Thread: Ending unwanted Defender Floor/Tunnel/Cabin Heat Issues - FOR GOOD

Originally Posted by spudfan

Over here I regard it as a beneficial high end option that they did not charge me for.!

Living the dream!

Double post I know - but it's a legitimate update!

So had a few minutes to myself today to knock over some odd jobs and get stuck into getting the Defender sorted. I'm taking stock of the TIC next weekend, and wanted to get everything in place and ready so I can maximise testing time whilst I have it, not installing.

Now, please hold your tongues here - I did an ATROCIOUS job of sanding and raptor coating the wing scoops. You wouldn't know it, but I did the bonnet only weeks ago which worked out (i think) amazing, so go figure. Anyway, besides the grill not being up to standard, and the finishing being very rough around the edges, I figured I was out of PETG filament, so instead of waiting they will work fine for testing purposes, gave up and slapped them on anyway. I'm still not sold on the some part of the look, so if they work successfully, I'll play with the aesthetics and they'll be printed in much better quality any for a final version, so no harm no foul. Besides looks, they are exceptional. Mount holes are spot on, incredibly strong and should net some serious airflow. We'll see. I might run a SimFlow CFD tomorrow night and see what numbers come back for throughput.

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The sheet metal came back from fabricators - it was absolutely spot on and fit really well, however, as is the way, I didnt account for certain parts of the car getting in the way of where I needed to be. I ended up moving the nozzle input towards the sides of the car instead of the middle and mounted slightly off my original as I couldn't drill the mounting tabs for rivets as too close to the chassis rails to get the drill in. I'll move the nozzle and shrink things by an inch or two for a good fit in CAD. I also came up with the idea whilst installing it, the idea being that I can actually vent this cooling pan towards the GEARBOX, instead of the rear of the car of the drivers seatbox area, which sort of kills two birds with one stone: baths the footwell with heat AND blasts cool air into the gearbox tunnel to break up the void. Let's see how it goes. I've just blocked the back off with some 100mph tape and will get some pics under the car tomorrow of the installed pan and the ducting.

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Will take it for a quick test spin tomorrow as well, and gather some anecdotal evidents and see how she flies!

Cheers,
Matt

I was thinking of installing ventilation flaps on the lower corner of the fender to catch cooler air that will be directed by ducts to the entrance of the gearbox tunnel.
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I have been told of two drawbacks to such installation:

1- the area behind the front wheel arch is a low air pressure area that will not give a sufficient air flow. (Like the top of the Fender and bonnet which creates a large area of turbulence at the base of the bulkhead under the windshield)
2- Creating an over pressurized area above the gearbox tunnel will draw the trapped hot air to the cabin once any of the windows is opened. This apparatus could give a result if the aircon is used.

It seems that the way to go is to create a suction effect underneath the gearbox (low pressure area) to drag the hot air out.
How to do it? to that I have no answer.

I ended up installing a thick mat of closed cell foam blanket over the entire floor of the Defender, the result was good both on the heat and noise reduction in the cabin. The draw back is in winter, when it gets soggy from the water ingress thus adding wetness the the cabin.


I hope that you will reach good results with your design.

Sorry it took me a few days to get back to you mate, been a little bit busy the last few days.

Interesting points Leb but I have a few questions on those.

1. Is there actually hard data to back this up? Has anyone run a CFD analysis and proven if this is actually for certain? The aircon seems to draw in plenty of fresh air from the top of the wing, even laying flat?
2. Again - hard data? It makes sense as I know from experience that just opening my window allows the the hot air to be sucked in but surely feeding cool air into the front of that can't be any worse?

I've yet to grab the TIC as I have a few approaching deadlines that I need to take care of for other projects so I've pushed things back a bit. I did take the defender for a spin though and anecdotally - there is a difference in the felt footwell temp when compared to passengers side. I wouldnt say ground breaking though. Definitely needs tweaking.

EDIT - I'm looking to avoid the soggy floor scenario for mold/corrosion reasons.

Cheers,
Matt

I have a snorkel vent mounted on my left guard for a couple of reasons, firstly so I can stick a snorkel sock on it if I'm at the back of a convoy to reduce the dust in the cab and secondly to try and overcome the tenancy for the aircon to suck hot air from the engine bay due to the poor seal from the vent ducting. My arrangement definitely improves airflow from the vents without the fan running so it should be possible to generate positive pressure from the guard top vents.



Regards,
Tote

Hi Tote,

Originally Posted by DFender

Sorry it took me a few days to get back to you mate, been a little bit busy the last few days.

Interesting points Leb but I have a few questions on those.

1. Is there actually hard data to back this up? Has anyone run a CFD analysis and proven if this is actually for certain? The aircon seems to draw in plenty of fresh air from the top of the wing, even laying flat?
2. Again - hard data? It makes sense as I know from experience that just opening my window allows the the hot air to be sucked in but surely feeding cool air into the front of that can't be any worse?

A study in a South African university was made years ago about the effect of rood racks on the fuel economy of LR, it also showed that placing the spare wheel on the bonnet will get less fuel consumption because of an decreased aerodynamics drag.

It has been shared in this thread Wheel on Bonnet = Aerodynamic improvement

Figure 39 on page 50 and 59 on page 72 of the attached study, you will notice that the wing tops show a light blue that represents a low pressure area.

I've yet to grab the TIC as I have a few approaching deadlines that I need to take care of for other projects so I've pushed things back a bit. I did take the defender for a spin though and anecdotally - there is a difference in the felt footwell temp when compared to passengers side. I wouldnt say ground breaking though. Definitely needs tweaking.

EDIT - I'm looking to avoid the soggy floor scenario for mold/corrosion reasons.

I was thinking of using Raptor Coating for that, it adds a new layer of material to insulate the cab both from noise and heat.


Cheers,
Matt

Cheers,
Patrick

Thanks for that info, all I can say is that those pressure zones are relative and that there is definitely a noticeable increase in the airflow through the vent with the snorkel on as compared to the standard flat grille. The diference in cool air from the AC is probably a much more subjective measure though

Regards,
tote

Originally Posted by lebanon

Hi Tote,

Cheers,
Patrick

Leb - quoted you so you'd get the notification! I remember this study as my old TD5 had the wheel on the bonnet. Never actually saw the full thing though. This is just a level of detail that gets me going, completely over the top hahaa. Thanks so much for posting it.

However low pressure it might be though - there is ALOT more air getting hooked into the scoops than there is in the flat mesh as per Tote.

I've been driving the defender lately and whilst I still haven't got the TIC for any data there is a NOTICEABLE difference in engine bay smell in the car from the aircon scoop and a monumental difference in footwell temperature from air getting channeled in from my RHS scoop. The issue is the transmission tunnel for sure and I'm working on a few things for that as time allows.

Will get some more photos etc this afternoon.