Engine Heat CF64

[Englishman]

Gents,
   I had thought of making a second Bonnet(hood) with louvres to get the hot air out of the engine bay, I have to replace the existing bonnet(hood) in any event. Now the coach builder, also an avid reader of this forum, recalls Andy Shepherd's story of the dog bowl on top of the air filter and has come up with the following suggestion.
   
   When he makes the new skin he can increase the hieght of the hump such that by the time it get to the windshield it will be half an inch higher than the original and he can cut the existing four apertures into a single opening to allow even more air out.
   
   At the same time he can fabricate a couple of air scoops behind the radiator ( between the rad and engine ) to force more air into the engine compartment. In theory this sounds very plausible to me, any input on this would be welcomed.
   
   Peter

[jbottini]

actually

[jbottini]

Actually sounds well thought out ala Jaguar E types and Aston. You'll have low pressure at windshield base.

[Englishman]

I Just looked at a couple of photos of the subframe that the bonnet skin will sit on and note that there are five holes in the hump in front of the windscreen at the rear edge, none the less these will be made into a single aperture and will be half an inch higher.
   
   The scoops I refered to will be at chassis level way down low and will not be visible as a protrusion under the car, well maybe just a little bit.
   
   Again any input is welcomed.
   
   Peter

[Classicus]

Though most definitely not technically minded I've followed this interesting topic elsewhere, especially the details posted by Andy plus Emmanuel's pics of their metal spoiler idea which fitted across the bottom of the front apron and apparently cured the heat problem instantly. Something about equalising air pressures above and below the engine I think ?
   
   However small as it was I always felt it might have been slightly visible so tending to detract from the car's great looks, so just a thought but how about doing things one at a time starting with the interesting hidden scoops idea first and see what happens ? Keeping the more visible bonnet option in reserve ?
   
   Just my ha'porth [:)]
   
   Edit: See "AC Front Spoiler" thread by Emmanuel for his pics. I think the details of Andy's spoiler idea, which he tested satisfactorily at some English or German race track, was in the same thread as the dog bowl one. Unfortunately I still can't remember where I read the equalisation of air pressures solution....

[Englishman]

Classicus,
   
   Thank you for your thoughts, all input welcome, I am not sure that a half inch rise in the profile of the bonnet would be as noticeable as the louvered solution I was considering.
   
   Unfortunately I do not have the luxury of trial and error as the original bonnet is buggered, we believe the car may have encountered a moose or something similar and done it some severe damage, whilst in Canada ( the Moose that is not the car ). The lower front valance has been totally replaced and some damage , now fixed was evident on the underside of the car.
   
   Peter

[Classicus]

Just found the thread which has a lot of info on this in "AC 428 owners experience?"
   
   Andy's 2 posts are about halfway down dated 28th and 30th January including -
   "I did once prop the bonnet open with a stainless dog bowl on top of the air filter."
   
   Hope this helps [:)]
   
   Cass (or Paul however there's another Paul already)

[runt]

I was surprised also to find that the cars had no oil cooler; only an oil temp guage to display the bad news..[:0]
   
   Paul.[:)]

[Classicus]

Hi Peter [:)]
   
   Just a thought, but before finally committing to the expense of making the final bonnet how about knocking up and experimenting with a dummy bonnet(s) first ? Made out of something cheap and malleable to discover the best air pressure and engine temperatures during actual road tests ? Fix some sensors under, around and in the engine bay etc. with the dials and readouts etc. in front of the driver and passenger to check whilst driving; i.e. whilst you're in such a useful testing position anyway to hopefully solve the annoying problem once and for all. Also everyone else could then share whatever results you get too ?
   
   Bit cheaper perhaps than getting the real bonnet wrong I reckon !
   
   Hope this might be of some help ? [:)]
   
   Cass

[david langford]

Hi All,
   Most of my overheating problems stem from sitting in traffic and lots of the solutions that have been mentioned seem to be great when you're moving but not so good when you're stationary (this happens quite a lot in the UK).  Like Cass I would hate to mess with the shape, so have been toying with the idea of fitting electric fans to draw the heat out of the engine bay through the wheel arch louvres.
   Does anyone think this would work?  Is anyone aware if this has been tried before?  Any thoughts would be most welcome.
   As regards to the oil cooler, mine has one and I thought they all did.
   Dave.

[Englishman]

Gents,
   
   Thank you for the input so far, please keep it coming.
   
   Classicus I appreciate your thoughts, I do noy believe that anyone would notice a half inch rise along the whole profile of the bonnet unless you were looking for it, any way for now the jury is still out.
   
   As regards sitting in traffic and overheating, I had a TVR Chimaera in the UK and used to pull over lift the bonnet and wait, it helped if you were in the car park of the pub.
   
   Cheers
   
   Peter

[Classicus]

I guess the suggestions I've made are what I'd personally go for, partly out of a secret life long hatred to always defeat all bloody minded, self-centred mechanical things in general, and partly out of curiosity to solve the heat problem once and for all [;)] Anyway final thought on the matter which I'd also go for on top as a final back-up....
   
   Instead of the existing double action (?) bonnet lock fit a new interior lever operated mechanical spring loaded one instead, that however will also permit several different lockable bonnet opening heights as well depending on how urgent the need is to remove excess heat build up. Then when all the temperatures are back to normal whether stationary or driving close the interior bonnet lever.
   
   Possibly avoiding the odd penalty point into the bargain too ! [:D]
   
   Good luck whatever you decide
   
   Cass

[runt]

quote:Originally posted by Englishman
   I had a TVR Chimaera in the UK and used to pull over lift the bonnet and wait, it helped if you were in the car park of the pub.
   
   Cheers
   
   Peter
   

   
   All part of the fun for a TVR man..! I also had a Chimaera, improved fans and a 'stat that actually worked (!) helped more than a dealer technician who advised that "a 4.6 litre motor in a fi-glass body holds its heat too much..!". Also of course bleeding the cooling system is essential; another thing not every owner bothers with when topping up.
   Some kit Cobra owners have apparently suffered high underbonnet temp when using a mesh grille in the large nose section, I have open front and splitter, never experienced any sign of high temps.
   When one notices the apparent amount of room in front of the FE in a Frua, as shown in the overhead shot from Car magazine, posted by Chuck, problem is clearly that heat rising from the mill has nowhere to go, but some have improved matters with alluminum rad, so..?
   
   Paul.

[Emmanueld]

quote:Originally posted by Englishman
   
Gents,
   I had thought of making a second Bonnet(hood) with louvres to get the hot air out of the engine bay, I have to replace the existing bonnet(hood) in any event. Now the coach builder, also an avid reader of this forum, recalls Andy Shepherd's story of the dog bowl on top of the air filter and has come up with the following suggestion.
   
   When he makes the new skin he can increase the hieght of the hump such that by the time it get to the windshield it will be half an inch higher than the original and he can cut the existing four apertures into a single opening to allow even more air out.
   
   At the same time he can fabricate a couple of air scoops behind the radiator ( between the rad and engine ) to force more air into the engine compartment. In theory this sounds very plausible to me, any input on this would be welcomed.
   
   Peter
   

   
   Hi Peter,
   
   Just came back from Europe!
   
   I was thinking of modifying my car's hood as well, but I was able to reduce engine heat so much that it is no longer needed. The engine now runs steady at 80c all day long and the temperature goes down to 70c on the highway likely because of the little spoiler I added at the front. Here in southern cal., outside temperatures can easily exceed 120F on a hot day. As far as inside the cabin, the heat which was unbearable before has now become insignificant with the use of Dynomat insulation  and the conversion to a manual 4 speed box. A lot of the heat that entered the cabin was from the huge C6 box through the shifter hole and the sides of the transmission tunnel.
   
   Emmanuel [:D]

[Englishman]

Welcome back Emmanual,
   
   The Dynamat option looks good, did you use the "Extreme" product and/or the spray on solution and how much of it does one have to order.
   
   Merci
   
   Pierre