GT6 Cabin Cooling

[AidanT]

As we all know you can tell the GT6 driver because he is the one in the shorts and T shirt! 

 

Has anyone considered making small detachable air scoops to sit on top of the front deck grills to force more air in when its a warm day?

 

I know its a bit of an odd one, but I was driving the car a few days ago, the wind must have been blowing in an odd direction, and my cabin cooled off, in fact so much so I actually had to open the heating up to warm up a bit! (No i wasn't ill and had a temperature!

 

Aidan

[Dave C]

My friend has a Jaguar XK120 that has air scoops in the lower wings. You open them manually and they allow air into the footwells.

 

Very effective.

 

The bonnet design would not allow them on our cars sadly.....

[Pete Lewis]

you could  add a cowl to the air intake , seal the air intake to the bonnet grill , and get some ram air in the cabin  

and later GT6 had the eyeball vents in the dash .

 

in the past cars like 47 Hillman minx had footwell vents that cranked out of the side  wing  and my first 53 minx had a giant scoop in

front of the screen that  poped up from a lever under the dash it gave a good   blast   and many cars didnt have a heater  Mine did.   progress and costs got rid of sensible ideas

[dougbgt6]

I have some small 12v computer fans which I've been thinking about attaching to the foot well air vents to try and pull some more air through the pathetic cooling system.

 

However there are some other things that can be done to alleviate the overpowering heat.

 

Block all unused bulkhead holes.

Attach the clutch and brake rubber boots, properly, to the bulkhead. 

Heat shield the gearbox cowling and re-seal it to the floor.

Replace (re-attach!) the steering column to bulkhead washer.

 

I also recently replaced my ammeter with a voltmeter as I realized the ammeter wires were running rather hot.

[Clive]

Ahyes, ammeters are a bit scary when you think about how they work!

But spot on about sealing everything up. I have spent time with a sheet of 1mm rigid plastic and a tube of sealant sorting the numerous holes on my Toledo. Still managed to miss a couple, and on teh RBRR ended up stuffing screwed up bits of paper in the holes, they were that draughty. These were cold (worst one right on passengers knee) but on other cars you do get hot air. Likewise the GT6 tunnel is notorious. I used silicone sealant and once dry, gaffa tape right round the joint. That helps a lot.

 

Not sure computer fans will be big enough?  although I gather some are pretty powerful. I have heard of boat bilge fans being used, think 4" bathroom extractor fans at home, same sort of thing but a bit more robust. However, rear window open and 1/4 vents open helped mine....still hot IIRC.

[AidanT]

Thanks guys

 

I have gone round everywhere to seal up the bulkhead and there is a distinct improvement Pete pointed out the hole for the wiper cables and that started me going!

 

Pete in principle then a small scoop on the intake vents would work?

 

If so I'm thinking of making something that could be removeable and only used in the summer. Not sure of what material yet

 

Aidan

[Pete Lewis]

You need to make a deep sponge sealing ring to connect the plenum air intake with the mesh on the bonnet

 

you could knock up a card scoop to see if the idea works, then develop it later

 

it doesnt need to be very high to collect air from the pressure wave infront of the screen

 

Just an idea

 

pete

[Colin Lindsay]

Opening the window works, especially with the rear quarter lights open too.... although I have had the cabin fill with snow on one memorable occasion....

[dougbgt6]

Clive,

 

I must come clean, my ammeter is/was a shunt ammeter. A small resistance sits in the battery wire, a volt meter attached across the resistance  shows amps, proportionally. They don't seem popular anymore but I think they show you more than a battery condition meter. The battery condition meter shows you battery condition (oh really!) and an ammeter shows you charging system condition. Unfortunately, the meter was not working too well and the giant resistor installation a bit messy, so it had to come out.  But I thought it worth a joke.

 

The fans are 3" dia, quite powerful and I think quite easy to attach. The project is number 27 on my list of things to do to the car!

[AidanT]

All

 

Well I am going to see if I can fabricate something.

 

My thoughts are that this if it works will be a really simple solution to increase the cabin Aiirflow thereby maling it cooler - Probably will need the quarter light windows combined will make a massive difference, hopefully easy to fit and remove and made from a plastic, as most scoops are.

 

I will let you know if successful

 

Aidan

[Pete Lewis]

probably only needs a raised lip along the back edge doesnt need a full scoop ,

 

play around with some card then you can trim to see how  small  you can get it without loss of effect

 

sounds an interesting idea , you could start to market it if it works. or sell the plans     Ha !

 

Pete

[Dave C]

From time to time I've thought about fitting one or two of these. Not cheap though......

 

http://www.carbuildersolutions.com/uk/axial-fan

[dougbgt6]

This is similar to what I've got. About 2" square, I'm gonna mount them in boxes and attach to the end of the foot well air vents. Worth a try for just a few quid?

 

http://www.ebay.co.uk/itm/12V-Mini-Cooling-Computer-Fan-Small-40mm-x-10mm-DC-Brushless-2-pin-UK-/282113590004?hash=item41af47c2f4:g:E8YAAOSwtnpXl1T0

[Alan C]

Adan

 

I have a Mk3 and I remember one memorable Summer journey when it got so hot that the alarm remote on the ignition keyring stopped working and I ended up driving in my bare feet.

I've found that the two most effective measures to stop heat from the engine bay was to wrap the exhaust in hessian heat wrap and line the gearbox tunnel with kitchen foil.

A common cause of gearbox heat intrusion is that either the sound deadening is missing or it's lying on the gearbox itself, blocking the air flow.

I strapped the insulation to the cover using the wire from two coat hangers hooked around four short bolts. The kitchen foil was attached to the underside of the insulation. Result, no more heat from the gearbox and it's worked faultlessly ever since.

The biggest aid however is the heat wrap. The reduction in underbonnet heat is tremendous.

The cabin never gets hot because I always drive with the driver's window open unless it's a monsoon outside. Not enough elbow room otherwise and this keeps you cool even on the hottest days.

 

Cheers

 

Alan

[Dave C]

I agree that gearbox tunnel insulation and careful fitting of the tunnel make a big difference, as does sealing all holes in the bulkhead.

 

I've been tempted by exhaust wrapping but haven't succumbed yet. I'm interested to hear that it has been so effective for you Alan.......

[JohnD]

I've repeated this so many times - ALL the heat that gets into the driving area comes from the radiator as hot air, and gets in there via poorly sealed holes and slits in the bulkhead and gearbox cover.

NONE comes from the exhaust pipe, or the gear box.

 

Why can I say this with such authority?  Because I built Silverback, an estate 'Vitesse' with the radiator in the back.

That car was cold to drive, because all the hot air went straight out through the tail gate.

Even under racing conditions, the gearbox and exhaust, let alone the heat radiated by the block, were a trivial contributor to cabin heat.

 

You say, doug, that you have sealed all the bulkhead holes and where the gearbox cover meets the floor pan, and it's still hot in there.

I suggest you need to look for leaks harder!

 

In hot weather, a different kettle of thermals, it gets hot in there.

My solution is holes in the windows, that carry right angled tubes.  These may be rotated to capture air into the cabin, or suck it out.

See below,  in capture mode.

 

JOhn

[AidanT]

Hi John

 

Thanks for your input. Is there any reason why a redesign of your "tubes" that would sit on the air intakes before the windscreen would not also work?

 

I have also gone over everything to try and seal up the bulkhead. Any thoughts out there on methods to find leaks?

 

Aidan

[dougbgt6]

"You say, doug, that you have sealed all the bulkhead holes and where the gearbox cover meets the floor pan, and it's still hot in there. I suggest you need to look for leaks harder!"

 

John, did I say that? I think not!   

 

But YOU said "In hot weather, a different kettle of thermals, it gets hot in there."  So who is it needs to look harder? Touché,  I think   

 

But seriously I would be very interested to know how you set up the rear radiator car. You've got to get the water from front to rear and back to the engine. Then there's the fan to think about and was there an air vent to get rid of the hot air?

[Alan C]

Sorry John I have to disagree. You could easily have had a barbeque on the uninsulated exhaust manifold before I applied the wrap as a result the heat resistant paint peeled off in short order. Admittedly it is a stainless steel tubular exhaust which runs hotter than the standard cast iron version due to it's greater surface area and inferior heat soaking capabilities.

I also made heat shields for the HS6 SU's which were also getting decidedly hot. Having the fuel system on top of the exhaust was not one of Triumph's greatest ideas, much better to have them on opposite sides as in the XK engine.

I have never had the engine valances or radiator ducting fitted so any heat from the radiator has plenty space in which to dissipate before it reaches the cabin.

I also run a thermostatically controlled electric water pump coupled with a two speed electric pusher fan which is far more efficient than the standard set-up. This means that the engine heats up quickly and the temperature gauge rarely moves past the halfway mark.

The gearbox was also a lesser source of heat made worse by the heat from the exhaust pipe underneath. Air flow over the gearbox is crucial to it's longevity and reliable operation.

 

Alan

[Paul H]

Hi you could use sound deadening pads to insulate the inside of gearbox cover - http://www.ebay.co.uk/itm/151155678947  They are available in smaller quantities . Currently im using them for the boot area and then working forward to the cabin area. The panels are pliable with heat , easily cut with an outer layer of aluminium which would act as a heat shield . Much cheaper than Dynamat - 

 

Paul 

[Pete Lewis]

The sealing of the bonnet to the bulkhead is pretty awful at its best

to stop hot underbonnet air and fumes downing the heater fresh air intake you do need to move the sealing up the heap its easy to make a foam ring doughnut to close the bonnet grill with the heater plenum so its outside air coming through the heater and not hot air from undr bonnet

 

gear box and diff generate a lot of heat due to efficiency losses , frying eggs on them is pretty normal

 

my vit 6 gear stick could be really to hot to handle but decent foil covered thick felt worked on tunnel temperates .

[Paul H]

The sealing of the bonnet to the bulkhead is pretty awful at its best

to stop hot underbonnet air and fumes downing the heater fresh air intake you do need to move the sealing up the heap its easy to make a foam ring doughnut to close the bonnet grill with the heater plenum so its outside air coming through the heater and not hot air from undr bonnet

 

gear box and diff generate a lot of heat due to efficiency losses , frying eggs on them is pretty normal

 

my vit 6 gear stick could be really to hot to handle but decent foil covered thick felt worked on tunnel temperates .

Hi Pete re "decent foil covered thick felt worked on tunnel temperatures "  the foil covered felt - was this under the gearbox cover or over ?

 

Regards

Paul 

[Pete Lewis]

Under 20mm thick sealed felt and covered some cheap ally roasting trays as they are cheap and tough enough or get some proprietry foil attached with glue and short big headed tap screws into the cover a few mm.

And tomseal tomthe wonky floor 1"square foam , fills all the gaps the original cant

but a long time ago

[JohnD]

Aidan,

In front of the windscreen is a pocket (vortex) of higher pressure air.    This is tapped by the standard air intake for the heater/cabin ventilation.

My 'tubes'   (if you can't see what they are, may I direct you to the rain water collection department of your local DiY store?) are there because the air shoots sideways off the windscreen, away from the A-post.  They are just long enough to tap that flow and draw air in, and the velocity will draw air out if they are reversed.

The air in the vortex below the windscreen is relatively slow moving, so no collection device is necessary, the pressure will drive the air flow, whereas my tubes depend on velocity.

 

Doug,

My apologies! I read your Post 4 to mean that you had done all those things!   Very much worthwhile, before you try more technical solutions.

The different thermals were infrared rays from the sun, just like a greenhouse.    Can't keep those out!

Plus, I've removed the heater, so no means of demisting, and my tubes are great at that!

 

Silverback's radiator vented out of the rear hatchback:

 

 

 

Assisted by two small-lorry fans:

 

 

and the water was pumped to the back via an oil/water cooler by a Davis-Craig water pump

 

 

The point was to reduce the airflow under the car, reducing lift.

 

 

Alan,

You misunderstand me.    I wouldn't handle the hot manifold, down pipes or the tail pipe without asbestos gloves.  Heat shields for the carburettors are definitely a good idea, or move to Pi.     What I do say is that the radiation of heat from that hot tail pipe, or the gearbox between it and the cover,  is trivial, and cannot account for the need for shorts in a GT6!  Radiation depends on both temperature difference and area, and a circular section pipe has a relatively small area for its volume.    Radiators flatten, multiply and add fins to the pipes in them, to increase that area, to get heat out, and would not be effective without that.  A simple pipe is a poor radiator - small bore central heating pipes  are uninsulated, because the increase in surface aea from the insultation would lose more heat than leaving them naked!

    My Silverback experiment proved this about the exhaust pipe, although that wasn't why I did it!

 

Pete,

Egg frying on the gearbox?    My dear old thing!   Your taste buds have been corrupted by the 20/50 you use for Brylcreem!

Seriously, egg frying requires at least 130C, which is hotter than the engine gets.    80C for a gearbox would be more usual.  Still too hot  to handle, but not scalding.   100C would be scalding - boiling water.

 

Please note, what I say is backed up by actual experience of a rear-radiatored car, not by supposition and assumption.

John

[Dave C]

So.....

 

accepting JohnD's evidence, is it likely that those people who have installed a larger radiator (eg the VW Golf conversion) will experience a cooler cabin owing to more efficient cooling?

 

Or am I going off down an irrelevant/unrelated tangent?