LBZ Heavy Towing Improvements

[moss6]

I have recently undertaken a project designed to lesson the heat load while towing heavy (14,000lbs) on a 2006 2500 Chevy LBZ. I started several threads on another forum in search of answers and guidance on the project; a mistake, I soon found out. Part of the problem, I am sure was mine, as I used the evidently taboo words like ‘hot’ or ‘overheating’ in my description of conditions that I experienced when towing heavy under adverse conditions. Talk about lighting a flame! You would think that I had insulted their mother; suggesting that there might be some benefit in lowering what I consider to be temperatures in the upper operating range ON MY TRUCK. The majority of responses avoided any question I posed, rather they just basically expounded on the ability of their trucks being able to tow loads in excess of listed maximums at any speed under any condition without so much as breaking a sweat. The general consensus being that I am a moron, or that, as they put it a ‘troll’?? looking to sell something.

In any case the project is very nearly complete but there still a few things to be done and some answers to be had.

First of all a list of modifications and any real or perceived effects that I can comment on at this time.
1. Banks Monster 4” cat back.
I truly can say this addition offered no benefit in the way of power or in the lowering of EGT’s on my truck. If anything, there may be a reduction in 1800 to 2000 rpm torque. I guess I should put the stock back on and re-evaluate but I don’t think there is enough difference to make a difference and the Banks is nice and quite, near stock sound. Besides I’m tired of crawling around under the truck for now.
2. Removal of the innards of the cat; this on the suggestion from John Kennedy, and there was some lowering of EGT’s.
Exhaust noise increase was very minimal; a good modification.
3. Addition of a 3” cold air supply to the stock air filter housing. Routing is from the passenger side recovery hook hole
(hook removed) up and through an enlarged hole in the bulkhead and then into a hole created in the housing. The
stock supply is maintained from the fender well but the holes were enlarged. The filter housing received some
additional sealing from engine compartment heat. IAT’s came down some and seemed to lower even futher when the
EGR was blocked. Total average gain I would put in the -8 to -15 degree range but I honestly don’t think it had much
effect on the EGT’s. The engine does make an intermittent hollow sound now when idleing that I assume is when the
EGR valve opens and there is no exhaust gas available. I would rate the modification as good if for no other reasons
than supply air IS cooler and the engine is no longer forced to ingest it’s own exhaust. I like the additional air supply
far better than any after market add on that I have seen, and I can use the stock filter and not have to accept the grit
that the after market filters let in the engine.
4. Installation of a Setrab 920FP as an engine oil cooler with an Earl’s sandwich plate with -10AN fittings for 5/8”
Aeroquip ‘blue’ 300degree hose. The Earl’s plate is the only one that I am aware of, that has the ability to use 5/8”
Hose which the Duramax needs for the amount of flow. The plate has a 175 degree stat. The ports in the plate were
A bit less than 5/8” so I did enlarge them; if you do this be aware that the thermostat seat is very close so care must be taken not to damage it. Also the adaptor bolt has a smaller hole that the stock filter bolt so I drilled it out to match the size of the stock unit, I believe 7/8”. The cooler was mounted about 2’ forward of the fuel cooler at a bit of a tilt so that it is protected by the truck frame, and a screened shroud was fabricated to capture and funnel a bit more air than what would normally go thru the cooler. The cooler fans are activated by a switch in the cab so they can be run as desired. I need to install an oil temperature gauge and have asked for some advice on this forum for a good location for the sensor but the choices so far are few and difficult. I really wonder now if there is any one out there that has installed one. I sure could use some help on this one!! With the gauge I can better tell how much the cooler helps, what I can say is that the oil pressure is now somewhat higher when the truck is hot and especially when pulling heavy. I cannot tell if it lessened the heat load on the radiator but in theory it should. I am very pleased with the install and am sure that the cooler oil has multiple benefits. The cooler adds near 1 qt. to the system.
5. Installation of a ‘MikeL’ transmission cooler, this also a Setrab product which is a replacement for the stock trans-
mission cooler and offers at least twice the cooling of the stocker. This cooler is very nearly a bolt in; the only mod-
ification needed is a little notching of the square tubing ‘A’ frame for the hood latch. The cooler comes with the
quick connect fittings installed. This is a remarkable cooler and I have yet to see temps above the half-way point on
stock temp gauge. The cooler adds a about a quart of oil to the system and must be relieving some of the radiator
heat load.
6. Installation of a Setrab 920 as an auxiliary radiator, this is the same cooler as the oil cooler but does not have the
fans, adds about a quart to the system. This cooler was installed under the bumper and behind the air dam with a
hole being cut in the plastic air dam for air supply. This cooler is tied into the EGR circuit which is 5/8” hose so
-10AN fittings were used on the cooler. In non towing driving the stock temperature gauge registers somewhat
lower than before so temperatures before I’m guessing were somewhat above the thermostats 195 degree control.
Towing heavy the stock gauge shows very much the same as without the cooler if conditions are favorable. If con-
ditions deteriorate, wind, steep long pulls etc the temperature stays well below what it was before and it is now
very rare for the fan clutch to engage. That being said the fan clutch does now seem to engage more when you
slow down from the highway and enter a town with slow speeds. The fan does not stay engaged very long but it
does seem to run more than before; I have no explaination for this nor for the fact that the fan clutch seems to
engage more on cold start ups even when the ambient temperature is high??????
I am considering adding a scoop below the hole in the air dam to capture even more air and futher enhance the
cooling when at highway speeds. This has already proven to be a real stress reliever for me; not having to monitor
the temp gauge so close and wondering how long before the fan clutch will finally kick in and cool things
down.
7. Custom tuning by John Kennedy. The tuning offers a lot more pull and the truck just does not have that feel anymore that is working a little to hard and that you might ought to ease up a tad. The EGT’s non towing are definitely lower about 75 to 100 degrees. Towing EGT’s are lower too as long as load is not too extreme. What
I observed during the only chance I have had to tow since the tune was installed, is that when loads approach
the 95% range the EGT’s will still become excessive. The highest that I ever saw before the tune and the other
modifications to cool things down was 1380 degrees and I immediately backed out of it. This time with the
additional cooling I went ahead and pushed things on a long steep grade out of Santa Rosa, N Mex. and the
EGT’s got to 1460 degrees before we crested the top. One instrument that I was lacking on that trip was a boost
gauge so I do not know what kind of pressure I was getting from the turbo; I have a good one now and will be able
to see how that looks on a trip in two or three weeks over some even demanding climbs. I will not let the EGT’s
get that high again but will be able to see what boost is at high load percentages and be able to talk to John to
see if any futher improvement is possible. It may very well be that this is as good as it gets and anything better
is beyond the realm of reason. The Kennedy tune is an exceptional value and far exceeds any generic that I have
had in the past. I am very pleased with this modification.
8. I am considering creating underhood ventilation to help in lowering underhood temperatures. I notice that Sun
Coast offers a hood that vents near the center of the windshield and see no reason that the stock hood wouldn’t
easily lend itself to the same type of venting. I also notice that Ford now has underhood ventilation on their new
diesels so there must be some benefit to it. Like to have some thoughts on this.

Overall I am very pleased with what I have been able to accomplish in the attempt to ease the heat load of the truck. It is a vast improvement over what it was before and is far less stressful on me and the truck when towing heavy; trips now are more what they are supposed to be…..a pleasure. Many thanks to those who did actually help; most notably Mike and John. I know much of what I cite as results is very lacking in documentation and I should have done much more to make it better, I do apologize for that. I did enjoy doing it and hope to even further improve on it with your input.

[DmaxMaverick]

Thanks for the detailed report. It's very clear you take your truck, its health, and your comfort (peace of mind) very seriously. Commendable, in my view.

The success of most mods are effective according to the perception of the user. Many/most of them may show an improvement of some sort. Most will be an improvement of a condition that isn't really necessary, meaning, only moving an already acceptable condition more into your comfort zone. Nothing wrong with that, at all. I'm that way. If I'm not comfortable with it, it gets fixed. The term "overheat" is relative to your comfort zone, and it does not mean the same to everyone. You may get responses relative to someone else's comfort zone, but there should be no flaming.

In regards to [most of] your mods.....
Overkill. Big time. Or not. It's your truck. There's nothing wrong with overkill, as long as the result doesn't have a negative return (not considering the funds). I like overkill, and tend to do this often, myself. Belt and suspenders....That's my way of doing things, and it keeps me in my "comfort zone".

When it comes to engine fluid temps, cooler is generally better. As long as they reach the minimum operating temp under normal driving conditions. Too cool can be as bad as too hot.

Your fan clutch operation change should be expected. You made significant changes to your cooling stack. The clutch engagement is only effected by the volume and temp of the air contacting it. Your result is predictable. As long as your ECT is under control, no worries.

[moss6]

Thanks for the kind words Dmax. I do think you do youself somewhat of a disservice with your description of 'over kill. big time' in the way you or I approach things. I would choose to think of the suspenders as an extra margin of safety much as I would describe a backup chute when you jump out of a perfectly good airplane, definately not overkill and probably recklessness if you should so chose to do without. Even more so if you did not pack your own chute.
Overkill bigtime might be pretty close if we didn't tow or only towed at half the GVWR of the truck. I think that there is a pretty significant change when we go up to and beyond the rated limits of our trucks and if you pay close attention when pushing these limits a little futher by not easing up against strong winds and pulling long steep grades I think the truck is telling you it is stressing.
Being of the same mind we go the extra mile to protect our investment (and love) by improveing over where the factory left off.
Randy

[carco]

I appreciate your post, thank you. I too am in the process of attempting to lower temps, but mine is one of the problem years 04 LLY. The cat trick I achieved when it "fell off" and I do believe it helped lower EGT's slightly but best of all my last 22000+ miles are 0.9 MPG better. I have added a trans cooler w/ fan in front of the fuel cooler and was pleased last Sunday with trans temp on a long grade @ 21000#+, engine temp still climbed to 241 degrees. Project now is install of an LBZ turbo intake tube around 3.25" dia. and closeing off hot engine air to air box and ducting in cooler intake air from out front and the inner fender. I believe these mods will be enough for me to feel more comfortable when we go to Colorado in August again @ 21500#+ over Cottonwood Pass. Based on your post I am in the ballpark.

[Kennedy]

If you wanted me to work on lowering EGT a bit I'm sure it could be done.

I'll need to know boost, engine speed, and approximate pedal position.

[moss6]

If you wanted me to work on lowering EGT a bit I'm sure it could be done.

I'll need to know boost, engine speed, and approximate pedal position.

Yeah John we will discuss after the next trip in a couple of weeks and see what kind of pressures at estimated loads. A shame that I was without the boost gauge on the first trip. I do miss the extensive monitoring of the Attitude, with it we could have had load % readouts to compare to boost pressures; but as you point out more negatives than positives with the Juice having to be hooked up to get the readouts.....oh well.
Again love the way your tune pulls, thanks again.
By the way do you have any ideas on where I could install a sensor for an engine oil temperature gauge?
Randy

[SoTxPollock]

Wow, talk about improvements, you've done an admirable job as far as I'm concerned. Just wanted to offer a bit of advice concerning the suncoast hood you mentioned. One does not vent underhood temperatures from the near center of the windshield, because that is a high pressure area due to the aerodynamics of the vehicle. The high pressure would actually be pushing air down into the hood if there is an opening there, so you won't be venting hot air at that location, but what it may do is force it out the bottom more, but the extra underhood pressure can intefere with the normal air flow through the cooling system and may reverse some of your improvements. You might vent from the rear corners of the hood, but then there is the additional sound level from the engine which would be exiting closer to your and passenger ear level.
Pretty much all of the hot air exiting the vehicle has to flow downward to get out, which is not the most efficient since it's hot air which always wants to flow upward naturally.
I've often wondered what effect cutting a couple of louvers into the rear corners of the hood would do for underhood temperatures. Why don't you put a thermocouple under there somewhere and monitor underhood temps for a while and then get a good body shop to cut you some cool looking louvers where I've suggested and see what happens. We might all want them if it does what I think it would do for temperatures, never mind the sound, just crank up the music.

[moss6]

Wow, talk about improvements, you've done an admirable job as far as I'm concerned. Just wanted to offer a bit of advice concerning the suncoast hood you mentioned. One does not vent underhood temperatures from the near center of the windshield, because that is a high pressure area due to the aerodynamics of the vehicle. The high pressure would actually be pushing air down into the hood if there is an opening there, so you won't be venting hot air at that location, but what it may do is force it out the bottom more, but the extra underhood pressure can intefere with the normal air flow through the cooling system and may reverse some of your improvements. You might vent from the rear corners of the hood, but then there is the additional sound level from the engine which would be exiting closer to your and passenger ear level.
Pretty much all of the hot air exiting the vehicle has to flow downward to get out, which is not the most efficient since it's hot air which always wants to flow upward naturally.
I've often wondered what effect cutting a couple of louvers into the rear corners of the hood would do for underhood temperatures. Why don't you put a thermocouple under there somewhere and monitor underhood temps for a while and then get a good body shop to cut you some cool looking louvers where I've suggested and see what happens. We might all want them if it does what I think it would do for temperatures, never mind the sound, just crank up the music.

Thanks for the good information. I knew that the center area was supposed to be a high pressure zone but assumed that the underhood pressure because of the stack would be substantially higher. It would be interesting to find out; SunCoasts information says that GM did not want the rear vent so that might be the reason, who knows. Funny that the very location that you mention, the hood corners, is where the fake louvers are on the new GM trucks; what a shame that they don't make them functional......maybe later??? Also of note that would substanciate your high pressure area not working is the fact that the new Ford's functional vents are located in the upper rear of the front quarter panels. This by the way is an irritation to me for Ford to do something so logically good and GM to just install some dummies for looks.
Randy

[moss6]

I appreciate your post, thank you. I too am in the process of attempting to lower temps, but mine is one of the problem years 04 LLY. The cat trick I achieved when it "fell off" and I do believe it helped lower EGT's slightly but best of all my last 22000+ miles are 0.9 MPG better. I have added a trans cooler w/ fan in front of the fuel cooler and was pleased last Sunday with trans temp on a long grade @ 21000#+, engine temp still climbed to 241 degrees. Project now is install of an LBZ turbo intake tube around 3.25" dia. and closeing off hot engine air to air box and ducting in cooler intake air from out front and the inner fender. I believe these mods will be enough for me to feel more comfortable when we go to Colorado in August again @ 21500#+ over Cottonwood Pass. Based on your post I am in the ballpark.

Indeed it sounds like you are on the right track and the cooler air should really help with your model of truck. Sounds like our loads are very similar in weight but my fifth is only 35'6". We have not been over to Cottonwood but many times camp in the area, about 16miles up the Cibola river off of the highway between Lake City and Gunnison. Have fished the Taylor but do not camp there because we have found no isolated primative locations there. Anything like that at Cottonwood that is on a stream or river?
Randy

[moss6]

Thought ya'll might want to see some of them.
Randy

[Mark Rinker]

Overkill?

Isn't that what this site is all about?

[jbplock]

Thought ya'll might want to see some of them.
Randy

Nice work Randy!

[moss6]

Overkill?

Isn't that what this site is all about?

Mark,
Overkill also means that you can't run with me!!

BTW, are you still thinking of installing the oil temp. gauge? Its really pretty easy if you tap the drain plug; and most of all I'm dieing to see the oil temps on a truck with only the factory cooler. Also after doing some extended driving yesterday, not towing, I find that the temperature is actually 190degrees not 200 as I stated in the other thread, need to correct.
Randy

[Mark Rinker]

We haven't installed a guage yet - interesting to read your results.

[carco]

Moss6, I have only been to Taylor Park Res. one time, sorry I'm not the one to ask about camp areas. Thanks for the pics!

[moss6]

We haven't installed a guage yet - interesting to read your results.

Sensor at drainplug in oil pan. Think I had made an earlier comment about the wires possibly getting snagged but I think you can see that there is actually not much chance of that.
Randy

[Mark Rinker]

What gauge did you use?

[moss6]

Mark,
It is just a gauge I picked up at Auto Zone or O'Reileys, don't recall the brand but it was only about $17. Seems to work real well.
Randy

[MaxACL]

About the high pressure area at the base of the windshield... I remember the "Cowl Induction" intake on my 72(?) Chevelle SS396. Boy I miss that car

Mike

[moss6]

About the high pressure area at the base of the windshield... I remember the "Cowl Induction" intake on my 72(?) Chevelle SS396. Boy I miss that car

Mike

I thought that was 68' or 69'. In anycase yes I am still considering that but the set up works so well now that it is not a very high priority. I think the next thing I will do is remove the mount and fans from the engine oil cooler and see if the oil temp. goes even lower with high loading, I'm thinking it will.
Randy