ok... How hot are these cars inside?

[Jim]

I have been pouring through the youtube videos on the GT40 mk1's and noticed that everybody driving the car in a car show or in the pits, etc. is doing so with the doors open. I assume they must be roasting in there! I know the RCR's car comes with AC (full kit) so I wonder if that will be on every time I'm in the car? I don't care, they are still the "coolest" car out there!

Do you guys do any subtle ventilation improvements that don't alter the car's aesthetics?

 

[Jim Craik]

Jim,

I can attest that they can be very hot and usually are very hot, but by no means are the always hot.

In the winter I have often used the heater and often use the defrost. That said, "as built" most of these cars have little in the way of insulation or sound proofing.

Add to that, the radiator is at your feet, the motor is at your back, the water pipes run between the seats and the windows do not open.

Now the good news, although almost all the original cars did not have AC, that's why you will see them with the doors open. Now almost all the "newer" GT-40s do have insulation, sound proofing and AC.

There are lots of "improvements" available, and done correctly the heat and noise are manageable.

Do some searching among the threads, you will fine the answers.

Good luck!

 

[Mike Pass]

Yes - they can get very very very hot. At the Le Mans Classic last year it was 40deg and very sunny. The cars are very small inside and with a big shallow screen they are like a solar cooker. I have a helicopter vent in the window which is good when you are moving along but useless when stationary. I have air con but it was still very hot inside. It also got too hot to keep the air con on in towns as it caused the engine to start overheating as the air con rad is in front of the main rad. Good insulation of the water pipes where they pass through the cabin is important as is a good seal at the front to stop hot air from the rad getting into the front bulkhead area. A deep nostril helps here. The ones which only come halfway down the rad will let a lot of hot air through. Maybe a a fan to blow cold air into the cabin when stationary would be a good idea. A lot of heat comes through the bulkhead behind the seats so insulation here is a good idea but there is no room for a thick layer so very high value insulation is the thing but quite expensive.
Cheers
Mike

 

[EGLITOM]

Run my RCR last year without AC. it was only one drive where it was quite hot inside. On all the other occassions, the good insulation of my rear Firewall and also of the heaterpipes helped to keep the temparatur acceptable. It also helped to have the front NACA ducts feeding fresh air into the cockpit ( as on original cars)

TOM

 

[Ian Anderson]

I Agree with Mike

But Air con is for wimps! None of the original cars had aircon - they were a race car that could be used on the road.

My car does not have aircon and at Le Mans 2 years back (2010 Classic) in the 40 degrees outside temperatuer it was damn hot in the car. For the event I removed my side windows (20 screws in each) and probably had the coolest cabin out of everyone!

At anything above 20 mph I have no problem with heat build up in the car (with windows in) as I have ducted air from where the brake cooling air is normally ducted and feed it into the cabin. I also have 2 fans in this ducting which can be individually swithced to keep the cabin air moving when stationary. Probably a bit overkill but at 250 cfm each a lot of hot air gets moved!

Ducts shown on my build post 132

Ian

 

[Jim]

Thanks for everyone's response and opinion. I'm pretty new to the GT40 scene. I'm embarking on a build sometime this year so right now, knowledge will help me plan!

Insulation - Check!

 

[Jimmy P]

One of the best things I've done was to install the helicopter vents in the side windows like Mike and I'm sure others have done. This really helped to route air onto me while the car is moving but does nothing while the car is stopped. I live in Florida and frankly drive the car sparringly in the summer as its just oppressive and I even have AC. Removing the windows is a very good option but if you're going to do this often I would check out installing inserts where the screws go as after a while the screw holes will enlarge.

 

[Jim Rosenthal]

Insulating the passenger compartment from the engine room is good, too. I just got Teknofibra delivered and we are going to use it for that bulkhead.

I agree with all above: I don't know that the radiator is a problem, but the proximity of the engine and the water pipes in the tunnel are both brisk sources of cockpit heat. My water pipes are insulated and the tunnel still gets hot. What would help is air ducted through there to carry the heat from the pipes away.

The greenhouse effect you can't do anything about, except to keep the car moving, use the helo vents, and drive the car naked. Well, maybe not that.

 

[Jim]

Jim, way too many jokes about the naked think so I'll kill it now ... I like the idea of removable "quick release" windows for when you are driving. I have put dynomatt and just used lizard skin in my 67 shelby clone that I'm building. I have heard that product works well. I just don't know yet. Sounds like insulating the tunnel is a good idea. Keep the heat from coming in rather than getting the heat out.

 

[Dave Hood]

I've got a Superformance Mk1 and I live in the Charlotte area. The AC keeps up to the point where I'm not sweating in the summer months. If you leave a GT40 sitting in the afternoon sun, they warm up pretty quickly, however. Dennis Olthoff also made a few changes to my car which help keep hot air off the radiator away from the firewall.

 

[David]

While I haven't got enough of a car built yet to suffer/experience how hot it gets (but I'm used to riding a V4 in full leathers in summer so it can't be *that* bad! ) I have picked up a few things wrt heat.

1) Seal the rear bulkhead. Really really seal it. I plan on using aluminium duct tape over all the seams and a foam seal round the access hatch. Insulation also a good idea. Some people double skin the bulkhead and fill the inside with rockwool. Also consider double glazing the window.
2) Duct *all* the radiator air out through the nostril. Any that escapes will heat up the front of the cockpit. Even then it'll still heat up the windscreen but that won't transfer heat as easily.
3) Seriously lag the coolant pipes and seal the centre tunnel (again duct tape for me). Some have proposed venting the tunnel, I'm not sure how practical this is but should cut down on heat transfer. I'm going to look into running a fan to blow air front to back through it.
4) Seal the front bulkhead - not half as important as the rear but any hot air 'leakage' from the rad or will find its way in as well as cold and even water. Don't forget that even with the radiator venting through the nostril the pipes to/from it still run in an enclosed space just in front of the cockpit, in slow traffic/hot weather that section will heat up significantly. Again some double skin it but obviously as with the rear bulkhead that adds weight.

Those 4 things should seriously cut down on the heat getting into the cabin, then you can use the brake ducts for 'fresh' air (taking into consideration these are at exhaust height ) or use the 'proper' ducts but then its worth putting some fins beside them to prevent the hot air from the radiator 'spilling' into the ducts (as per the Pathfinder GT40R)

Then an exhaust vent top rear of the cabin (which should help exhaust hot air).

Cutting down on the hot air getting in should reduce the requirement for air-con and if you have it make it much more effective.

 

[Jim Craik]

Before I sealed the firewall and center tunnel area, I found that if I opened the stock window vents, when underway, it created a low pressure area inside the car, I could literally feel the heat entering around my feet and comming out of the hand brake area. With the side windows closed, the heat entry was greatly reduced.

 

[Jim Rosenthal]

Good points. Does anyone have a suggestion on where to get the helicopter vents? I was planning on getting them from Aircraft Spruce unless someone has a better idea. Also, is there a particular model of helo vent that is best for this? I don't want to end up buying a second set of plexi side windows......

 

[Jim Rosenthal]

I think venting the tunnel is a good idea, too; the problem in my car is that there isn't a lot of room for air to get out at the back of the tunnel. Right now we have a heavy rubber block in the front which is holding the water pipes so they don't move around. If the cockpit heat in my car is controlled by insulating the back bulkhead, I may not need to vent heat out of the tunnel. The Teknofibra won't work on the tunnel because it is backwards, with the adhesive on the black side, and the metal foil outwards; I don't think sticking it to the tunnel will help much. We'll use it up on the bulkhead and see where we are.

Note that my engine, which "only" had about 360 hp, probably makes less waste heat than a lot of the engine in other forum members' cars...that's not to say that I might not upsize at some point....

 

[Bill Musarra]

You might consider adding a set of fans to the engine bay at the firewall. I have two 5" fans at the corners. They are controlled by a run on relay that keeps going for 3 minutes after shutdown. Makes a big difference in the engine bay area and helps eliminate the heat soak problem. Will be adding the water pump to that circuit later on.

Bill

 

[Ian Anderson]

Good points. Does anyone have a suggestion on where to get the helicopter vents? I was planning on getting them from Aircraft Spruce unless someone has a better idea. Also, is there a particular model of helo vent that is best for this? I don't want to end up buying a second set of plexi side windows......

Jim
As you have an original style chassis you should be able to utilise the Naca ducts - these should move sufficient air to keep the cockpit air "fresh"

Ian

 

[J. Salmon]

It has been suggested to me to use fans in the engine bay. Mine will pull heat off the headers and out of the engine bay. It is said to really help, especially at slow to no speed.

 

[Steve C]

Once I tweaked the AC system, added insulation to the rear bulkhead, insulated the tunnell, added shroulding around fans, vented the engine cover, opened a few holes in rear brake duct pipes over the headers (even though I have brake ducting this helped) and helo vents have had no complaints even in 90F summer drives.

Look at pics in SPF forum under "mods/options ect to P2125

Steve P2125 that is cool in the summer

PS: AS I think Jim C said above when running the AC I find better to close the toll windows but, open helo vents at speed OK

 

[Seymour Snerd]

Does anyone have a suggestion on where to get the helicopter vents?

Alan Peterson / Pathfinder sells them. FWIW he also sells a nifty sliding window a la Mk IV (replacement for typical toll window)

And while we're at it this is a plug for Rick Muck's chassis sealing kits.

 

[Rick Muck- Mark IV]

"Heli" vents here: SNAPVENT® - MODEL F318 from Aircraft Spruce