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7.3 pulling heavy and high egts

 
  #46  
Old 07-11-2019, 05:41 PM
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Originally Posted by z31freakify View Post
If you aint towing nothing, towing heavy opens a whole new can of worms.
The powerband is the same whether your towing or not. 4.10s would waste fuel on the highway.
 
  #47  
Old 07-11-2019, 05:50 PM
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Originally Posted by 00t444e View Post
The powerband is the same whether your towing or not. 4.10s would waste fuel on the highway.
No disrespect, but you have alot to learn towing heavy loads.
 
  #48  
Old 07-11-2019, 06:05 PM
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Originally Posted by z31freakify View Post
No disrespect, but you have alot to learn towing heavy loads.
I would rather have 3.73s and downshift when needed vs having 4.10s and not downshifting as much but running higher rpms in OD. With 35s and 3.73s I don't need to downshift hardly at all as long as I can keep my speed above 60 or so.
 
  #49  
Old 07-11-2019, 08:44 PM
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On the contrary, less fuel would be consume because it will stay in the powerband with out down shifting all the time, plus the tranny will thank you.
 
  #50  
Old 07-11-2019, 08:56 PM
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Originally Posted by 00t444e View Post
I would rather have 3.73s and downshift when needed vs having 4.10s and not downshifting as much but running higher rpms in OD. With 35s and 3.73s I don't need to downshift hardly at all as long as I can keep my speed above 60 or so.
You need to study what the actual ratio is when comparing 265/75-16 and 275/75-18.

I'll save you the trouble.
The 265/75-16 @ 70mph turns 1968 rpm
The 275/75-18 @ 70mph turns 2000 rpm
The 275/75-18 @ 70mph, with 3.73, turns 1819 rpm

The 265/75-16 is considered 31.50 diameter and the 275/75-18 is considered 34.25 diameter.
 
  #51  
Old 07-11-2019, 09:04 PM
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My L99 being all stock, was much happier towing a 6500# empty T.H. with 4.10s then with the 3.73's...She told me
 
  #52  
Old 07-11-2019, 09:56 PM
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Originally Posted by Dan V View Post
You need to study what the actual ratio is when comparing 265/75-16 and 275/75-18.

I'll save you the trouble.
The 265/75-16 @ 70mph turns 1968 rpm
The 275/75-18 @ 70mph turns 2000 rpm
The 275/75-18 @ 70mph, with 3.73, turns 1819 rpm

The 265/75-16 is considered 31.50 diameter and the 275/75-18 is considered 34.25 diameter.
No studying needed it's a simple formula
RPM= axle ratio x transmission gear ratio x 336 divided by tire diameter. So what argument are you trying to make with that post?
 
  #53  
Old 07-11-2019, 10:16 PM
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Hook up a 12k 5r and see if it performs the same.
 
  #54  
Old 07-12-2019, 01:29 AM
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Originally Posted by Tugly View Post
Yeah... I could have worded that better to better reflect how I'm not trying to be an ***. Fail. Sorry.
In hindsight I was perhaps too pointed, my apologies. Kudos for responding like the mensch I know you are.

Originally Posted by 00t444e View Post
A stock 7.3 intercooloer is all you need, money would be better spent on tuning and a good turbo setup. There are 7.3 trucks that dyno 700+ HP with the factory intercooler.
If the dyno was the only challenge I'd agree. But you know as well as I that a long steep grade with a heavy load for 30 minutes is a different situation. You need the coolest charge for the longest time. A bigger IC will help that. Not as bigly as fine tunes or a gazillion CFMs from a T4 setup like you say, but a bigger IC will help all day long. Plus I can pass CA smog with it neatly tucked away under the tool shelf.
 
  #55  
Old 07-12-2019, 06:28 AM
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Originally Posted by bennyhick2 View Post
Thanks for all the responses so far. But what I meant before about backing out of the go peddle. I back out and I'm less than half peddle trying to pull a substantial hill and still maintining 1100. I know that if I hammer it to the floor it will go but I'm going to have a melt down of my pistons. It started last year in feb of 18 when I bought this 5th wheel. My truck didn't have a tuner. I had just put in the guages so I could see where things were at. When I pulled the 5th wheel home for the first time I was getting some high egts. And I talk to a friend of mine that works on busses and he gave a number to a diesel shop that he trusted. So I called that guy and he said I need a tuner. So I got one not that I didn't want to get one any way but it helped greese the wheels with my wife. I was thinking gears then but my friend doesn't think I'm going to see as much of a return as its going to cost to change the gears.

OK... now we have another piece of the puzzle that was missing before. In response to this particular post, we need to back up a bit and start troubleshooting instead of shotgunning.

I would yank the chip and do some logging with the "Big 10" on an OBDII app: MAP, EBP, FIPW, IPR, ICP, MPH, RPM, TC Slip, EOT, and TFT. You can't log EGTs, but you can make a mental note of the time during high EGTs for later documentation.

Onto tire size: I tow heavy in the mountains in the summertime, as timmyboy76 alluded:



I beefed my engine up a bit, and it has way more torque to pull (and accelerate) than a stocker. I have 3.73 gears, and I went from a stock 31" to a 33" tire. While my "race mode" improved with the bigger tires, my towing mode took a hit. I have hills that I have memorized every PID performance while towing heavy or towing nothing - and that measly 2" more diameter punished me under certain towing scenarios, but rewarded me in others. You're towing the limit of the stock truck, but you moved the line by putting non-stock tire size on the truck. If I were to tow that heavy on a stock engine with tuning, the "short" answer is I'd be shopping for altitudinally-challenged gears - or tires.

As for tuning, you went the opposite direction of lower EGTs - they're worse now. 1023 tuning does a respectable job. They do some weird stuff when they try to get fancy... like an "economy" tune, or a tractor pull tune - but the plain ol' elevated horsepower tune behaved quite nicely on Frankenstinky. The only caveat is the shift points sucked, but that's an easy thing to fix with a phone call.

If you don't mind going TS chip, Brian at BTS still rocks. This is the least expensive option (tuning-wise), and he knows a thing or two about how to treat your transmission while towing. If I didn't have Cody, Brian would tune for me - but I would have missed out on a great friendship.
 
  #56  
Old 07-12-2019, 08:55 AM
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Originally Posted by z31freakify View Post
Hook up a 12k 5r and see if it performs the same.
Originally Posted by Tugly View Post
You're towing the limit of the stock truck, but you moved the line by putting non-stock tire size on the truck. If I were to tow that heavy on a stock engine with tuning, the "short" answer is I'd be shopping for altitudinally-challenged gears - or tires.
I respectfully DISAGREE!

Stock injector truck, SXE turbo, 35 inch tires and 3.73 grades running 1023, PHP AND Cody tunes (all maxing out the stock injectors at roughly 65HP), I pull 6-7% grades in Colorado at 6-9K ft of elevation towing a 12K+ toy hauler with ease. 1150 degrees + or - . I have no problem accelerating from 50 MPH to 65 MPH up hills in third gear.

I do AGREE to PO's problem is running larger tires with his stock turbo though

Originally Posted by bennyhick2 View Post
I forgot to mention when I'm backing out of the throtle I am less than half peddle to keep egts down
With my setup, there is no such thing as backing out of the peddle unless I'm trying to stop from going to fast!



 
  #57  
Old 07-12-2019, 09:41 AM
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I dunno, if I have to back off the throttle in OD or 4th (usually not in 4th though) and drive by the EGT gauge, I don't really see it as a problem precisely and I am not racing anybody to the top of the hill. I like to tow slowly even on flat ground (60-65) and conserve fuel economy so maybe switching to 4.10's would not be a bad idea in my case. With 3.73's and 16" small 2wd DRW rubber effective final drive is already pretty low but it still lugs down in OD a bit lower than I like in the low 60's mph. ST chinabomb tires are only rated for 65 mph anyway
 
  #58  
Old 07-12-2019, 09:53 AM
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Originally Posted by aawlberninf350 View Post
If the dyno was the only challenge I'd agree. But you know as well as I that a long steep grade with a heavy load for 30 minutes is a different situation. You need the coolest charge for the longest time. A bigger IC will help that. Not as bigly as fine tunes or a gazillion CFMs from a T4 setup like you say, but a bigger IC will help all day long. Plus I can pass CA smog with it neatly tucked away under the tool shelf.
That is what I was going to comment also. I don't doubt somebody made 700 hp that one time on a dynojet with the stock CAC, but that is in a controlled environment and not really indicative of what happens towing up steep grades in high heat. I have heard some guys claiming it dropped EGT's 200*F by swapping the stocker for one of the bigger aftermarket ones. There is probably a little efficiency gain there also since they tend to flow better than stock units (less pressure drop across the cooling core)
 
  #59  
Old 07-13-2019, 08:16 AM
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Originally Posted by akcooper9 View Post
...I do AGREE to PO's problem is running larger tires with his stock turbo though ...
Yep... that was my point.
 
  #60  
Old 07-13-2019, 08:27 AM
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Originally Posted by Brandonpdx View Post
That is what I was going to comment also. I don't doubt somebody made 700 hp that one time on a dynojet with the stock CAC, but that is in a controlled environment and not really indicative of what happens towing up steep grades in high heat. I have heard some guys claiming it dropped EGT's 200*F by swapping the stocker for one of the bigger aftermarket ones. There is probably a little efficiency gain there also since they tend to flow better than stock units (less pressure drop across the cooling core)
Pressure drop across the cooling core? I'm one of the odd ducks who had my Boost gauges BEFORE the IC, and I had that to compare with the MAP sensor.



The only difference I saw in pressure is what you would expect from cooler air out being less voluminous than the hotter air pumped in. My Manifold Air Temperature was not much above ambient, so I had no reason to believe a bigger IC would help above and beyond what my 38R and CAI was already doing for me.
 

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