Builds TheGrrrrr Build Thread - 2013 LC (1 Viewer)

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Post-LCDC Update:

The Timbren Active Offroad Bump Stop upgrade was probably single biggest improvement I've made to the vehicle since upgrading to 4.88 gears and Eaton Lockers front and Rear. The truck was loaded heavier than it has been for any event trip I've taken and yet my rear bumper did not make contact with anything, and I never bottomed out even when dropping off shelves with more speed than is ideal. Before I upgraded the bump stops, I was pretty consistently scraping up the rear bumper corners and more than a few times I landed the rear end on the spare tire underneath. None of that happened on this trip despite plenty of situations where it would have happened in the past.

Before this trip I switched to Mobile 1 synthetic 5w-30 and was keen to see if it impacted fuel efficiency at all. It did not. If anything, I probably had my best overall fuel efficiency for this type of trip. I averaged 13.94 mpg over 1827.98 miles, including trails, according to OBD Fusion (calibrated to manually calculated efficiency before the trip), but did not track manually during the trip. The truck seemed to run smoother with better overall engine sound (hard to explain aside from sounding less like a diesel sewing machine) and temps were great even under heavy load on mountain passes.

iPad mount worked great, but still not happy with the data setup. Will probably upgrade to a 5G iPad and ditch the hotspot. Gathered a lot of good feedback on the WeBoost option I've been considering and not really thinking it makes enough of a difference. Open to data indicating otherwise.
 
Who did you buy the Timbren bumps from?
 
Post-LCDC Update:

The Timbren Active Offroad Bump Stop upgrade was probably single biggest improvement I've made to the vehicle since upgrading to 4.88 gears and Eaton Lockers front and Rear. The truck was loaded heavier than it has been for any event trip I've taken and yet my rear bumper did not make contact with anything, and I never bottomed out even when dropping off shelves with more speed than is ideal. Before I upgraded the bump stops, I was pretty consistently scraping up the rear bumper corners and more than a few times I landed the rear end on the spare tire underneath. None of that happened on this trip despite plenty of situations where it would have happened in the past.

Before this trip I switched to Mobile 1 synthetic 5w-30 and was keen to see if it impacted fuel efficiency at all. It did not. If anything, I probably had my best overall fuel efficiency for this type of trip. I averaged 13.94 mpg over 1827.98 miles, including trails, according to OBD Fusion (calibrated to manually calculated efficiency before the trip), but did not track manually during the trip. The truck seemed to run smoother with better overall engine sound (hard to explain aside from sounding less like a diesel sewing machine) and temps were great even under heavy load on mountain passes.

iPad mount worked great, but still not happy with the data setup. Will probably upgrade to a 5G iPad and ditch the hotspot. Gathered a lot of good feedback on the WeBoost option I've been considering and not really thinking it makes enough of a difference. Open to data indicating otherwise.
I followed (as in was the rig behind him) and watch him drop off shelves with his stock rear bumper and not hit anything and thought, OK no bid deal for me with by Dissent bumper, yet I've hit stuff. I still keep a spare in the stock location and that was part of it. I managed to knock the spare out of position a bit. I think my real issue is that I am "undersprung" (2721s) with my current weight. I'll fix that but I'm going to add the Timbren stops too.
 
I plan to make the switch at my next oil change as well.
 
I switched 3 oil changes ago. No downsides, truck is much quieter. Oil pressure is tick mark higher.

I've always hated how low the oil pressure reads on these vehicles.
 
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0W-30 can be a great option year round too, especially for those that visit or live in areas with cold winters.
 
Post-LCDC Update:

The Timbren Active Offroad Bump Stop upgrade was probably single biggest improvement I've made to the vehicle since upgrading to 4.88 gears and Eaton Lockers front and Rear. The truck was loaded heavier than it has been for any event trip I've taken and yet my rear bumper did not make contact with anything, and I never bottomed out even when dropping off shelves with more speed than is ideal. Before I upgraded the bump stops, I was pretty consistently scraping up the rear bumper corners and more than a few times I landed the rear end on the spare tire underneath. None of that happened on this trip despite plenty of situations where it would have happened in the past.

Before this trip I switched to Mobile 1 synthetic 5w-30 and was keen to see if it impacted fuel efficiency at all. It did not. If anything, I probably had my best overall fuel efficiency for this type of trip. I averaged 13.94 mpg over 1827.98 miles, including trails, according to OBD Fusion (calibrated to manually calculated efficiency before the trip), but did not track manually during the trip. The truck seemed to run smoother with better overall engine sound (hard to explain aside from sounding less like a diesel sewing machine) and temps were great even under heavy load on mountain passes.

iPad mount worked great, but still not happy with the data setup. Will probably upgrade to a 5G iPad and ditch the hotspot. Gathered a lot of good feedback on the WeBoost option I've been considering and not really thinking it makes enough of a difference. Open to data indicating otherwise.
Is there any impact to ride quality?
 
Is there any impact to ride quality?

Nothing to speak of in terms of normal driving, literally no difference, but when it comes to speed tables and speed bumps, the truck reacts much less harshly and is more stable feeling. I never had much issue with potholes and such, but I suspect it would benefit there as well.
 
Nothing to speak of in terms of normal driving, literally no difference, but when it comes to speed tables and speed bumps, the truck reacts much less harshly and is more stable feeling. I never had much issue with potholes and such, but I suspect it would benefit there as well.
Thanks. Trying to imagine how much it’d also help when adding another 1000# when towing. Seems like they might be worth a shot. I had so much rocking coming over moguls and such in Breck that I cranked up the compression on my rear shocks here in Ouray. It helped but more support that isn’t harsh would be awesome.

Do you know if the Timbrens are sufficient to keep 35s from hitting the top of the wheel wells, or is there additional spacers required?
 
Thanks. Trying to imagine how much it’d also help when adding another 1000# when towing. Seems like they might be worth a shot. I had so much rocking coming over moguls and such in Breck that I cranked up the compression on my rear shocks here in Ouray. It helped but more support that isn’t harsh would be awesome.

Do you know if the Timbrens are sufficient to keep 35s from hitting the top of the wheel wells, or is there additional spacers required?
The rear Timbrens I believe actually limit articulation compared to stock by a small bit, maybe half an inch so I would think they would be fine for 35s. One thing to consider might be the Timbren SES instead of the Off-Road as they are specifically designed for towing.

 
Post-LCDC OBD Fusion Log Upload: Red Cone

I haven't yet done any analysis as I didn't really have any issues, but if anyone wants to dig into the data and provide insights, have at it. I did have some gas boiling on Red Cone, but do not remember exactly where I smelled it or if it was always me I was smelling since I was tail gunning. The truck in front of me was a 62 Series and he was not having the gas boiling issue.
 

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Post-LCDC OBD Fusion Log Upload: Red Cone

I haven't yet done any analysis as I didn't really have any issues, but if anyone wants to dig into the data and provide insights, have at it. I did have some gas boiling on Red Cone, but do not remember exactly where I smelled it or if it was always me I was smelling since I was tail gunning. The truck in front of me was a 62 Series and he was not having the gas boiling issue.
I don't think it's temps. You're just not running that hot, man!

I compiled all your CSV's into one file, removed any "0" values, and then calculated the min/max/average for everything. It's ~9900 lines of data. There's nothing in this data that would concern me. Seriously my A/T 1 temp routinely runs at 215-217 when towing, A/T 2 temp can hit 250F for sustained climbs. Engine oil will get up to 212F regularly when towing, and coolant temps at ~203F. Granted I'm moving so there's a lot of airflow in these cases. But even when you're at the top (I think) the numbers just aren't concerning - they're hardly above idle.

Now that said at rock crawling speeds there's limited airflow across the gas tank. There's also latent heat from the exhaust that we're not accounting for (though it would be cool if fuel temperature was somehow available...) And the pressure within the tank we're not tracking either, but regardless of heat I'm sure the *air* (and vapors) trapped inside the tank will expand a whole lot as you go up in elevation (even if the fuel itself doesn't expand much)

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I don't think it's temps. You're just not running that hot, man!

I compiled all your CSV's into one file, removed any "0" values, and then calculated the min/max/average for everything. It's ~9900 lines of data. There's nothing in this data that would concern me. Seriously my A/T 1 temp routinely runs at 215-217 when towing, A/T 2 temp can hit 250F for sustained climbs. Engine oil will get up to 212F regularly when towing, and coolant temps at ~203F. Granted I'm moving so there's a lot of airflow in these cases. But even when you're at the top (I think) the numbers just aren't concerning - they're hardly above idle.

Now that said at rock crawling speeds there's limited airflow across the gas tank. There's also latent heat from the exhaust that we're not accounting for (though it would be cool if fuel temperature was somehow available...) And the pressure within the tank we're not tracking either, but regardless of heat I'm sure the *air* (and vapors) trapped inside the tank will expand a whole lot as you go up in elevation (even if the fuel itself doesn't expand much)

View attachment 3085039

View attachment 3085038

Nicely done collating the data.

I agree, and the data supports that it's not the cooling performance of the vehicle. At least for @TheGrrrrr 's truck.

What stands out to me is the max ambient (104*F) and max intake (131*F) temps. I'm not sure the conditions experienced out there. And while not direct measures, those would suggest the degree of underbody heat radiating sufficient to elevate temperatures all around. The underchassis areas would be that much higher and further heat soaked. Potentially more with under armor.

There was a great thread in the 100-series section where someone put a temp probe in the fuel system. Highest temps that would see ~130*F. Fuel would have deltas of 30-50F over ambient when stock. The intake temps recorded above would suggest fuel heat saturation to that level is possible in slow crawls or idle.

After his extensive heat treatment, including heat shields around the tank, re-routing fuel lines around motor, and others, improved fuel temps to 10-20*F above ambient.

I think the 200-series could benefit from much the same mods.

 
Nicely done collating the data.

I agree, and the data supports that it's not the cooling performance of the vehicle. At least for @TheGrrrrr 's truck.

What stands out to me is the max ambient (104*F) and max intake (131*F) temps. I'm not sure the conditions experienced out there. And while not direct measures, those would suggest the degree of underbody heat radiating sufficient to elevate temperatures all around. The underchassis areas would be that much higher and further heat soaked. Potentially more with under armor.

There was a great thread in the 100-series section where someone put a temp probe in the fuel system. Highest temps that would see ~130*F. Fuel would have deltas of 30-50F over ambient when stock. The intake temps recorded above would suggest fuel heat saturation to that level is possible in slow crawls or idle.

After his extensive heat treatment, including heat shields around the tank, re-routing fuel lines around motor, and others, improved fuel temps to 10-20*F above ambient.

I think the 200-series could benefit from much the same mods.

I suspect there are actually two issues at play at various times. It's just that the symptoms are the same, so we conflate them.
  1. High altitude causes air expansion in the tank (really vapor-filled air). The tank has to vent. It's no different than the bag of Skinny Pop that my kids had that exploded in the truck going over Mosquito Pass. I would think the breather should allow this, which makes me think maybe it gets clogged and makes the issue worse? (Also are we sure the breather is really 2-way and open to atmosphere or does it require some pressure to allow fumes to vent?)
  2. Heat can also cause the fuel in the tank to warm up. This is more likely what people in Moab experience. It's 100F there and the fuel atomizes in the tank and wants to expand. It's similar to how my rotopax balloons up just from sitting in the sun all day if I put 87 octane in it. I actually think high octane fuel should help in this case... or some different fuel mix in any case. Putting 93 in my rotopax it still expands and contracts a little bit but it doesn't significant vaporize and then explode in my face when I open the rotopax like 87 does. (BTW, gas on the lips tastes awful).
Anyway I'm not a chemical engineer nor do I have emissions experience, so the above may be totally off base. In both cases above heat shielding and cooling of fuel and fuel lines/components will help, though I'm not convinced particularly in the first case that it will have a significant impact to improve the situation.
 
I suspect there are actually two issues at play at various times. It's just that the symptoms are the same, so we conflate them.
  1. High altitude causes air expansion in the tank (really vapor-filled air). The tank has to vent. It's no different than the bag of Skinny Pop that my kids had that exploded in the truck going over Mosquito Pass. I would think the breather should allow this, which makes me think maybe it gets clogged and makes the issue worse? (Also are we sure the breather is really 2-way and open to atmosphere or does it require some pressure to allow fumes to vent?)
  2. Heat can also cause the fuel in the tank to warm up. This is more likely what people in Moab experience. It's 100F there and the fuel atomizes in the tank and wants to expand. It's similar to how my rotopax balloons up just from sitting in the sun all day if I put 87 octane in it. I actually think high octane fuel should help in this case... or some different fuel mix in any case. Putting 93 in my rotopax it still expands and contracts a little bit but it doesn't significant vaporize and then explode in my face when I open the rotopax like 87 does. (BTW, gas on the lips tastes awful).
Anyway I'm not a chemical engineer nor do I have emissions experience, so the above may be totally off base. In both cases above heat shielding and cooling of fuel and fuel lines/components will help, though I'm not convinced particularly in the first case that it will have a significant impact to improve the situation.

Yes we're conflating multiple contributors, including potentially what @TheGrrrrr points out. Each is ultimately a contributor to heat into the fuel system. With some mods further exacerbating the issue. So there's truth to everything being pointed out. To your point, results in a common fuel boiling symptom.

A stock vehicle in good repair, using best practices like low range, high octane/non-ehtanol/locally sourced fuel, is going to stand the best chance avoid boiling. I think it's possible that in certain weather and use, could still occur.

Which leads to the need to perform mods that minimize heat input to the fuel system - which is the piece of the puzzle we haven't really identified. I think the 100-series thread above is going to be a great template for what could be done.

On your points

1) It's a bit more complicated. The fuel tank is generally breathing inward (via air inlet valve) in normal operation to make up volume for fuel consumed. In a scenario where fuel heating occurs and increases fuel vapor pressure past atmospheric (measured by vapor pressure sensor), the air inlet is closed - to contain evap emissions (the whole point of the evap system). The pressurizing strategy also further mitigates increasing vapor pressure. Yet the system has a design pressure envelop, and when exceeded, will vent at the pressure safety valve which is the fuel cap. That safety is normal and by design when using the system outside of its envelop, which should also preclude damage to the fuel system. Note it is not a good idea to open and vent the fuel system because that will cause a pressure drop creating further vapors and potential boiling. The problem is not how the system is managing pressure and over-pressure. The root problem is still heat sources and use.

2) Yup. I did some research and you're right that higher octane has lower vapor pressures under the same conditions. Ethanol blends have higher vapor pressures and should be avoided if possible. I posted this elsewhere

It's an issue with the fuels in the US. The volatility and gas vapor pressure is regulated by the EPA. Known as Reid Vapor Pressures (RVP).

Simplified explanation​


EPA regulates RVPs to either 7.8PSI and 9 PSI (@100 °F) depending on region and season. Generally, summer blends have lower RVP requirements (to protect fuel loss to atmosphere). Winter, higher RVP (as gas is less volatile in lower temps and this helps starting).

EPA also allows an additional 1 PSI margin higher for ethanol blends.

Other factors - 87 octane tends to have higher vapor pressures. 91, lower. Higher octane is naturally more stable with combustion inhibitors, and less volatile. Another way to say it is that higher octane fuels tend to have less light end petroleum components - the stuff that tend to vaporize easily.


Takeaways​

- Use high octane fuel even if your vehicle may not call for it
- Avoid ethanol blends
- Get local gas from higher elevations as its likely blended for the higher altitude locale
- I would not recommend opening the gas cap as the system pressure can help it from over-boiling. Relieving the pressure in only going to increase boiling and vaporization. It's normal for the gas tank to vent once it exceeds it's safe design pressure and that's likely designed into the cap

Slow vehicle operation, high weather temps, and increase altitude will all increase fuel volatility.
 
Yes we're conflating multiple contributors, including potentially what @TheGrrrrr points out. Each is ultimately a contributor to heat into the fuel system. With some mods further exacerbating the issue. So there's truth to everything being pointed out. To your point, results in a common fuel boiling symptom.

A stock vehicle in good repair, using best practices like low range, high octane/non-ehtanol/locally sourced fuel, is going to stand the best chance avoid boiling. I think it's possible that in certain weather and use, could still occur.

Which leads to the need to perform mods that minimize heat input to the fuel system - which is the piece of the puzzle we haven't really identified. I think the 100-series thread above is going to be a great template for what could be done.

On your points

1) It's a bit more complicated. The fuel tank is generally breathing inward (via air inlet valve) in normal operation to make up volume for fuel consumed. In a scenario where fuel heating occurs and increases fuel vapor pressure past atmospheric (measured by vapor pressure sensor), the air inlet is closed - to contain evap emissions (the whole point of the evap system). The pressurizing strategy also further mitigates increasing vapor pressure. Yet the system has a design pressure envelop, and when exceeded, will vent at the pressure safety valve which is the fuel cap. That safety is normal and by design when using the system outside of its envelop, which should also preclude damage to the fuel system. Note it is not a good idea to open and vent the fuel system because that will cause a pressure drop creating further vapors and potential boiling. The problem is not how the system is managing pressure and over-pressure. The root problem is still heat sources and use.

2) Yup. I did some research and you're right that higher octane has lower vapor pressures under the same conditions. Ethanol blends have higher vapor pressures and should be avoided if possible. I posted this elsewhere
For reference I had some boiling (or at least leakage/smelliness) back in 2017 when I went to Grand Mesa, CO after my first Breck LCDC. I had a lift and 34” tires but was otherwise stock - no skids, no bumpers. I noticed it when I stopped while approaching 10k heading up into Grand Mesa. I was pulling the trailer in 2nd, A/T temps were in the 240s on the climb but I was still going 30 or so mph in 2nd gear as I got near the top. Stopped just before the top at an overlook which is when I noticed the smell. Which is my long explanation as to why I don’t think it’s necessarily (or always) heat-related. Yes my A/T was hit, but engine cooling temp was normal, I was moving, and no mods to trap the heat at that time.

As you note I think venting at the gas cap is actually a design decision and by itself not a problem per-se. higher tank pressures should keep the fuel from boiling, similar to how higher pressure keeps the cooling system from boiling. Even some leakage (via the cap, if intended by engineers) would be ok so long as it’s generally allowing for higher pressures, and the cap is just ensuring the tank doesn’t go over the “high limit” in the design. Actually the rapid boiling that I think Eric had where fuel was visibility dripping from under the vehicle makes me think the pressure is not being properly contained, and ultimately that seems more likely to me to be the ultimate cause of charcoal canister issues and the like.

Not that reducing heat isn’t helpful, but if it’s largely due to high pressure and not heat in this scenario it may not help much.
 
For reference I had some boiling (or at least leakage/smelliness) back in 2017 when I went to Grand Mesa, CO after my first Breck LCDC. I had a lift and 34” tires but was otherwise stock - no skids, no bumpers. I noticed it when I stopped while approaching 10k heading up into Grand Mesa. I was pulling the trailer in 2nd, A/T temps were in the 240s on the climb but I was still going 30 or so mph in 2nd gear as I got near the top. Stopped just before the top at an overlook which is when I noticed the smell. Which is my long explanation as to why I don’t think it’s necessarily (or always) heat-related. Yes my A/T was hit, but engine cooling temp was normal, I was moving, and no mods to trap the heat at that time.

As you note I think venting at the gas cap is actually a design decision and by itself not a problem per-se. higher tank pressures should keep the fuel from boiling, similar to how higher pressure keeps the cooling system from boiling. Even some leakage (via the cap, if intended by engineers) would be ok so long as it’s generally allowing for higher pressures, and the cap is just ensuring the tank doesn’t go over the “high limit” in the design. Actually the rapid boiling that I think Eric had where fuel was visibility dripping from under the vehicle makes me think the pressure is not being properly contained, and ultimately that seems more likely to me to be the ultimate cause of charcoal canister issues and the like.

Not that reducing heat isn’t helpful, but if it’s largely due to high pressure and not heat in this scenario it may not help much.

Useful data point on the stock rig. I'm not familiar with Eric's situation?

Fuel vapor pressure and boiling is a function of only two things: temperature and pressure. Pressure is surely a main component. The boiling point happens when atmospheric pressure equals the vapor pressure of fuel. So when the atmosphere and fuel system is no longer able to exert or contain pressure, and there is enough heat, fuel will boil. If the fuel happens to be 87 octane with ethanol, that threshold will be at a lower point.

The fuel cap safety relief valve works on relative and not absolute pressure. To your earlier point, going up in altitude will reduce pressure that the fuel system will hold (atmosphere + fuel system containment delta) before it vents.

Two variables are colluding in our problem: 1) Climbing puts heat in the system 2) Reducing atmospheric pressure to contain vapor pressure

There's two critical pressures: a) point in which the fuel system vents b) point in which fuel boils

If the fuel system has enough heat and can no longer contain vapor pressure, it may vent. If the fuel system is venting, hopefully it's still below the boiling point.

Which bring up another point that gas caps can wear. And that may effect the containment ability of the fuel system.
 

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