NACA duct installation advise

[R400svn]

I was wondering how effective these were when used on the 485 as in the picture as i have an SV with RBTB so no filter sticking through the bonnet.  Do you think it would provide much air as an intake with how the air flows down the side of the body 

[ScottR400D]

#24 That would be just as bad. The duct would need the right sort of air flow inside the hood and it isn’t going to happen. And, of course, a proper ND. 

#25 Not going to make a lot of difference to what you’d get with the standard louvres. 

#26 No again. I think it’s been established that the CC ND is more cosmetic than functional. It has severe issues in terms of being a functional ND. If you look at the air box of a 485 you will see why it’s been used but it’s definitely not functioning as a ND. I reckon the best you can say for it there is that it’s not hindering the airflow much.

My SV R400 is RBTB, 220bhp 6 speed and I have no issues with underhood temperatures even on warm track days. I’m guessing that those who do have the high temperature stat fitted. That’s where efforts should be directed IMO. The solution is well known and proven.  

I’m not aware of any issues with it getting enough air either. I like the advantages of no cut out in terms of noise and protection from wet, but guess that if you are suffering from high temps under there, it might affect the engine. 

 

 

[pete_h]

What are people's thoughts on the 620R nosecone? Could the inlet to the intercooler (I guess that is what it is) be used to duct cold air? Just idle thoughts while my hands warm up - it's cold in the garage!

[ScottR400D]

Possibly but it shouldn’t be necessary, IMO. 

I have an 82c stat fitted and the under hood temperature is fine. To me that indicates that there’s plenty of airflow through the engine bay to remove heat and that the issue may be a higher stat keeping the rad, block and everything else 10/15c hotter perhaps. 

How hot do your engines run? 

 

[7 wonders of the world]

The R300 nose has the triangular outlet on the top similar to the CSR which the rad can be ducted thro, as on the race cars.

620r noses are deeper to allow for the oil cooler at the bottom and therefore have a more bulbous appearance

[7 wonders of the world]

Here:

https://caterhamparts.co.uk/nose-cones/5377-nosecone-black-r300-race.html

[L66TEY]

Hi Simon,

Your comments got me thinking. 

Are you (or another L7C member) able to explain why the teardrop shape vent was added both sides circa 2011 - Sigma Supersport looks to be the earliest introduction?

I appreciate the one on the inlet side is for the airbox. 

But the one on the exhaust side is that aesthetic or airflow (cooling) related?

With thanks

Chris

[simon_h]

Not sure if this was aimed at me but this is what I was told. 

It was done for aesthetics primarily, keep both sides looking the same as that was what was wanted. I think they did try to use it to duct cooling air into the pedal box but it wasn’t very successful. That’s the story I was given by someone from the factory so I see no reason to disbelieve it. 

[L66TEY]

Thank you Simon,

The aesthetic reason for the exhaust side vent makes sense, albeit I had hoped that beneficial air flow would have been an additional reason - but alas. 

Have to admit I'm still wondering whether adding a NACA duct (as vents) to each side of the bonnet would be detrimental. 

Acknowledging that the exhaust side NACA Duct would point the opposite direction on the bonnet to the inlet side - and I'd expect this to cause air to flow out of the engine bay  

"Simplify, then add lightness” ????

 

 

[Tazio]

Stop the heat in the first place, as I said before ceramic coat the primaries, and duct the air leaving the rad. All this talking about Naca ducts is just about aesthetics, and nothing about your stated desire to remove heat. It's ok to personalise your car, but that's all its going to do. IMHO, of course.

[ScottR400D]

I’m not sure the aesthetics would be improved to be honest. I’m pretty certain there’s be no cooling effect above that of  simply having a couple of holes in the hood. 

#34, presumably you’ve measured the under hood temperature? What is it? 

[L66TEY]

Reply to #35

Hi Tazio,

The headers are already wrapped - but to be honest the heat is not causing an issue as such, merely my children commenting on it, plus my feet getting a bit toasty on a warm day :D

In the spirit of all "IMHO" are appreciated - I'll totally acknowledge that for me at the moment its about personalisation.
But with the aim of personalisations having positive byproducts, ie above and beyond one's own subjective opinion on aesthetics.

[L66TEY]

Reply to #36

Hi Scott,
Have to admit Ive not measured the under hood temperature, but admittedly the heat is not enough to cause me masses of concern - simply an observation based on getting toasty feet at times.

On the aesthetic element - "beauty is in the eye of the beholder” springs to mind, and as per my comment to Tazio - I like to personalise, but want the personalisation to be reasoned beyond aesthetic.

Which brings me to saying I still believe that the (not technically) NACA ducts by CC would aid airflow performance in and out of the engine bay.

Im not an expert on this topic, hence was intrigued by these videos on the subject matter of NACA ducts being used for air flow in and out;

Backward Naca Ducts

VAPE smoke to test backward NACA duct theory!

NACA Ducts Wind Tunnel Test

[ScottR400D]

The box full of smoke one doesn’t particularly show that it’s any better than having just a hole there. Air flow over that surface would lower the pressure so the smoke would be drawn out in any case. A back to back test would be interesting. 

The NASCAR example shows a raised backward scoop immediately before the reversed ND. Again it would lower pressure and pull air out. I see nothing that suggests that the ND principles are at work in either example.

The last one shows ducts in the right orientation but there’s no evidence to show that they’re acting as NDs, lowering pressure without drag. Again, in that application are they much better than any other type of scoop/opening?

One small point, as far as you can tell all those ducts are fitted flush and have sharp edges, basic principles for a ND. That’s where the CC ones fall at the first hurdle. 

If you like the look of them, give it a go but I wouldn’t be too hopeful, that’s all. I couldn’t do it, they just look completely wrong to me. 

Another interesting discussion might be why footwells get hot. Is pulling hot air from under the hood going to make much difference? That will reduce convected heat but not radiated or conducted. A whole new can of worms! 

[Toughie]

"...the heat is not causing an issue as such, merely my children commenting on it"

Perhaps if you let the children travel in the cockpit, rather than keeping them under the bonnet.

[ScottR400D]

*clap*

[Tazio]

I am with Scott, the radiated and conducted heat are the killers, I run a 2 litre VX, with big primaries, car is stripped out, no tunnel carpets etc. and no heater. In cold weather the hot tunnel panels keep me warm, in the summer when in shorts I have to remember not to rest my knee on the tunnel....ouch, yes I could put heat reflective pads on, but don't consider it bad enough. I suppose with the Duratec an Sigma cars having the primaries on the 'wrong' side, it maybe worse than mine...

 

I personalise mine in different ways, aero, only one seat, race tonneau etc, so no passengers can complain lol.

[ScottR400D]

I’m undecided because I’ve not really considered it in depth but my instinct is that most of the cockpit heat is from the gearbox, bell housing area which is pushed up or at least very close to the insulation/tunnel. 

My R400 runs nicely cool, typically around 80c and the under hood space never seems particularly hot, even in track days. But the tunnel sides do get quite hot, you wouldn’t want to rest a bare leg against them! 

[7 wonders of the world]

Duratec with 2" wrapped thro the bonnet primaries, no heat problem- even when exercising all the ponies, I keep the carpet on the tunnel as SWMBO objects to 'grey' stains on her trousers.....   

[K7 VCT]

Aren't toasted feet just part of 7 life, my old Kseries toasted the passengers, my sigma toasts mine especially in southern Europe in summer.

No worries or problems here

[L66TEY]

Thought I'd reignite this thread as I'm soon to cut a hole in my bonnet. 

My plan has changed to using the NACA duct as a footwell cooling vent. 

Am fine tuning it's position, but give or take it'll be as per these pics. 


 

[L66TEY]

Before I cut a hole in the bonnet, please could I ask someone to measure and advise the distance between the edge of the bonnet and the tear drop breather hole Caterham do as standard on present models, ie blue line below;

With thanks

Chris

Edit: Dimensions established, thanks to "HandWheels"
185mm and 92mm

[BenF]

Surely the NACA duct is facing in the wrong direction compared to the airflow?

Unless you just want cooling when driving in reverse?

[L66TEY]

Hi Ben,

This video is the evidence I have that it will work in reverse, hence I feel comfortable (sort of);

Pushing the Envelope - Backward Naca Ducts

To clarify - Im looking to suck air out of the footwell.

Chris

[BenF]

Hi Chris,

I've never seen a NACA duct installed that way around before, but fair enough.  Is the aim then to not have the cover on the top of the pedalbox?

I remember discussing this with a colleague when I had my 7 about 10 years ago.  From his background in making racing cars get reliably to the finish, he thought the best solution to heat problems was to just gold foil all areas adjacent to the engine bay.  However I did not have gold foil to hand and anyway it would have meant disassembling the car.

BTW, I note you've got a very nice solution for stopping brake fluid drips from your reservoir.

Edit - I now see there's a separate thread for this topic as well, sorry only saw that now!