Rear bulkhead air vents

[David Goodwin]

Another beginners question.

Reading the Chimaera Bible tells me that if you use the rear bulkhead vents for speakers, you need to add extra vents to assist with de-misting. That makes sense.

What he doesn’t say is if there has to be a vent in the boot panel/carpeting as well or if you just have to let the air into the gap between the two. I have seen a few cars with air vents but do people have vents in their boot above the tank?

[PabloGee]

I have rear speakers and no vents in my car, yes it will mist up in cold/rainy weather much like any other car, and yes it's bad at clearing that mist because it's not a very well sealed 1990s hand built TVR.
I wouldn't worry about vents.

[taylormj4]

Mine has no vents and no problems. Shouldn't mist up unless you have moisture in the car, e.g. damp carpets.

Just be careful not to shut the boot lid too fast as it will force air through your speakers into the cab, which I would think could damage them eventually.

[citizen smith]

With the Ventilation Controls set to the Upper Vents of the car and the Central tunnel vent turned off, not forgetting to turn Heater control Control set to Max.Temperature - Turn the Fan Speed Control Max, then Press Fan Speed Control button to the Second Speed for Max. power.

The screen would hopefully demist quite quickly.

[David Goodwin]

So the general view is:
1) No one has vents inside their boot above the tank.
2) I don't need to worry about venting the cabin anyway.

[PabloGee]

1. Some do
2. Correct

[RobXjcoupe]

I’m going with what I found in my Griffith boot. The rear air vents in the boot are covered/hidden behind a piece of carpet covered fibreglass trim
If you look at the picture to the right first then below the circular vent hole, you see a rectangular shape away from the bulkhead with a rectangular hole that goes down and exits the boot to create a vent I suppose. One on the other side as well.
I think in a steel bodied car with properly sealed rear and side windows you need these vents to allow the ventilation system to work properly. In a griff or chim I’m sure there are plenty of air leaks elsewhere to not worry if you seal the rear bulkhead vent with a speaker

[citizen smith]

David Goodwin said:

So the general view is:
1) No one has vents inside their boot above the tank.
2) I don't need to worry about venting the cabin anyway.

1) A lot of people use the rear vent locations their rear speaker location.
2) There is generally a fair amount of draft in the cabin anyway due to the door/window seals etc., etc.

[miniman]

citizen smith said:

With the Ventilation Controls set to the Upper Vents of the car and the Central tunnel vent turned off, not forgetting to turn Heater control Control set to Max.Temperature - Turn the Fan Speed Control Max, then Press Fan Speed Control button to the Second Speed for Max. power.

The screen would hopefully demist quite quickly.

I’m intrigued by the part “press fan speed control button to second speed” - I thought the switch (on the later dash) was just on / off?

[indigochim]

miniman said:

I m intrigued by the part press fan speed control button to second speed - I thought the switch (on the later dash) was just on / off?

On mine You press the switch to turn on the fan and then rotate it to increase the fan speed. I don't think there is a 1,2,3 setting as such more of a linear increases.

[David Goodwin]

RobXjcoupe said:

I m going with what I found in my Griffith boot. The rear air vents in the boot are covered/hidden behind a piece of carpet covered fibreglass trim
If you look at the picture to the right first then below the circular vent hole, you see a rectangular shape away from the bulkhead with a rectangular hole that goes down and exits the boot to create a vent I suppose. One on the other side as well.
I think in a steel bodied car with properly sealed rear and side windows you need these vents to allow the ventilation system to work properly. In a griff or chim I m sure there are plenty of air leaks elsewhere to not worry if you seal the rear bulkhead vent with a speaker

I will look under the carpet for those downward ducts which would make sense of it. It does seem that even people who have vents behind the seats probably haven't finished the routing to the outside world. I wouldn't have even thought of it but it is discussed in the TVR bible, hence my post.

[citizen smith]

Perhaps the 3 holes ringed are the down-air duct exit locations.

[PabloGee]

I believe those holes are there to make shutting the boot easier - air displacement, though air would push over the wheel arches into the cabin at a push.
It might be just to help routing the petrol away from the hot exhaust pipes as it pours out of a leaky tank..