Heat management in engine bay

[will_968]

I have a Lotus Motorsport Elise race car and am looking to improve the heat management in the engine bay. Due to the car's transverse engine layout, the exhaust exits the engine directly next to the firewall, which I'm sat in front of. Also, the radiator pipes run down the sill right next to me to the radiator in the nose. The cabin gets to about 55-60 degrees during a race (32 degree ambient air temp yesterday - I live/race in China).

I need to cool the cabin down and get the heat out of the car more efficiently. I have bought fibreglass exhaust insulation wrap to wrap the manifold, but want to add some heat insulation mapping against the firewall and also inside the sill before next season. I have seen the gold foil people fit, but am wondering what real word experiences you guys may have with different products? I have about 2-3 m2 of firewall I would need to cover. I am wondering if there are better industrial products I should consider rather than just the options demon tweeks sell. Any info on engineering specs of thermal efficiency vs. weight (and price) would be appreciated.

Separately to insulation in the engine bay, I will also be fitting some more cooling to get more fresh air into the cabin. None of this is about comfort; but instead it's about avoiding heat exhaustion and keeping cool enough to perform optimally during a race. I've considered a cool box, but would prefer to address the problem rather than symptom.

Edited to change longitudinal to transverse.

Edited by will_968 on Monday 16th September 09:18

[Steve_D]

The exhaust and the coolant pipes are doing just what you want....removing heat from the system.

You could wrap the exhaust but better still would be ceramic coating inside and out.

The gold foil reflects heat so is normally used to stop the heat getting at something so would go on the hot side of the bulkhead. Real gold may work but i'm not convinced gold coloured foil does anything bar looks. Ali. foil covered GF cloth works well and is easy to use.

I would do nothing with the coolant pipes as they are working. Better still to work on removing the heat from the cockpit.

Steve

[will_968]

Steve_D said:

You could wrap the exhaust but better still would be ceramic coating inside and out.

Understood and agreed, but getting it done in China of HK is difficult. I will investigate further.

Steve_D said:

gold foil reflects heat so is normally used to stop the heat getting at something so would go on the hot side of the bulkhead. Real gold may work but i'm not convinced gold coloured foil does anything bar looks. Ali. foil covered GF cloth works well and is easy to use.

From my recollection of A-level physics, I think "gold" is the best reflector of heat. I don't think it's the material that matters, but instead the colour (as it is literally reflected off the surface, so don't think the matter is relevant). But this is the crux of the questions really; what's best. I think the silver coloured matting is likely 99% as good as the gold stuff for 1/2 the price. Agreed, it would go inside the engine bay, against the firewall.

Also, my fuel tank sits in the lower portion of the firewall too, between the cabin and engine bay. It is getting very hot at present, which is unlikely to be the best idea from a safety perspective (high concentration of hot vapour build up within the tank) and also hot fuel makes less power than cold.

I'm curious as to the exact specs of different options of the materials though if anyone knows? Demon Tweaks doesn't list proper thermal properties, just terms I see as being marketing such as "reflects 90% of radiated heat".

[PaulKemp]

I have addressed heat issues in a 7 and witnessed solutions for a Fury
We wrap exhausts, then construct heat shields and insulate bulkheads inside and out
You can use silvered heat mat and simple insulating bubble wrap or domestic radiator reflector sheet for outside of the bay, the radiator pipes need reflective material on the surface of the containing sill and vents on the external surface to take the hot air away from you.
You are dealing with thermal conduction, thermal convection, thermal radiation so your solution should deal with all these points.

[Evoluzione]

Steve_D said:

The exhaust and the coolant pipes are doing just what you want....removing heat from the system.

You could wrap the exhaust but better still would be ceramic coating inside and out.



I would do nothing with the coolant pipes as they are working. Better still to work on removing the heat from the cockpit.

Steve

That's not quite correct, pipes are for transference of gas & coolant, they aren't for cooling it.

[will_968]

Evoluzione said:

Steve_D said:

The exhaust and the coolant pipes are doing just what you want....removing heat from the system.

That's not quite correct, pipes are for transference of gas & coolant, they aren't for cooling it.

I get what Steve means and agree with him; they are getting heat out of the engine and dissipating it. My issue is it is being dissipated to me and reducing MY performance. My challenge is that the surfaces in the cabin (firewall and sill and then any metal connected to them through conduction) get so hot that I almost burn myself on them. You can touch the surfaces with a bare hand for 5-10 seconds or so, but after that you have to pull your hand away (not tested them with the IR thermometer). However much I cool the cabin, they are still uncomfortable to sit next to. Hence the plan to add insulation.

[Evoluzione]

will_968 said:

I have a Lotus Motorsport Elise race car and am looking to improve the heat management in the engine bay. Due to the car's longitudinal engine layout, the exhaust exits the engine directly next to the firewall, which I'm sat in front of. Also, the radiator pipes run down the sill right next to me to the radiator in the nose. The cabin gets to about 55-60 degrees during a race (32 degree ambient air temp yesterday - I live/race in China).

I need to cool the cabin down and get the heat out of the car more efficiently. I have bought fibreglass exhaust insulation wrap to wrap the manifold, but want to add some heat insulation mapping against the firewall and also inside the sill before next season. I have seen the gold foil people fit, but am wondering what real word experiences you guys may have with different products? I have about 2-3 m2 of firewall I would need to cover. I am wondering if there are better industrial products I should consider rather than just the options demon tweeks sell. Any info on engineering specs of thermal efficiency vs. weight (and price) would be appreciated.

Separately to insulation in the engine bay, I will also be fitting some more cooling to get more fresh air into the cabin. None of this is about comfort; but instead it's about avoiding heat exhaustion and keeping cool enough to perform optimally during a race. I've considered a cool box, but would prefer to address the problem rather than symptom.

Try DEI: http://www.designengineering.com/catalog/design-en...

Consider sending your exhaust to the US for ceramic coating, it helps.

What diameter are the cooling pipes in the cabin? If they are up to 28mm an easy solution is grey foam household pipe lagging:
https://www.google.co.uk/search?q=pipe+lagging+wra...

Cheap!
Bigger diameters may be available, but harder to find.

[Manicminer]

will_968 said:

I have a Lotus Motorsport Elise race car and am looking to improve the heat management in the engine bay. Due to the car's longitudinal engine layout, the exhaust exits the engine directly next to the firewall, which I'm sat in front of. Also, the radiator pipes run down the sill right next to me to the radiator in the nose. The cabin gets to about 55-60 degrees during a race (32 degree ambient air temp yesterday - I live/race in China).

I need to cool the cabin down and get the heat out of the car more efficiently. I have bought fibreglass exhaust insulation wrap to wrap the manifold, but want to add some heat insulation mapping against the firewall and also inside the sill before next season. I have seen the gold foil people fit, but am wondering what real word experiences you guys may have with different products? I have about 2-3 m2 of firewall I would need to cover. I am wondering if there are better industrial products I should consider rather than just the options demon tweeks sell. Any info on engineering specs of thermal efficiency vs. weight (and price) would be appreciated.

Separately to insulation in the engine bay, I will also be fitting some more cooling to get more fresh air into the cabin. None of this is about comfort; but instead it's about avoiding heat exhaustion and keeping cool enough to perform optimally during a race. I've considered a cool box, but would prefer to address the problem rather than symptom.

Is your engine mounted differently to a normal Elise? I thought they were transverse?

[will_968]

Manicminer said:

Is your engine mounted differently to a normal Elise? I thought they were transverse?

I'm an idiot. You're correct and I did not engage my brain.

[Manicminer]

I was wondering, thought maybe the Motorsport version was different!

Anyway, back to heat management

[anonymous-user]

Hi Will, what restriction you got in the regs on a safety side, my Sylva has the drivers well, lined with silver heat reflector around 9mm thick, as the panels get so Hoy it will burn you through a two layer race suit. Works great, but I have actually used polystyrene sheet be for now when we left the heat sheets at home, cheap but doesn't last long and I don't think it would be accepted by race scrutiners, worth trying as a lining on a test or track day see if it works and then use as a pattern to cut the good stuff

[will_968]

Berw said:

Hi Will, what restriction you got in the regs on a safety side, my Sylva has the drivers well, lined with silver heat reflector around 9mm thick, as the panels get so Hoy it will burn you through a two layer race suit. Works great, but I have actually used polystyrene sheet be for now when we left the heat sheets at home, cheap but doesn't last long and I don't think it would be accepted by race scrutiners, worth trying as a lining on a test or track day see if it works and then use as a pattern to cut the good stuff

I know polystyrene has great thermal vs. weight vs. price properties, but don't think I want any in my car I'm afraid! I'm thinking more along the lines of the silver self adhesive mat and wondering if there's one that's much better than another. Also I suspect the stuff sold as "motor sport" insulation may cost 10x the price of a similar product sold for industry which I may be able to pick up in HK/China.

And well done this weekend. Pleased to see the Sylvia finishing. As you see, I bought a new car rather than getting something built. Made more financial sense.

[Krikkit]

will_968 said:

From my recollection of A-level physics, I think "gold" is the best reflector of heat. I don't think it's the material that matters, but instead the colour (as it is literally reflected off the surface, so don't think the matter is relevant). But this is the crux of the questions really; what's best. I think the silver coloured matting is likely 99% as good as the gold stuff for 1/2 the price. Agreed, it would go inside the engine bay, against the firewall.

Also, my fuel tank sits in the lower portion of the firewall too, between the cabin and engine bay. It is getting very hot at present, which is unlikely to be the best idea from a safety perspective (high concentration of hot vapour build up within the tank) and also hot fuel makes less power than cold.

I'm curious as to the exact specs of different options of the materials though if anyone knows? Demon Tweaks doesn't list proper thermal properties, just terms I see as being marketing such as "reflects 90% of radiated heat".

Gold is used because it has the best reflectivity in the right spectrum (i.e. infra-red) for heat shielding purposes. If you wanted to reflect UV, X-rays, microwaves etc you'd need something different.

Insulation is a different matter, there your best option is vacuum insulation (or, more commonly, air gap) because the conduction, convection and/or radiation through the insulator is disrupted. (The first two in air/vacuum gap.)

Things that look like gold aren't necessarily any good for thermal reflectivity, but they may combine a reflective with an insulating layer to provide a bit of protection...

As for practical advice - I would get the exhaust manifold ceramic coated, then look at foil/insulated sheeting. This looks quite good from demon-tweeks, combining reflective and air-gap. Some pipe insulation on the water hoses would also help, but the exhaust will be giving off most of the heat to be honest.

Edited by Krikkit on Monday 16th September 22:03

[Steve_D]

Evoluzione said:

Steve_D said:

The exhaust and the coolant pipes are doing just what you want....removing heat from the system.

You could wrap the exhaust but better still would be ceramic coating inside and out.

I would do nothing with the coolant pipes as they are working. Better still to work on removing the heat from the cockpit.

Steve

That's not quite correct, pipes are for transference of gas & coolant, they aren't for cooling it.

What I was getting at is that the coolant pipes are dissipating heat along their length and at the moment are an integral part of the system heat loss. If you wrap them the heat will stay in the coolant until it gets to the radiator. My concern is that the rad may then prove to be inadequate in a motorsport application.

Steve

[chuntington101]

Have you considered a cool suit type device? Might help keep you cool. You will still need to work on keeping the heat out though.

[nsa]

Can you scoop some air up from the undertray and direct it across the exhaust and up out of the grill on top of the engine bay?

[chuntington101]

nsa said:

Can you scoop some air up from the undertray and direct it across the exhaust and up out of the grill on top of the engine bay?

Not sure hoe effective the Elise is, but i know the Ultima and Noble guys tend to concentrate on getting the air air before looking at getting additional air in! after all, bigger scoops will just turn the rear clam into a massive parer chute if you cant get the air out.

[sospan]

Shiney Al foil surface reflects the radiant heat and the fibrous backing insulates heat getting past the foil.These materials work up to certain temperatures.Anything higher and they will degrade.
Manifolds need ceramic/wrap
Solid heatshielding aluminium can be formed and bolted to provde shielding as well where there is no opportunity to stick the matting type.
Cold air ducts into the cabin will aid driver cooling as well as window vents.
See suppliers like Merlin Motorsport/Demon Tweekes etc for all types of product.
Possibly, air ducts may be used to flow cool air to under bonnet areas and help flush out hot air.
All the above can be used as needed.