardly keep the EGT less than that even pulling my small trailer or dragging along the boat.
I remember throwing out a question about maximum EGTs and @WarWagon replied something about not to worry even up to 1500 or maybe it was 1550 degrees F so after that I never give it another though. I think the highest EGT ever reached was about 1300*F.
ATT I’m running came from War Wagon, and now I have not had an opportunity to drag a good load along.
I can remember reading something about not exceeding 1200 or 1250 degrees F.
I could not hardly keep the EGT less than that even pulling my small trailer or dragging along the boat.
I remember throwing out a question about maximum EGTs and @WarWagon replied something about not to worry even up to 1500 or maybe it was 1550 degrees F so after that I never give it another though. I think the highest EGT ever reached was about 1300*F.
ATT I’m running came from War Wagon, and now I have not had an opportunity to drag a good load along.
Turbine Doc
Just Another Diesel Guy
Thank for replies, I'm not sure which PCM I'm running or tune in it, I have multiple PCMs with different tunes, I'll have to check it out when I get home.
I opted on side of caution not wanting to "beat up my truck" with miles more to go, plus being 8 hours away from home, and 6 hours to go to Mom's house in VA this weekend, then 17 hours (down hill) relatively after that back to MS mostly I-85.
When I built the"project engine" now nearing 40K in the truck, I did use ARP studs throughout for hopefully a little better strength and ability to sustain higher boost pressures.
I opted on side of caution not wanting to "beat up my truck" with miles more to go, plus being 8 hours away from home, and 6 hours to go to Mom's house in VA this weekend, then 17 hours (down hill) relatively
after that back to MS mostly I-85.When I built the"project engine" now nearing 40K in the truck, I did use ARP studs throughout for hopefully a little better strength and ability to sustain higher boost pressures.
Will L.
Well-Known Member
The egt is what leads to cracks - it isn’t that all the metal starts melting down. I remember talking to Bill Heath one time asking how far he would drive at sustained 1100, he said “To the moon.” Haha.
We know lower egt is better, higher egt, especially sustained is where we get the cracks in precups, and between the valves from.
But what temp & for how long … No one has come up with good numbers for that I am aware.
And it seems to me larger turbos are affected less than gm small ones. Simply 1,000° to a gm3 in that small mass heats the whole turbo more and raises iat more than say an ATT. I never saw anyone create an actual chart, but we could.
Just log egt to iat and report it with what turbo and if you have a cac, maybe ambient temperature and humidity would be smart to log as well.
I know myself and a couple local guys did it just making runs to different places here and the difference shows up in turbos. Me and two guys were all hauling materials from Vegas to Mesquite and logged it comparing each other’s pickups.
Then one guy swapped his gm5 out for an hx35, and the next weekend we all hauled another load. Tracking it again, mine and Mark’s was the same but Gary’s with the new holset - egt was lower and his iat stayed lower. Going up an hill at one point his egt hit same number in that area, but iat stayed lower. Then the egt dropped sooner.
Later I did that run with my hummer and the egt to iat relation and iat to ect relation became amazingly obvious in that brickwall on wheels. The ridiculous gearing, wide tires, flat windshield- driving down the hiway weighing 6,200 lbs was like a 3500 with a pallet of bricks in the back for how hard it works. Maybe same as a 2 axle car trailer that’s empty. Not enough to really slow it down a ton- just that you feel it and work the skinny pedal a lot more.
Idk how much you guys notice it, but here the difference of 10% humidity and 30% really impacts a 6.5. Then being over 105° does as well. The egt and ect both take a serious hit. Out here we can watch the iat push up egt, then the egt pushes up the ect - like dominos tipping one into the next.
@Turbine Doc you mentioned having a wmi system you haven’t installed and thinking about going back to the cac but we all read the lag became noticeable with the ATT and it together.
The cac is nice because after installing, you do nothing. The wmi is annoying to refill but there is the opposite effect from lag. When I ran mine, even just distilled water and no meth in it- it improves acceleration- but my environment here of low humidity (lowest levels on the continent) maybe I see a bigger impact than you guys will? When you add meth at 50/50, you will definitely see faster spool times even engine cold so it isn’t just the egt-iat-ect chase game.
You get the added bonus of eliminating any carbon build up on piston & valves- which if you have a muffler or soot trap you are proud of and dont want to fill up sooner- remove for the first 100 miles of adding a wmi system. I got to the point where before tearing down any engine for rebuilding, I did the water bottle version of wmi just sitting still to clean it all before tear down.
But as some here could testify- a manual shut off valve somewhere is best because if the electric valve fails, and you drain your tank overnight into a couple cylinders- you start in the morning thinking “dead battery or is that a bad starter?”
And after removing all the glow plugs & an oil change later you are back in business. Knowing maybe 800 people through the years that ran wmi- 5ish went through this. None had any long term engine effects but it sure rattles your brain.
So for the paranoid like me, a manual ball valve at the driver’s seat is a requirement.
So the trade offs become a personal flavor thing. But the funny part I miss about wmi on just water- was me pulling up to a gas station fueling up outside no one pays attention to. But going inside and buying a sodapop and 6-7 gallons of distilled water. And telling the clerk “ill be back and grab these ones in a minute, my fuel tank (lifting water up at that time) is empty.” And someone offers to carry out a couple gallons often. And they see me put a funnel into one of the fuel tank doors and pour in all the water… HAHAHA!
“Mr., are you really pouring water into your gas tank?” And the fun begins…
I so wanna do that in my hummer- “sure, these can run on any fuel- why not water?” Haha
We know lower egt is better, higher egt, especially sustained is where we get the cracks in precups, and between the valves from.
But what temp & for how long … No one has come up with good numbers for that I am aware.
And it seems to me larger turbos are affected less than gm small ones. Simply 1,000° to a gm3 in that small mass heats the whole turbo more and raises iat more than say an ATT. I never saw anyone create an actual chart, but we could.
Just log egt to iat and report it with what turbo and if you have a cac, maybe ambient temperature and humidity would be smart to log as well.
I know myself and a couple local guys did it just making runs to different places here and the difference shows up in turbos. Me and two guys were all hauling materials from Vegas to Mesquite and logged it comparing each other’s pickups.
Then one guy swapped his gm5 out for an hx35, and the next weekend we all hauled another load. Tracking it again, mine and Mark’s was the same but Gary’s with the new holset - egt was lower and his iat stayed lower. Going up an hill at one point his egt hit same number in that area, but iat stayed lower. Then the egt dropped sooner.
Later I did that run with my hummer and the egt to iat relation and iat to ect relation became amazingly obvious in that brickwall on wheels. The ridiculous gearing, wide tires, flat windshield- driving down the hiway weighing 6,200 lbs was like a 3500 with a pallet of bricks in the back for how hard it works. Maybe same as a 2 axle car trailer that’s empty. Not enough to really slow it down a ton- just that you feel it and work the skinny pedal a lot more.
Idk how much you guys notice it, but here the difference of 10% humidity and 30% really impacts a 6.5. Then being over 105° does as well. The egt and ect both take a serious hit. Out here we can watch the iat push up egt, then the egt pushes up the ect - like dominos tipping one into the next.
@Turbine Doc you mentioned having a wmi system you haven’t installed and thinking about going back to the cac but we all read the lag became noticeable with the ATT and it together.
The cac is nice because after installing, you do nothing. The wmi is annoying to refill but there is the opposite effect from lag. When I ran mine, even just distilled water and no meth in it- it improves acceleration- but my environment here of low humidity (lowest levels on the continent) maybe I see a bigger impact than you guys will? When you add meth at 50/50, you will definitely see faster spool times even engine cold so it isn’t just the egt-iat-ect chase game.
You get the added bonus of eliminating any carbon build up on piston & valves- which if you have a muffler or soot trap you are proud of and dont want to fill up sooner- remove for the first 100 miles of adding a wmi system. I got to the point where before tearing down any engine for rebuilding, I did the water bottle version of wmi just sitting still to clean it all before tear down.
But as some here could testify- a manual shut off valve somewhere is best because if the electric valve fails, and you drain your tank overnight into a couple cylinders- you start in the morning thinking “dead battery or is that a bad starter?”
And after removing all the glow plugs & an oil change later you are back in business. Knowing maybe 800 people through the years that ran wmi- 5ish went through this. None had any long term engine effects but it sure rattles your brain.
So for the paranoid like me, a manual ball valve at the driver’s seat is a requirement.
So the trade offs become a personal flavor thing. But the funny part I miss about wmi on just water- was me pulling up to a gas station fueling up outside no one pays attention to. But going inside and buying a sodapop and 6-7 gallons of distilled water. And telling the clerk “ill be back and grab these ones in a minute, my fuel tank (lifting water up at that time) is empty.” And someone offers to carry out a couple gallons often. And they see me put a funnel into one of the fuel tank doors and pour in all the water… HAHAHA!
“Mr., are you really pouring water into your gas tank?” And the fun begins…
I so wanna do that in my hummer- “sure, these can run on any fuel- why not water?” Haha