Ecodiesel towing test. Suspension sag, mpg, power, and cooling

[AH64ID]

Unless you are operating above the full open point of the thermostat, or even more realisticlly the max allowed temp of the thermostat, the heat source in doesn't mean much.

You are over thinking the addition of a water cooled turbo.

When I installed my water cooled turbo there was no noticeable increase in coolant temp while towing grades with EGT's above 1100°.

The portion of the turbo that is cooled, on a true water cooled turbo, is the bearing. The bearing is not as hot as the exhaust, and it also has oil in it. I would venture that the oil picks up more heat from the piston coolers than the coolant does from the turbo. The bearing shouldn't be that hot, or it would damage the oil and then the bearing would fail.

According to the link you posted the thermostat cracks at 208°, and isn't full open until 228° which means it probably has a max allowed temp of 235°-245°.

For reference the 190° in my truck cracks at 190°±3°, goes full open at 207°, with a max allowed of 225°. I pull big hills on hot days at 213°-215°, well within the range. If I had a 200° you could add approx 10° to those numbers, subtract 10° for a 180°. Make sense?

If you didn't hit a grade and downshift to a higher rpm the coolant flow thru the radiator was lower, pulling a hill with more rpms and more fan speed will increase heat production and heat rejection.

It's also possible that only the electronics on the turbo are cooled, as it the case with the 6.7 turbo, which would mean less heat into the system.

It's still nothing to worry about, with or without a water cooled turbo. Water cooled turbo's just don't add that much heat to the system.

 

[NIsaacs]

Keep in mind your coolant boiling point increases with antifreeze. A 50/50 mix is 265* with a 15 lb radiator cap. High elevation will decrease that some.

Nick

 

[RangerGress]

Unless you are operating above the full open point of the thermostat, or even more realisticlly the max allowed temp of the thermostat, the heat source in doesn't mean much.

You are over thinking the addition of a water cooled turbo.

When I installed my water cooled turbo there was no noticeable increase in coolant temp while towing grades with EGT's above 1100°.

The portion of the turbo that is cooled, on a true water cooled turbo, is the bearing. The bearing is not as hot as the exhaust, and it also has oil in it. I would venture that the oil picks up more heat from the piston coolers than the coolant does from the turbo. The bearing shouldn't be that hot, or it would damage the oil and then the bearing would fail.

According to the link you posted the thermostat cracks at 208°, and isn't full open until 228° which means it probably has a max allowed temp of 235°-245°.

For reference the 190° in my truck cracks at 190°±3°, goes full open at 207°, with a max allowed of 225°. I pull big hills on hot days at 213°-215°, well within the range. If I had a 200° you could add approx 10° to those numbers, subtract 10° for a 180°. Make sense?

If you didn't hit a grade and downshift to a higher rpm the coolant flow thru the radiator was lower, pulling a hill with more rpms and more fan speed will increase heat production and heat rejection.

It's also possible that only the electronics on the turbo are cooled, as it the case with the 6.7 turbo, which would mean less heat into the system.

It's still nothing to worry about, with or without a water cooled turbo. Water cooled turbo's just don't add that much heat to the system.

Re. thermostat full open at 228deg. Good catch. I posted the info then forgot that important nugget. That really does make my 222deg a non-issue.

Thanks for the info re. water cooled turbos.

I disagree about fan speed tho. Once a vehicle gets up to 30mph or so, I don't think the fan appreciably adds to the airflow thru the radiator(s). Race cars only use radiator cooling fans when stationary or nearly so.

 

[AH64ID]

I cannot speak for the fan on the VM 3.0, but the one on the HD trucks will make a difference at highway speeds if it gets commanded to 100%.

 

[RustyJC]

Yes, on my 2011, the fan cooling is CRITICAL at highway speeds. Example: Pulling a 6% grade in West Texas towing a 16K 5th wheel in 105 degF ambient temperatures at around 60 MPH, the coolant temperature displayed on the EVIC climbed from its normal 202 degF to 219 degF, at which point the cooling fan kicked in at full bore. Within a minute or so, even though we were still on the grade and still around 60 MPH, coolant temp dropped back to 202 degF, and the fan switched off.

Rusty

 

[RangerGress]

Yes, on my 2011, the fan cooling is CRITICAL at highway speeds. Example: Pulling a 6% grade in West Texas towing a 16K 5th wheel in 105 degF ambient temperatures at around 60 MPH, the coolant temperature displayed on the EVIC climbed from its normal 202 degF to 219 degF, at which point the cooling fan kicked in at full bore. Within a minute or so, even though we were still on the grade and still around 60 MPH, coolant temp dropped back to 202 degF, and the fan switched off.

Rusty

I am frankly amazed to hear that. Well.....good to know. Being corrected makes a person smarter. At least that's my wife's philosophy re. me. Thanks for the info.

 

[Bob4x4]

Airforums.com was full of dorks...........people that question everything and understand nothing. I'll never go there again!

I agree with most of that I got reprimanded when I brought up the reasons not to tow with a 300c with a 3.6

 

[gtoli]

Don't know about the new VM, but with the the 6.7 you can hear the fan kick on, even at highway speeds, and watch the temperature drop soon after.

 

[RangerGress]

This morning on my commute to work I watched the coolant temp go up to 210deg relatively quickly, then drop down to 203-204deg. That seems to me pretty conclusive that the tstat does indeed open at 208deg.

 

[Bob4x4]

The fsm does in fact show 208 as the open number

 

[RangerGress]

I decided how to mount the air nozzle for the Airlift1000's. There's a couple holes in the hitch receiver that are about the right size.

 

[Tuesdak]

Yes, it has the washers to set hitch angle.

I think we've beat this one to death folks. Per the first post, the droopy hitch ball was just an intermediate experiment as I played around adjusting the hitch for the new tow vehicle. Can we get back to how fabulous the truck is?

I salute you for obtaining and using the proper WD hitch equipment - after all it is a very important step in keeping the truck looking fabulous rather than a spectacular wreck like our RV broker posted on the board for months. Driver did not use the WD bars and rolled after jackknifing. It is rare to see towing threads starting out with the proper equipment.

Couple of pointers on the WD hitch.

Grease as metal on metal will wear faster without it: Grease the spring bars where they go into the hitch and the hitch ball itself.

Use a galvanized pipe as a cheater bar to get tension on the spring bar chains. Faster than jacking things up.

Unlike non-WD hitch designs that don't have this issue: The WD ball angle being tilted back as recommended helps the shelf below the ball clear the trailer tongue when you go over a big weird angle like railroad tracks. With the back of the truck and front of the trailer both high from the tracks the ball shelf can hit and try and uncouple (via breaking something) the trailer. Specifically the shelf just behind the ball (or the sides of the ball on a turn) will hit the trailer coupler just behind the ball and try and pop the trailer off the ball.

Big deep dips in the road can be so severe as to break the spring bars with high tension. Dips putting the rear of the truck low with front high and the trailer front low and rear high increase spring tension. If in doubt over a steep driveway etc. reduce the tension or take the bars off for that 'bump'. They make one big loud bang when they break.

Leverage:
As above example of levers for a cheater bar we have overlooked the real reason for the length of the WD hitch you have drilled to be 'shorter'. It has nothing to do with clearing a tailgate. You have effectively reduced by 2" the amount of leverage your spring bars have to work with to shift the trailer weight. If this length wasn't important to the overall design of the WD hitch they would come shorter saving the length and weight from the factory.

Try both hitch pin settings - the factory and your new hole with the trailer at the scale with the same tight chain link used on the spring bars and see the difference on the truck's front/rear axle weights.

 

[Tuesdak]

Re. thermostat full open at 228deg. Good catch. I posted the info then forgot that important nugget. That really does make my 222deg a non-issue.

Thanks for the info re. water cooled turbos.

I disagree about fan speed tho. Once a vehicle gets up to 30mph or so, I don't think the fan appreciably adds to the airflow thru the radiator(s). Race cars only use radiator cooling fans when stationary or nearly so.

With high ECT's IMO GM's design hand shows up in this engine. GM is known for hot running diesels that bake hoses and ruin oil. To counteract this I am curious as to what oil the engine calls for? I would recommend doing some oil samples to double check it's condition. The conventional vs. synthetic oil debate has one clear point of synthetic taking the heat better. You will know if you need to run synthetic from oil sample results. Our results in 2008-10 towing hot long steep grades in AZ had us pushing the limits of the then new emissions compliant conventional oil and exceeded them a few times. Scuffed pistons from going over the limit was not fun.

So at 30 mph what do you think the airspeed is through the restrictive: grill, condenser, intercooler, radiator, oil coolers and then having to find a way around the big wall of an engine? They you have the air pressures around and under the vehicle affecting places and reasons for air to move at all through the radiator stack.

Watching the temp climb at 60 MPH and then the temp levels off or goes back down when the fan comes on means the fan does some good. The fan even takes serious power to run thus increasing the cooling system load. Taking a 7% grade out here at 60 MPH with 'turn off ac next several miles' warning signs will clearly demonstrate how effective the fan is at 60 MPH.

The race car towing that big sail of a trailer here would be a burned up black mark of charred asphalt on the side of the road.

 

[RangerGress]

I salute you for obtaining and using the proper WD hitch equipment - after all it is a very important step in keeping the truck looking fabulous rather than a spectacular wreck like our RV broker posted on the board for months. Driver did not use the WD bars and rolled after jackknifing. It is rare to see towing threads starting out with the proper equipment.

Couple of pointers on the WD hitch.

Grease as metal on metal will wear faster without it: Grease the spring bars where they go into the hitch and the hitch ball itself.

Use a galvanized pipe as a cheater bar to get tension on the spring bar chains. Faster than jacking things up.

Unlike non-WD hitch designs that don't have this issue: The WD ball angle being tilted back as recommended helps the shelf below the ball clear the trailer tongue when you go over a big weird angle like railroad tracks. With the back of the truck and front of the trailer both high from the tracks the ball shelf can hit and try and uncouple (via breaking something) the trailer. Specifically the shelf just behind the ball (or the sides of the ball on a turn) will hit the trailer coupler just behind the ball and try and pop the trailer off the ball.

Big deep dips in the road can be so severe as to break the spring bars with high tension. Dips putting the rear of the truck low with front high and the trailer front low and rear high increase spring tension. If in doubt over a steep driveway etc. reduce the tension or take the bars off for that 'bump'. They make one big loud bang when they break.

Leverage:
As above example of levers for a cheater bar we have overlooked the real reason for the length of the WD hitch you have drilled to be 'shorter'. It has nothing to do with clearing a tailgate. You have effectively reduced by 2" the amount of leverage your spring bars have to work with to shift the trailer weight. If this length wasn't important to the overall design of the WD hitch they would come shorter saving the length and weight from the factory.

Try both hitch pin settings - the factory and your new hole with the trailer at the scale with the same tight chain link used on the spring bars and see the difference on the truck's front/rear axle weights.

Re. WD tension bars and cheater bar. I jack up the trailer foot pretty high and then use a cheater bar so I guess I do both. When I started towing the big trailer 3yrs ago I went to some scales to do some learning. One of the things I found is that the WD bars have to be really tight to shift much weight forward. W/o jacking up the trailer I was only shifting around 60lbs from rear to front axles. By jacking up the trailer to get to the next chain link I xfered 3x as much weight from rear to front.

Re. tilted back and tension bars breaking. I didn't know that, good info, thanks.

Re. effectively reducing the leverage the spring bars have to shift trailer weight. I don't agree. Moving the hitch shank deeper into the reciever doesn't change the geometry of the tension bars, ball and tongue.

 

[RangerGress]

With high ECT's IMO GM's design hand shows up in this engine. GM is known for hot running diesels that bake hoses and ruin oil. To counteract this I am curious as to what oil the engine calls for? I would recommend doing some oil samples to double check it's condition. The conventional vs. synthetic oil debate has one clear point of synthetic taking the heat better. You will know if you need to run synthetic from oil sample results. Our results in 2008-10 towing hot long steep grades in AZ had us pushing the limits of the then new emissions compliant conventional oil and exceeded them a few times. Scuffed pistons from going over the limit was not fun.

So at 30 mph what do you think the airspeed is through the restrictive: grill, condenser, intercooler, radiator, oil coolers and then having to find a way around the big wall of an engine? They you have the air pressures around and under the vehicle affecting places and reasons for air to move at all through the radiator stack.

Watching the temp climb at 60 MPH and then the temp levels off or goes back down when the fan comes on means the fan does some good. The fan even takes serious power to run thus increasing the cooling system load. Taking a 7% grade out here at 60 MPH with 'turn off ac next several miles' warning signs will clearly demonstrate how effective the fan is at 60 MPH.

The race car towing that big sail of a trailer here would be a burned up black mark of charred asphalt on the side of the road.

Re. Oil. The spec'd oil is some low-ash synthetic, the name of which escapes me. Both it and the oil filter is a little hard to find. I'll look into it harder in a couple months. I do oil analysis pretty routinely on the race car, but less often on the tow vehicle and daily driver. I'll certainly send in oil samples for the first couple of oil changes for the Ecodiesel so I can get a handle on it's desired oil change intervals.

Re. 30mph and what is most restrictive. Well, I don't know. At 30mph the amount of air flow is not high, so I figure that's what is limiting cooling. Altho there is other coolers forward of the radiator, AC, oil, transmission and intercooler, they shouldn't restrict air flow too much. People look at a heat exchanger forward of the radiator and think that it's blocking all the air flow and that's wrong. It's reducing some of the air flow, but not blocking. The high pressure zone at the grill and the low pressure zone behind the radiator will still ensure lots of air flow. Static high pressure will get around any obstruction. The extra heat exchangers also don't significantly increase the temp of the air hitting the radiator. This is because the radiator is dumping huge amounts of heat and everything else is orders of magnatude less.

Re. fan doing some good at freeway speeds. I'm still surprised by this, but you guys have seen it so I'm happy to accept it. Fan ratings are hopelessly optimistic because the fan blades are too close to the radiator for the air flow to efficient. What happens is in the absense of "stators" to turn the spinning airflow into longitudinal flow. 3000-5000 cfm is a common range for aftermarket fans, using those hopelessly optimistic #'s. Lets say the hopelessly optimistic # for the Cummins fan is 10k cfm. Assuming 9 ft^2 of radiator, 60mph works out to 427k cfm, 2 orders of magnatude higher. That's why I'm surprised that turning on the fan at freeway speeds is helpful.

Re. burned up black mark of charred asphalt. If there were serious mountains in my part of the country I might have reconsidered. The truck does 1/2 of the daily driver duty tho and I was highly motivated to get the 3/4ton truck out of the daily driver business. If, when the day comes that the Ecodiesel is laboring up a steep grade, I'll just go a little slower. All decisions have trade-offs.

 

[EDankievitch]

I'm not so sure you want the hitch ball any closer to the rear of the truck.... Remember when you make a tight turn where the tounge of the trailer will be hitting on the truck....

 

[RangerGress]

I'm not so sure you want the hitch ball any closer to the rear of the truck.... Remember when you make a tight turn where the tounge of the trailer will be hitting on the truck....

The tongue is no where near hitting the truck in tight turns.

Is the TDR forum always kinda lean on love and sunshine?

 

[DonFitzwater]

"Is the TDR forum always kinda lean on love and sunshine?"

Sometimes! Most of the time it's people offering their experience at no charge though.

 

[RangerGress]

Most of the time it's people offering their experience at no charge though.

A fair point. Lots of experience here.

 

[Tuesdak]

Is the TDR forum always kinda lean on love and sunshine?

Re. effectively reducing the leverage the spring bars have to shift trailer weight. I don't agree. Moving the hitch shank deeper into the reciever doesn't change the geometry of the tension bars, ball and tongue.

I am on diesel forums out of love for diesel trucks. It is entertaining and educational at times. Absolutely it is a nice looking truck and you are braver than I for trying out a 1st year model/engine. Sometimes the 1st year is the best year. I do hope you will post more stories and experiences with the new engine for our enjoyment and curiosity on how the new engine is doing.

As far as the distance to the hitch receiver to the hitch ball I suggest we look at it a different way in a thought experiment. Put a long solid bar into the hitch receiver. Lets make it really long. Now imagine standing on the end of this long bar. The long bar is simply a lever. The fulcrum is the rear wheels. Now imagine your weight on this long lever lifted the front wheels off the ground. Just like trailer tongue weight alone does. This is a standard hitch. The length we need to lift the wheels off the grounds depends on if you or your significant other stands on it. (I assume you are different weights or she has a heavy purse...)

Now we add the WD hitch spring tension. What exactly does the spring tension act on? We need to add the other items to make this work like a ball (hinge) and another fulcrum specifically a set of 'trailer' wheels to the above example. You see there is a second lever set at play to counteract the above lever of you standing on the bar to lift the front wheels. The lever for the weight is still the same, but, we change it up to illustrate the WD hitch operation.

We start at the front pickup wheels that are now the fulcrum turning into a lever that comes to the back of the truck and continues to the trailer ball at a specific distance. (The rear wheels are not part of the 2nd lever set example.) We add the hinge (trailer ball) and going back the WD torsion spring attach point and a distance (2nd lever) to the trailer wheels. Trailer wheels being a second fulcrum. This second set of hinged spring loaded levers is what counteracts the simple weight lever.

So you have a simple weight lever using the pickup's rear wheels to lift the front wheels off the ground being counteracted by two other levers and a spring. The spring tension wants to lift the front of the trailer by pulling down on the lever (at the chain attach point) going to the trailer wheel fulcrum. Yes, down. The other lever between the front pickup wheels and the hinge (ball/front of springs attach point) is also pushing down on the front pickup wheels and literately lifting the rear wheels as just a point of the lever. Imagine if you had a really loose hitch receiver you would see the top rear most part of the hitch pinned to the top of the receiver and the bottom toward the front of the truck would have the hitch pinned to the bottom from this lever set. (Of course weight from the trailer may overcome this visual example.) It is literately torquing the front wheels back to the ground by lifting the rear wheels with the spring tension.

If you had extreme spring tension and no weight the rear wheels of the pickup would be off the ground. The trailer tires and front pickup tires would have all the weight.

So changing the distance of the WD hitch ball closer to the rear bumper is changing the length of two separate lever systems. Sure it is taking the weight lever closer to the pickup and reducing it's effect. It is reducing the length of the front wheel to the trailer ball lever. By reducing the weight effect you are reducing the WD's torque to the second lever system that transfers the weight to the front wheels. Further you are reducing the lever length to put weight on the front wheels. the 2" shorter change is reducing the WD hitch setup's ability in two separate ways.

A bunch of math and measured lengths later you could determine the exact change that 2" shorter levers comes out to. Like this example and diagram.

The 5th wheel and GN hitches eliminate the lever mess as the weight is all over the rear wheels.

Re. 30mph and what is most restrictive. Well, I don't know. At 30mph the amount of air flow is not high, so I figure that's what is limiting cooling. Altho there is other coolers forward of the radiator, AC, oil, transmission and intercooler, they shouldn't restrict air flow too much. People look at a heat exchanger forward of the radiator and think that it's blocking all the air flow and that's wrong. It's reducing some of the air flow, but not blocking. The high pressure zone at the grill and the low pressure zone behind the radiator will still ensure lots of air flow. Static high pressure will get around any obstruction. The extra heat exchangers also don't significantly increase the temp of the air hitting the radiator. This is because the radiator is dumping huge amounts of heat and everything else is orders of magnatude less.

Re. fan doing some good at freeway speeds. I'm still surprised by this, but you guys have seen it so I'm happy to accept it. Fan ratings are hopelessly optimistic because the fan blades are too close to the radiator for the air flow to efficient. What happens is in the absense of "stators" to turn the spinning airflow into longitudinal flow. 3000-5000 cfm is a common range for aftermarket fans, using those hopelessly optimistic #'s. Lets say the hopelessly optimistic # for the Cummins fan is 10k cfm. Assuming 9 ft^2 of radiator, 60mph works out to 427k cfm, 2 orders of magnatude higher. That's why I'm surprised that turning on the fan at freeway speeds is helpful.

Re. burned up black mark of charred asphalt. If there were serious mountains in my part of the country I might have reconsidered. The truck does 1/2 of the daily driver duty tho and I was highly motivated to get the 3/4ton truck out of the daily driver business. If, when the day comes that the Ecodiesel is laboring up a steep grade, I'll just go a little slower. All decisions have trade-offs.

Electric fans are CFM rated freestanding - that is without any radiators or other restrictions. I recall the wimpy e-things top out around 5000 CFM freestanding.

Radiators are restrictive. Bug screens are a known restriction. A radiator hung out the window at 60 MPH isn't going to have 60 MPH of air going through it. Air's escape path is also a big factor. Most of the air that goes thought the radiator stack goes under the vehicle. The air dam under the front bumper makes a difference to a low pressure area under the vehicle.

Yes, you get some airflow at 60 MPH. There is a point on some vehicles where fans are a 'windmill' restriction as the fan with the clutch kicked out is spinning faster than engine RPM from airflow. Downshifting to higher RPM can move more air. One reason you may need a lower gear to keep cool with high loads.

Long time ago I had a Trailblazer SS that wouldn't keep cool. 395hp/400 TQ in a little SUV and a 21" fan. I took a wind speed meter and measured MPH using a grid to average airflow. Hood closed 0 MPH in the garage to eliminate wind effects with the AC condenser, radiator, and engine in the way I measured 10,000 CFM from the mechanical fan. I tested RPM all the way up till the fan belt started to squeal. It had an EV fan I could force to go 100% lockup and then a friend to hold higher RPM steady. My conclusion is that electrics don't stand a chance at moving the amount of air a mechanical fan will. Further, although there was plenty of airflow, the radiator was too thin and couldn't use it all. The solution I helped a aftermarket company bring to market was a ~1.5" thick radiator vs. the factory 1" unit.

As a popular mod on GM 6.5 diesels is to drop in a improved 19" or 21" Duramax fan and I had an extra 21" Trailblazer SS fan sitting around... It cools 2x the HP and the same TQ of course I tried it. The first grade with the windows down and heater on high I learned something about blade pitch. The 10,000 CFM fan did not have enough airflow for the IDI diesel. The 6.5 GM bodystyle has an airflow problem with plenty of radiator.

So mechanical diesel fans pull way more than 10,000 CFM. Dodge fan sizes may vary, but, pitch and driven RPM make a difference.

I am not sure I could see very well over a 9' tall and 9' wide radiator. CAT?