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aardvarcus · 01-03-2014, 09:02 AM

I am the one with the failed belly pan in question in the first post. My gas tank overheated with a partial aluminum belly pan, complete 4’ wide down the middle but with the sides fully open. The air from the engine bay was free to enter and flow through the pan and out the back. The sides were open by several inches as it wasn’t yet completed, yet it still didn’t allow the heat to dissipate. It melted plastic parts up under my car. It heated the bolts holding my seat down up so much you couldn’t hold your finger on them for more than a second or two. And it boiled over a gallon of gas out of my tank. I went back and cut holes in the pan under the exhaust to let more heat escape, but things kept heating up and I ended up removing the back portion of the pan halfway home.

I thought the exact same thing about heat dissipation with my belly pan, painting the top and bottom, cutting holes, insulating the exhaust pipe, etcetera. I have some even crazier/better ideas than those for dealing with the issue. Note the pan overheated while driving down the interstate and highway, 65-75 MPH the entire time. I don’t want to think about what would have happened if I had suddenly been stuck in stop and go traffic for an hour.

What I ended up deciding for myself is that a 90% belly pan is good enough for me. As I rebuild by belly pan V2 I am going to leave the 10% or so of the exhaust exposed. I am going to radius the edges of the pan as I near the exhaust to limit the aerodynamic consequences of having a small section of the pan missing. If you look at other “full” pans, many of them have screen wire under where the exhaust is, so basically the exhaust is kind of “exposed” on those pans anyway.

Just conceptually, my vehicle is less than ideal in a number of areas. There are still a lot of aerodynamic areas for improvement with my car. It isn’t impossible to reduce the heat transfer from the exhaust to the car as it travels from the engine bay out the back. Honestly it isn’t rocket science or really that hard. All it takes is thinking, time, money, and effort. But since my car isn’t perfect in so many other areas, I decided that I will start with my 90% pan, and then focus on fixing all the other areas on my car that need work. As it sits now, I don’t even know if you would be able to measure the difference in effectiveness between a 90% and 100% pan. Maybe if I get all the other areas taken care of I will revisit the 10% of the pan under the exhaust.

I tell you nothing makes you want to stop eco-modding more than spraying a boiling gas tank with a garden hose or trying to take a belly pan off a low car on the side of the road with no lift. Frankly it is very discouraging. I would try to stick to the easier no risk almost guaranteed reward projects first.

Maybe your vehicle will work with a 100% full pan with no special work around the exhaust. Several people on here state it will work fine. Why do you think I tried it in the first place? All I know is mine won’t.

01-03-2014, 09:02 AM	#14 (permalink)
aardvarcus Master EcoModder Join Date: Apr 2012 Location: Evensville, TN Posts: 676 Deep Blue - '94 GMC Suburban K2500 SLE 90 day: 23.75 mpg (US) Griffin (T4R) - '99 Toyota 4Runner SR5 90 day: 25.43 mpg (US) Thanks: 237 Thanked 580 Times in 322 Posts	I am the one with the failed belly pan in question in the first post. My gas tank overheated with a partial aluminum belly pan, complete 4’ wide down the middle but with the sides fully open. The air from the engine bay was free to enter and flow through the pan and out the back. The sides were open by several inches as it wasn’t yet completed, yet it still didn’t allow the heat to dissipate. It melted plastic parts up under my car. It heated the bolts holding my seat down up so much you couldn’t hold your finger on them for more than a second or two. And it boiled over a gallon of gas out of my tank. I went back and cut holes in the pan under the exhaust to let more heat escape, but things kept heating up and I ended up removing the back portion of the pan halfway home. I thought the exact same thing about heat dissipation with my belly pan, painting the top and bottom, cutting holes, insulating the exhaust pipe, etcetera. I have some even crazier/better ideas than those for dealing with the issue. Note the pan overheated while driving down the interstate and highway, 65-75 MPH the entire time. I don’t want to think about what would have happened if I had suddenly been stuck in stop and go traffic for an hour. What I ended up deciding for myself is that a 90% belly pan is good enough for me. As I rebuild by belly pan V2 I am going to leave the 10% or so of the exhaust exposed. I am going to radius the edges of the pan as I near the exhaust to limit the aerodynamic consequences of having a small section of the pan missing. If you look at other “full” pans, many of them have screen wire under where the exhaust is, so basically the exhaust is kind of “exposed” on those pans anyway. Just conceptually, my vehicle is less than ideal in a number of areas. There are still a lot of aerodynamic areas for improvement with my car. It isn’t impossible to reduce the heat transfer from the exhaust to the car as it travels from the engine bay out the back. Honestly it isn’t rocket science or really that hard. All it takes is thinking, time, money, and effort. But since my car isn’t perfect in so many other areas, I decided that I will start with my 90% pan, and then focus on fixing all the other areas on my car that need work. As it sits now, I don’t even know if you would be able to measure the difference in effectiveness between a 90% and 100% pan. Maybe if I get all the other areas taken care of I will revisit the 10% of the pan under the exhaust. I tell you nothing makes you want to stop eco-modding more than spraying a boiling gas tank with a garden hose or trying to take a belly pan off a low car on the side of the road with no lift. Frankly it is very discouraging. I would try to stick to the easier no risk almost guaranteed reward projects first. Maybe your vehicle will work with a 100% full pan with no special work around the exhaust. Several people on here state it will work fine. Why do you think I tried it in the first place? All I know is mine won’t.