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I agree that this is an eventual failure mode, and thank you for pointing this out. To turn your concern into a design spec, I'll restate it this way: we need to figure out the depth of water such that the cabin displacement is large enough to balance the mass of the vehicle (neutral buoyancy).

Here's the math: I estimated the interior volume of the FJ at 100 cu feet (it's 70 CF cargo space with the seats down, so I think that's reasonable; if anyone knows the actual number please tell me). For a 5200 lb FJ and subtracting out buoyancy of the (my) tires, you have net mass of 2000kg, which requires 2000 liters of cabin volume under the waterline for neutral buoyancy. That's 70 CF, so at the point that the FJ starts to float is when all but 30 CF is submerged.

The FJ is roughly 8' x 4' around the top, so a foot down from the roofline is about the spot. Note that this is true no matter what the actual height of the vehicle is.

Note further that this is a little higher than the empirical data point we have from Bluecuss about mid-windshield being where things got sketchy. You would expect things to start getting increasingly sketchy as you got within a few hundred pounds of neutral buoyancy; the hydrodynamic forces from any movement of water would start to push you around more and more.

I wonder if there are FJs out there with enough extra gear that could submerge completely and not float. It would take another thousand kilos.
OK sure. What do I know...
 

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Yeah, when you put it like that, I can't argue with you; that'll take a lot of time. Ordered.

You may go to bed tonight knowing you helped Australia's trade balance.


Let me get the dimensions off that bra and I’ll stitch some up for us in Houston

I definitely went through deeper water than I should have

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Discussion Starter #103
OK sure. What do I know...
You know enough to help me establish the most important primary design consideration for my whole build. Thank you.
 

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I know lots of people in Kingwood. You probably helped some of them. Thank you, from my heart.
Thanks, that is the reason I got into this line of work was helping people (and making a living for my family). I try to show compassion all the time because even though I've seen thousands of homes destroyed I can almost guarantee this is the first time for the family I'm helping. Also thank you.
 

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Discussion Starter #105
Does the air intake box serve any purpose other than holding the filter? It seems with the design of this snorkel you could (with modification) stick the air filter in that cowling, and just run sealed tubing straight to the engine air intake.

 

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Does the air intake box serve any purpose other than holding the filter? It seems with the design of this snorkel you could (with modification) stick the air filter in that cowling, and just run sealed tubing straight to the engine air intake.



Yes it serves a purpose. Dust falls out of the filter into that void, and any water that makes it in thru the intake will pool there rather than going straight into the engine.
The Toyota engineers kind of know what they are doing....
 

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Discussion Starter #107 (Edited)
Yes it serves a purpose. Dust falls out of the filter into that void, and any water that makes it in thru the intake will pool there rather than going straight into the engine.
The Toyota engineers kind of know what they are doing....
Not "kind of".

What void space are you talking about? If you are talking about the space below the filter in the air box, I just went and looked at mine. There is a fine coating of dust in there, but nothing to suggest that what you are saying is actually happening in my vehicle. I'm going to reiterate that I live in a swamp- dust is not ... I don't have a clear understanding of why I'm still talking about dust. It just isn't an issue for me.

I will offer another opinion as to why this box has the design that it does: Toyota calculated a mass air flow rate for the engine at the top of its torque curve. They then picked an air filter whose air flow resistance matched the resistance of the upstream intake pipe. Since the filter has a higher flow resistance than the intake pipe, that requires a larger filter than pipe in order not to impede airflow and choke the engine.

The air box looks to me like it was designed to have the minimum volume to still be able to include that filter, understanding that you want the filter to be oriented perpendicular to the air flow stream.

In any case, it doesn't matter whether I'm correct about anything I just wrote, at least for the purposes of this discussion. A liquid reservoir function is easy to add to the intake piping, before the engine, whether or not it happens to reside in the air box.
 

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Discussion Starter #108
Here's a shot of the rear vents.... The wider rectangular ones on the bottom left are literally just flaps of rubber.

So don't forget to check your rear areas too if you go really deep.
Open it up, dry it out.

:cheers:


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Are there any more of these vents on the vehicle? Thanks in advance.
 

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Are there any more of these vents on the vehicle? Thanks in advance.
The passenger rear is identical.... I don't think there are any other areas that have that.

:cheers:
 

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Discussion Starter #112 (Edited)
The passenger rear is identical.... I don't think there are any other areas that have that.

:cheers:
What's behind that flap? Empty space enclosed by the sheet metal of the fender?

Edit: I get that it is open to the cabin in some fashion, I presume via where the stock jack is located.
 
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