R400 D Very Hot Foot Well

[Chunkadeemus]

Hi, all, having just re-entered the world of Caterham motoring from a previous K-Series 1.8 Superlight to an R400D I have noticed (after 4 hours of driving on Monday) that the pedal box gets VERY hot. I have been told to line the engine bay and possibly exhaust manifold. Has anyone already done this and can recommend which product to use to be most effective and where to apply please? 

[AdamQ]

Caterham do a tailor-made set of heat-shielding for the engine bay and transmission tunnel.  Others have used various DIY insulation products from B&Q or wherever, including foil-backed polystyrene (only 3 or 4 mm thick) and thicker foil-backed bubblewrap-type stuff.  Lining the tunnel is obviously infinitely easier with the gearbox (and therefore engine) removed - I think that was the advantage of the foil-backed polystyrene - it can be applied underneath the carpet (if you have carpet) in the cockpit so no need to remove the engine and gearbox.

Wrapping the primaries seems to be a slightly contentious subject - my simplistic understanding is that wrapping the primaries hinders heat dissipation from the head.  In my (subjective) experience, it made little or no difference to footwell temperature.

One school of thought is that rather than blocking the heat, it needs to be given somewhere to go, i.e. some sort of flow route through the tunnel needs to be created.  To this end, I perforated my handbrake and exhaust gaiters.  The amount of heat coming up through them was significant, but, again, I can't claim it made a massive difference to footwell temperature - though there might have been some slight improvement.  ISTR reading somewhere of somebody who'd opened up the top rear end of the tunnel top and I think that was moderately successful.

I hope that helps a little bit.

[Stridey]

I added the Caterham insulating sheets, adapted to fit my older 7.

I wrapped the exhaust with tape.

Both seemed to help a little.

I also fitted a cutoff to the heater matrix (which some modern Caterhams have as standard), my thinking being to prevent a large heater full of hot water sitting above my legs.

Best mod I’ve seen, and I will do one day, was to fit a pipe to the footwell with a sink plug operated by foot to get air flowing down there. 

[Highside43]

I've been reading / following similar threads about this problem for a short while now, and my own amateur diagnosis is that of getting air movement in the footwell, instead of preventing it coming in in the first place - my philosophy (rightly or wrongly) is the heat still has to dissipate somewhere and will cook the engine bay even more if I preclude it's passage into the cockpit.

For myself, I have been looking at either ductwork from the front or rear of the car, and 12v fans to assist flow?  Something like a centrifugal blower which I can switch off and on.  Just my 2p's worth.

This is for a 1998 S3 with carpets, and I while not unbearable, it is uncomfortable to the extant I shuffle around.

 

 

[Golf Juliet Tango]

The key aspect in my consideration is that the heat has to go somewhere, so I would try to vent it into the open air.
At the same time, as mentioned above, bring fresh air into the cockpit; vortices will extract heat from the footwell.

One very hot day I took the doors off and was very comfortable afterwards.

You remind me that I would like to find a way to lower the under-bonnet temperatures I experience with the 21. It is wonderful when moving but stuck in traffic, even with a RadTec Extreme (which is a HUGE radiator with a 11" fan), the temperature was rising inexorably. Once I got past the jam, a decent speed did disperse the heat after 15-20 minutes. Without the new radiator, I would have had to pull up.

[7 wonders of the world]

Wrap the primaries with exhaust wrap use the 2" wide version overlaping 50 % and secure with stainless lock wire.

You will see a significant reduction in under bonnet temps and heat soak into the cockpit, engine performance will not suffer, in fact it will increase performance as the gas will be hotter in the primaries and therefore its velocity will be higher.

Rather than focussing on how to deal with the the symptons of heat soak look at the cause - no need to faff about with ducts and fans, simply move the heat source outside - simple.

[john milner]

If the car has a heater check that off is really off. The cable is often incorrectly set so the valve is slightly open when in the off position.

[Jonathan Kay]

... in fact it will increase performance as the gas will be hotter in the primaries and therefore its velocity will be higher.

Why is that, please?

Thanks

Jonathan

[Wodybode]

Wrapping the primaries helped but the biggest help was to duct tape the pedal box cover which was letting a furnace draft into the footwell from the engine bay.

[anthonym]

hot gas expands, so in the same space with a hole, it escapes faster due to increased pressure.

like a pan of milk boiling over...

[Jonathan Kay]

like a pan of milk boiling over...

I don't get the analogy... milk boils over because of some pretty complex chemistry. (Which is why water doesn't.)

hot gas expands, so in the same space with a hole, it escapes faster due to increased pressure.

What flow do you have in mind... cylinder to exhaust system or exhaust system to atmosphere? If the former the destination space is hotter in the wrapped state compared to the unwrapped...

Jonathan

[anthonym]

that's the best I can offer. Someone will be along momentarily.

anthony

[Paul Mason]

Or just move oop North where it's always cold.......my feet and legs always get freezing in my "K" (so admittedly I'm not familiar with the "D" issue) so with a cooler ambient, you'd probably be just right. I haven't really helped there have I??

[anthonym]

well now.. maybe you have added a bit :-) I come from ooop North and now live a long way darn sarf (Southern Europe) and ambient temperature does make a difference - so does altitude. My K has the heat issue, but in the passenger side where the primaries are. I've tried many solutions and nothing ever worked, wifey won't do more than 20 minutes before resting her feet on the dash. Then she goes to sleep. (!!)  

The only thing I haven't tried is that expensive "wrap" stuff which reports suggest does work. It's a high tech material, painted, sprayed, applied in some way. I'll see if I can find it again, it's been mentioned in here. (JK might know where it is)

My heat solutions have been for some years now, half doors and a small bottle of water to spray copiously into the footwell. Temperature drops like a stone. And i'm never wet when I exit the car... all that heat - and that's just on my side. Not shorted anything yet. 

edit: ceramic coating, as mentioned in here: https://www.torquecars.com/tuning/exhaust-wraps.php though not sure that's the very one I have in mind. This is interesting in the context of time it takes for the cat to become effective (like at m.o.t .time) "A hot catalyst is more efficient so your catalyst will last longer and work better if you apply a wrap!-"

@Jonathan that page also explains more of the heat tech flows, molecular flows etc

 

Anthony

[Dr Slotter]

Perhaps it is https://www.zircotec.com you were thinking of Anthony?

[anthonym]

yes that looks faintly familiar. 

edit: and here's the thread I think I was recalling:

https://www.lotus7.club/forum/techtalk/csr-heat-problems-solved-zirotech-headers-radiator-problems

and from post #6 in that thread:

The Zircotec coating has made an enormous difference and it's noticed first in the cockpit where, even on a hot day, the rails can still he held by hand.  Very warm, yes, but nowhere near as burning hot as before. 

[john milner]

As the gasses travel down the pipe they cool and contract this causes low pressure which helps to suck the higher pressure hot gasses from the engine/manifold. This in turn gives a bit more space and a semi-vacuum for the next burst of hot gas to go. Wrapping the primaries will keep the gasses at peak temperature for a bit longer so they get a bit further down the pipe before getting to somewhere a lot cooler. The sudden temperature drop in theory should help pull the gasses away from the engine and the first few feet of pipework which should now have a larger volume for the semi-vacuum. Without the wrap the primaries will disapate more heat directly through the metal of the pipework so the gasses will not shift as quickly from this area as the next part of the exhaust system will not have such a large temperature diferential. It is also true that hot moves to cold and a larger differential should enhance this effect. Cooler air in the engine bay should result in slightly cooler higher density air going in the intake which is another performance boost.

Having said that I doubt that wrapping will make a noticeable difference to road or most track cars as the improvement to gas flow must be tiny. After all the exhaust gasses are under pressure anyway so it is hard to see how the flow can be enhanced significantly by managing the heat differently and the cooling effect at the intake must be marginal in a Caterham. I think the performance side of it could be proved by pro race teams and in labs.

My primaries are wrapped, mainly to help protect the alternator and starter but also to make the area a bit safer if I ever have to work on a hot engine. I have read that wrapping can cause manifolds to crack through overheating. I don't know how true this is but it made some sense to me so I left the first few inches unwrapped to get some heat away from the hottest area as quickly as possible by any means.

[chrisbeddoe]

Hi Chuckadeemus, I have a R500D which are know for their heat soak issues and have been battling with it for years now.

Not wanting to change the external appearance of my car with ducting for air into the footwell, or add grills in the side panels to let the hot air in the engine bay out (which i agree would be the most efficient solution), i have updated my car with the following:

• Heat shield on footwell
• ​Zircotech Primaries
• Fix to heater cable 
• Thundersport Transmission Tunnel Heat Insulation

If i am honest the biggest changes came from fixing the heater cable which was always slighly on, and the Thundersport side panels, both of which where really cost effective!

Perhaps this would therefore be a good starting point?

[2004Academy80]

I found that lining the inside of the tunnel help a little.

Fitted this product under new carpet from Caterham (I used the carpet as a template).

https://www.advantage-motorsport.co.uk/thermo-tec-thermo-guard-fr-sound-heat-insulation-mat.html

https://www.advantage-motorsport.co.uk/thermo-tec-heavy-duty-spray-on-adhesive-glue.html

https://caterhamparts.co.uk/carpets/6013-tunnel-carpet-96dd.html

There are also air gaps between panels and small holes in the foot well that allow hot air to flow in.  I'm going to use a foil tape to close these gaps off.  I'm also considering ducting cold air from the front to the footwell.