Skid Plates vs Heat

GTV

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Dissent is offering their skids again and it’s got me thinking…

It’s not uncommon for our 100’s to have fuel issues related to heat. I don’t (yet) and I’d like to keep it that way.

I’ve been holding off getting a set of skids for a while as I’m concerned their presence could be a factor in what some owners here are experiencing when it comes to fuel boiling, pressurized tanks, etc. I’m also concerned that they could hasten catalytic converter demise as that area that was once open to fresh air is now covered. From what I’ve seen Toyota covered that area in 100’s with I-6 engines in the rest of the world, but in the 2uz V8 powered units it was left intentionally open (corrections welcome). IMO that had to be for a reason.

What says the group? Has anyone done underbelly temperature testing before/after skids? Has anyone started experiencing problems once skids were installed? As far as I’ve seen @J1000 is the only one who has added an inline fuel cooler, did this seem to help?
 
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Aluminum is a great conductor, that's why it's used a heat sink for so many widgets. I wouldn't worry to much about big sheets of aluminum trapping too much heat. By adding aluminum skids, you're basically adding huge heat sinks with a massive blower (air from your velocity) over them.
 
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A while back I was looking at the parts diagrams for ROW 100 series trucks and on most there are three skids with the third being a plastic skid to the rear of middle one we all typically have. Further, the Toyota skids actually appear to make a better seal around the perimeter of the frame under the truck than most aftermarket metal skids.

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A while back I was looking at the parts diagrams for ROW 100 series trucks and on most there are three skids with the third being a plastic skid to the rear of middle one we all typically have. Further, the Toyota skids actually appear to make a better seal around the perimeter of the frame under the truck than most aftermarket metal skids.

View attachment 3141804

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Nice find. So these are OEM for the 100 series? Did you happen to piece together the price for everything?
 

GTV

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Aluminum is a great conductor, that's why it's used a heat sink for so many widgets. I wouldn't worry to much about big sheets of aluminum trapping too much heat. By adding aluminum skids, you're basically adding huge heat sinks with a massive blower (air from your velocity) over them.

And when your velocity is at a crawling speed what do you think is happening?
 
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And when your velocity is at a crawling speed what do you think is happening?
2 things are happening, the aluminum is still transmitting heat to the cooler surrounding air via convection and it's giving off heat via radiation (hopefully more than it's reflecting). It's very good at both.

What do you think is happening?
 
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GTV

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2 things are happening, the aluminum is still transmitting heat the cooler surrounding air via convection and it's giving off heat via radiation (hopefully more than it's reflecting). It's very good at both.

What do you think is happening?

I feel like I made that clear in my first post, compared to the OEM design the skids are trapping a lot of air, not allowing the cats to shed heat and the entire underbelly is warming up. I don’t care what the skids are made out of, if they aren’t allowing a sufficient amount fresh air to flow in and out things will get hot.

I fully understand aluminium is a great heat conductor as I spent the first two decades of my car life modifying performance air cooled street engines, mostly in the desert southwest.
 

saucebox

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I'm not convinced the skids have anything to do with the heat problems (or if they do, it's a very minor knock-on effect). My LX had a full set of Slee skids when it was IFS, and runs just the belly plate now. Obviously Slee =/= Dissent, but I noticed zero change in the likelihood of boiling by adding skids. I did pull all the skids at one point, thinking it might help my problem—it didn't. Not one bit.

If you're worried about heat or are currently boiling fuel, follow the steps in the boiling thread. That the system has too much heat is the problem—it's not the skids holding exhaust heat in that will push fuel temps over the edge (in my experience).

OP, if you do end up adding skids, just add a few feet of fuel return line insulation while you're at it. NBD, and loads easier than installing skids anyway.
 

suprarx7nut

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I had fuel boiling problems on my 99 with no skids. I have similar issues now with my 06 with Dissent skids. I'm sure the skids change the heat transfer dynamics in some way, but I'm not convinced any arrangement of skids in this context are worth worrying about.

If you have fuel concerns I would shield/reroute the lines regardless of your skid situation. Or add a cooler or something.

2 things are happening, the aluminum is still transmitting heat to the cooler surrounding air via convection and it's giving off heat via radiation (hopefully more than it's reflecting). It's very good at both.

What do you think is happening?

I feel like I made that clear in my first post, compared to the OEM design the skids are trapping a lot of air, not allowing the cats to shed heat and the entire underbelly is warming up. I don’t care what the skids are made out of, if they aren’t allowing a sufficient amount fresh air to flow in and out things will get hot.

I fully understand aluminium is a great heat conductor as I spent the first two decades of my car life modifying performance air cooled street engines, mostly in the desert southwest.

Aluminum is a good heat conductor for a solid material, but it's only a "heat sink" when the geometry is such that the aluminum has a ton of cool surface area per heated surface area (IE a CPU heat sink). If it's just a sheet of aluminum it's a 1:1 ratio - I'm pretty sure it's a heat shield. Not a heat sink. The geometry makes the difference. Either way, I don't think it's worth worrying about here, but just figured I'd throw that into the conversation.
 

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Don't shut your truck of when wheeling. That solves the problem of vapor lock. Would you rather have a truck that wont start fort an hour or a busted transfer case?
 

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A while back I was looking at the parts diagrams for ROW 100 series trucks and on most there are three skids with the third being a plastic skid to the rear of middle one we all typically have. Further, the Toyota skids actually appear to make a better seal around the perimeter of the frame under the truck than most aftermarket metal skids.

View attachment 3141804

View attachment 3141805
I am trying to buy this exact part and cannot locate the actual part number on Partsouq. Would you be kind enough to locate that number for me? Thanks in advance.
 

jLB

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I am trying to buy this exact part and cannot locate the actual part number on Partsouq. Would you be kind enough to locate that number for me? Thanks in advance.

I’d have to wonder if there is a reason that Toyota didn’t put a plastic skid plate, directly under the catalytic converters, on the US market 100 series.
 
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YezusLX

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I’d have to wonder if there is a reason that Toyota didn’t put a plastic skid plate, directly under the catalytic converters, on the US market 100 series.
I am guessing a shipping or final cost issue. Or perhaps due to California requiring annual inspections of cats. Usually, we are the victims of California's emissions policies in the US. Again just guesses. Since my LX lives in a state that does not have emissions at all, I would like this to cover up my soon-to-be "R&R" cats.
 

jLB

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I am guessing a shipping or final cost issue. Or perhaps due to California requiring annual inspections of cats. Usually, we are the victims of California's emissions policies in the US. Again just guesses. Since my LX lives in a state that does not have emissions at all, I would like this to cover up my soon-to-be "R&R" cats.

Shipping wouldn’t really make much difference on a nearly 6000lb vehicle. Neither would final cost on a vehicle that they’re putting night vision on. I’m wondering more about heat + plastic issues.
 

YezusLX

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Shipping wouldn’t really make much difference on a nearly 6000lb vehicle. Neither would final cost on a vehicle that they’re putting night vision on. I’m wondering more about heat + plastic issues.
High temp plastic would negate this issue would it not? Like the OEM trans cover? Engine cover?
 

jLB

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I suspect engine (based on coolant temps), and transmission (based on fluid temps) are going to be substantially lower than exhaust manifolds or catalytic converters, but what do I know…
 
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